Publications by year
2023
McCabe K (2023). Climate change impacts on Mytilus spp. and Nucella lapillus: co-occurring species of different biogeographic origins.
Abstract:
Climate change impacts on Mytilus spp. and Nucella lapillus: co-occurring species of different biogeographic origins.
The intertidal zone is a thermally complex and physiologically stressful environment. Mytilid mussels are ecologically and commercially important species, however, many intertidal populations live close to their upper thermal limits. The observed rise in seawater and air temperature and the increase in frequency and duration of heatwave events, as a result of climate change, is leading to mass mortality of intertidal mussel populations globally. Changes to climate are being observed in the UK, data analysed here found that the sea surface temperature during winter of 2020 was up to 2.9 °C warmer compared to the long term mean, between 1980 and 1999. Therefore, this study examines the impacts of climate change on the physiology and biogeography of UK Mytilus spp. and considers the indirect effects resulting from the response of their common predator, Nucella lapillus.
Analysis undertaken here on the Marine Biological Association’s Marine Biodiversity and Climate Change project reveals changes in the abundance of 20 populations of Mytilus spp. and 17 populations of Nucella lapillus has been observed around the UK coastline in the last two decades. The majority of the changes observed are declines in species abundance and were mostly located in the south west of England and northern Wales.
Correlative analysis with monthly mean seawater and air temperature was performed but did not reveal significant causal links between changes in climate with the observed abundance change. Therefore, biomimetic body temperature data was analysed to examine the intricate and individual interaction between organisms and their environment. When exposed to the same seawater and air temperatures UK mussels populations in the high shore experience body temperatures up to 12 °C warmer than mussels in the low shore and mussels attached to open rock surfaces experience body temperatures up to 19 °C warmer than those attached in under-hang, shaded, locations. Additionally, the analysis has shown that UK intertidal mussels attached to open rock surfaces are routinely experiencing temperatures above their thermally stressful threshold, defined in this study as 29 °C, for up to 9 hours in one day. However, further monitoring of intertidal populations and research distinguishing whether acute extreme temperature exposure or chronic low levels of thermal stress is needed to determine what is driving these population level effects observed in UK shores.
Analysis on data from observational fieldwork undertaken at 4 intertidal zones in the south-west of England demonstrates that the abundance and morphology of Nucella lapillus differs on a localised basis, influenced by local environmental variables and species composition.
This thesis demonstrates the complexity of the interactions between species and their environment in the intertidal zone and highlights to importance for future research to incorporate body temperature measurements in their analysis and to consider the indirect effects of species interactions on the physiological and biogeographic response of intertidal mytilid mussels to climate change.
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Alava JJ, McMullen K, Jones J, Barragán-Paladines MJ, Hobbs C, Tirapé A, Calle P, Alarcón D, Muñoz-Pérez JP, Muñoz-Abril L, et al (2023). Multiple anthropogenic stressors in the Galápagos Islands' complex social-ecological system: Interactions of marine pollution, fishing pressure, and climate change with management recommendations.
Integr Environ Assess Manag,
19(4), 870-895.
Abstract:
Multiple anthropogenic stressors in the Galápagos Islands' complex social-ecological system: Interactions of marine pollution, fishing pressure, and climate change with management recommendations.
For decades, multiple anthropogenic stressors have threatened the Galápagos Islands. Widespread marine pollution such as oil spills, persistent organic pollutants, metals, and ocean plastic pollution has been linked to concerning changes in the ecophysiology and health of Galápagos species. Simultaneously, illegal, unreported, and unregulated fishing are reshaping the composition and structure of endemic and native Galápagos pelagic communities. In this novel review, we discuss the impact of anthropogenic pollutants and their associated ecotoxicological implications for Galápagos species in the face of climate change stressors. We emphasize the importance of considering fishing pressure and marine pollution, in combination with climate-change impacts, when assessing the evolutionary fitness of species inhabiting the Galápagos. For example, the survival of endemic marine iguanas has been negatively affected by organic hydrocarbons introduced via oil spills, and endangered Galápagos sea lions exhibit detectable concentrations of DDT, triggering potential feminization effects and compromising the species' survival. During periods of ocean warming (El Niño events) when endemic species undergo nutritional stress, climate change may increase the vulnerability of these species to the impacts of pollutants, resulting in the species reaching its population tipping point. Marine plastics are emerging as a deleterious and widespread threat to endemic species. The Galápagos is treasured for its historical significance and its unparalleled living laboratory and display of evolutionary processes; however, this unique and iconic paradise will remain in jeopardy until multidisciplinary and comprehensive preventative management plans are put in place to mitigate and eliminate the effects of anthropogenic stressors facing the islands today. We present a critical analysis and synthesis of anthropogenic stressors with some progress from local and international institutional efforts and call to action more precautionary measures along with new management philosophies focused on understanding the processes of change through research to champion the conservation of the Galápagos. Integr Environ Assess Manag 2023;19:870-895. © 2022 SETAC.
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Lewis C (2023). Plastic and the Ocean. In (Ed) The Ocean and Us, Springer Nature, 113-121.
Rowlands E, Galloway T, Cole M, Lewis C, Hacker C, Peck VL, Thorpe S, Blackbird S, Wolff GA, Manno C, et al (2023). Scoping intergenerational effects of nanoplastic on the lipid reserves of Antarctic krill embryos.
Aquat Toxicol,
261Abstract:
Scoping intergenerational effects of nanoplastic on the lipid reserves of Antarctic krill embryos.
Antarctic krill (Euphausia superba) plays a central role in the Antarctic marine food web and biogeochemical cycles and has been identified as a species that is potentially vulnerable to plastic pollution. While plastic pollution has been acknowledged as a potential threat to Southern Ocean marine ecosystems, the effect of nanoplastics (
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Porter A, Barber D, Hobbs C, Love J, Power AL, Bakir A, Galloway TS, Lewis C (2023). Uptake of microplastics by marine worms depends on feeding mode and particle shape but not exposure time.
Sci Total Environ,
857(Pt 1).
Abstract:
Uptake of microplastics by marine worms depends on feeding mode and particle shape but not exposure time.
The uptake of microplastics into marine species has been widely documented across trophic levels. Feeding mode is suggested as playing an important role in determining different contamination loads across species, but this theory is poorly supported with empirical evidence. Here we use the two distinct feeding modes of the benthic polychaete, Hediste diversicolor (The Harbour Ragworm) (O.F. Müller, 1776), to test the hypothesis that filter feeding will lead to a greater uptake of microplastic particles than deposit feeding. Worms were exposed to both polyamide microfragments and microfibres in either water (as filter feeders) or sediment (as deposit feeders) for 1 week. No effect of exposure time was found between 1 day and 1 week (p > 0.19) but feeding mode was found to significantly affect the number of microfibres recovered from each worm (p < 0.001). When exposed to microfibers, filter feeding worms took up ≈15,000 % more fibres than deposit feeding worms (p < 0.001), whereas when feeding on microfragments there was no difference between feeding modes. Our data demonstrate that both feeding mode and particle characteristics significantly influence the uptake of microplastics by H. diversicolor. Using imaging flow cytometry, filter feeders were found to take up a broader size range of particles, with significantly more smaller and larger particles than deposit feeders (p < 0.05), commensurate with the range of plastics isolated from the guts of ragworms recovered from the environment. These results demonstrate that biological traits are useful in understanding the uptake of plastics into marine worms and warrant further exploration as a tool for understanding the bioaccessibility of plastics to marine organisms.
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2022
Colvin K (2022). A rapid assessment toolkit to monitor the ecotoxicological impact of oil spills.
Abstract:
A rapid assessment toolkit to monitor the ecotoxicological impact of oil spills
Crude oils are natural substances derived from the degraded remains of organic matter and are typically complex and highly variable in nature. Toxicological assessment following an oil spill is challenging not only due to the variable chemical characteristics as a slick spreads and weathers, but also to the vulnerability of the affected ecosystem. Rapid decisions must be made to determine how to respond to the spill to protect the environment. Hence, a rapid assessment toolkit specific to the ecotoxicological assessment of crude oil and its components has been recommended. This thesis aimed to develop such a rapid assessment toolkit based on state of the art, environmentally relevant, diagnostic chemical and biological tools. Challenges to be addressed included the choice of test species, the dosing method for ensuring a consistent exposure concentration and the extrapolation of the data to predict species sensitivity and ecosystem relevance using computational modelling tools. To determine the applicability and comparative sensitivity of cyst-based zooplankton survival assays (using brine shrimp Artemia franciscana and marine rotifer Brachionus plicatilis) a novel, miniature passive dosing method was developed. Using three exemplar aromatic hydrocarbons, brine shrimp and rotifer were found to be within 51- 75% and 76–100% of most resistant species respectively when compared to 79 other species. When these species sensitivities were extrapolated using computational modelling (PETROTOX) to predict the relative toxicity of crude oil, they provided a conservative estimate when compared to empirical data derived from laboratory tests. In addition, comparison of novel, passively dosed water accommodated fraction preparation methods and traditional low energy, and chemically enhanced, water accommodated fraction methods showed both methods to be applicable to laboratory testing. Finally, investigation of cardiotoxicity as a non-invasive, sublethal biomarker was investigated as an endpoint potentially more sensitive than the whole organism cyst based tests. The sensitivity of three life stages (pediveliger eyed larvae, spat and adults) of Pacific oyster (Crassostrea gigas) was assessed using a novel combination of passive dosing and non-invasive video graphic and infrared methods. Illustrating both the utility of the methods and relative insensitivity of the organisms to phenanthrene as a model compound. Owing to the lack of sensitivity observed in these studies, it was not possible to recommend the biological test methods used above as a complete rapid assessment toolkit. However, the combination of chemical and computational tools showed effectiveness in reaching and maintaining exposure concentrations and providing a conservative estimate of toxicity. A synthesis of findings concludes with suggestions for future directions for the development of oil spill monitoring tools; the consideration of multi-stressor impacts; recommendations of a screening matrix for the future identification of sensitive bioindicators; and alternative endpoints of interest (e.g. indicators of membrane damage, the aryl hydrocarbon receptor and indicators of oxidative stress).
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Lewis C, Jones JS, Guézou A, Medor S, Nickson C, Savage G, Alarcón-Ruales D, Galloway TS, Muñoz-Pérez JP, Nelms SE, et al (2022). Microplastic Distribution and Composition on Two Galápagos Island Beaches, Ecuador: a Spatiotemporal Assessment Using Citizen Science Derived Data.
Jones JS, Guézou A, Medor S, Nickson C, Savage G, Alarcón-Ruales D, Galloway TS, Muñoz-Pérez JP, Nelms SE, Porter A, et al (2022). Microplastic distribution and composition on two Galápagos island beaches, Ecuador: Verifying the use of citizen science derived data in long-term monitoring. Environmental Pollution, 311, 120011-120011.
Hobbs C (2022). Movement of plastic debris through the benthic marine ecosystem and its interactions with benthic organisms.
Abstract:
Movement of plastic debris through the benthic marine ecosystem and its interactions with benthic organisms
Plastics, including those of buoyant polymers are increasingly found in high concentrations in benthic sediments where they have the potential to be ingested and interact with a diverse range of benthic marine species. This thesis combines field work and laboratory mesocosm experiments to look at the presence and characteristics of synthetic particles found in situ within estuarine benthic habitats, and then investigates experimentally how interactions with benthic species might influence the fragmentation and movement of plastics within a test benthic ecosystem.
Firstly, a field study was undertaken to determine the abundance and particle characteristics of synthetic particles in benthic sediment and within natural populations of the benthic-dwelling polychaete, Hediste diversicolor. Sediment (10 samples per site) and worm (30 individuals per site) were collected from three locations of differing anthropogenic influence across South Devon, UK. Samples were analysed for synthetic particle content using density separation for sediments or tissue digestion, followed by particle identification using Fourier-transform infrared spectroscopy (FTIR). All sediment samples analysed contained synthetic (i.e. plastic and/or modified cellulose) particles, but with significantly higher abundance in sediment from the Plym estuary (mean 116 synthetic particles kg-1 +/- 18.09 SE) compared to Kingsbridge (mean 62 synthetic particles kg-1 +/- 13.55 SE; P < 0.001). of the H. diversicolor sampled, 48% of the worms contained synthetic particles with a mean of 0.73 synthetic particles per worm +/- 0.15 SE and no difference in particles per worm by site (P = 0.30). The dominant polymer type found within the sediment was polypropylene, accounting for 30 % of the total synthetic particles across the three sites. Semi-synthetic cellulose fibres and polystyrene particles were the most prevalent particle types found within H. diversicolor.
