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Grant D. Stentiford - One of the best experts on this subject based on the ideXlab platform.
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Spatial and temporal axes impact ecology of the gut microbiome in juvenile European lobster (Homarus Gammarus)
The ISME Journal, 2020Co-Authors: Corey C. Holt, Carly L. Daniels, Mark Van Der Giezen, Grant D. Stentiford, David BassAbstract:Microbial communities within the gut can markedly impact host health and fitness. To what extent environmental influences affect the differential distribution of these microbial populations may therefore significantly impact the successful farming of the host. Using a sea-based container culture (SBCC) system for the on-growing of European lobster ( Homarus Gammarus ), we tracked the bacterial gut microbiota over a 1-year period. We compared these communities with lobsters of the same cohort, retained in a land-based culture (LBC) system to assess the effects of the culture environment on gut bacterial assemblage and describe the phylogenetic structure of the microbiota to compare deterministic and stochastic assembly across both environments. Bacterial gut communities from SBCCs were generally more phylogenetically clustered, and therefore deterministically assembled, compared to those reared in land-based systems. Lobsters in SBCCs displayed significantly more species-rich and species-diverse gut microbiota compared to those retained in LBC. A reduction in the bacterial diversity of the gut was also associated with higher infection prevalence of the enteric viral pathogen Homarus Gammarus nudivirus (HgNV). SBCCs may therefore benefit the overall health of the host by promoting the assembly of a more diverse gut bacterial community and reducing the susceptibility to disease.
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The first clawed lobster virus Homarus Gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae
Scientific Reports, 2019Co-Authors: Corey C. Holt, Carly L. Daniels, David Bass, Michelle Stone, Kelly S. Bateman, Ronny Van Aerle, Mark Van Der Giezen, Stuart H. Ross, Chantelle Hooper, Grant D. StentifordAbstract:Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters ( Homarus Gammarus ). Transmission electron microscopy revealed infection with a bacilliform virus containing a rod shaped nucleocapsid enveloped in an elliptical membrane. Assembly of PCR-free shotgun metagenomic sequencing produced a circular genome of 107,063 bp containing 97 open reading frames, the majority of which share sequence similarity with a virus infecting the black tiger shrimp: Penaeus monodon nudivirus (PmNV). Multiple phylogenetic analyses confirm the new virus to be a novel member of the Nudiviridae: Homarus Gammarus nudivirus (HgNV). Evidence of occlusion body formation, characteristic of PmNV and its closest relatives, was not observed, questioning the horizontal transmission strategy of HgNV outside of the host. We discuss the potential impacts of HgNV on juvenile lobster growth and mortality and present HgNV-specific primers to serve as a diagnostic tool for monitoring the virus in wild and farmed lobster stocks.
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The first clawed lobster virus Homarus Gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae
'Springer Science and Business Media LLC', 2019Co-Authors: Cc Holt, Stone M, Bass D, Ks Bateman, Van Aerle R, Cl Daniels, Van Der Giezen M, Sh Ross, Hooper C, Grant D. StentifordAbstract:This is the final version. Available from Nature Research via the DOI in this record. Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters (Homarus Gammarus). Transmission electron microscopy revealed infection with a bacilliform virus containing a rod shaped nucleocapsid enveloped in an elliptical membrane. Assembly of PCR-free shotgun metagenomic sequencing produced a circular genome of 107,063 bp containing 97 open reading frames, the majority of which share sequence similarity with a virus infecting the black tiger shrimp: Penaeus monodon nudivirus (PmNV). Multiple phylogenetic analyses confirm the new virus to be a novel member of the Nudiviridae: Homarus Gammarus nudivirus (HgNV). Evidence of occlusion body formation, characteristic of PmNV and its closest relatives, was not observed, questioning the horizontal transmission strategy of HgNV outside of the host. We discuss the potential impacts of HgNV on juvenile lobster growth and mortality and present HgNV-specific primers to serve as a diagnostic tool for monitoring the virus in wild and farmed lobster stocks.Centre for Environment, Fisheries and Aquaculture Science (CEFAS)Innovate UKBBSR
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Halioticida noduliformans infection in eggs of lobster (Homarus Gammarus) reveals its generalist parasitic strategy in marine invertebrates
