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Reproduction and parasites have significant impacts on marine animal populations globally. This study aimed to investigate the associative effects of host reproduction and a host–parasite interplay on a marine bivalve, along a geographic gradient of latitude. Cockles Cerastoderma edule were sampled from five European sites (54°N to 40°N), between April 2018 and October 2019. A histological survey provided data on trematode (metacercaria and sporocyst life stages), prevalence, and cockle stage of gametogenesis to assess the influence of a latitudinal gradient on both interplays. Sex ratios at the northernmost sites were skewed toward females, and spawning size was reduced at the lower latitudes. Trematode infection did not follow a latitudinal gradient. Localized site‐related drivers, namely seawater temperature, varied spatially, having an impact on cockle–trematode interactions. Spawning was related to elevated temperatures at all sites. Prolonged spawning occurred at southern latitudes, where seawater temperatures were warmer. Trematode prevalence and the impact of trematodes on gametogenesis were found to be spatially variable, but not latitudinally. Therefore, it is not possible to determine the likelihood of boom and bust events in cockles, based on the latitudinal location of a population. In terms of sublethal impacts, it appeared that energy was allocated to reproduction rather than somatic growth in southern populations, with less energy allocated to reproduction in the larger, northern cockles. The demonstrated spatial trend of energy allocation indicates the potential of a temporal trend of reduced cockle growth at northern sites, as a result of warming sea temperatures. This awareness of the spatially varying drivers of populations is crucial considering the potential for these drivers/inhibitors to be exacerbated in a changing marine environment., A European‐wide field study was conducted on parasitism and reproduction in Cerastoderma edule, an ecologically and economically important bivalve. Spatially varying health status of cockles resulted from localized drivers and allocation of energy to reproduction rather than growth at southern locations. Of particular importance was the influence of seawater temperature, with prolonged spawning at southern, warmer sites.

Trematodes are the main macroparasites in coastal waters. The most abundant and widespread form of these parasites is metacercaria. Their impact on their host fitness is considered relatively low but metacercarial larvae of some species can have deleterious effects on individuals and/or populations. This review focused on the cockle Cerastoderma edule and four species of the genus Himasthla; a common host–parasite system in marine coastal environments. Our aims were (1) to review literature concerning Himasthla continua, Himasthla elongata, Himasthla interrupta and Himasthla quissetensis in cockles; (2) to provide molecular signatures of these parasites and (3) to analyse infection patterns using a 20-year monthly database of cockle monitoring from Banc d'Arguin (France). Due to identification uncertainties, the analysis of the database was restricted to H. interrupta and H. quissetensis, and it was revealed that these parasites infect cockles of the same size range. The intensity of parasites increased with cockle size/age. During the colder months, the mean parasite intensity of a cockle cohort decreased, while infection occurred in the warmest season. No inter-specific competition between trematode parasites was detected. Furthermore, even if the intensity of H. interrupta or H. quissetensis infection fluctuated in different years, this did not modify the trematode community structure in the cockles. The intensity of infection of both species was also positively correlated with trematode species richness and metacercarial abundance. This study highlighted the possible detrimental role of Himasthla spp. in cockle population dynamics. It also revealed the risks of misidentification, which should be resolved by further molecular approaches.

A better understanding of growth drivers in shellfish populations including the common cockle Cerastoderma edule is essential, as their future is challenged by unsustainable fishing practices and climate change. In this study the spatial and temporal variabilities in common cockle growth across latitudes were assessed and compared with historical data. Six locations were examined at bimonthly intervals over 19 months; three Irish, two Welsh and one French, spanning the latitudes 54°N to 44°N. The results demonstrated that local abiotic and biotic factors have a larger impact on cockle growth than latitude. Cockles at similar latitudes grew at different rates and sizes, possibly due to factors such as density, fishing activity and interspecific competition. Cockles (0–3 years) impacted by low salinity and parasites (trematodes), exhibited reduced growth in later years. At the warmest, southernmost site growth was lowest in cockles >2 years. Previously, cockles at that site have been shown to spawn almost year-round, possibly diverting energy to gonad development rather than growth. The results opposed previously literature which demonstrated significantly greater growth at lower latitudes. These findings affirm that cockle growth and size is variable due to local abiotic (reduced salinity) and biotic (potentially trematode infection) drivers. Additionally, the synergistic relationship between these factors, i.e. warmer temperatures driving prolonged spawning, and the potential association between lower salinities and trematode prevalence, is concerning due to predicted climate related increases in temperature, precipitation and trematode prevalence/transmission, which may result in northern cockles reaching smaller maximum sizes.