The potential role of benthic invertebrates in the fragmentation and movement of plastic litter within a test benthic ecosystem was investigated via a mesocosm study. Biofouled polyethylene (PE) crates (half a crate per tank) were used as the test macroplastic. Mesocosms comprising three benthic species with different functional roles; the purple sea urchin Paracentrotus lividus, the blue mussel Mytilus edulis and the sediment-dwelling polychaete, Alitta virens were maintained for 13 days under four treatment scenarios (3 tanks per treatment); 1) a no plastic control comprising all species and macroalgae but no added crate, 2) plastic crate, all organisms but macroalgae absent, 3) plastic crate, all organisms and macroalgae present and 4) plastic crate, urchins and ragworms (no mussels) with macroalgae present. In every tank containing a plastic crate and urchins, small plastic fragments were recovered from the water and from the sediment. PE fragments were present within 100 % of urchins (6.3 +/- 1.6 (SE) particles per individual), 62 % of mussels (3.5 +/- 0.6 (SE) particles per individual) and 65 % of ragworms (2.2 +/- 0.5 (SE) particles per individual), confirming urchins are effective at generating plastic fragments (size range 10.2 μm to 5816.6 μm) that are subsequently bioavailable for uptake by benthic-dwelling organisms. In this experimental system, a combination of urchin food availability and mussel presence acted to increase the bioavailability and uptake of plastic fragments into a sediment-dwelling polychaete with a ~ four-fold increase in PE fragments found within ragworms when both macroalgae and mussels were present (3.6 +/- 0.5 (SE) particles per individual) compared to mussel absence (0.9 +/- 0.2 (SE) particles per individual), and a ~ 1.6-fold increase compared to macroalgae absence (2.2 +/- 0.7 (SE) particles per individual).
Overall, this work advances the understanding of how organisms alter the distribution, accumulation and fate of microplastic in the benthic ecosystem while also highlighting the prevalence of synthetic particle contamination in benthic sediments.
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Bowley J, Baker-Austin C, Michell S, Lewis C (2022). Pathogens transported by plastic debris: does this vector pose a risk to aquatic organisms?.
Emerging Topics in Life Sciences,
6(4), 349-358.
Abstract:
Pathogens transported by plastic debris: does this vector pose a risk to aquatic organisms?
Microplastics are small (&lt;5
mm) plastic particles of varying shapes and polymer types that are now widespread global contaminants of marine and freshwater ecosystems. Various estimates suggest that several trillions of microplastic particles are present in our global oceanic system, and that these are readily ingested by a wide range of marine and freshwater species across feeding modes and ecological niches. Here, we present some of the key and pressing issues associated with these globally important contaminants from a microbiological perspective. We discuss the potential mechanisms of pathogen attachment to plastic surfaces. We then describe the ability of pathogens (both human and animal) to form biofilms on microplastics, as well as dispersal of these bacteria, which might lead to their uptake into aquatic species ingesting microplastic particles. Finally, we discuss the role of a changing oceanic system on the potential of microplastic-associated pathogens to cause various disease outcomes using numerous case studies. We set out some key and imperative research questions regarding this globally important issue and present a methodological framework to study how and why plastic-associated pathogens should be addressed.
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Rowlands E, Galloway TS, Cole M, Lewis C, Peck VL, Thorpe S, Blackbird S, Wolff GA, Manno C (2022). Scoping Intergenerational Effects of Nanoplastic on the Lipid Reserves of Antarctic Krill Embryos.
2021
Wilson Mcneal A (2021). Changing carbonate chemistry alters the toxicity of contaminants to marine invertebrates.
Abstract:
Changing carbonate chemistry alters the toxicity of contaminants to marine invertebrates
The oceans are changing, globally and locally. Two stressors already impacting marine life on both scales are changing carbonate chemistry, whether induced by the worldwide increases in atmospheric concentrations of carbon dioxide termed ocean acidification (OA) or by small-scale spatiotemporal fluctuations in coastal waters; and contamination, caused by the countless anthropogenically-produced chemicals that enter the marine environment each year. The potential for these two stressors to interact, causing novel toxicity outcomes for marine life, has only been acknowledged in recent years. In this thesis, I investigate interactions between carbonate chemistry alterations and contaminants to explore whether certain aspects of animal physiology and contaminant chemistry consistently determine outcomes for marine invertebrates.
Through a review of the state of knowledge on the biological impacts of these interactions, I highlighted key knowledge gaps. Whilst established models exist for the effect of freshwater pH on the toxicity of contaminants, this has rarely been investigated in a marine context. This was particularly significant for ionisable organic contaminants: in general, acidic compounds increase in toxicity within the OA-relevant pH range, whilst basic compounds decrease in toxicity. Additionally, there was strong potential for the fluctuations in carbonate chemistry which naturally occur in coastal habitats to alter the toxicity of pH-sensitive marine contaminants.
To address these knowledge gaps, I first exposed two marine invertebrates, the common mussel Mytilus edulis and the king ragworm Alitta virens, to the pH-sensitive contaminant copper under a fluctuating pCO2/pH regime representative of coastal conditions and which was expected to increase its toxicity. Fluctuating pCO2/pH induced an extracellular acidosis of 0.2 units for mussels, likely contributing to the twofold increases in oxidative stress and DNA damage induced by copper compared to in non-fluctuating conditions. For A. virens, its ability to maintain acid-base homeostasis in fluctuating conditions via accumulation of bicarbonate resulted in an extracellular alkalosis of 0.3 units. This mitigated copper toxicity which resulted in reduced DNA damage and oxidative stress compared to exposure to copper in non-fluctuating pCO2/pH conditions.
Secondly, I assessed reproductive parameters in early life stages of the painted urchin Lytechinus pictus and the lugworm Arenicola marina when exposed to two ionisable pharmaceuticals in OA conditions: tolcapone, which behaves as an acid and hence may increase in toxicity, and fluoxetine, which behaves as a base and hence may decrease in toxicity. In OA treatments both with and without pharmaceuticals, measurements of sperm swimming speed (curvilinear velocity, straight-line velocity and average path velocity) increased twofold for urchins, but decreased by half for lugworms, compared to ambient pH conditions. Pharmaceuticals altered the magnitude of the OA effects but not consistently: both pharmaceuticals decreased velocity measurements for lugworms in OA conditions, whilst tolcapone increased and fluoxetine decreased these effects for urchins. Additionally, these swimming parameters were differentially linked to fertilisation success for each species, resulting in differing outcomes which appeared to be driven predominantly by the physiology and reproductive ecology of each species in response to OA.
Finally, I exposed adult common mussels, Mytilus edulis, and purple urchins, Paracentrotus lividus, to these same pharmaceuticals in OA conditions, hypothesising that differences in species acid-base physiology would impact toxicity changes alongside the theorised ionisation changes. OA increased the effect of tolcapone on oxidative stress by 50 % in urchins, but not mussels. OA also increased the effect of fluoxetine on urchin antioxidant activity by 183 % and decreased ammonia excretion rate by 57 %; however, mussel antioxidant activity decreased by 73 % whilst oxygen uptake increased by 81 %. Importantly, the direction of OA-induced effects on these responses did not correspond to theorised changes to pharmaceutical ionisation, and the magnitude of effects did not correspond to differences in acid-base physiology.
Taken together, my findings demonstrate the importance of differences between species and life stages in determining their responses to the combination of altered carbonate chemistry and contaminants, and that the final toxicity outcomes for marine invertebrates cannot be estimated based solely on theorised chemical changes to contaminants in OA conditions. Whilst our knowledge of contaminants and changing carbonate chemistry as single stressors is increasing, marine organisms will experience both concurrently and this work contributes to our understanding of how these global and local stressors will interact in a future ocean.
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Colvin KA, Parkerton TF, Redman AD, Lewis C, Galloway TS (2021). Miniaturised marine tests as indicators of aromatic hydrocarbon toxicity: Potential applicability to oil spill assessment.
Mar Pollut Bull,
165Abstract:
Miniaturised marine tests as indicators of aromatic hydrocarbon toxicity: Potential applicability to oil spill assessment.
Assessing oil spill toxicity in real time is challenging due to dynamic field exposures and lack of simple, rapid, and sensitive tests. We investigated the relative sensitivity of two commercially available marine toxicity tests to aromatic hydrocarbons using the target lipid model (TLM). State of the art passive dosing in sealed vials was used to assess the sensitivity of brine shrimp (Artemia franciscana) and rotifer (Brachionus plicatilis). Organisms were exposed to toluene, 1-methylnaphthalene and phenanthrene for 24 h. Toxicity results were analysed using the TLM to estimate the critical target lipid body burden and support comparison to empirical data for 79 other aquatic organisms. Our findings demonstrate the applicability of passive dosing to test small volumes and indicate that the two rapid cyst-based assays are insensitive in detecting hydrocarbon exposures compared to other aquatic species. Our results highlight the limitations of applying these tests for oil pollution monitoring and decision-making.
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Bowley J, Baker-Austin C, Porter A, Hartnell R, Lewis C (2021). Oceanic Hitchhikers – Assessing Pathogen Risks from Marine Microplastic. Trends in Microbiology, 29(2), 107-116.
Nascimento-Schulze JC, Bean TP, Houston RD, Santos EM, Sanders MB, Lewis C, Ellis RP (2021). Optimizing hatchery practices for genetic improvement of marine bivalves.
Reviews in Aquaculture,
13(4), 2289-2304.
Abstract:
Optimizing hatchery practices for genetic improvement of marine bivalves
Aquaculture currently accounts for approximately half of all seafood produced and is the fastest growing farmed food sector globally. Marine bivalve aquaculture, the farming of oysters, mussels and clams, represents a highly sustainable component of this industry and has major potential for global expansion via increased efficiency, and numbers of, production systems. Artificial spat propagation (i.e. settled juveniles) in hatcheries and selective breeding have the potential to offer rapid and widespread gains for molluscan aquaculture industry. However, bivalves have unique life-histories, genetic and genomic characteristics, which present significant challenges to achieving such genetic improvement. Selection pressures experienced by bivalve larvae and spat in the wild contribute to drive population structure and animal fitness. Similarly, domestication selection is likely to act on hatchery-produced spat, the full implications of which have not been fully explored. In this review, we outline the key features of these taxa and production practices applied in bivalve aquaculture, which have the potential to affect the genetic and phenotypic variability of hatchery-propagated stock. Alongside, we compare artificial and natural processes experienced by bivalves to investigate the possible consequences of hatchery propagation on stock production. In addition, we identify key areas of investigation that need to be prioritized to continue to the advancement of bivalve genetic improvement via selective breeding. The growing accessibility of next-generation sequencing technology and high-powered computational capabilities facilitate the implementation of novel genomic tools in breeding programmes of aquatic species. These emerging techniques represent an exciting opportunity for sustainably expanding the bivalve aquaculture sector.
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Jones JS, Porter A, Muñoz-Pérez JP, Alarcón-Ruales D, Galloway TS, Godley BJ, Santillo D, Vagg J, Lewis C (2021). Plastic contamination of a Galapagos Island (Ecuador) and the relative risks to native marine species.
Science of the Total Environment,
789Abstract:
Plastic contamination of a Galapagos Island (Ecuador) and the relative risks to native marine species
Ecuador's Galapagos Islands and their unique biodiversity are a global conservation priority. We explored the presence, composition and environmental drivers of plastic contamination across the marine ecosystem at an island scale, investigated uptake in marine invertebrates and designed a systematic priority scoring analysis to identify the most vulnerable vertebrate species. Beach contamination varied by site (macroplastic 0–0.66 items·m−2, microplastics 0–448.8 particles·m−2 or 0–74.6 particles·kg−1), with high plastic accumulation on east-facing beaches that are influenced by the Humboldt Current. Local littering and waste management leakages accounted for just 2% of macroplastic. Microplastics (including anthropogenic cellulosics) were ubiquitous but in low concentrations in benthic sediments (6.7–86.7 particles·kg−1) and surface seawater (0.04–0.89 particles·m−3), with elevated concentrations in the harbour suggesting some local input. Microplastics were present in all seven marine invertebrate species examined, found in 52% of individuals (n = 123) confirming uptake of microplastics in the Galapagos marine food web. Priority scoring analysis combining species distribution information, IUCN Red List conservation status and literature evidence of harm from entanglement and ingestion of plastics in similar species identified 27 marine vertebrates in need of urgent, targeted monitoring and mitigation including pinnipeds, seabirds, turtles and sharks.
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Rowlands E, Galloway T, Cole M, Lewis C, Peck V, Thorpe S, Manno C (2021). The Effects of Combined Ocean Acidification and Nanoplastic Exposures on the Embryonic Development of Antarctic Krill.
FRONTIERS IN MARINE SCIENCE,
8 Author URL.
2020
Lindeque PK, Cole M, Coppock RL, Lewis CN, Miller RZ, Watts AJR, Wilson-McNeal A, Wright SL, Galloway TS (2020). Are we underestimating microplastic abundance in the marine environment? a comparison of microplastic capture with nets of different mesh-size.