Journal of Invertebrate Pathology, 2018Co-Authors: Corey C. Holt, Rachel Foster, Carly L. Daniels, Mark Van Der Giezen, Stephen W. Feist, Grant D. Stentiford, David BassAbstract:Abstract A parasite exhibiting Oomycete-like morphology and pathogenesis was isolated from discoloured eggs of the European lobster (Homarus Gammarus) and later found in gill tissues of adults. Group-specific Oomycete primers were designed to amplify the 18S ribosomal small subunit (SSU), which initially identified the organism as the same as the ‘Haliphthoros’ sp. NJM 0034 strain (AB178865.1) previously isolated from abalone (imported from South Australia to Japan). However, in accordance with other published SSU-based phylogenies, the NJM 0034 isolate did not group with other known Haliphthoros species in our Maximum Likelihood and Bayesian phylogenies. Instead, the strain formed an orphan lineage, diverging before the separation of the Saprolegniales and Pythiales. Based upon 28S large subunit (LSU) phylogeny, our own isolate and the previously unidentified 0034 strain are both identical to the abalone pathogen Halioticida noduliformans. The genus shares morphological similarities with Haliphthoros and Halocrusticida and forms a clade with these in LSU phylogenies. Here, we confirm the first recorded occurrence of H. noduliformans in European lobsters and associate its presence with pathology of the egg mass, likely leading to reduced fecundity.
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histological intersex ovotestis in the european lobster Homarus Gammarus and a commentary on its potential mechanistic basis
Diseases of Aquatic Organisms, 2012Co-Authors: Grant D. StentifordAbstract:This paper provides the first report of the intersex (ovotestis) condition in the Euro- pean lobster Homarus Gammarus. A single specimen (10% of males sampled) presenting the con- dition was discovered as part of routine sampling, from the Weymouth Bay region of the English Channel, UK. The lobster presented externally as a male, but upon histological examination was seen to contain an ovotestis, containing elements of both male and female gonadal tissue. Previtel- logenic oocytes were present in several otherwise normal seminiferous tubules throughout the testis. The seminiferous tubules were also engaged in the production of apparently normal sperm lineages, and mature spermatozoa were present within the tubule lumens. In some cases, oocytes were in direct contact with mature spermatozoa within the same seminiferous tubules. The signif- icance of this finding is placed into context with a previous observation of elevated intersexuality in the congeneric species H. americanus collected from specific sites in Canadian waters. The potential mechanism for development of intersex in lobsters, which is probably related to a dis- rupted signalling to the germinal component of the testis from the decapod androgenic gland, may be an effect of exposure to endocrine disrupting chemicals in the marine environment.
Carly L. Daniels - One of the best experts on this subject based on the ideXlab platform.
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ageing european lobsters Homarus Gammarus using dna methylation of evolutionarily conserved ribosomal dna
Evolutionary Applications, 2021Co-Authors: Eleanor A Fairfield, Carly L. Daniels, David S Richardson, Christopher L Butler, Ewen Bell, Martin I TaylorAbstract:Crustaceans are notoriously difficult to age because of their indeterminate growth and the moulting of their exoskeleton throughout life. The poor knowledge of population age structure in crustaceans therefore hampers accurate assessment of population dynamics and consequently sustainable fisheries management. Quantification of DNA methylation of the evolutionarily conserved ribosomal DNA (rDNA) may allow for age prediction across diverse species. However, the rDNA epigenetic clock remains to be tested in crustaceans, despite its potential to inform both ecological and evolutionary understanding, as well as conservation and management practices. Here, patterns of rDNA methylation with age were measured across 5154 bp of rDNA corresponding to 355 quality-filtered loci in the economically important European lobster (Homarus Gammarus). Across 0- to 51-month-old lobsters (n = 155), there was a significant linear relationship between age and percentage rDNA methylation in claw tissue at 60% of quality-filtered loci (n = 214). An Elastic Net regression model using 46 loci allowed for the accurate and precise age estimation of individuals (R 2 = 0.98; standard deviation = 1.6 months). Applying this ageing model to antennal DNA from wild lobsters of unknown age (n = 38) resulted in predicted ages that are concordant with estimates of minimum size at age in the wild (mean estimated age = 40.1 months; range 32.8-55.7 months). Overall, the rDNA epigenetic clock shows potential as a novel, nonlethal ageing technique for European lobsters. However, further validation is required across a wider range of known-age individuals and tissue types before the model can be used in fisheries management.