Haplosporidian protist parasites are a major concern for aquatic animal health, as they have been responsible for some of the most significant marine epizootics on record. Despite their impact on food security, aquaculture and ecosystem health, characterizing haplosporidian diversity, distributions and host range remains challenging. In this study, water filtering bivalve species, cockles Cerastoderma edule, mussels Mytilus spp. and Pacific oysters Crassostrea gigas, were screened using molecular genetic assays using deoxyribonucleic acid (DNA) markers for the Haplosporidia small subunit ribosomal deoxyribonucleic acid region. Two Haplosporidia species, both belonging to the Minchinia clade, were detected in C. edule and in the blue mussel Mytilus edulis in a new geographic range for the first time. No haplosporidians were detected in the C. gigas, Mediterranean mussel Mytilus galloprovincialis or Mytilus hybrids. These findings indicate that host selection and partitioning are occurring amongst cohabiting bivalve species. The detection of these Haplosporidia spp. raises questions as to whether they were always present, were introduced unintentionally via aquaculture and or shipping or were naturally introduced via water currents. These findings support an increase in the known diversity of a significant parasite group and highlight that parasite species may be present in marine environments but remain undetected, even in well-studied host species.

Relatively high E. coli and Faecal Streptococci (FS) numbers have been reported in the waters surrounding Blakeney Point, East Anglia, UK, an area containing significant shellfishery industries including mussels and cockles, despite the implementation of development works aimed at reducing residual contamination problems. The aim of this study was to evaluate the potential of using bacterial analyses and sterol profiling to assess the current levels and source of faecal pollution at Blakeney Point. No evidence of significant human faecal contamination of water in and around Blakeney Point could be found using either traditional microbiological analyses or sterol profile analysis. The presence of significant quantities of sitosterol, however, suggests that faecal contamination of water from birds does occur but at the concentration detected would not affect water quality. Analysis of cockles and mussels taken from the area show that negligible levels of coprostanol were present, confirming that faecal pollution was not causing any contamination issues. Apart from cholesterol, brassicasterol, an algal biomarker, as expected was dominant in shellfish flesh. The results confirm that current water treatment processes are successful in ensuring water quality at Blakeney Point and that a combination of microbial testing with sterol profile analysis confirmed that low microbial concentrations of faecal contaminants present in and around Blakeney Point most probably originate from migratory and/or resident bird species.

Cockles are highly appreciated mollusks and provide important services in coastal areas. The two European species, edible (Cerastoderma edule) and lagoon (Cerastoderma glaucum) cockles, are not easily distinguishable, especially when young. Interestingly, the species show different resistance to Marteilia cochillia, the parasite responsible for marteiliosis outbreaks, which is devastating cockle production in some areas. C. edule is severely affected by the parasite, while C. glaucum seems to be resistant, although underlying reasons are still unknown. Hybrids between both species might be interesting to introgress allelic variants responsible for tolerance, either naturally or through artificial selection, from lagoon into edible cockle. Here, we used 2b restriction site-associated DNA sequencing (2b–RAD) to identify single nucleotide polymorphisms (SNP) diagnostic for cockle discrimination (fixed for alternative allelic variants). Among the nine diagnostic SNPs selected, seven were validated using a SNaPshot assay in samples covering most of the distribution range of both species. The validated SNPs were used to check cockles that were suggested to be hybrids by a claimed diagnostic tool based on the internal transcribed spacers of the ribosomal RNA. Although these were shown to be false positives, we cannot rule out the fact that hybrids can occur and be viable. The SNP tool here developed will be valuable for their identification and management. This research funded by INTERREG EUROPEAN PROGRAMME, grant number EAPA_458/2016 (COCKLES project) SI