Environmental Pollution,
265Abstract:
Are we underestimating microplastic abundance in the marine environment? a comparison of microplastic capture with nets of different mesh-size
Microplastic debris is ubiquitous and yet sampling, classifying and enumerating this prolific pollutant in marine waters has proven challenging. Typically, waterborne microplastic sampling is undertaken using nets with a 333 μm mesh, which cannot account for smaller debris. In this study, we provide an estimate of the extent to which microplastic concentrations are underestimated with traditional sampling. Our efforts focus on coastal waters, where microplastics are predicted to have the greatest influence on marine life, on both sides of the North Atlantic Ocean. Microplastic debris was collected via surface trawls using 100, 333 and 500 μm nets. Our findings show that sampling using nets with a 100 μm mesh resulted in the collection of 2.5-fold and 10-fold greater microplastic concentrations compared with using 333 and 500 μm meshes respectively (P < 0.01). Based on the relationship between microplastic concentrations identified and extrapolation of our data using a power law, we estimate that microplastic concentrations could exceed 3700 microplastics m−3 if a net with a 1 μm mesh size is used. We further identified that use of finer nets resulted in the collection of significantly thinner and shorter microplastic fibres (P < 0.05). These results elucidate that estimates of marine microplastic concentrations could currently be underestimated.
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Colvin KA, Lewis C, Galloway TS (2020). Current issues confounding the rapid toxicological assessment of oil spills.
Chemosphere,
245Abstract:
Current issues confounding the rapid toxicological assessment of oil spills.
Oil spills of varying magnitude occur every year, each presenting a unique challenge to the local ecosystem. The complex, changeable nature of oil makes standardised risk assessment difficult. Our review of the state of science regarding oil's unique complexity; biological impact of oil spills and use of rapid assessment tools, including commercial toxicity kits and bioassays, allows us to explore the current issues preventing effective, rapid risk assessment of oils. We found that despite the advantages to monitoring programmes of using well validated standardised tests, which investigate impacts across trophic levels at environmentally relevant concentrations, only a small percentage of the available tests are specialised for use within the marine environment, or validated for the assessment of crude oil toxicity. We discuss the use of rapid tests at low trophic levels in addition to relevant sublethal toxicity assays to allow the characterisation of oil, dispersant and oil and dispersant mixture toxicity. We identify novel, passive dosing techniques as a practical and reproducible means of improving the accuracy and maintenance of nominal concentrations. Future work should explore the possibility of linking this tiered testing system with ecosystem models to allow the prediction and risk assessment of the entire ecosystem.
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Wilson-McNeal A, Hird C, Hobbs C, Nielson C, Smith KE, Wilson RW, Lewis C (2020). Fluctuating seawater pCO2/pH induces opposing interactions with copper toxicity for two intertidal invertebrates.
Sci Total Environ,
748Abstract:
Fluctuating seawater pCO2/pH induces opposing interactions with copper toxicity for two intertidal invertebrates.
Global ocean pCO2 is increasing as a result of anthropogenic CO2 emissions, driving a decline in seawater pH. However, coastal waters already undergo fluctuations in pCO2/pH conditions over far shorter timescales, with values regularly exceeding those predicted for the open ocean by the year 2100. The speciation of copper, and therefore its potential toxicity, is affected by changing seawater pH, yet little is known concerning how present-day natural fluctuations in seawater pH affect copper toxicity to marine biota. Here, we test the hypothesis that a fluctuating seawater pCO2/pH regime will alter the responses of the mussel Mytilus edulis and the ragworm Alitta virens to sub-lethal copper, compared to a static seawater pCO2/pH scenario. Mussels and worms were exposed to 0.1 and 0.25 μM copper respectively, concentrations determined to produce comparable toxicity responses in these species, for two weeks under a fluctuating 12-hour pCO2/pH cycle (pH 8.14-7.53, pCO2 445-1747 μatm) or a static pH 8.14 (pCO2 432 μatm) treatment. Mussels underwent a haemolymph acidosis of 0.1-0.2 pH units in the fluctuating treatments, alongside two-fold increases in the superoxide dismutase activity and DNA damage induced by copper, compared to those induced by copper under static pH conditions. Conversely, ragworms experienced an alkalosis of 0.3 pH units under fluctuating pH/pCO2, driven by a two-fold increase in coelomic fluid bicarbonate. This mitigated the copper-induced oxidative stress to slightly reduce both antioxidant activity and DNA damage, relative to the static pH + copper treatment. These opposing responses suggest that differences in species acid-base physiology were more important in determining toxicity responses than the pH-induced speciation change. With variability in seawater chemistry predicted to increase as climate change progresses, understanding how fluctuating conditions interact with the toxicity of pH-sensitive contaminants will become more crucial in predicting their risk to coastal biota.
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Scott N (2020). Investigating the environmental partitioning of microplastics in two contrasting marine ecosystems.
Abstract:
Investigating the environmental partitioning of microplastics in two contrasting marine ecosystems.
Plastic is a pervasive pollutant of marine ecosystems globally, found throughout the water column, in sediments, and biota. Small plastic particles, or microplastics, are numerous and readily ingested by marine organisms. However, these plastic particles are distributed unevenly throughout marine environments and the physical properties of the particle can influence how they are transported, and ultimately where they are found. In this thesis I review the current literature to explain how plastic particles behave in the marine environment according to their physical attributes, and how this might influence the number and types of plastic to which organisms are exposed. I then explore two cases of plastic partitioning across compartments of an Arctic fjord (Kongsfjorden, Svalbard), and in rocky shore habitats of Devon and Cornwall, UK via an extensive field sampling campaign.
Using a boat based sampling programme, seawater microplastic contamination for two different water bodies, local Arctic and Atlantic, within an Arctic fjord was assessed via sampling at two different depths of the water column. Salinity-temperature-depth (CTD) profiles were acquired, and microplastic particles collected from sea surface and 160 m depth at three different locations in Kongsfjorden, Svalbard, using surface plankton net trawls and niskin bottles. The isolated microplastic particles were counted and analysed by FTIR spectroscopy. The parameters defining Atlantic water were not detected, however the mean microplastic concentration in deep waters (2.9 (± 1.7) x 104 particles m-3) was significantly greater than surface waters (112 ± 53 particles m-3). The most common polymers identified were polyester (18%), ethylene-propylene copolymer (11.8 %), and polyacrylic acid and polyethylene (10 % each). Particles at the surface were significantly larger than particles at 160 m, fragments were on average 5430 µm larger, and fibres 850 µm longer. Significantly greater proportions of white fragments and blue fibres were found at the surface compared to 160 m, and black and blue fragments at 160 m compared to surface water.
The environmental partitioning of macro-, meso- and microplastics across surface sediment, seawater, and mussels Mytilus edulis were then analysed from 9 intertidal locations in the South West of England. Micro- and mesoplastic-like particles were found in 88.5% of the 269 mussels sampled, ranging from 1.43 to 7.64 items per mussel. of these plastic particles, 70.9% were identified as semi-synthetic (mainly modified-cellulose). Mussel microplastic abundance, but not polymer type, was correlated with that of their surrounding sediment, but not with sea-surface microplastic concentration or mussel size. Significant differences were present in the relative abundance of polymers and particle sizes between seawater, sediment, and mussels, with mussels containing a greater abundance of cellulose fibre but less polyvinyl polymer. The particle characteristics of mussel microplastic contamination are not directly proportional to that of the microplastics in their surrounding environment.
The data from these two contrasting ecosystems both add to the growing evidence that microplastics are not just a sea surface problem and partition across marine ecosystems with particle characteristics such as polymer type (density), shape, and size all likely playing a role. Although uptake of particles by organisms may be subject to processes of selection, ultimately, the distribution of plastic particles governs the particles to which organisms are exposed and might ingest. Therefore, understanding particle characteristics and dynamics will play a role in determining the biological consequences of microplastic pollution in marine biota.
Abstract.
Pereira JM, Rodríguez Y, Blasco-Monleon S, Porter A, Lewis C, Pham CK (2020). Microplastic in the stomachs of open-ocean and deep-sea fishes of the North-East Atlantic.
Environmental Pollution,
265Abstract:
Microplastic in the stomachs of open-ocean and deep-sea fishes of the North-East Atlantic
The presence of microplastic in marine fishes has been well documented but few studies have directly examined differences between fishes occupying contrasting environmental compartments. In the present study, we investigated the gut contents of 390 fishes belonging to three pelagic (blue jack mackerel, chub mackerel, skipjack tuna) and two deep-sea species (blackbelly rosefish, blackspot seabream) from the Azores archipelago, North-East Atlantic for microplastic contamination. Our results revealed that pelagic species had significantly more microplastic than the deep-water species. In all of the species studied, fragments were the most common plastic shape recovered and we found a significant difference in the type of polymer between the pelagic and deep-water species. In deep-sea fish we found almost exclusively polypropylene, whereas in the pelagic fish, polyethylene was the most abundant polymer type. Overall, the proportion of fish containing plastic items varied across our study species from 3.7% to 16.7% of individuals sampled, and the average abundance of plastic items ranged from 0.04 to 0.22 per individual (the maximum was 4 items recovered in one stomach). Despite the proximity of the Azores archipelago to the North Atlantic subtropical gyre, a region of elevated plastic abundance, the proportion of individuals containing plastic (9.49%) were comparable with data reported elsewhere.
Abstract.
Coppock R (2020). Microplastics in the marine environment: from top to bottom.
Abstract:
Microplastics in the marine environment: from top to bottom
The first reports of small plastic debris floating at the ocean surface were recorded in the 1970s, but it is only in the last decade that scientific and media attention has soared. Microplastics (plastic 1 µm – 5 mm) have since been acknowledged as a global marine contaminant, raising concerns about the interactions between anthropogenic debris and natural biological processes. In this thesis, I explore the hypothesis that microplastics can be transported via biotic-driven mechanisms through the water column and into coastal sediments, leading to adverse impacts on the health and functioning of marine fauna and ecosystems. In Chapter 2, I demonstrate that a key pelagic species, the copepod Calanus helgolandicus, alter their prey selection dependent upon the size or shape of the plastic in their ambient surroundings. with the capacity to reduce feeding. I also establish that C. helgolandicus faecal pellets sink slower when contaminated with low density polyethylene (PE), whereas sinking rates increase when contaminated with high density polyethylene terephthalate (PET), highlighting potential impacts to marine nutrient flux. In Chapter 3, I develop a method utilising the differential density of sediment and plastic to isolate and recover microplastics from sediments; I apply this method in Chapter 4, and latterly discuss harmonisation of microplastic estimates between studies and its use across the wider international field (Chapter 5). In Chapter 4, I employ a multi-faceted study to explore the role that benthic fauna play in the uptake of microplastics by the seabed. My environmental data demonstrate that microplastics are being permanently buried in coastal sediments, and that this process is ubiquitous across sampled sites and seasons. I further identify that benthic faunal functional groups that move sediment vertically (“conveyors”) and randomly (“biodiffusers”) influence sediment plastic loading differently, affecting ultimate burial and deep sediment loading. Furthermore, experimental data indicate that a key benthic species, the brittlestar Amphiura filiformis, buries nylon fibres along its burrow structure and that burial activity deep in the burrow is impaired when plastic is consumed. Collectively, my research contributes to our understanding of the mechanisms governing microplastic transport through the water column and into the sediment matrix, highlights risks posed to marine fauna and ecosystems and provides evidence that coastal sediments are final sinks for microplastics.
Abstract.
Alava JJ, Jones J, Calle P, Alarcón D, Muñoz-Pérez JP, Tirapé A, Muñoz-Abril L, Hobbs C, Townsend KA, Domínguez GA, et al (2020). Multiple Anthropogenic Stressors Reshape Evolutionary Processes in Galapagos: Marine Pollution and Climate Change.
Jones J, Porter A, Muñoz-Pérez J, Alarcón-Ruales D, Galloway T, Godley B, Santillo D, Vagg J, Lewis C (2020). Plastic contamination of the Galapagos marine food web and the relative risks to native species.
Abstract:
Plastic contamination of the Galapagos marine food web and the relative risks to native species
Abstract
. Ecuador’s Galapagos Islands and their unique biodiversity are a global conservation priority. We investigated the presence, partitioning and environmental drivers of plastic contamination across the marine ecosystem, designing a systematic risk scoring analysis to identify the most vulnerable species. Beach contamination varied by site (macroplastic 0 - 0.66 items.m-2, large microplastics 0 - 448.8 particles.m-2, small microplastics 0 – 74.6 particles.kg-1), with high plastic accumulation on east-facing beaches indicating input from the Humboldt Current. Local littering and waste management leakages accounted for 2% of macroplastic. Microplastics (including synthetic cellulosics) were prevalent in sediments (6.7 - 86.7 particles.kg-1) and surface seawater (0.04 - 0.89 particles.m-3), with elevated concentrations in the harbour suggesting local input. Microplastics were present in all seven marine invertebrate species examined, found in 52% of individuals (n = 123). Risk scoring identified 32 species in need of urgent, targeted monitoring and mitigation including pinnipeds, seabirds, turtles, sharks and corals.