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Spatial and temporal axes impact ecology of the gut microbiome in juvenile European lobster (Homarus Gammarus)
The ISME Journal, 2020Co-Authors: Corey C. Holt, Carly L. Daniels, Mark Van Der Giezen, Grant D. Stentiford, David BassAbstract:Microbial communities within the gut can markedly impact host health and fitness. To what extent environmental influences affect the differential distribution of these microbial populations may therefore significantly impact the successful farming of the host. Using a sea-based container culture (SBCC) system for the on-growing of European lobster ( Homarus Gammarus ), we tracked the bacterial gut microbiota over a 1-year period. We compared these communities with lobsters of the same cohort, retained in a land-based culture (LBC) system to assess the effects of the culture environment on gut bacterial assemblage and describe the phylogenetic structure of the microbiota to compare deterministic and stochastic assembly across both environments. Bacterial gut communities from SBCCs were generally more phylogenetically clustered, and therefore deterministically assembled, compared to those reared in land-based systems. Lobsters in SBCCs displayed significantly more species-rich and species-diverse gut microbiota compared to those retained in LBC. A reduction in the bacterial diversity of the gut was also associated with higher infection prevalence of the enteric viral pathogen Homarus Gammarus nudivirus (HgNV). SBCCs may therefore benefit the overall health of the host by promoting the assembly of a more diverse gut bacterial community and reducing the susceptibility to disease.
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The first clawed lobster virus Homarus Gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae
Scientific Reports, 2019Co-Authors: Corey C. Holt, Carly L. Daniels, David Bass, Michelle Stone, Kelly S. Bateman, Ronny Van Aerle, Mark Van Der Giezen, Stuart H. Ross, Chantelle Hooper, Grant D. StentifordAbstract:Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters ( Homarus Gammarus ). Transmission electron microscopy revealed infection with a bacilliform virus containing a rod shaped nucleocapsid enveloped in an elliptical membrane. Assembly of PCR-free shotgun metagenomic sequencing produced a circular genome of 107,063 bp containing 97 open reading frames, the majority of which share sequence similarity with a virus infecting the black tiger shrimp: Penaeus monodon nudivirus (PmNV). Multiple phylogenetic analyses confirm the new virus to be a novel member of the Nudiviridae: Homarus Gammarus nudivirus (HgNV). Evidence of occlusion body formation, characteristic of PmNV and its closest relatives, was not observed, questioning the horizontal transmission strategy of HgNV outside of the host. We discuss the potential impacts of HgNV on juvenile lobster growth and mortality and present HgNV-specific primers to serve as a diagnostic tool for monitoring the virus in wild and farmed lobster stocks.
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Halioticida noduliformans infection in eggs of lobster (Homarus Gammarus) reveals its generalist parasitic strategy in marine invertebrates
Journal of Invertebrate Pathology, 2018Co-Authors: Corey C. Holt, Rachel Foster, Carly L. Daniels, Mark Van Der Giezen, Stephen W. Feist, Grant D. Stentiford, David BassAbstract:Abstract A parasite exhibiting Oomycete-like morphology and pathogenesis was isolated from discoloured eggs of the European lobster (Homarus Gammarus) and later found in gill tissues of adults. Group-specific Oomycete primers were designed to amplify the 18S ribosomal small subunit (SSU), which initially identified the organism as the same as the ‘Haliphthoros’ sp. NJM 0034 strain (AB178865.1) previously isolated from abalone (imported from South Australia to Japan). However, in accordance with other published SSU-based phylogenies, the NJM 0034 isolate did not group with other known Haliphthoros species in our Maximum Likelihood and Bayesian phylogenies. Instead, the strain formed an orphan lineage, diverging before the separation of the Saprolegniales and Pythiales. Based upon 28S large subunit (LSU) phylogeny, our own isolate and the previously unidentified 0034 strain are both identical to the abalone pathogen Halioticida noduliformans. The genus shares morphological similarities with Haliphthoros and Halocrusticida and forms a clade with these in LSU phylogenies. Here, we confirm the first recorded occurrence of H. noduliformans in European lobsters and associate its presence with pathology of the egg mass, likely leading to reduced fecundity.
