Padstow, United Kingdom
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Ellis C.D.,University of Exeter | Hodgson D.J.,University of Exeter | Daniels C.L.,National Lobster Hatchery | Collins M.,University of Exeter | Griffiths A.G.F.,The Warehouse
Marine Ecology Progress Series | Year: 2017

The European lobster Homarus gammarus is a marine crustacean prized for seafood, but populations across its range are threatened by fishery overexploitation. The species' larval stages are planktonic, suggesting considerable dispersal among populations. The potential threats of overexploitation and erosion of population structure due to hatchery releases or inadvertent introductions make it important to understand the genetic structuring of populations across multiple geographic scales. Here we assess lobster population structure at a fine scale in Cornwall, southwestern UK, where a hatchery-stocking operation introduces cultured individuals into the wild stock, and at a broader European level, in order to compare the spatial scale of hatchery releases with that of population connectivity. Microsatellite genotypes of 24 individuals from each of 13 locations in Cornwall showed no fine-scale population structure across distances of up to ~230 km. Significant differentiation and isolation by distance were detected at a broader scale, using 300 additional individuals comprising a further 15 European samples. Signals of genetic heterogeneity were evident between an Atlantic cluster and samples from Sweden. Connectivity within the Atlantic and Swedish clusters was high, although evidence for isolation by distance and a transitional zone within the eastern North Sea suggested that direct gene exchange between these stocks is limited and fits a stepping-stone model. We conclude that hatchery-reared lobsters should not be released where broodstock are distantly sourced but, using Cornwall as a case study, microsatellites revealed no evidence that the normal release of hatchery stock exceeds the geographic scale of natural connectivity. © The authors 2017. Open Access under Creative Commons by Attribution Licence.

Small D.P.,St. Francis Xavier University | Small D.P.,University of Plymouth | Small D.P.,Plymouth Marine Laboratory | Calosi P.,University of Plymouth | And 4 more authors.
Marine Biology | Year: 2016

The early benthic juvenile stage of many marine invertebrates is a key step in the transition from the planktonic larval stages to the benthic adult stage. It is characterised by high mortality, in part, due to sensitivities to abiotic factors. The impacts of elevated pCO2 and temperature on the physiology and life history of these sensitive life stages are, however, poorly understood. Consequently, the aim of the present study was to investigate the vulnerability of survival, growth, metabolic rate, feeding rate, organic content, and carapace mineralisation of the early benthic juvenile stage of the European lobster Homarus gammarus (L.) to predicted levels of elevated pCO2 [ocean acidification (OA) and carbon capture and storage (CCS) scenarios] and elevated temperature [ocean warming (OW)]. Early benthic juvenile H. gammarus exhibited increased mortality under both OA and CCS conditions at both experimental temperatures, and these mortalities were due to moult death syndrome. There were OA-related reductions in metabolism, food acquisition, and carapace mineral content, while CCS-exposed lobsters exhibited severe shell dissolution. We suggest that disruption of metabolic and calcium homoeostasis is associated with, and possible the cause of, the increased incidence of moult-related mortalities in juvenile lobsters. We conclude that early benthic juvenile lobsters are sensitive, in terms of physiology and life history traits, to both OA and CCS, with OW sometimes mitigating and at other times increasing sensitivities. © 2016, Springer-Verlag Berlin Heidelberg.

Small D.P.,St. Francis Xavier University | Small D.P.,University of Plymouth | Small D.P.,Plymouth Marine Laboratory | Calosi P.,University of Plymouth | And 4 more authors.
Physiological and Biochemical Zoology | Year: 2015

An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C: N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment. © 2015 by The University of Chicago. All rights reserved.

Daniels C.L.,National Lobster Hatchery | Daniels C.L.,University of Plymouth | Merrifield D.L.,University of Plymouth | Boothroyd D.P.,National Lobster Hatchery | And 3 more authors.
Aquaculture | Year: 2010

The effect of dietary application of a commercial probiotic (Bacillus spp.) and mannan oligosaccharides (MOS), used singularly and combined, on the survival, growth performance and feed cost-benefit of larval Homarus gammarus was assessed. Un-supplemented Artemia (control) or Artemia enriched with probiotics (100 mg l-1 Bacillus spp.), MOS (12 mg l-1) or probiotics + MOS (100 mg l-1 Bacillus spp. + 12 mg l-1 MOS) was fed to four replicate groups of zoeal I lobsters for 30 days. Carapace length and weight of five H. gammarus from each replicate was recorded on 1, 3, 9, 13, 18 days post hatch (dph) and for post-larval condition at 18 dph. Additionally, moulting success was recorded from 14 to 30 dph with survival calculated at 30 dph. Morphological analysis of the posterior intestine was also conducted on larval and post-larval H. gammarus using light and electron microscopy. In a secondary experiment the effects on gut microbiota were assessed using both culture-dependent and culture-independent methods. After 18 dph, larval H. gammarus fed a diet containing Bacillus spp + MOS had significantly (P < 0.01) improved weight gain, carapace length, weight to carapace length ratio, specific growth rate (SGR), food conversion ratio (FCR) and post-larval condition, compared to all other groups. The individual supplementation of either Bacillus or MOS also significantly improved growth parameters, survival and post-larval condition compared to the control group, but to a lesser extent. Survival of all groups was significantly (P < 0.01) elevated after 30 days compared to the control group. Light microscopy demonstrated no significant increases in gut absorptive surface area in larvae or post-larvae receiving biotic supplemented diets. However, electron microscopy revealed significant increases in microvilli length and density in larval and post-larval H. gammarus fed biotic supplemented diets compared to the control group (P < 0.05). Culture-based analysis of gut microbiota demonstrated probiotic Bacillus spp. colonisation in Bacillus and Bacillus + MOS fed larvae. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA revealed that microbial species richness and diversity was reduced in Bacillus + MOS fed post-larval lobsters. Subsequently the microbial profiles of Bacillus + MOS were the most dissimilar to the control group. Improvements seen in the present study appear to be an amalgamation of effects highlighted with the individual use of Bacillus and MOS, and so are probably additive rather than synergistic in nature. © 2010 Elsevier B.V. All rights reserved.