tBivalves are frequently used to assess environmental contamination, and are often considered goodsentinel and/or bioindicator species. For that reason the bioaccumulation and toxicity induced by metalsand As in the cockle Cerastoderma glaucum, collected from areas with different contamination levelsalong the Óbidos lagoon (Portugal), were used to evaluate the use of this species as sentinel and/orbioindicator. The results showed that areas in the middle of the lagoon presented lower metals and Asconcentrations, lower total organic matter content and lower percentage of fine particles than areasin the Bom Sucesso arm. In all areas Cr, Pb and Cu were the most abundant elements, while Ni, As,Cd and Hg were less abundant. Results also showed a moderate correlation between total elementsconcentrations found in C. glaucum and in sediment, and thus caution should be taken when consideringthis species as a good sentinel species. The present study also revealed that, in general, C. glaucum fromareas in the middle of the lagoon accumulated higher concentrations of metals and As (Biota-SedimentAccumulation Factor >1) than cockles from the most polluted areas located in the Bom Sucesso arm.However, in all areas, the majority of metals (Cu, Cr, Pb) were found in cockles insoluble fraction whichmay explain low cellular damage and reduced oxidative stress responses observed. Therefore, our resultsmay further alert for caution when identifying C. glaucum as a good bioindicator species. Thus, our findingshighlight the fact that studies should be cautious when selecting species for environmental monitoring,since good sentinels or bioindicators in highly polluted systems may not act in the same way in lowor moderately contaminated areas. Furthermore, our study warns for the misclassification of cockles indifferent ecosystems.© 2015 Elsevier Ltd. All rights reserved.1. IntroductionCoastal systems have been constantly threatened by pollution,due to the increase of urbanization, agriculture and industrialactivities (Green-Ruiz and Páez-Osuna, 2001; Poulos et al., 2000).Considering this, it is well established that sediment act as a sink fora variety of contaminants, such as metals and metalloids (Buruaemet al., 2012; Hoffman et al., 2002), affecting benthic organisms(Dauvin, 2008). Environmental impact assessment studies haverelied on monitoring benthic community parameters (e.g. speciesrichness and abundance), measuring the concentrations of selected∗Corresponding author at: Departamento de Biologia & CESAM, Universi-dade de Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.Tel.: +351 234370782; fax: +351 234372587.E-mail info:eu-repo/semantics/publishedVersion

The Federal Government created in 2012 the National Shellfish Sanitation Program which states the rules for the sanitary control in the production and trade of oysters, mussels, scallops and cockles. This report points out some possibilities to set up the trade chain according to the stated requirements and discusses the advantages and disadvantages of these alternatives. The presented possibilities are: Shellfishermen selling their production to Processing Plants; Shellfisherman hiring Processing Plants to process their production; Implementation of new Processing Plants; Implementation of cooperatives; Registration of fish markets within the Inspection Authority. Resumo: O Governo Federal instituiu, em 2012, o Programa Nacional de Controle Higiênico-Sanitário de Moluscos Bivalves, que definiu as regras para o controle sanitário na produção e na comercialização de ostras, mexilhões, vieiras e berbigões. Este informativo aponta algumas possibilidades para a adequação da cadeia produtiva às regras estabelecidas nessa legislação e discute as vantagens e desvantagens dessas alternativas. As possibilidades apresentadas são: venda da produção dos maricultores para estabelecimentos processadores; estabelecimentos processadores prestando serviço de processamento para maricultores; implantação de novos estabelecimentos processadores de moluscos; criação de cooperativas; registro de peixarias junto ao órgão de inspeção.