Abstract.
Cornwell LE, Fileman ES, Bruun JT, Hirst AG, Tarran GA, Findlay HS, Lewis C, Smyth TJ, McEvoy AJ, Atkinson A, et al (2020). Resilience of the Copepod Oithona similis to Climatic Variability: Egg Production, Mortality, and Vertical Habitat Partitioning. Frontiers in Marine Science, 7
2019
Mangan S, Wilson R, Findlay H, Lewis CN (2019). Acid–base physiology over tidal periods in the mussel Mytilus edulis: size and temperature are more influential than seawater pH. Proceedings of the Royal Society B: Biological Sciences, 286
Nielson C, Hird C, Lewis C (2019). Ocean acidification buffers the physiological responses of the king ragworm Alitta virens to the common pollutant copper.
Aquatic Toxicology,
212, 120-127.
Abstract:
Ocean acidification buffers the physiological responses of the king ragworm Alitta virens to the common pollutant copper
Ocean acidification (OA) has the potential to alter the bioavailability of pH sensitive metals contaminating coastal sediments, particularly copper, by changing their speciation in seawater. Hence OA may drive increased toxicity of these metals to coastal biota. Here, we demonstrate complex interactions between OA and copper on the physiology and toxicity responses of the sediment dwelling polychaete Alitta virens. Worm coelomic fluid pCO2 was not increased by exposure to OA conditions (pHNBS 7.77, pCO2 530 μatm) for 14 days, suggesting either physiological or behavioural responses to control coelomic fluid pCO2. Exposure to 0.25 μM nominal copper caused a decrease in coelomic fluid pCO2 by 43.3% and bicarbonate ions by 44.6% but paradoxically this copper-induced effect was reduced under near-future OA conditions. Hence OA appeared to ‘buffer’ the copper-induced acid-base disturbance. DNA damage was significantly increased in worms exposed to copper under ambient pCO2 conditions, rising by 11.1% compared to the worms in the no copper control, but there was no effect of OA conditions on the level of DNA damage induced by copper when exposed in combination. These interactions differ from the increased copper toxicity under OA conditions reported for several other invertebrate species. Hence this new evidence adds to the developing paradigm that species’ physiology is key in determining the interactions of these two stressors rather than it purely being driven by the changes in metal chemistry under lower seawater pH.
Abstract.
Scott N, Porter A, Santillo D, Simpson H, Lloyd-Williams S, Lewis C (2019). Particle characteristics of microplastics contaminating the mussel Mytilus edulis and their surrounding environments.
Marine Pollution Bulletin,
146, 125-133.
Abstract:
Particle characteristics of microplastics contaminating the mussel Mytilus edulis and their surrounding environments
We investigated the environmental partitioning and particle characteristics of macro-, meso- and microplastics and their uptake into the mussel, Mytilus edulis. Sediment samples, overlying seawater and mussels from 9 intertidal locations in the South West of England were analysed for abundance and type of microplastic. Micro- and mesoplastic-like particles were found in 88.5% of the 269 mussels sampled, ranging from 1.43 to 7.64 items per mussel. of these plastic particles, 70.9% were identified as semi-synthetic (mainly modified-cellulose). Mussel microplastic abundance, but not polymer type, was correlated with that of their surrounding sediment, but not with sea-surface microplastic concentration or mussel size for our study sites. We found significant differences in the relative abundance of polymer types and particle sizes between seawater, sediment, and mussels, with mussels over-representing modified-cellulose fibre abundance but under-representing polyvinyl. Mussels contained significantly smaller plastic fragments than their surrounding sediment and shorter fibres than their overlying seawater.
Abstract.
Smith KE, Byrne M, Deaker D, Hird CM, Nielson C, Wilson-McNeal A, Lewis C (2019). Sea urchin reproductive performance in a changing ocean: poor males improve while good males worsen in response to ocean acidification.
Proc Biol Sci,
286(1907).
Abstract:
Sea urchin reproductive performance in a changing ocean: poor males improve while good males worsen in response to ocean acidification.
Ocean acidification (OA) is predicted to be a major driver of ocean biodiversity change. At projected rates of change, sensitive marine taxa may not have time to adapt. Their persistence may depend on pre-existing inter-individual variability. We investigated individual male reproductive performance under present-day and OA conditions using two representative broadcast spawners, the sea urchins Lytechinus pictus and Heliocidaris erythrogramma. Under the non-competitive individual ejaculate scenario, we examined sperm functional parameters (e.g. swimming speed, motility) and their relationship with fertilization success under current and near-future OA conditions. Significant inter-individual differences in almost every parameter measured were identified. Importantly, we observed strong inverse relationships between individual fertilization success rate under current conditions and change in fertilization success under OA. Individuals with a high fertilization success under current conditions had reduced fertilization under OA, while individuals with a low fertilization success under current conditions improved. Change in fertilization success ranged from -67% to +114% across individuals. Our results demonstrate that while average population fertilization rates remain similar under OA and present-day conditions, the contribution by different males to the population significantly shifts, with implications for how selection will operate in a future ocean.
Abstract.
Author URL.
Porter A (2019). The movement of plastics through marine ecosystems and the influences on bioavailability and uptake into marine biota.
Abstract:
The movement of plastics through marine ecosystems and the influences on bioavailability and uptake into marine biota.
Microplastics are a diverse array of contaminants comprising a suite of sizes, shapes, and polymer types. Here I present a body of work investigating the distribution and movement of microplastics through the marine ecosystems via transportation and transformation pathways. First, I look at litter items of beaches of the Cornish coast, demonstrating that 41% of litter was plastics fragments unattributable to source and that this litter was continually re-stocked such that it was always present despite cleaning efforts. Then I took to the seas to conduct sea surface trawls in the North East Atlantic to investigate the floating proportion of marine plastic debris. Microplastics were found in every sample, yet were highly variable in concentration over geographic space ranging from 0.038 to 0.45 particles m-3. Counter to the prevailing trends, plastic fragments (84 μm – 21.8 mm) were the dominant shape (63%), with fewer fibres present. The likelihood of encounter and therefore risk of plastic to plankton was calculated and it was found that for every 1 plastic particle, there were between 500 and 1000 plankton, suggesting very low risk of biological uptake for this region. Plastics are not just found on the sea surface and are increasingly found in benthic sediments and biota. I tested whether marine snows would act as a transport mechanism of plastics from the surface to the seafloor. I demonstrate that under experimental conditions a range of plastic particle sizes, shapes, and polymer types, all readily incorporated into marine snows. This incorporation into marine snows both overcame the buoyancy of floating particles but also increased the sinking rate of dense particles. Buoyant polyethylene went from floating as a free particle to sinking at 818 m day–1
Abstract.
Porter A, Smith KE, Lewis C (2019). The sea urchin Paracentrotus lividus as a bioeroder of plastic. Science of the Total Environment, 693, 133621-133621.
2018
Brettell D (2018). Assessing the threat of microplastics to commercial oysters, particularly those of the genus Crassostrea.
Abstract:
Assessing the threat of microplastics to commercial oysters, particularly those of the genus Crassostrea
Current statistics show that China is the largest producer of plastics in the world, contributing to almost 30% of production worldwide (Plastics Europe, 2017). In particular, mega-cities in China connected with the Pearl River Estuary contribute to much of this production, and locations in the Estuary’s proximity are potential sites for plastic pollution. In this thesis, the hypothesis that Crassostrea hongkongensis oysters cultured in Deep Bay, Hong Kong would be susceptible to microplastic uptake was tested. Extensive sampling was conducted across the bay through the collection of oysters, water and sediment from five selected sites (rafts). Follow up analysis of samples revealed that an average of 15.1 ± 6.1 microplastics per individual were present within the oysters, and oysters situated in the outer part of the bay took up more microplastics compared to those situated in the inner part of the bay. The numbers and types of microplastics quantified in sediment and water samples across sites did not correspond to the number of microplastics quantified in Crassostrea hongkongensis specimens across sites, suggesting that there was an element of selection during the biological uptake of these particles, and this was potentially influenced by particles’ properties such as size, shape and polymer type.
Having established that wild Crassostrea hongkongensis in Deep Bay were taking up microplastics, an experiment was set up to investigate whether a genetically similar oyster species, Crassostrea gigas, would exhibit selective uptake up microplastics according to plastics’ size, shape or polymer type, and whether microplastic exposure would induce biological responses within the oysters. Eight microplastic types of various polymers, sizes and shapes were supplied in equal concentrations to Crassostrea gigas oysters at a final concentration of 100 microplastics mL-1, where they were exposed for a 24 hour period. Findings revealed that microplastic polymer type and size did indeed influence uptake (Pr (>Chi)=0.034), and oysters readily took up 0.29% of 8-30 m polyethylene beads and 0.31% of 115-156 m polyvinyl chloride fragments supplied when exposed solely to plastics; oysters exposed to a combination of algae and plastics (same microplastic concentrations) took up 0.25% of the former plastic type, and 0.32% of the latter plastic type supplied. A post-hoc Tukey test confirmed that uptake of these two plastic types were significantly higher (p
Abstract.
Porter A, Lyons BP, Galloway TS, Lewis C (2018). Role of Marine Snows in Microplastic Fate and Bioavailability.
Environ Sci Technol,
52(12), 7111-7119.
Abstract:
Role of Marine Snows in Microplastic Fate and Bioavailability.
Microplastics contaminate global oceans and are accumulating in sediments at levels thought sufficient to leave a permanent layer in the fossil record. Despite this, the processes that vertically transport buoyant polymers from surface waters to the benthos are poorly understood. Here we demonstrate that laboratory generated marine snows can transport microplastics of different shapes, sizes, and polymers away from the water surface and enhance their bioavailability to benthic organisms. Sinking rates of all tested microplastics increased when incorporated into snows, with large changes observed for the buoyant polymer polyethylene with an increase in sinking rate of 818 m day-1 and for denser polyamide fragments of 916 m day-1. Incorporation into snows increased microplastic bioavailability for mussels, where uptake increased from zero to 340 microplastics individual-1 for free microplastics to up to 1.6 × 105 microplastics individual-1 when incorporated into snows. We therefore propose that marine snow formation and fate has the potential to play a key role in the biogeochemical processing of microplastic pollution.
Abstract.
Author URL.
Cornwell LE, Findlay HS, Fileman ES, Smyth TJ, Hirst AG, Bruun JT, McEvoy AJ, Widdicombe CE, Castellani C, Lewis C, et al (2018). Seasonality of Oithona similis and Calanus helgolandicus reproduction and abundance: Contrasting responses to environmental variation at a shelf site.
Journal of Plankton Research,
40(3), 295-310.
Abstract:
Seasonality of Oithona similis and Calanus helgolandicus reproduction and abundance: Contrasting responses to environmental variation at a shelf site
The pelagic copepods Oithona similis and Calanus helgolandicus have overlapping geographic ranges, yet contrast in feeding mode, reproductive strategy and body size. We investigate how these contrasting traits influence the seasonality of copepod abundance and reproductive output under environmental variation, using time series data collected over 25 years at the Western Channel Observatory station, L4. The proportional change in egg production rate (EPR, eggs female '1 d '1) over the annual cycle was ∼10-fold and similar for both species, although EPR of O. similis was only ∼ 11% that of C. helgolandicus. The timing of EPR maxima for O. similis coincided with increased sea surface temperature (SST) in summer, likely due to a temperature-dependent brooding period. Conversely, EPR of broadcast spawning C. helgolandicus was more strongly related to net heat flux and diatom biomass, both parameters associated with the spring phytoplankton bloom. In both species, female body mass correlated negatively with SST, with a 7.5% reduction in body mass per °C in C. helgolandicus compared to just 2.3% in O. similis. Finally, seasonality of EPR and adult and copepodite abundance was strongly decoupled in both species, suggesting that optimum conditions for reproduction and abundance occurred at different times of the year.
Abstract.
Hodgson D (2018). The impacts of microplastic ingestion on marine polychaete worms.