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sea based container culture sbcc hydrodynamic design assessment for european lobsters Homarus Gammarus
Aquacultural Engineering, 2016Co-Authors: Peter Halswell, Carly L. Daniels, Lars JohanningAbstract:Abstract 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.
Corey C. Holt - One of the best experts on this subject based on the ideXlab platform.
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Spatial and temporal axes impact ecology of the gut microbiome in juvenile European lobster (Homarus Gammarus)
The ISME Journal, 2020Co-Authors: Corey C. Holt, Carly L. Daniels, Mark Van Der Giezen, Grant D. Stentiford, David BassAbstract:Microbial communities within the gut can markedly impact host health and fitness. To what extent environmental influences affect the differential distribution of these microbial populations may therefore significantly impact the successful farming of the host. Using a sea-based container culture (SBCC) system for the on-growing of European lobster ( Homarus Gammarus ), we tracked the bacterial gut microbiota over a 1-year period. We compared these communities with lobsters of the same cohort, retained in a land-based culture (LBC) system to assess the effects of the culture environment on gut bacterial assemblage and describe the phylogenetic structure of the microbiota to compare deterministic and stochastic assembly across both environments. Bacterial gut communities from SBCCs were generally more phylogenetically clustered, and therefore deterministically assembled, compared to those reared in land-based systems. Lobsters in SBCCs displayed significantly more species-rich and species-diverse gut microbiota compared to those retained in LBC. A reduction in the bacterial diversity of the gut was also associated with higher infection prevalence of the enteric viral pathogen Homarus Gammarus nudivirus (HgNV). SBCCs may therefore benefit the overall health of the host by promoting the assembly of a more diverse gut bacterial community and reducing the susceptibility to disease.
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The first clawed lobster virus Homarus Gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae
Scientific Reports, 2019Co-Authors: Corey C. Holt, Carly L. Daniels, David Bass, Michelle Stone, Kelly S. Bateman, Ronny Van Aerle, Mark Van Der Giezen, Stuart H. Ross, Chantelle Hooper, Grant D. StentifordAbstract:Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters ( Homarus Gammarus ). Transmission electron microscopy revealed infection with a bacilliform virus containing a rod shaped nucleocapsid enveloped in an elliptical membrane. Assembly of PCR-free shotgun metagenomic sequencing produced a circular genome of 107,063 bp containing 97 open reading frames, the majority of which share sequence similarity with a virus infecting the black tiger shrimp: Penaeus monodon nudivirus (PmNV). Multiple phylogenetic analyses confirm the new virus to be a novel member of the Nudiviridae: Homarus Gammarus nudivirus (HgNV). Evidence of occlusion body formation, characteristic of PmNV and its closest relatives, was not observed, questioning the horizontal transmission strategy of HgNV outside of the host. We discuss the potential impacts of HgNV on juvenile lobster growth and mortality and present HgNV-specific primers to serve as a diagnostic tool for monitoring the virus in wild and farmed lobster stocks.
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Halioticida noduliformans infection in eggs of lobster (Homarus Gammarus) reveals its generalist parasitic strategy in marine invertebrates
Journal of Invertebrate Pathology, 2018Co-Authors: Corey C. Holt, Rachel Foster, Carly L. Daniels, Mark Van Der Giezen, Stephen W. Feist, Grant D. Stentiford, David BassAbstract:Abstract A parasite exhibiting Oomycete-like morphology and pathogenesis was isolated from discoloured eggs of the European lobster (Homarus Gammarus) and later found in gill tissues of adults. Group-specific Oomycete primers were designed to amplify the 18S ribosomal small subunit (SSU), which initially identified the organism as the same as the ‘Haliphthoros’ sp. NJM 0034 strain (AB178865.1) previously isolated from abalone (imported from South Australia to Japan). However, in accordance with other published SSU-based phylogenies, the NJM 0034 isolate did not group with other known Haliphthoros species in our Maximum Likelihood and Bayesian phylogenies. Instead, the strain formed an orphan lineage, diverging before the separation of the Saprolegniales and Pythiales. Based upon 28S large subunit (LSU) phylogeny, our own isolate and the previously unidentified 0034 strain are both identical to the abalone pathogen Halioticida noduliformans. The genus shares morphological similarities with Haliphthoros and Halocrusticida and forms a clade with these in LSU phylogenies. Here, we confirm the first recorded occurrence of H. noduliformans in European lobsters and associate its presence with pathology of the egg mass, likely leading to reduced fecundity.