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-07T14:47:19Z No. of bitstreams: 2 Dissertacao Ana Beatriz Azevedo Ramos Parte 1.pdf: 2179312 bytes, checksum: e86cf4e74b4900df6df15643de96f2c8 (MD5) Dissertacao Ana Beatriz Azevedo Ramos Parte 2.pdf: 1018261 bytes, checksum: d201f1c2a1daab670b190f55dfce1681 (MD5) Made available in DSpace on 2021-01-07T14:47:19Z (GMT). No. of bitstreams: 2 Dissertacao Ana Beatriz Azevedo Ramos Parte 1.pdf: 2179312 bytes, checksum: e86cf4e74b4900df6df15643de96f2c8 (MD5) Dissertacao Ana Beatriz Azevedo Ramos Parte 2.pdf: 1018261 bytes, checksum: d201f1c2a1daab670b190f55dfce1681 (MD5) Previous issue date: 2016-08-31 Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro Polycyclic aromatic hydrocarbons (PAHs) are broadly studied due to their deleterious effects on organisms and humans. Many compounds of PAHs are capable to reacting with the DNA and making it carcinogenic and/or mutagenic. The objective of this study was to evaluate the presence of PAHs in tissue of Crassostrea sp. (oyster), Perna perna (mussels) e Anomalocardia brasiliana (clams/cockles) and the distribution of these compounds in suspended particular matter (SPM) and surface sediments in two contrasting Brazilian coastal areas that it is subject to different levels of anthropogenic impact. PAHs were analyzed by GC-MS in three mussels and oyster size-classes samples and two clams size-classes samples further sediments and SPM. The results for Σ total PAHs in the sediments were 160.8 to 219.9 ng.g-1 and 200.5 to 8139.5 in Ribeirão da Ilha and Ilha do Governador, respectively. To the SPM was obtained a variation between 57.2 to 654.5 ng.g-1 in Ribeirão da Ilha and 25.9 to 133.9 ng.g-1 in the Ilha do Governador. In relation to biological samples, the concentration of Σ total PAHs in the Ribeirão da Ilha varied between 432.7 and 700.2 ng.g-1, 115.7 and 731.9 and 159.9 and 888.9 ng.g-1 for mussels, cockles and oysters, respectively. And in Ilha do Governador the mussels, cockles and oysters composite samples varied between 544.9 and 848.8 ng.g-1, 186.2 and 329.9 ng.g-1, and 941.8 and 1785.1 ng.g-1, respectively. In general, it was observed a greater accumulation of the compounds of lowest molecular weight in the samples. And the predominance of the alkylated compounds, which represent more than 75% of the Σ total PAHs for all biological samples, that can indicate an oil contamination and/or derivatives thereof. There were no significant differences between the different size-class, as there were no significant differences for Σ 16 PAHs and Σ total PAHs between the two regions studied. Our results show that Ribeirão da Ilha and Ilha do Governador organisms display low to moderate contamination, confirming the use of these organisms as sentinels of environmental contamination. All samples had benzo(a)pyrene concentrations below the established European Union threshold to tissue of bivalve mollusks. Os hidrocarbonetos policíclicos aromáticos (HPAs) têm sido largamente estudados devido aos seus efeitos tóxicos em espécies aquáticas e seres humanos. Muitos compostos do grupo dos HPAs são capazes de reagir com o DNA, tornando-se potencialmente carcinogênicos e/ou mutagênicos. O objetivo deste estudo foi avaliar a presença de HPAs em tecido de Crassostrea sp. (ostra), Perna perna (mexilhão) e Anomalocardia brasiliana (vôngole/berbigão) e a distribuição destes compostos no material particulado em suspensão (MPS) e no sedimento superficial em duas áreas da costa brasileira, sujeitas a diferentes graus de contaminação por hidrocarbonetos. Os HPAs foram analisados por cromatografia gasosa acoplada à espectrofotometria de massas em amostras compostas de 3 diferentes classes de tamanhos para mexilhão e ostra e 2 classes de tamanho para os berbigões, no sedimento e no MPS. Os resultados encontrados para o Σ HPAs totais no sedimento foram de 160,8 a 219,9 ng.g-1 e de 200,5 a 8.139,5 em Ribeirão da Ilha e Ilha do Governador, respectivamente. Já para o MPS foi obtido uma variação de 57,2 a 654,5 ng.g-1em Ribeirão da Ilha e 25,9 a 133,9 ng.g-1 na Ilha do Governador. Em relação às amostras biológicas, a concentração do ΣHPAs totais nas amostras de Ribeirão da Ilha variaram entre 432,7 e 700,2 ng.g-1, 115,7 e 731,9 ng.g-1 e 159,9 e 888,9 ng.g-1 para mexilhões, berbigões e ostras, respectivamente. E na Ilha do Governador as amostras compostas de mexilhões, berbigões e ostras variaram entre 544,9 e 848,8 ng.g-1, 186,2 e 329,9 ng.g-1, e 941,8 e 1.785,1 ng.g-1, respectivamente. De modo geral foi observado um maior acúmulo dos compostos de menor peso molecular nas amostras estudadas e um predomínio dos compostos alquilados, que representaram, em todas as amostras biológicas, sempre mais que 75 % dos HPAs totais determinados, apontando uma contaminação por petróleo e/ou derivados. Em relação a diferença de tamanho dos moluscos bivalves, não houve diferenças significativas entre os mesmos, assim como não houve diferenças significativas para o Σ 16 HPAs e Σ HPAs totais entre as duas regiões estudadas. Os resultados apontam para uma baixa e moderada contaminação de HPAs nos sedimentos em Ribeirão da Ilha e Ilha do Governador, respectivamente. Todas as amostras tiveram concentrações de benzo(a)pireno abaixo dos valores limite estabelecido pela Comissão Europeia para tecido mole dos moluscos bivalves.