Abstract:
The impacts of microplastic ingestion on marine polychaete worms
The benthic marine habitat is a sink for microplastics, however, our understanding of their impacts on marine organisms is still limited. This thesis investigates the ingestion and subsequent impacts of microplastics in the marine benthic dwelling polychaete worms, Hediste diversicolor and Ophryotrocha labronica. Firstly, microplastic ingestion by H. diversicolor in three estuaries across South Devon, UK, each of which were exposed to either high, medium or low levels of infrastructure and human population was assessed. The data showed 58.58% of H. diversicolor individuals ingested plastic-like particles, with fibres accounting for 86.8 % of all plastics observed. However, no significant differences in the amount of plastic-like particles ingested between sites were found. Microplastic fibres are the most commonly reported plastic shape in environmental samples, such as sediments, and during gut contents analysis of numerous phyla worldwide. However, the majority of research assessing the impacts of ingested plastics focus on microplastic spherical in shape. Therefore, the difference in toxicity between microplastic beads and fibres in H. diversicolor was investigated. The project found ingested fibres induced a greater oxidative stress response compared to that of microbeads and consequently caused cellular damage in the form of lipid peroxidation. Cellular repair and maintaining homeostasis is energetically expensive and in turn, may impact an individual’s fitness. Therefore, the impacts of microplastic exposure on the feeding and fitness of O. labronica were assessed. O. labronica exposed to plastics produced less offspring and significantly smaller eggs than unexposed mating pairs, which ultimately could lead to deleterious impacts at the population level. However, the protein content of those eggs had a similar energetic content and consequently, there was no difference in the offspring survival rate.
Abstract.
2017
McNeal AW, Cole M, Galloway TS, Lewis C, Watts A, Wright S, Miller RZ, Lindeque P (2017). Are Smaller Microplastics Underestimated? Comparing Anthropogenic Debris Collected with Different Mesh Sizes. In (Ed) Fate and Impact of Microplastics in Marine Ecosystems, Elsevier.
Mangan S, Urbina MA, Findlay HS, Wilson RW, Lewis C (2017). Fluctuating seawater pH/pCO2 regimes are more energetically expensive than static pH/pCO2 levels in the mussel Mytilus edulis.
Proc Biol Sci,
284(1865).
Abstract:
Fluctuating seawater pH/pCO2 regimes are more energetically expensive than static pH/pCO2 levels in the mussel Mytilus edulis.
Ocean acidification (OA) studies typically use stable open-ocean pH or CO2 values. However, species living within dynamic coastal environments can naturally experience wide fluctuations in abiotic factors, suggesting their responses to stable pH conditions may not be reflective of either present or near-future conditions. Here we investigate the physiological responses of the mussel Mytilus edulis to variable seawater pH conditions over short- (6 h) and medium-term (2 weeks) exposures under both current and near-future OA scenarios. Mussel haemolymph pH closely mirrored that of seawater pH over short-term changes of 1 pH unit with acidosis or recovery accordingly, highlighting a limited capacity for acid-base regulation. After 2 weeks, mussels under variable pH conditions had significantly higher metabolic rates, antioxidant enzyme activities and lipid peroxidation than those exposed to static pH under both current and near-future OA scenarios. Static near-future pH conditions induced significant acid-base disturbances and lipid peroxidation compared with the static present-day conditions but did not affect the metabolic rate. These results clearly demonstrate that living in naturally variable environments is energetically more expensive than living in static seawater conditions, which has consequences for how we extrapolate future OA responses in coastal species.
Abstract.
Author URL.
Uren Webster TM, Williams TD, Katsiadaki I, Lange A, Lewis C, Shears JA, Tyler CR, Santos EM (2017). Hepatic transcriptional responses to copper in the three-spined stickleback are affected by their pollution exposure history.
Aquat Toxicol,
184, 26-36.
Abstract:
Hepatic transcriptional responses to copper in the three-spined stickleback are affected by their pollution exposure history.
Some fish populations inhabiting contaminated environments show evidence of increased chemical tolerance, however the mechanisms contributing to this tolerance, and whether this is heritable, are poorly understood. We investigated the responses of two populations of wild three-spined stickleback (Gasterosteus aculeatus) with different histories of contaminant exposure to an oestrogen and copper, two widespread aquatic pollutants. Male stickleback originating from two sites, the River Aire, with a history of complex pollution discharges, and Siblyback Lake, with a history of metal contamination, were depurated and then exposed to copper (46μg/L) and the synthetic oestrogen ethinyloestradiol (22ng/L). The hepatic transcriptomic response was compared between the two populations and to a reference population with no known history of exposure (Houghton Springs, Dorset). Gene responses included those typical for both copper and oestrogen, with no discernable difference in response to oestrogen between populations. There was, however, some difference in the magnitude of response to copper between populations. Siblyback fish showed an elevated baseline transcription of genes encoding metallothioneins and a lower level of metallothionein induction following copper exposure, compared to those from the River Aire. Similarly, a further experiment with an F1 generation of Siblyback fish bred in the laboratory found evidence for elevated transcription of genes encoding metallothioneins in unexposed fish, together with an altered transcriptional response to 125μg/L copper, compared with F1 fish originating from the clean reference population exposed to the same copper concentration. These data suggest that the stickleback from Siblyback Lake have a differential response to copper, which is inherited by the F1 generation in laboratory conditions, and for which the underlying mechanism may include an elevation of baseline transcription of genes encoding metallothioneins. The genetic and/or epigenetic mechanisms contributing to this inherited alteration of metallothionein transcription have yet to be established.
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Author URL.
Campbell AL, Ellis RP, Urbina MA, Mourabit S, Galloway TS, Lewis C (2017). Impacts of ocean acidification on sperm develop with exposure time for a polychaete with long lived sperm.
Mar Environ Res,
129, 268-276.
Abstract:
Impacts of ocean acidification on sperm develop with exposure time for a polychaete with long lived sperm.
The majority of marine invertebrate species release eggs and sperm into seawater for external fertilisation. Seawater conditions are currently changing at an unprecedented rate as a consequence of ocean acidification (OA). Sperm are thought to be particularly vulnerable to these changes and may be exposed to external environmental conditions for variable periods of time between spawning and fertilisation. Here, we undertook a mechanistic investigation of sperm swimming performance in the coastal polychaete Arenicola marina during an extended exposure to OA conditions (pHNBS 7.77, 1000 μatm pCO2). We found that key fitness-related aspects of sperm functioning declined faster under OA conditions i.e. impacts became apparent with exposure time. Sperm swimming speed (VCL), the number of motile sperm and sperm path linearity all dropped significantly after 4 h under OA conditions whilst remaining constant under ambient conditions at this time point. Our results highlight the importance of sperm exposure duration in ocean acidification experiments and may help towards explaining species specific differences in response.
Abstract.
Author URL.
Galloway TS, Cole M, lewis C (2017). Interactions of microplastics throughout the marine ecosystem. Nature Ecology and Evolution, 1
Galloway T, Lewis C (2017). Marine microplastics.
Curr Biol,
27(11), R445-R446.
Abstract:
Marine microplastics.
Galloway and Lewis discuss marine microplastics and their devastating effects on ocean ecosystems.
Abstract.
Author URL.
Watts A, Urbina M, Lewis C, Galloway T (2017). Primary (Ingestion) and Secondary (Inhalation) Uptake of Microplastic in the Crab Carcinus maenas, and its Biological Effects. In (Ed) Fate and Impact of Microplastics in Marine Ecosystems, Elsevier.
Watts AJR, Porter A, Hembrow N, Sharpe J, Galloway TS, Lewis C (2017). Through the sands of time: Beach litter trends from nine cleaned north cornish beaches.
Environ Pollut,
228, 416-424.
Abstract:
Through the sands of time: Beach litter trends from nine cleaned north cornish beaches.
Marine litter and its accumulation on beaches is an issue of major current concern due to its significant environmental and economic impacts. Yet our understanding of spatio-temporal trends in beach litter and the drivers of these trends are currently limited by the availability of robust long term data sets. Here we present a unique data set collected systematically once a month, every month over a six year period for nine beaches along the North Coast of Cornwall, U.K. to investigate the key drivers of beach litter in the Bude, Padstow and Porthcothan areas. Overall, an average of 0.02 litter items m-2 per month were collected during the six year study, with Bude beaches (Summerleaze, Crooklets and Widemouth) the most impacted (0.03 ± 0.004 litter items m-2 per month). The amount of litter collected each month decreased by 18% and 71% respectively for Padstow (Polzeath, Trevone and Harlyn) and Bude areas over the 6 years, possibly related to the regular cleaning, however litter increased by 120% despite this monthly cleaning effort on the Padstow area beaches. Importantly, at all nine beaches the litter was dominated by small, fragmented plastic pieces and rope fibres, which account for 32% and 17% of all litter items collected, respectively. The weathered nature of these plastics indicates they have been in the marine environment for an extended period of time. So, whilst classifying the original source of these plastics is not possible, it can be concluded they are not the result of recent public littering. This data highlights both the extent of the marine litter problem and that current efforts to reduce littering by beach users will only tackle a fraction of this litter. Such information is vital for developing effective management strategies for beach and marine litter at both regional and global levels.
Abstract.
Author URL.
2016
Watts AW, Mauricio A. Urbina MU, Goodhead RG, Moger JJ, Lewis CL, Galloway TG (2016). Effect of microplastic on the gills of the Shore Crab Carcinus maenas.
Environmental Science and Technology (Washington)Abstract:
Effect of microplastic on the gills of the Shore Crab Carcinus maenas
Microscopic plastic debris (microplastics,
Abstract.
Hird CM, Urbina MA, Lewis CN, Snape JR, Galloway TS (2016). Fluoxetine Exhibits Pharmacological Effects and Trait-Based Sensitivity in a Marine Worm.
Environ Sci Technol,
50(15), 8344-8352.
Abstract:
Fluoxetine Exhibits Pharmacological Effects and Trait-Based Sensitivity in a Marine Worm.
Global production of pharmacologically active compounds exceeds 100 000 tons annually, a proportion of which enters aquatic environments through patient use, improper medicine disposal, and production. These compounds are designed to have mode-of-action (MoA) effects on specific biological pathways, with potential to impact nontarget species. Here, we used MoA and trait-based approaches to quantify uptake and biological effects of fluoxetine, a selective serotonin reuptake inhibitor, in filter and deposit feeding marine worms (Hediste diversicolor). Worms exposed to 10 μg L(-1), accumulated fluoxetine with a body burden over 270 times greater than exposure concentrations, resulting in ∼10% increased coelomic fluid serotonin, a pharmacological effect. Observed effects included weight loss (up to 2% at 500 μg L(-1)), decreased feeding rate (68% at 500 μg L(-1)), and altered metabolism (oxygen consumption, ammonia excretion, and O/N from 10 μg L(-1)). Bioconcentration of fluoxetine was dependent on route of uptake, with filter feeding worms experiencing up to 130 times greater body burden ratios and increased magnitudes of effects than deposit feeders, a trait-based sensitivity likely as a consequence of fluoxetine partitioning to sediment. This study highlights how novel approaches such as MoA and trait-based methods can supplement environmental risk assessments of pharmaceuticals.
Abstract.
Author URL.
Clark JR, Cole M, Lindeque PK, Fileman E, Blackford J, Lewis C, Lenton TM, Galloway TS (2016). Marine microplastic debris: a targeted plan for understanding and quantifying interactions with marine life. Frontiers in Ecology and the Environment, 14, 317-324.
Galloway TS, Lewis CN (2016). Marine microplastics spell big problems for future generations.
Proc Natl Acad Sci U S A,
113(9), 2331-2333.
Author URL.
Cole M, Lindeque PK, Fileman E, Clark J, Lewis C, Halsband C, Galloway TS (2016). Microplastics Alter the Properties and Sinking Rates of Zooplankton Faecal Pellets.
Environ Sci Technol,
50(6), 3239-3246.
Abstract:
Microplastics Alter the Properties and Sinking Rates of Zooplankton Faecal Pellets.
Plastic debris is a widespread contaminant, prevalent in aquatic ecosystems across the globe. Zooplankton readily ingest microscopic plastic (microplastic, < 1 mm), which are later egested within their faecal pellets. These pellets are a source of food for marine organisms, and contribute to the oceanic vertical flux of particulate organic matter as part of the biological pump. The effects of microplastics on faecal pellet properties are currently unknown. Here we test the hypotheses that (1) faecal pellets are a vector for transport of microplastics, (2) polystyrene microplastics can alter the properties and sinking rates of zooplankton egests and, (3) faecal pellets can facilitate the transfer of plastics to coprophagous biota. Following exposure to 20.6 μm polystyrene microplastics (1000 microplastics mL(-1)) and natural prey (∼1650 algae mL(-1)) the copepod Calanus helgolandicus egested faecal pellets with significantly (P < 0.001) reduced densities, a 2.25-fold reduction in sinking rates, and a higher propensity for fragmentation. We further show that microplastics, encapsulated within egests of the copepod Centropages typicus, could be transferred to C. helgolandicus via coprophagy. Our results support the proposal that sinking faecal matter represents a mechanism by which floating plastics can be vertically transported away from surface waters.