David Bass - One of the best experts on this subject based on the ideXlab platform.
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Spatial and temporal axes impact ecology of the gut microbiome in juvenile European lobster (Homarus Gammarus)
The ISME Journal, 2020Co-Authors: Corey C. Holt, Carly L. Daniels, Mark Van Der Giezen, Grant D. Stentiford, David BassAbstract:Microbial communities within the gut can markedly impact host health and fitness. To what extent environmental influences affect the differential distribution of these microbial populations may therefore significantly impact the successful farming of the host. Using a sea-based container culture (SBCC) system for the on-growing of European lobster ( Homarus Gammarus ), we tracked the bacterial gut microbiota over a 1-year period. We compared these communities with lobsters of the same cohort, retained in a land-based culture (LBC) system to assess the effects of the culture environment on gut bacterial assemblage and describe the phylogenetic structure of the microbiota to compare deterministic and stochastic assembly across both environments. Bacterial gut communities from SBCCs were generally more phylogenetically clustered, and therefore deterministically assembled, compared to those reared in land-based systems. Lobsters in SBCCs displayed significantly more species-rich and species-diverse gut microbiota compared to those retained in LBC. A reduction in the bacterial diversity of the gut was also associated with higher infection prevalence of the enteric viral pathogen Homarus Gammarus nudivirus (HgNV). SBCCs may therefore benefit the overall health of the host by promoting the assembly of a more diverse gut bacterial community and reducing the susceptibility to disease.
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The first clawed lobster virus Homarus Gammarus nudivirus (HgNV n. sp.) expands the diversity of the Nudiviridae
Scientific Reports, 2019Co-Authors: Corey C. Holt, Carly L. Daniels, David Bass, Michelle Stone, Kelly S. Bateman, Ronny Van Aerle, Mark Van Der Giezen, Stuart H. Ross, Chantelle Hooper, Grant D. StentifordAbstract:Viral diseases of crustaceans are increasingly recognised as challenges to shellfish farms and fisheries. Here we describe the first naturally-occurring virus reported in any clawed lobster species. Hypertrophied nuclei with emarginated chromatin, characteristic histopathological lesions of DNA virus infection, were observed within the hepatopancreatic epithelial cells of juvenile European lobsters ( Homarus Gammarus ). Transmission electron microscopy revealed infection with a bacilliform virus containing a rod shaped nucleocapsid enveloped in an elliptical membrane. Assembly of PCR-free shotgun metagenomic sequencing produced a circular genome of 107,063 bp containing 97 open reading frames, the majority of which share sequence similarity with a virus infecting the black tiger shrimp: Penaeus monodon nudivirus (PmNV). Multiple phylogenetic analyses confirm the new virus to be a novel member of the Nudiviridae: Homarus Gammarus nudivirus (HgNV). Evidence of occlusion body formation, characteristic of PmNV and its closest relatives, was not observed, questioning the horizontal transmission strategy of HgNV outside of the host. We discuss the potential impacts of HgNV on juvenile lobster growth and mortality and present HgNV-specific primers to serve as a diagnostic tool for monitoring the virus in wild and farmed lobster stocks.