Activities of Po-210 in cockles Anadara granosa around Peninsular Malaysia have been determined by Alpha Spectrometry using a radiochemical separation technique. The results showed that Po-210 activity distribution varies according to sampling sites. The range of activity was 2.61 ± 1.50 to 309 ± 26 Bq/kg. The lowest mean was recorded from Kuala Selangor and the highest mean was from Mersing. The activity pattern shown by this radionuclide was a decrease with an increase in cockles mass. The activity was higher in cockles of smaller sizes than the larger sized cockles, a pattern attributed to their digestion and metabolism system. The activity intake and effective dose was found to be less than international guidelines and seafood intake was considered safe for human consumption. These findings suggest that regular monitoring should be carried out to help reduce morbidity and mortality among humans as a result of occasional seafood consumption.

The pre-ingestive selection of microphytobenthic algae by the cockle Cerastoderma edule was studied in comparison with diets containing the pelagic diatom Phaeodactylum tricornutum. Treatments with the different diets covered a range of seston concentrations and organic content similar to field conditions. Rejection rates of C. edule exposed to the different treatments were significantly correlated with the concentration of total particulate matter. No significant differences in total rejection rates were found between pelagic and benthic diets. Organic rejection rate was significantly correlated with particulate organic matter of the treatments and no significant differences were found between both diets. Selection efficiency was significantly correlated with particulate organic matter concentration in both diets and no significant differences were found between the diets. Analysis of the pseudofeces composition by flow cytometry from cockles exposed to a mixed diet of microphytobenthic algae and P. tricornutum, showed a preferential ingestion of the pelagic diatom. Benthic species, such as small pennates and Navicula sp., were preferentially ingested in comparison to larger microphytobenthic species. The largest microphytobenthic species, Cylindrotheca sp., was significantly rejected. In general, C. edule is an opportunistic filter feeder that takes advantage of both pelagic and benthic algal cells.

Cockles (Tegillarca granosa) species that found throughout the Indo-Pacific region and this study was conducted in South Korea from late autumn (November 2015) through early spring (April 2016). The proximate composition, mineral content, free amino acid, and fatty acid (FA) profiles and the nutritional quality of the cockles were studied at different stages during the processing. The contents of protein (11.7–13.9/100 g), lipids (1.1–2.5/100 g) and ash (1.6–2.7/100 g) varied significantly (p