Abstract.
Author URL.
Campbell AL, Levitan DR, Hosken DJ, Lewis C (2016). Ocean acidification changes the male fitness landscape.
Sci Rep,
6Abstract:
Ocean acidification changes the male fitness landscape.
Sperm competition is extremely common in many ecologically important marine taxa. Ocean acidification (OA) is driving rapid changes to the marine environments in which freely spawned sperm operate, yet the consequences of OA on sperm performance are poorly understood in the context of sperm competition. Here, we investigated the impacts of OA (+1000 μatm pCO2) on sperm competitiveness for the sea urchin Paracentrotus lividus. Males with faster sperm had greater competitive fertilisation success in both seawater conditions. Similarly, males with more motile sperm had greater sperm competitiveness, but only under current pCO2 levels. Under OA the strength of this association was significantly reduced and there were male sperm performance rank changes under OA, such that the best males in current conditions are not necessarily best under OA. Therefore OA will likely change the male fitness landscape, providing a mechanism by which environmental change alters the genetic landscape of marine species.
Abstract.
Author URL.
Lewis C, Ellis RP, Vernon E, Elliot K, Newbatt S, Wilson RW (2016). Ocean acidification increases copper toxicity differentially in two key marine invertebrates with distinct acid-base responses.
Scientific Reports,
6Abstract:
Ocean acidification increases copper toxicity differentially in two key marine invertebrates with distinct acid-base responses
Ocean acidification (OA) is expected to indirectly impact biota living in contaminated coastal environments by altering the bioavailability and potentially toxicity of many pH-sensitive metals. Here, we show that OA (pH 7.71; pCO 2 1480 μatm) significantly increases the toxicity responses to a global coastal contaminant (copper ∼0.1 μM) in two keystone benthic species; mussels (Mytilus edulis) and purple sea urchins (Paracentrotus lividus). Mussels showed an extracellular acidosis in response to OA and copper individually which was enhanced during combined exposure. In contrast, urchins maintained extracellular fluid pH under OA by accumulating bicarbonate but exhibited a slight alkalosis in response to copper either alone or with OA. Importantly, copper-induced damage to DNA and lipids was significantly greater under OA compared to control conditions (pH 8.14; pCO 2 470 μatm) for both species. However, this increase in DNA-damage was four times lower in urchins than mussels, suggesting that internal acid-base regulation in urchins may substantially moderate the magnitude of this OA-induced copper toxicity effect. Thus, changes in metal toxicity under OA may not purely be driven by metal speciation in seawater and may be far more diverse than either single-stressor or single-species studies indicate. This has important implications for future environmental management strategies.
Abstract.
2015
Watts AJR, Urbina MA, Corr S, Lewis C, Galloway TS (2015). Ingestion of Plastic Microfibers by the Crab Carcinus maenas and its Effect on Food Consumption and Energy Balance.
Environ Sci Technol,
49(24), 14597-14604.
Abstract:
Ingestion of Plastic Microfibers by the Crab Carcinus maenas and its Effect on Food Consumption and Energy Balance.
Microscopic plastic fragments (
Abstract.
Author URL.
Findlay HS, Edwards LA, Lewis CN, Cooper GA, Clement R, Hardman-Mountford N, Vagle S, Miller LA (2015). Late winter biogeochemical conditions under sea ice in the Canadian High Arctic.
POLAR RESEARCH,
34 Author URL.
2014
Pope EC, Ellis RP, Scolamacchia M, Scolding JWS, Keay A, Chingombe P, Shields RJ, Wilcox R, Speirs DC, Wilson RW, et al (2014). European sea bass, Dicentrarchus labrax, in a changing ocean.
Biogeosciences,
11(9), 2519-2530.
Abstract:
European sea bass, Dicentrarchus labrax, in a changing ocean
Ocean acidification, caused by rising concentrations of carbon dioxide (CO2), is widely considered to be a major global threat to marine ecosystems. To investigate the potential effects of ocean acidification on the early life stages of a commercially important fish species, European sea bass (Dicentrarchus labrax), 12 000 larvae were incubated from hatch through metamorphosis under a matrix of two temperatures (17 and 19 °C) and two seawater pCO2 levels (ambient and 1,000 μatm) and sampled regularly for 42 days. Calculated daily mortality was significantly affected by both temperature and pCO2, with both increased temperature and elevated pCO2 associated with lower daily mortality and a significant interaction between these two factors. There was no significant pCO2 effect noted on larval morphology during this period but larvae raised at 19 °C possessed significantly larger eyes and lower carbon:nitrogen ratios at the end of the study compared to those raised under 17 °C. Similarly, when the incubation was continued to post-metamorphic (juvenile) animals (day 67-69), fish raised under a combination of 19 °C and 1000 μatm pCO2 were significantly heavier. However, juvenile D. labrax raised under this combination of 19 °C and 1000 μatm pCO2 also exhibited lower aerobic scopes than those incubated at 19 °C and ambient pCO2. Most studies investigating the effects of near-future oceanic conditions on the early life stages of marine fish have used incubations of relatively short durations and suggested that these animals are resilient to ocean acidification. Whilst the increased survival and growth observed in this study supports this view, we conclude that more work is required to investigate whether the differences in juvenile physiology observed in this study manifest as negative impacts in adult fish. copyright © Author(s) 2014.
Abstract.
Campbell AL, Mangan S, Ellis RP, Lewis C (2014). Ocean acidification increases copper toxicity to the early life history stages of the polychaete Arenicola marina in artificial seawater.
Environ Sci Technol,
48(16), 9745-9753.
Abstract:
Ocean acidification increases copper toxicity to the early life history stages of the polychaete Arenicola marina in artificial seawater.
The speciation and therefore bioavailability of the common pollutant copper is predicted to increase within the pH range anticipated under near-future ocean acidification (OA), hence the potential exists for copper toxicity to marine organisms to also increase. We investigated the impact of OA (seawater pH values of 7.77 (pCO2 1400 μatm) and 7.47 (pCO2 3000 μatm)) upon copper toxicity responses in early life history stages of the polychaete Arenicola marina and found both synergistic and additive toxicity effects of combined exposures depending on life history stage. The toxicity of copper on sperm DNA damage and early larval survivorship was synergistically increased under OA conditions. Larval survival was reduced by 24% when exposed to both OA and copper combined compared to single OA or copper exposures. Sperm motility was negatively affected by both OA and copper singularly with additive toxicity effects of the two stressors when combined. Fertilization success was also negatively affected by both OA and copper individually, but no additive effects when exposed as combined stressors were present for this stage. These findings add to the growing body of evidence that OA will act to increase the toxicity of copper to marine organisms, which has clear implications for coastal benthic ecosystems suffering chronic metal pollution as pCO2 levels rise and drive a reduction in seawater pH.
Abstract.
Author URL.
Watts AJR, Lewis C, Goodhead RM, Beckett SJ, Moger J, Tyler CR, Galloway TS (2014). Uptake and retention of microplastics by the shore crab Carcinus maenas.
Environ Sci Technol,
48(15), 8823-8830.
Abstract:
Uptake and retention of microplastics by the shore crab Carcinus maenas.
Microplastics, plastics particles
Abstract.
Author URL.
2013
Pope EC, Ellis RP, Scolamacchia M, Scolding JWS, Keay A, Chingombe P, Shields RJ, Wilcox R, Speirs DC, Wilson RW, et al (2013). Is the perceived resiliency of fish larvae to ocean acidification masking more subtle effects?.
Abstract:
Is the perceived resiliency of fish larvae to ocean acidification masking more subtle effects?
Abstract. Ocean acidification, caused by rising concentrations of carbon dioxide (CO2), is widely considered to be a major global threat to marine ecosystems. To investigate the potential effects of ocean acidification on the early life stages of a commercially important fish species, European sea bass (Dicentrarchus labrax), 12 000 larvae were incubated from hatch through metamorphosis under a matrix of two temperatures (17 and 19 °C) and two seawater pCO2s (400 and 750 μatm) and sampled regularly for 42 days. Calculated daily mortality was significantly affected by both temperature and pCO2, with both increased temperature and elevated pCO2 associated with lower daily mortality and a significant interaction between these two factors. There was no significant pCO2 effect noted on larval morphology during this period but larvae raised at 19 °C possessed significantly larger eyes and lower carbon:nitrogen ratios at the end of the study compared to those raised under 17 °C. These results suggest that D. labrax larvae are resilient to near-future oceanic conditions. However, when the incubation was continued to post-metamorphic (juvenile) animals (day 67–69), fish raised under a combination of 19 °C and 750 μatm pCO2 were significantly heavier and exhibited lower aerobic scopes than those incubated at 19 °C and 400 μatm. Most other studies investigating the effects of near-future oceanic conditions on the early life stages of marine fish have used incubations of relatively short durations and suggested these animals are resilient to ocean acidification. We propose the durations of these other studies may be insufficient for more subtle effects, such as those observed in this study, to become apparent. These findings may have important implications for both sea bass in a changing ocean and also for the interpretation of results from other studies that have shown resiliency in marine teleosts exposed to higher atmospheric concentrations of CO2.
Abstract.
Lewis C, Clemow K, Holt WV (2013). Metal contamination increases the sensitivity of larvae but not gametes to ocean acidification in the polychaete <i>Pomatoceros lamarckii</i> (Quatrefages).
MARINE BIOLOGY,
160(8), 2089-2101.
Author URL.
Lewis CN, Brown KA, Edwards LA, Cooper G, Findlay HS (2013). Sensitivity to ocean acidification parallels natural pCO<inf>2</inf> gradients experienced by Arctic copepods under winter sea ice.
Proceedings of the National Academy of Sciences of the United States of America,
110(51).
Abstract:
Sensitivity to ocean acidification parallels natural pCO2 gradients experienced by Arctic copepods under winter sea ice
The Arctic Ocean already experiences areas of low pH and high CO 2, and it is expected to be most rapidly affected by future ocean acidification (OA). Copepods comprise the dominant Arctic zooplankton; hence, their responses to OA have important implications for Arctic ecosystems, yet there is little data on their current under-ice winter ecology on which to base future monitoring or make predictions about climate-induced change. Here, we report results from Arctic under-ice investigations of copepod natural distributions associated with late-winter carbonate chemistry environmental data and their response tomanipulated pCO2 conditions (OA exposures). Our data reveal that species and life stage sensitivities to manipulated OA conditions were correlated with their vertical migration behavior and with their natural exposures to different pCO2 ranges. Vertically migrating adult Calanus spp. crossed a pCO2 range of
Abstract.
2012
Lewis C, Watson GJ (2012). Expanding the ecotoxicological toolbox: the inclusion of polychaete reproductive endpoints.
Mar Environ Res,
75, 10-22.
Abstract:
Expanding the ecotoxicological toolbox: the inclusion of polychaete reproductive endpoints.
In the last 15 years the diversity of pollutants and routes of impact have increased. However, the polychaete families, species and endpoints investigated have remained fairly constant. Reproductive outputs are more ecologically relevant than adult physiological or biochemical changes. Nevertheless, there remains a paucity of data on the reproductive responses of the popular species to pollutants which limits our ability to understand the true ecological impacts of such contaminants on natural populations. We highlight the current knowledge gaps in our understanding of the impacts of pollutants on the 'model' species' reproductive biology and therefore the potential ecological impacts of such contaminants on their natural populations, and the potential benefits of a wider use of polychaete reproductive endpoints for ecotoxicological assessments. The following priority areas are suggested for inclusion in the polychaete ecotoxicology toolbox: 1. Include reproductive endpoints as assessments of ecotoxicology for the traditional 'model' species and those that have different reproductive traits to ensure broad ecological relevance. 2. Nereids and Arenicola marina should be used to investigate the interaction of pollutants with the endocrine/environmental control of reproduction. 3. Polychaetes are ideal for addressing the under representation of male eco-toxicity effects. 4. Emerging pollutants should be assessed with reproductive endpoints together with the traditional biomarkers. 5. Effects of pollutants on larval behaviour need to be explored considering the limited but equivocal results so far.
Abstract.
Author URL.
Lewis C, Ford AT (2012). Infertility in male aquatic invertebrates: a review.
Aquat Toxicol,
120-121, 79-89.
Abstract:
Infertility in male aquatic invertebrates: a review.