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Halioticida noduliformans infection in eggs of lobster (Homarus Gammarus) reveals its generalist parasitic strategy in marine invertebrates
Journal of Invertebrate Pathology, 2018Co-Authors: Corey C. Holt, Rachel Foster, Carly L. Daniels, Mark Van Der Giezen, Stephen W. Feist, Grant D. Stentiford, David BassAbstract:Abstract A parasite exhibiting Oomycete-like morphology and pathogenesis was isolated from discoloured eggs of the European lobster (Homarus Gammarus) and later found in gill tissues of adults. Group-specific Oomycete primers were designed to amplify the 18S ribosomal small subunit (SSU), which initially identified the organism as the same as the ‘Haliphthoros’ sp. NJM 0034 strain (AB178865.1) previously isolated from abalone (imported from South Australia to Japan). However, in accordance with other published SSU-based phylogenies, the NJM 0034 isolate did not group with other known Haliphthoros species in our Maximum Likelihood and Bayesian phylogenies. Instead, the strain formed an orphan lineage, diverging before the separation of the Saprolegniales and Pythiales. Based upon 28S large subunit (LSU) phylogeny, our own isolate and the previously unidentified 0034 strain are both identical to the abalone pathogen Halioticida noduliformans. The genus shares morphological similarities with Haliphthoros and Halocrusticida and forms a clade with these in LSU phylogenies. Here, we confirm the first recorded occurrence of H. noduliformans in European lobsters and associate its presence with pathology of the egg mass, likely leading to reduced fecundity.
Annlisbeth Agnalt - One of the best experts on this subject based on the ideXlab platform.
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exposure to teflubenzuron negatively impacts exploratory behavior learning and activity of juvenile european lobster Homarus Gammarus
Ecotoxicology and Environmental Safety, 2018Co-Authors: Alessandro Cresci, Ole Bent Samuelsen, Caroline M F Durif, Reidun M Bjelland, Anne Berit Skiftesvik, Howard I Browman, Annlisbeth AgnaltAbstract:Abstract Infestations with salmon lice, a parasitic copepod, is a major problem in the salmon farming industry. Teflubenzuron is an in-feed pharmaceutical applied to control lice outbreaks; the standard medication is 10 mg per kg fish per day for seven days. Surveys reveal that teflubenzuron accumulates and persists in the sediment around fish farms and causes deformities and mortality in juvenile European lobster (Homarus Gammarus), a species commonly found in the vicinity of salmon farms in Norway. To date, there is no information on sub-lethal effects of teflubenzuron on, for example, behavior. We conducted an experiment to assess possible difference in the shelter seeking behavior of teflubenzuron-exposed (N = 19) vs. not exposed (N = 19) H. Gammarus juveniles. The teflubenzuron-exposed juveniles had been given very low concentrations, 1.7 µg per pellet twice per week for 113 days prior to this experiment. The concentration of teflubenzuron was estimated to be less than 1 ng/g lobster when they were tested in the behavior experiment. Animals were placed in a lane with a shelter at one end. Once a lobster had found and entered the shelter, they were repeatedly displaced back to the opposite end of the lane, for a total of 3 repeated runs per animal. Three of the exposed juveniles failed to settle in the shelter, and the remaining teflubenzuron-exposed animals took significantly more time to explore the environment and to find and recognize shelter. Furthermore, exposed lobsters also exhibited slower walking speed compared to the controls. These results demonstrate that teflubenzuron significantly reduces exploratory behavior, learning and activity of juvenile H. Gammarus. Thus, exposure to teflubenzuron could increase predation mortality of juvenile lobsters in the wild.
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an enriched environment promotes shelter seeking behaviour and survival of hatchery produced juvenile european lobster Homarus Gammarus
PLOS ONE, 2016Co-Authors: Stian Aspaas, Ellen Sofie Grefsrud, Anders Ferno, Knut Helge Jensen, Henrik Trengereid, Annlisbeth AgnaltAbstract:The high loss of newly released hatchery-reared European lobster (Homarus Gammarus) juveniles for stock enhancement is believed to be the result of maladaptive anti-predator behaviour connected to deprived stimuli in the hatchery environment. Our objective was to learn if an enriched hatchery environment enhances shelter-seeking behaviour and survival. In the “naive” treatment, the juveniles were raised in single compartments without substrate and shelter whereas juveniles in the “exposed” treatment experienced substrate, shelter and interactions with conspecifics. Three experiments with increasing complexity were conducted. Few differences in shelter-seeking behaviour were found between treatments when one naive or one exposed juvenile were observed alone. When observing interactions between one naive and one exposed juvenile competing for shelter, naive juveniles more often initiated the first aggressive encounter. The third experiment was set up to simulate a release for stock enhancement. Naive and exposed juveniles were introduced to a semi-natural environment including substrate, a limited number of shelters and interactions with conspecifics. Shelter occupancy was recorded three times during a period of 35 days. Exposed juveniles occupied more shelters, grew larger and had higher survival compared with naive juveniles. Our results demonstrate that experience of environmental complexity and social interactions increase shelter-seeking ability and survival in hatchery reared lobster juveniles.