The available feeding time of coastal Oystercatchers varies from day to day due to the effect of wind direction and wind force on the water level. If the birds are not able to feed at all during a day, they lose 30 g, or 6% of their body weight. The body weight increases with the duration of the available feeding time, irrespective whether it is day or night. Oystercatchers continue to feed at night, at least in autumn and winter. Although wind force and wind direction affect the daily duration of the available feeding time, this variation fades away if calculated over a number of days, and therefore does not affect the birds in the long-term. Does the body weight increase, or decrease, with the higher costs of living associated with low temperatures and strong winds? A decrease in body weight with increased cost of living would suggest. that the birds are not able to find the extra food required to compensate for the higher maintenance level ('undercompensation'). An increase in body weight, on the other hand, would suggest that the birds in these difficult circumstances eat even more than needed in order to increase their body reserves in cases still worse conditions arrive ('overcompensation'). Unfortunately, the field data are confusing. The weak increase in body weight at low temperatures suggests an overcompensation, but the observed clear decrease in body weight with strong winds suggests an undercompensation. However, the increase of body weight with lower temperature is not large and is possibly due to intervening variables, so it is not clear whether this was an actual overcompensation. The negative effect of wind force on body weight is presumably caused by undercompensation in combination with a decrease in the feeding success.

The available feeding time of coastal Oystercatchers varies from day to day due to the effect of wind direction and wind force on the water level. If the birds are not able to feed at all during a day, they lose 30 g, or 6% of their body weight. The body weight increases with the duration of the available feeding time, irrespective whether it is day or night. Oystercatchers continue to feed at night, at least in autumn and winter. Although wind force and wind direction affect the daily duration of the available feeding time, this variation fades away if calculated over a number of days, and therefore does not affect the birds in the long-term. Does the body weight increase, or decrease, with the higher costs of living associated with low temperatures and strong winds? A decrease in body weight with increased cost of living would suggest. that the birds are not able to find the extra food required to compensate for the higher maintenance level ('undercompensation'). An increase in body weight, on the other hand, would suggest that the birds in these difficult circumstances eat even more than needed in order to increase their body reserves in cases still worse conditions arrive ('overcompensation'). Unfortunately, the field data are confusing. The weak increase in body weight at low temperatures suggests an overcompensation, but the observed clear decrease in body weight with strong winds suggests an undercompensation. However, the increase of body weight with lower temperature is not large and is possibly due to intervening variables, so it is not clear whether this was an actual overcompensation. The negative effect of wind force on body weight is presumably caused by undercompensation in combination with a decrease in the feeding success.

Physiological responses can be used as effective parameters to identify environmentally stressful conditions. In this study, physiology changes such as oxygen consumption, clearance rate, survival in air, condition index and energy reserves were measured on natural populations of cockles collected from different sites at Ria de Aveiro, Portugal. At those sites, sediment samples were collected for Hg concentration analysis. Cockles were used for the evaluation of both the Hg concentration and physiological response. Mercury was detected in the cockle tissue and in the sediment collected from the sampling points both nearby and distant from the main mercury contamination source. The energy content was negatively correlated with both Hg concentration in cockle tissues and survival in air. Nonetheless, the energy content was positively correlated with the condition index, and there was a positive correlation between the survival in air test and the tissue mercury concentration. A PCA-factor analysis explained 86.8% of the total variance. The principal factor (62.7%) consisted of the air survival, the Hg in soft tissues (positive) and the condition index (negative). The second factor (24.1%) consisted of a negative correlation between the oxygen consumption and the clearance rate. Due to their sensitivity to environmental conditions, the physiological responses of cockles can be used to assess the ecological status of aquatic environments. More effort should be invested in investigating the effects of environmental perturbations on cockle health once they are a good reporter organism.

The nomination of the Dutch and German parts of the Wadden Sea as a World Heritage Site within the framework of the World Heritage Convention (WHC) represents high-level recognition of the global importance of this area for millions of migratory birds. It was not the first accolade for the unique wilderness area, but arguably the most prestigious. In its nomination, the World Heritage Convention requests the two countries to strengthen cooperation within the African-Eurasian Flyways, a system of global connectedness by migrant waterbirds in which the Wadden Sea plays a vital role. Here we review the origin and (lack of) implementation of the international conservation instruments available to protect values that are easily undervalued and forgotten, instruments that involve cooperation along the flyway axes. We describe how scientific information sometimes helps governments to implement their obligations, but also how, in spite of indisputable scientific data, governments take decisions contrary to their obligations under international conservation instruments. In some cases such decisions are reversed after scientists have shown measurable declines in the global populations of the migratory waterbirds and established the causality of such declines. At a global level, a few more regional flyway conservation instruments may be needed, but for most parts of the world the instrumentation to secure the well-being of the flyways are in place. It boils down to the determination by governments, informed by good science and under close scrutiny by NGOs, to put them into concrete action. (C) 2012 Elsevier Ltd. All rights reserved.