As a result of endocrine disruptor studies, there are numerous examples of male related reproductive abnormalities observed in vertebrates. Contrastingly, within the invertebrates there have been considerably less examples both from laboratory and field investigations. This has in part been due to a focus of female related endpoints, inadequate biomarkers and the low number of studies. Whether contaminant induced male infertility is an issue within aquatic invertebrates and their wider communities therefore remains largely unknown and represents a key knowledge gap in our understanding of pollutant impacts in aquatic wildlife. This paper reviews the current knowledge regarding pollutants impacting male infertility across several aquatic invertebrate phyla; which biomarkers are currently being used and where the science needs to be expanded. The limited studies conducted so far have revealed reductions in sperm numbers, examples of poor fertilisation success, DNA damage to spermatozoa and inhibition of sperm motility that can be induced by a range of environmental contaminants. This limited data is mainly comprised from laboratory studies with only a few studies of sperm toxicity in natural populations. Clearly, there is a need for further studies in this area, to include both laboratory and field studies from clean and reference sites, with a focus on broadcast spawners and those with direct fertilisation. Biomarkers developed for measuring sperm quantity and quality in vertebrates are easily transferable to invertebrates but require optimisation for particular species. We discuss how sperm tracking and techniques for measuring DNA strand breaks and sperm viability have been successfully transferred from human infertility clinics to aquatic invertebrate ecotoxicology. Linking sperm toxicity and male infertility effects to higher level impacts on the reproductive biology and dynamics of populations requires a much greater understanding of fertilisation dynamics and sperm competition/limitation for invertebrate species and represents the next challenge in our understanding of male toxicity effects in natural populations.
Abstract.
Author URL.
Roberts DA, Birchenough SNR, Lewis C, Sanders MB, Bolam T, Sheahan D (2012). Ocean acidification increases the toxicity of contaminated sediments. Global Change Biology
2011
Caldwell GS, Lewis C, Pickavance G, Taylor RL, Bentley MG (2011). Exposure to copper and a cytotoxic polyunsaturated aldehyde induces reproductive failure in the marine polychaete Nereis virens (Sars).
Aquat Toxicol,
104(1-2), 126-134.
Abstract:
Exposure to copper and a cytotoxic polyunsaturated aldehyde induces reproductive failure in the marine polychaete Nereis virens (Sars).
A number of metabolites from microalgae, including polyunsaturated aldehydes (PUAs), have been implicated as inducers of reproductive failure in aquatic invertebrates. Current work describes the impacts of the model PUA 2E, 4E-decadienal and copper sulphate applied in isolation and combination on the reproductive performance of the infaunal polychaete, Nereis virens (Sars). The reproductive and life cycle parameters investigated were; fertilisation success, larval survival, sperm motility (percent motility and curvilinear velocity) and sperm DNA damage. Exposure to decadienal and copper sulphate in isolation resulted in dose- and time-dependent reductions for each evaluated endpoint. Fertilisation success was heavily impacted at concentrations of up to 10μM for both compounds. Copper sulphate was more toxic in larval survival assays. Sperm motility impacts, although variable, exhibited rapid onset with pronounced reductions in sperm swimming performance observed within 3min of exposure. The extent of DNA damage was dose-dependent, and in the case of decadienal, rapid in onset. Dual compound exposures resulted in enhanced overall toxicity in all assays. Logistic regression analysis of fertilisation and larval survival assays showed significant synergistic interactions between decadienal and copper sulphate; an increase in concentration of either compound resulted in enhanced toxicity of the other. Longer exposure durations during larval survival assays demonstrated a further increase in both toxicity and synergism. The results indicate that the effects of additional environmental stressors must be considered when attempting to extrapolate laboratory-derived single compound exposures to field situations.
Abstract.
Author URL.
2010
Galloway. T, Lewis C, Hagger J (2010). Assessment of Genotoxicity Following Exposure to Hydrocarbons: the Micronucleus Assay. In (Ed) Handbook of Hydrocarbon and Lipid Microbiology, Springer Nature, 4473-4480.
Melzer D, Rice NE, Lewis C, Henley WE, Galloway TS (2010). Association of urinary bisphenol a concentration with heart disease: evidence from NHANES 2003/06.
PLoS One,
5(1).
Abstract:
Association of urinary bisphenol a concentration with heart disease: evidence from NHANES 2003/06.
BACKGROUND: Bisphenol a (BPA) is a high production volume chemical widely used in food and drinks packaging. Associations have previously been reported between urinary BPA concentrations and heart disease, diabetes and liver enzymes in adult participants of the National Health and Nutrition Examination Survey (NHANES) 2003/04. We aimed to estimate associations between urinary BPA concentrations and health measures in NHANES 2005/06 and in data pooled across collection years. METHODOLOGY AND FINDINGS: a cross-sectional analysis of NHANES: subjects were n = 1455 (2003/04) and n = 1493 (2005/06) adults aged 18-74 years, representative of the general adult population of the United States. Regression models were adjusted for age, sex, race/ethnicity, education, income, smoking, BMI, waist circumference, and urinary creatinine concentration. Main outcomes were reported diagnoses of heart attack, coronary heart disease, angina and diabetes and serum liver enzyme levels. Urinary BPA concentrations in 2005/06 (geometric mean 1.79 ng/ml, 95% CI: 1.64 to 1.96) were lower than in 2003/04 (2.49 ng/ml, CI: 2.20 to 2.83, difference p-value = 0.00002). Higher BPA concentrations were associated with coronary heart disease in 2005/06 (OR per z-score increase in BPA = 1.33, 95%CI: 1.01 to 1.75, p = 0.043) and in pooled data (OR = 1.42, CI: 1.17 to 1.72, p = 0.001). Associations with diabetes did not reach significance in 2005/06, but pooled estimates remained significant (OR = 1.24, CI: 1.10 to 1.40, p = 0.001). There was no overall association with gamma glutamyl transferase concentrations, but pooled associations with alkaline phosphatase and lactate dehydrogenase remained significant. CONCLUSIONS: Higher BPA exposure, reflected in higher urinary concentrations of BPA, is consistently associated with reported heart disease in the general adult population of the USA. Studies to clarify the mechanisms of these associations are urgently needed.
Abstract.
Author URL.
Lewis C, Guitart C, Pook C, Scarlett A, Readman J, Galloway T (2010). INTEGRATED ASSESSMENT OF OIL POLLUTION USING BIOLOGICAL MONITORING
AND CHEMICAL FINGERPRINTING. Environmental Toxicology and Chemistry, 29(6), 1358-1366.
Lewis C, Caldwell G, Galloway T (2010). Impacts of Environmental Contamination on the Reproductive Ecology of Marine Invertebrates. Meeting of the Division of Chemical Toxicology of the American-Chemical-Society. 16th - 20th Aug 2009.
Uren-Webster TM, Lewis C, Filby AL, Paull GC, Santos EM (2010). Mechanisms of toxicity of di(2-ethylhexyl) phthalate on the reproductive health of male zebrafish.
Aquat Toxicol,
99(3), 360-369.
Abstract:
Mechanisms of toxicity of di(2-ethylhexyl) phthalate on the reproductive health of male zebrafish.
Phthalates are ubiquitous in the aquatic environment and are known to adversely affect male reproductive health in mammals through interactions with multiple receptor systems. However, little is known about the risks they pose to fish. This project investigated the effects of di(2-ethylhexyl) phthalate (DEHP), the most commonly used phthalate, on the reproductive health of male zebrafish (Danio rerio). Males were treated with 0.5, 50 and 5000 mg DEHP kg(-1) (body weight) for a period of 10 days via intraperitoneal injection. The effects of the exposure were assessed by analysing fertilisation success, testis histology, sperm DNA integrity and transcript profiles of the liver and testis. A significant increase in the hepatosomatic index and levels of hepatic vitellogenin transcript were observed following exposure to 5000 mg DEHP kg(-1). Exposure to 5000 mg DEHP kg(-1) also resulted in a reduction in fertilisation success of oocytes spawned by untreated females. However, survival and development of the resulting embryos were unaffected by all treatments, and no evidence of DEHP-induced sperm DNA damage was observed. Exposure to 50 and 5000 mg DEHP kg(-1) caused alterations in the proportion of germ cells at specific stages of spermatogenesis in the testis, including a reduction in the proportion of spermatozoa and an increase in the proportion of spermatocytes, suggesting that DEHP may inhibit the progression of meiosis. In parallel, exposure to 5000 mg DEHP kg(-1) increased the levels of two peroxisome proliferator-activated receptor (PPAR) responsive genes (acyl-coenzyme a oxidase 1 (acox1) and enoyl-coenzyme A, hydratase/3-hydroxyacyl coenzyme a dehydrogenase (ehhadh). These data demonstrated that exposure to high concentrations of DEHP disrupts spermatogenesis in adult zebrafish with a consequent decrease in their ability to fertilise oocytes spawned by untreated females. Furthermore, our data suggest that the adverse effects caused by exposure to DEHP are likely to occur preferentially via PPAR signalling pathways in the testis and oestrogen signalling pathways in the liver. We found no evidence of adverse effects on zebrafish reproductive health following exposure to the concentrations occurring in most aquatic systems, indicating that DEHP alone may not be a causative agent of the reproductive abnormalities seen in wildlife, at least as a result of short-term exposures.
Abstract.
Author URL.
Lewis C, Galloway T (2010). Sperm toxicity and the reproductive ecology of marine invertebrates. Integrated Environmental Assessment and Management, 6(1), 188-190.
Galloway T, Lewis C, Dolciotti I, Johnston BD, Moger J, Regoli F (2010). Sublethal toxicity of nano-titanium dioxide and carbon nanotubes in a sediment dwelling marine polychaete.
Environ Pollut,
158(5), 1748-1755.
Abstract:
Sublethal toxicity of nano-titanium dioxide and carbon nanotubes in a sediment dwelling marine polychaete.
The ecotoxicology of manufactured nanoparticles (MNPs) in estuarine environments is not well understood. Here we explore the hypothesis that nanoTiO(2) and single walled nanotubes (SWNT) cause sublethal impacts to the infaunal species Arenicola marina (lugworm) exposed through natural sediments. Using a 10 day OECD/ASTM 1990 acute toxicity test, no significant effects were seen for SWNT up to 0.03 g/kg and no uptake of SWNTs into tissues was observed. A significant decrease in casting rate (P = 0.018), increase in cellular damage (P = 0.04) and DNA damage in coelomocytes (P = 0.008) was measured for nanoTiO(2), with a preliminary LOEC of 1 g/kg. Coherent anti-stokes Raman scattering microscopy (CARS) located aggregates of TiO(2) of >200 nm within the lumen of the gut and adhered to the outer epithelium of the worms, although no visible uptake of particles into tissues was detected.
Abstract.
Author URL.
2009
Morales-Caselles C, Lewis C, Riba I, Delvalls TA, Galloway T (2009). A multibiomarker approach using the polychaete Arenicola marina to assess oil-contaminated sediments.
Environ Sci Pollut Res Int,
16(6), 618-629.
Abstract:
A multibiomarker approach using the polychaete Arenicola marina to assess oil-contaminated sediments.
BACKGROUND, AIM AND SCOPE: Marine and coastal sediments can accumulate substantial concentrations of metals and hydrocarbons, yet the consequences of this contamination for exposed biota in situ can be difficult to establish. Here, we examine the hypothesis that exposure to contaminated sediments can lead to detrimental effects in sediment-dwelling species. The combination of chemical and biological assessment allows the identification of the impact of chemical contamination, and their use as assessment tools is becoming increasingly important. MATERIALS AND METHODS: the study was applied to marine sediments from the Bay of Algeciras (S Spain) impacted by multiple, low-level contaminant inputs, and the Galician Coast (NW Spain), historically impacted by an oil spill (Prestige 2002), with two reference sites selected in UK and Spain. The common lugworm Arenicola marina was exposed in the laboratory for 14 days to the marine sediments, and a suite of biomarkers of sublethal toxicity was combined with analytical chemistry to test for relationships between sediment contamination and effect. RESULTS: Moderate to strong correlations between organics, metals, and biological responses were observed, with DNA damage as measured using the Comet assay forming the largest contribution toward the observed differences (p < 0.05). The responses of worms from sites experiencing different contamination loads were clearly distinguishable. DISCUSSION: We show how a combination of multibiomarkers with analytical chemistry can be used to investigate the toxicity of marine sediments, enabling the differentiation of sites showing different types of contamination. There are clear relationships in sublethal assays that can be related to the putative mode of toxicity of the contaminants. CONCLUSIONS: the use of A. marina in this way provides a sensitive, holistic approach to sediment toxicity assessment, enabling comparisons between oil-polluted sites to be quantified. RECOMMENDATIONS AND PERSPECTIVES: These tools provide a relatively simple, rapid, and economic way to test the environmental status of oil-contaminated sediment.
Abstract.
Author URL.
Lewis C, Beggah S, Pook C, Guitart C, Redshaw C, Van der Meer JR, Readman JW, Galloway T (2009). Novel Use of a Whole Cell <i>E-coli</i> Bioreporter as a Urinary Exposure Biomarker.