Ellis C.D.,University of Exeter | Hodgson D.J.,University of Exeter | Daniels C.L.,National Lobster Hatchery | Boothroyd D.P.,National Lobster Hatchery | And 2 more authors.
ICES Journal of Marine Science | Year: 2015

Historically, hatcheries in Europe and North America attempted to contribute to the conservation and enhancement of clawed lobster stocks, but lacked monitoring programmes capable of assessing success. In the 1990s, this perspective was changed by the results of restocking and stock enhancement experiments that inserted microwire tags into hatchery-reared juvenile European lobsters (Homarus gammarus) before release. This allowed recapture in sufficient numbers to prove that lobsters had survived and recruited to the mature fishable stock. However, evidence of recruitment still failed to answer key questions about the ultimate ecological and economic benefits. As a result, a growing number of lobster stocking ventures remain hindered by a lack of clear evidence of the effects of their stocking schemes. This review evaluates these experiments and related studies on other fished species, summarizes key findings, and identifies data and knowledge gaps. Although studies of fitness in cultured lobsters provide some of the most encouraging results from the wider field of hatchery-based stocking, the limitations of physical tagging technology have significantly hindered appraisals of stocking impacts. We lack basic knowledge of lobster ecology and population dynamics, especially among prerecruits, and of the impact of stocking on wild lobster population genetics. We advocate the use of genetic methods to further our understanding of population structure, rearing processes, and stocking success. We also recommend that more focused and comprehensive impact assessments are required to provide a robust endorsement or rejection of stocking as a viable tool for the sustainable management of lobster fisheries. © 2014 International Council for the Exploration of the Sea 2014. All rights reserved. For Permissions, please email:

Ellis C.D.,University of Exeter | Knott H.,National Lobster Hatchery | Knott H.,University of Plymouth | Daniels C.L.,National Lobster Hatchery | And 2 more authors.
ICES Journal of Marine Science | Year: 2015

Fecundity in the European lobster (Homarus gammarus) has been shown to exhibit extensive spatial variation across northern Europe. Previously, this has been attributed to a lack of methodological standardization among samples. Instead, we show significant correlations between fecundity and both geographical and environmental drivers. We use linear mixed-effect models to assess the contribution of latitude, longitude, and measures of sea surface temperatures on the size-fecundity relationships of 1058 ovigerous females from 11 locations in the UK, Ireland, and Norway. We include new data for 52 lobsters from Falmouth, UK, the southwest limit of existing samples. Fecundity at mean female size correlated positively with eastings and greater annual ranges in sea surface temperature, but not with mean temperature or latitude. This contradicts the established latitudinal and mean temperature dependence reported for the closely related H. americanus. We postulate that proximity to stable Atlantic currents is the most likely driver of the relationship between fecundity and longitude. Mechanisms are discussed by which egg production or retention may be influenced by temperature range rather than by mean temperature. With further validation, we propose that temperature-correlated fecundity predictions will provide a valuable tool in ensuring that management thresholds are appropriate for the reproductive characteristics of lobster populations. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email:

Halswell P.,University of Exeter | Daniels C.L.,National Lobster Hatchery | Johanning L.,University of Exeter
Aquacultural Engineering | Year: 2016

The presented work describes the hydrodynamic assessment studies of a much needed technical innovation of Sea Based Container Culture (SBCC) as part of a semi-intensive, passive aquaculture culture system for farming the European lobster (Homarus gammarus). Factors that are known to influence growth and survival rates were obtained from previous literature, including flow rate, wave energy and motion characteristics; these factors defined performance criteria for SBCC containers. The internal flow velocities and external flow patterns for different SBCC container designs were measured and used to inform design decisions. Suitable graphical representations have been developed to assess SBCC containers on specific performance criteria. Oyster SBCC containers were found to provide stable motion characteristics but perform poorly against the lower velocity limit, indicating insufficient supply of Dissolved Oxygen (DO) to allow for optimal growth of European lobsters. Internal flow velocities were also measured on un-fouled and fouled SBCC containers; results showed SBCC 2 would not provide enough DO with 66% biofouling coverage (66% biofouling replicates one year deployment) and triggered a redesign. SBCC 1 at 90° yaw angle of attack demonstrated all round good performance against upper and lower velocity limits and motion characteristics; thus showed greatest promise for cultivation of European Lobster. © 2016 The Authors

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