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population characteristics of the world s northernmost stocks of european lobster Homarus Gammarus in tysfjord and nordfolda northern norway
New Zealand Journal of Marine and Freshwater Research, 2009Co-Authors: Annlisbeth Agnalt, Knut Eirik Jorstad, Eva Farestveit, Kaare Gundersen, Tore S KristiansenAbstract:Abstract The northernmost self‐sustaining populations of European lobster (Homarus Gammarus) are found north of the Arctic Circle (66°33'N), in Tysfjord and Nordfolda, two large, deep, and relatively warm fjord systems in northern Norway. In contrast to most other Norwegian lobster populations, these genetically distinct populations are still found at relative high densities. This paper presents results from surveys conducted in the fjord systems in 1964–65 and between 1992 to 2005, and compares reproductive characteristics, morphology, growth, and catch‐per‐unit‐effort (CPUE). The lobster population in Stefjord, one of four individual fjords in the Tysfjord fjord system, was characterised by a small mean carapace length (CL, 78±11 mm SD), and less than 18% of the catches were larger than the minimum legal size of 88 mm CL. Growth rates were also low, with an average increment per moult of 4.0 ± 0.9 mm CL for females and 5.6 ± 2.1 mm for males. The crusher claw increased on average 5.5 ± 2.3 mm at each mo...
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fecundity of the european lobster Homarus Gammarus off southwestern norway after stock enhancement do cultured females produce as many eggs as wild females
Ices Journal of Marine Science, 2008Co-Authors: Annlisbeth AgnaltAbstract:Agnalt A-L. 2008. Fecundity of the European lobster (Homarus Gammarus) off southwestern Norway after stock enhancement; do cultured females produce as many eggs as wild females? - ICES Journal of Marine Science, 65: 164-170.An enhancement project with European lobster (Homarus Gammarus) began in 1990, and over the following 5 years some 128 000 hatchery-produced juveniles of average age about 9 months were released around the islands of Kvitsoy, southwestern Norway. Recaptures of reproductive female lobsters of cultured origin raised the question as to whether hatchery-reared females could perform as well as wild females in terms of egg production. A fecundity study therefore compared females of wild and cultured origin during autumn of 1996, and spring and autumn of 1997. No significant differences were found in size-specific fecundity (F = 0.0045 CL 3.22 ; n = 215; r 2 = 0.88; CL is carapace length), weight of egg mass, embryonic development, or egg size (diameter or dry weight). Further, the number of eggs produced per female was in the same range as it was about 90 years ago, i.e. before the local stock collapsed. There were no indications of significant differences in fecundity between seasons and therefore no egg loss for the incubation period from October 1996 to the end of May 1997. The results suggest that more eggs are produced by the larger females than in lobsters elsewhere in Europe, but compare well with American lobsters (H. americanus) of the same size range and living in the same temperature regime (off Newfoundland).
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growth reproductive cycle and movement of berried european lobsters Homarus Gammarus in a local stock off southwestern norway
Ices Journal of Marine Science, 2007Co-Authors: Annlisbeth Agnalt, Tore S Kristiansen, Knut Eirik JorstadAbstract:AbstractAgnatt, A-L., Kristiansen T. S., and Jorstad K. E. 2007. Growth, reproductive cycle, and movement of berried kuropean lobsters (Homarus Gammarus) in a local stock off southwestern Norway. - ICES Journal of Marine Science, 64: 288-297.The Norwegian fishery for the European lobster (Homarus Gammarus) collapsed between 1960 and 1980, to 90% of the females. A small number moulted and spawned a few weeks after hatching. More than 95% of the recaptures were taken within a radius of 1 km of the release area. Egg production varied considerably between seasons. Reproductive potential (RP) of landed berried females underestimated egg production compared with what was actually produced (AE). For the entire period, RP was estimated to be about 15.0 million eggs, and AE to be 17.2 million eggs. Cultured females contributed 27% of AE. To reduce the fishing mortality in a heavily fished and depleted population is vital. A ban on landing berried females would be a valuable first step in attempting to increase the spawning biomass.