The pre-ingestive selection of microphytobenthic algae by the cockle Cerastoderma edule was studied in comparison with diets containing the pelagic diatom Phaeodactylum tricornutum. Treatments with the different diets covered a range of seston concentrations and organic content similar to field conditions. Rejection rates of C. edule exposed to the different treatments were significantly correlated with the concentration of total particulate matter. No significant differences in total rejection rates were found between pelagic and benthic diets. Organic rejection rate was significantly correlated with particulate organic matter of the treatments and no significant differences were found between both diets. Selection efficiency was significantly correlated with particulate organic matter concentration in both diets and no significant differences were found between the diets. Analysis of the pseudofeces composition by flow cytometry from cockles exposed to a mixed diet of microphytobenthic algae and P. tricornutum, showed a preferential ingestion of the pelagic diatom. Benthic species, such as small pennates and Navicula sp., were preferentially ingested in comparison to larger microphytobenthic species. The largest microphytobenthic species, Cylindrotheca sp., was significantly rejected. In general, C. edule is an opportunistic filter feeder that takes advantage of both pelagic and benthic algal cells.

Detection of an emerging disease is a crucial aspect for animal health. For the french marine mollusc aquaculture the interest is obvious, after three catastrophic epizooties. The methodological approach must be done by three different disciplines : epidemiology, ecology and marine pathology. Those three approachs are complementary in the special context of marine outbreaks. The uncertainty about many criteria and the lack of proofs feasible for showing the causality link, make the different approachs a necessity. The first step is the study of the three boxes, host, agent, environrnent. This approach, made for studying the cockles of the Croisic's bay could help us to make hypothesis about the possible origins ofmortality, and to a void measurement, sampling and analysis bias. The study of mortality in the Croisic's bay show the practical problem of a study in an open environrnent. An epidemiological strategy is proposed in order to investigate a new-emerging disease in molluscan aquaculture. Specifie and practical arguments are proposed for making causality inferences. A precautionary approach can be deduced from those arguments. Finally a new grid of evaluation of a zoosanitary network making epidemiovilance in marine molluscan aquaculture is proposed., La détection d'une maladie émergente est une question impOliante en santé animale. Elle est particulièrement ressentie en aquaculture des mollusques puisque déjà trois épizooties ont, depuis une vingtaine d'années, provoqué des dégâts irréversibles sur la production française. Les méthodologies à considérer en cas de mortalité anonnale de coquillages sont issues de trois disciplines : l'épidémiologie, l'écologie et la pathologie marine. Ces trois approches sont complémentaires dans un domaine qui traite davantage de la précaution que de la prévention, compte tenu des nombreuses incertitudes et du manque de faisabilité de certains critères de causalité. L'étude des trois compartiments hôte-agent pathogène-milieu est le préalable indispensable à l'étude d'un cas de mortalité anormale, et dans le cas présent, celui des coques du Croisic. Cette approche va permettre de cerner de la façon la plus exhaustive possible toutes les Oligines de mortalité, et d'éviter les principaux biais de mesure, d'échantillonnage et d'analyse. L'étude du cas de mortalité anormale de coques du Croisic de 1997 montre les difficultés pratiques d'application d'une méthodologie standard et la complexité d'interprétation d'un phénomène en milieu ouvert. Cette expérience a été mise à profit pour bâtir une stratégie préventive d'autres cas de mortalités anormales de coquillages en milieu ouvert. Un tableau de critères de causalité ainsi que de nouveaux critères d'évaluation d'un réseau d'épidémiovigilance sont proposés qui s'appliquent en théorie à tout cas de maladie émergente sur les mollusques marins.