ENVIRONMENTAL SCIENCE & TECHNOLOGY,
43(2), 423-428.
Author URL.
Lewis C, Galloway TS (2009). Reproductive consequences of paternal genotoxin exposure in marine invertebrates.
Environmental Science and Technology,
43(3), 928-933.
Abstract:
Reproductive consequences of paternal genotoxin exposure in marine invertebrates.
Chemicals with the potential to damage DNA are increasingly present in the marine environment, yet our understanding of the long term consequences of DNA damage for populations remains limited. We explore the impact of paternal genotoxin exposure on the reproductive biology of two ecologically important free-spawning marine invertebrates; the polychaete Arenicola marina and the mussel Mytilus edulis. Males were exposed in vivo for 72 h to methyl methanesulfonate and benzo(a)pyrene and the impact on somatic cells and sperm assessed using the Comet assay. A strong correlation between DNA damage in somatic cells and sperm was observed after 24 h exposure (P < 0.001). Recovery in sperm was significantly lower than in coelomocytes after 72 h. The fertilization success of DNA-damaged sperm was unaffected, but a significant percentage of embryos derived from sperm with induced DNA damage exhibited severe developmental abnormalities within 24 h of fertilization, with potential long-term consequences for population success. Further research is required to determine the mechanism by which paternal DNA damage causes disruption of development at this early stage.
Abstract.
Pook C, Lewis C, Galloway T (2009). The metabolic and fitness costs associated with metal resistance in Nereis diversicolor.
Mar Pollut Bull,
58(7), 1063-1071.
Abstract:
The metabolic and fitness costs associated with metal resistance in Nereis diversicolor.
The population of Nereis diversicolor inhabiting the upper reaches of Restronguet Creek, Cornwall, UK is highly resistant to acute zinc and copper toxicity. Here we employ bioenergetic accounting and fecundity counts to demonstrate the energetic costs associated with this phenomenon in terms of the worms' allocation of metabolic resources and reproductive output [P(r)]. Metal-resistant animals exhibited a scope for growth that was 46-62% less than that of animals from two non-resistant reference populations, corresponding to a mean metabolic cost of 1.31 mJ h(-1)mg DW(-1). The resistant population also contained 13% less lipid than animals from the reference populations and 73-81% less carbohydrates. Consequently, mass-specific fecundity was reduced in resistant animals by 39-45%, although material investment in individual gametes did not appear to vary. This demonstrates fitness costs associated with metal resistance in this ecologically important polychaete and adds to our understanding of phenotypic trade-offs associated with resistance.
Abstract.
Author URL.
2008
Lewis C, Karageorgopoulos P (2008). A new species of Marphysa (Eunicidae) from the western Cape of South Africa.
Journal of the Marine Biological Association of the United Kingdom,
88(2), 277-287.
Abstract:
A new species of Marphysa (Eunicidae) from the western Cape of South Africa
The eunicid polychaete Marphysa sanguinea was until recently believed to be a cosmopolitan species, with a distribution ranging from the south-west coast of England to the Pacific coast of America, and New Zealand and Australia in the western Pacific. However, there are many morphological and ecological inter-population differences that render the definitive identification of these numerous populations difficult. The recent designation of a neotype, together with a more detailed morphological description of specimens from the type locality in south-west England, has allowed the concept that M. sanguinea represents a series of cryptic species, to be investigated by examining populations of species previously referred to as Marphysa sanguinea. A new species Marphysa mullawa was described from Moreton Bay Queensland, Australia. In this paper we describe a new species from the western Cape of South Africa which has previously been referred to as 'Marphysa sanguinea', using an integrative approach combining morphological data, RAPD-PCR analysis and a study of the sperm ultra-structure. The South African species is a popular bait animal for local sea anglers and is heavily exploited throughout the western Cape. The RAPD-PCR analysis also demonstrates that populations referred to as 'Marphysa sanguinea' from other geographical locations studied have distinct genetic pools, providing further evidence that Marphysa sanguinea is not a cosmopolitan species and consists of a suite of cryptic species. © 2008 Marine Biological Association in the United Kingdom.
Abstract.
Lewis C, Galloway, T.S. (2008). Genotoxic damage. in polychaetes: a study of species and cell-type sensitivities. Mutation Research-Genetic Toxicology and Environmental Mutagenesis, 654, 69-75.
Lewis C, Pook C, Galloway T (2008). Reproductive toxicity of the water accommodated fraction (WAF) of crude oil in the polychaetes Arenicola marina (L.) and Nereis virens (Sars).
Aquat Toxicol,
90(1), 73-81.
Abstract:
Reproductive toxicity of the water accommodated fraction (WAF) of crude oil in the polychaetes Arenicola marina (L.) and Nereis virens (Sars).
Accidental pollution incidents are common in the marine environment and are often caused by oil-related activities. Here the potential of such an incident to disrupt reproduction in two polychaete species is investigated, using an environmentally relevant preparation of weathered Forties crude oil, i.e. the water accommodated fraction (WAF). Oocytes were collected and exposed to three concentrations of WAF for 1h prior to the addition of sperm, so that fertilization took place under exposure conditions. Fertilization success was significantly reduced in both species by an exposure to WAF concentrations equivalent to 0.38 mgL(-1) PAHs, to just 26.8% in Arenicola marina compared to 76% in Nereis virens. The effects of WAF exposure on fertilization were greatly enhanced at lower sperm concentrations in N. virens, with a complete lack of fertilization reactions observed at sperm concentrations of 10(3)sperm per mL. We therefore suggest a mechanism of toxicity related to sperm swimming behaviour, resulting in reduced sperm:egg collision rates. WAF was found to reduce post-fertilization development rates and have teratogenic effects on early embryonic stages in both species, which exhibited abnormal cleavage patterns and high levels of fluctuating asymmetry. These results illustrate how the presence of crude oil in its soluble form in seawater at the time of a spawning event for either A. marina or N. virens could impact on fertilization success with implications for the fertilization ecology of these free spawning marine invertebrates.
Abstract.
Author URL.
Pook C, Lewis C, Galloway T (2008). The metabolic and fitness costs of resistance to copper and zinc toxicity in <i>Nereis diversicolor</i>.
Author URL.
2005
Lewis C (2005). Aspects of the reproductive biology of the south african polychaete, arenicola loveni loveni (kinberg 1866).
Abstract:
Aspects of the reproductive biology of the south african polychaete, arenicola loveni loveni (kinberg 1866)
Abstract.
Caldwell GS, Lewis C, Olive PJW, Bentley MG (2005). Exposure to 2,4-decadienal negatively impacts upon marine invertebrate larval fitness.
Mar Environ Res,
59(5), 405-417.
Abstract:
Exposure to 2,4-decadienal negatively impacts upon marine invertebrate larval fitness.
Diatoms liberate volatile, biologically active unsaturated aldehydes following cell damage, which negatively impact upon invertebrate reproductive processes such as fertilization, embryogenesis and larval survival. 2,4-Decadienal is frequently identified among the aldehydes produced and is one of the more biologically active. The majority of studies which have examined the toxic effects of diatom aldehydes to invertebrate reproduction have scored egg production and/or hatching success as indicators of biological impacts. There are very few studies which have dealt specifically with the impacts of diatom-derived aldehydes on larval fitness. Larval stages of the polychaetes Arenicola marina and Nereis virens and the echinoderms Asterias rubens and Psammechinus miliaris exposed to 2,4-decadienal at sub 1 microg ml(-1) concentrations suffered reduced survival over the incubation period (day 1-8 post fertilization) with detectable differences for the polychates at a concentration of 0.005 and 0.01-0.1 microg ml(-1) for the echinoderms. Susceptibility of larval N. virens was investigated using stage specific 24 h exposures at 2,4-decadienal concentrations up to 1.5 microg ml(-1). A clear stage specific effect was found, with earlier larval stages most vulnerable. Nectochaete larvae (9-10 d) showed no reduction in survival at the concentrations assayed. Fluctuating asymmetry (FA), defined as random deviations from perfect bilateral symmetry, was used to analyse fitness of larval P. miliaris exposed to 2,4-decadienal at concentrations of 0.1, 0.5 and 1 microg ml(-1). The degree and frequency of asymmetrical development increased with increasing 2,4-decadienal concentration. Equally, as FA increased larval survival decreased. These results provide further support for the teratogenic nature of 2,4-decadienal and its negative impact on invertebrate larval fitness.
Abstract.
Author URL.
Lewis C (2005). Fertilization, post-fertilization development and larval biology of the south african polychaete, arenicola loveni loveni (kinberg 1866).
Abstract:
Fertilization, post-fertilization development and larval biology of the south african polychaete, arenicola loveni loveni (kinberg 1866)
Abstract.
2004
Lewis C, Caldwell GS, Bentley MG, Olive PJW (2004). Effects of a bioactive diatom-derived aldehyde on developmental stability in Nereis virens (Sars) larvae: an analysis using fluctuating asymmetry.
Journal of Experimental Marine Biology and Ecology,
304(1), 1-16.
Abstract:
Effects of a bioactive diatom-derived aldehyde on developmental stability in Nereis virens (Sars) larvae: an analysis using fluctuating asymmetry
Fluctuating asymmetry (FA) is regularly used as an indicator of individual or population fitness and can provide a useful measure of environmental stress. Here the validity of FA as a measure of larval fitness in the polychaete Nereis virens, and hence its value in ecotoxicological bioassays, was determined via a series of laboratory experiments. FA measurements were taken from two or three morphological traits at the nechtochaete larval stage from a number of larval batches with different fertilization dates. Post-fertilization survival for each batch was also measured. Regression analysis revealed a significant negative correlation between the FA index for each batch and percentage survival. The diatom-derived aldehyde 2-trans,4-trans decadienal (DD) is known to disrupt fertilization and early development in N. virens and other marine invertebrates. Here FA is applied to quantify the chronic/sub-lethal effects of DD exposure on post-embryonic development to the nechtochaete stage. Trait size, development rate and FA were all significantly affected by increasing concentrations of DD. This provides further evidence for the teratogenic effects of DD on larval development. It can be concluded from these experiments that FA can be a useful tool for sensitive monitoring of chronic environmental stress and sub-lethal effects of toxins in N. virens larvae, and could provide a useful tool for invertebrate larval ecotoxicology studies. © 2004 Elsevier B.V. All rights reserved.
Abstract.
2003
Lewis C, Olive PJW, Bentley MG (2003). Pre-emptive competition as a selective pressure for early reproduction in the polychaete Nereis virens.
Marine Ecology Progress Series,
254, 199-211.
Abstract:
Pre-emptive competition as a selective pressure for early reproduction in the polychaete Nereis virens
Reproduction in the semelparous polychaete Nereis virens occurs at a time of year when seawater temperatures are lower than the optimum temperatures for fertilization and larval development and at a time when seawater temperatures are rising. This study assesses the possible role of intra-specific competitive interactions between settling N. virens post-larvae as a selective pressure for 'early' reproduction. A series of laboratory competition experiments were conducted between 2 cohorts of N. virens post-larvae, under a range of environmental conditions. Significant pre-emptive competition between settling post-larvae was recorded at 15°C, whereby a survival advantage was gained via prior residence with early larval settlers out-competing later arrivals. This competitive interaction was reduced at lower temperatures and no significant effect was measured at 5°C. An increase in age difference between the 2 cohorts of post-larvae increased the competitive effect, whilst photoperiod regime and food availability had no significant effect on the outcome of these experiments. Intra-specific competition was greatest at the temperatures at which maximum fertilization and development are known to occur, but was reduced at the temperature range at which spawning occurs in the field. It is suggested, therefore, that pre-emptive competition between settling post-larvae forms a strong selective pressure for breeding early at a time of year when temperatures are below the optimum for fertilization and development.
Abstract.
2002
Lewis C, Olive PJ, Bentley MG, Watson G (2002). Does seasonal reproduction occur at the optimal time for fertilization in the polychaetes Arenicola marina L. and Nereis virens Sars?.
Abstract:
Does seasonal reproduction occur at the optimal time for fertilization in the polychaetes Arenicola marina L. and Nereis virens Sars?
Abstract.
2001
Olive PJW, Lewis CN, Last K, Beardall V, Bentley MG (2001). Fitness consequences of seasonal reproduction: Experiments on the polychaete Nereis virens. In Atkinson D, Thorndyke M (Eds.) Environment and animal development: genes, life histories and plasticity, Oxford: BIOS Scientific Publishers Ltd.
2000
Olive PJW, Lewis C, Beardall V (2000). Fitness components of seasonal reproduction: an analysis using Nereis virens as a life history model.
Abstract:
Fitness components of seasonal reproduction: an analysis using Nereis virens as a life history model
Abstract.