Suite aux mortalités massives de coques apparues au Croisic en août 1997, des études ont été mises en place en 1998, avec une coordination des travaux des différents laboratoires impliqués: suivi de la température et de la matière organique dans le sédiment, suivi des animaux et observation des parasites. Les principaux résultats sont: - l'enregistrement de brusques amplitudes thermiques dans le sédiment; - des taux anormalement élevés de matière organique dans le sédiment (20 à 40%) à l'automne 1997, puis des taux plus habituels (

Trois études de zones ont été conduites en 1997/1998 dans le bassin de Marennes-Oléron (Charente-Maritime). Deux concernaient la contamination des coquillages fouisseurs de la Seudre et du banc de Ronce-Perquis. La troisième concernait la contamination des coquillages filtreurs des bouchots à moules des Saumonards (Ile d'Oléron). Ces études avaient pour objet d'évaluer les niveaux de contamination microbiologique et chimique de ces zones de production de coquillages afin que l'Administration puisse en effectuer le classement sanitaire conformément à l'arrêté du 21 juillet 1995. La Seudre, à l'aval de la rivière, a montré, pour les fouisseurs, une qualité microbiologique de catégorie B et une qualité microbiologique de catégorie C pour la partie amont. De son côté, le Banc de Ronce-Perquis a présenté, pour les fouisseurs, une qualité microbiologique de catégorie B. Enfin, la catégorie microbiologique des moules des bouchots des Saumonards est de type A. Le suivi du mercure total, du cadmium et du plomb dans la chair des coquillages a mis en évidence des teneurs inférieures aux valeurs seuil.

The available feeding time of coastal Oystercatchers varies from day to day due to the effect of wind direction and wind force on the water level. If the birds are not able to feed at all during a day, they lose 30 g, or 6% of their body weight. The body weight increases with the duration of the available feeding time, irrespective whether it is day or night. Oystercatchers continue to feed at night, at least in autumn and winter. Although wind force and wind direction affect the daily duration of the available feeding time, this variation fades away if calculated over a number of days, and therefore does not affect the birds in the long-term. Does the body weight increase, or decrease, with the higher costs of living associated with low temperatures and strong winds? A decrease in body weight with increased cost of living would suggest. that the birds are not able to find the extra food required to compensate for the higher maintenance level ('undercompensation'). An increase in body weight, on the other hand, would suggest that the birds in these difficult circumstances eat even more than needed in order to increase their body reserves in cases still worse conditions arrive ('overcompensation'). Unfortunately, the field data are confusing. The weak increase in body weight at low temperatures suggests an overcompensation, but the observed clear decrease in body weight with strong winds suggests an undercompensation. However, the increase of body weight with lower temperature is not large and is possibly due to intervening variables, so it is not clear whether this was an actual overcompensation. The negative effect of wind force on body weight is presumably caused by undercompensation in combination with a decrease in the feeding success.

Ecosystem engineers can strongly modify habitat structure and resource availability across space. In theory, this should alter the spatial distributions of trophically interacting species. In this article, we empirically investigated the importance of spatially extended habitat modification by reef-building bivalves in explaining the distribution of four avian predators and their benthic prey in the Wadden Sea-one of the world's largest intertidal soft-sediment ecosystems. We applied Structural Equation Modeling to identify important direct and indirect interactions between the different components of the system. We found strong spatial gradients in sediment properties into the surrounding area of mixed blue mussel (Mytilus edulis) and Pacific oyster (Crassostrea gigas) reefs, indicating large-scale (100s of m) engineering effects. The benthic community was significantly affected by these gradients, with the abundance of several important invertebrate prey species increasing with sediment organic matter and decreasing with distance to the reefs. Distance from the reef, sediment properties, and benthic food abundance simultaneously explained significant parts of the distribution of oystercatchers (Haematopus ostralegus), Eurasian curlews (Numenius arquata), and bar-tailed godwits (Limosa lapponica). The distribution of black-headed gulls (Chroicoceph ridibundus)-a versatile species with many diet options-appeared unaffected by the reefs. These results suggest that intertidal reef builders can affect consumer-resource dynamics far beyond their own boundaries, emphasizing their importance in intertidal soft-bottom ecosystems like the Wadden Sea.

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010

Johann Heinrich von Thunen-Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries began publishing the Informationen aus der Fischereiforschung – Information on Fishery research in 2010