RESUMO
Knowledge of genetic structure at the finest level is essential for the conservation of genetic resources. Despite no visible barriers limiting gene flow, significant genetic structure has been shown in marine species. The common cockle (Cerastoderma edule) is a bivalve of great commercial and ecological value inhabiting the Northeast Atlantic Ocean. Previous population genomics studies demonstrated significant structure both across the Northeast Atlantic, but also within small geographic areas, highlighting the need to investigate fine-scale structuring. Here, we analysed two geographic areas that could represent opposite models of structure for the species: (1) the SW British Isles region, highly fragmented due to biogeographic barriers, and (2) Galicia (NW Spain), a putative homogeneous region. A total of 9250 SNPs genotyped by 2b-RAD on 599 individuals from 22 natural beds were used for the analysis. The entire SNP dataset mostly confirmed previous observations related to genetic diversity and differentiation; however, neutral and divergent SNP outlier datasets enabled disentangling physical barriers from abiotic environmental factors structuring both regions. While Galicia showed a homogeneous structure, the SW British Isles region was split into four reliable genetic regions related to oceanographic features and abiotic factors, such as sea surface salinity and temperature. The information gathered supports specific management policies of cockle resources in SW British and Galician regions also considering their particular socio-economic characteristics; further, these new data will be added to those recently reported in the Northeast Atlantic to define sustainable management actions across the whole distribution range of the species.
Assuntos
Cardiidae , Humanos , Animais , Oceano Atlântico , Espanha , Genótipo , Estruturas GenéticasRESUMO
Background: Early life stress is a key predisposing factor for depression and anxiety disorders. Selective serotonin re-uptake inhibitors (SSRI) are frequently used as the first line of pharmacology treatment for depression but have several negative qualities, i.e. a delay or absence of effectiveness and negative side-effects. Therefore, there is a growing need for new nutraceutical-based strategies to blunt the effects of adverse-life events.Objectives: This study aimed to use the maternal separation model in rats to test the efficacy of fish oil dietary supplementation, on its own and in conjunction with the SSRI anti-depressant fluoxetine, as a treatment for depressive and anxiety-like symptoms associated with early life stress.Methods: Behavioural tests (open field test, elevated plus maze test and forced swim test) and biochemical markers (corticosterone, BDNF, brain fatty acids and short chain fatty acids) were used to analyse the effects of the dietary treatments. Gut microbial communities and relating metabolites (SCFA) were analysed to investigate possible changes in the microbiota-gut-brain axis.Results: Maternally separated rats showed depressive-like behaviours in the forced swim and open field tests. These behaviours were prevented significantly by fluoxetine administration and in part by fish oil supplementation. Associated biochemical changes reported include altered brain fatty acids, significantly lower plasma corticosterone levels (AUC) and reduced brain stem serotonin turnover, compared to untreated, maternally separated (MS) rats. Untreated MS animals had significantly lower ratios of SCFA producers such as Caldicoprobacteraceae, Streptococcaceae, Rothia, Lachnospiraceae_NC2004_group, and Ruminococcus_2, along with significantly reduced levels of total SCFA compared to non-separated animals. Compared to untreated MS animals, animals fed fish oil had significantly higher Bacteroidetes and Prevotellaceae and reduced levels of butyrate, while fluoxetine treatment resulted in significantly higher levels of Neochlamydia, Lachnoclostridium, Acetitomaculum and Stenotrophomonas and, acetate and propionate.Conclusion: Despite the limitations in extrapolating from animal behavioural data and the notable differences in pharmacokinetics between rodents and humans, the results of this study provide a further advancement into the understanding of some of the complex systems within which nutraceuticals and pharmaceuticals effect the microbiota-gut-brain axis.
Assuntos
Ansiedade , Depressão , Óleos de Peixe , Estresse Psicológico , Animais , Ratos , Comportamento Animal , Suplementos Nutricionais , Modelos Animais de Doenças , Óleos de Peixe/farmacologia , Privação MaternaRESUMO
Despite coinfections being recognized as the rule in animal populations, most studies focus on single pathogen systems. Pathogen interaction networks and the drivers of such associations are lacking in disease ecology studies. Common cockle Cerastoderma edule populations are exposed to a great diversity of pathogens, thus making them a good model system to investigate. This study examined the diversity and prevalence of pathogens from different taxonomic levels in wild and fished C. edule on the Irish coast. Potential interactions were tested focussing on abiotic (seawater temperature and salinity) and biotic (cockle size and age, and epiflora on shells) factors. No Microsporidia nor OsHV-1µVar were detected. Single infections with Haplosporidia (37.7%) or Vibrio (25.3%) were more common than two-pathogen coinfected individuals (9.5%), which may more easily succumb to infection. Fished C. edule populations with high cockle densities were more exposed to infections. Higher temperature and presence of epiflora on cockle shells promoted coinfection in warmer months. Low seawater salinity, host condition and proximity to other infected host species influenced coinfection distribution. A positive association between two Minchinia spp. was observed, most likely due to their different pathogenic effect. Findings highlight the major influence that ecological factors have on pathogen interactions and hostpathogen interplay.
Assuntos
Cardiidae , Haplosporídios , Animais , Especificidade de Hospedeiro , Água do MarRESUMO
Seaweeds contain a number of health enhancing and antimicrobial bioactive compounds including sulfated polysaccharides (SP). In the present study, SP extracted from a European red seaweed Irish moss Chondrus crispus was chemically analyzed, SP content extracted and the immune-response effect on wild Irish mussels Mytilus spp. investigated for the first time. A high percent yield of SP was extracted from C. crispus and the immune-stimulant activity of SP was assessed in a laboratory trial with mussels exposed to three different treatments of low (10⯵gâ¯mL-1), medium (20⯵gâ¯mL-1) and high (50⯵gâ¯mL-1)â¯SP dose concentrations and a control mussel group with no exposure to SP. An initial mussel sample was processed prior to the trial commencing and mussels were subsequently sampled on Days 1, 2, 3, 4, 7, and 10 post SP exposure. Both cell, humoral and immune related gene responses including haemocyte cell viability, haemocyte counts, lysozyme activity and expression of immune related genes (defensin, mytimycin and lysozyme mRNA) were assessed. No mussel mortalities were observed in either the treated or non-treated groups. Mussels exposed with SP showed an increase in haemocyte cell viability and the total number of haemocytes compared to control mussels. Lysozyme activity was also higher in treated mussels. Additionally, up-regulated expression of defensin, mytimycin and lysozyme mRNA was observed in SP treated mussels shortly after exposure (on Days 1, 2, and 3) to SP. These results indicate that a high quality yield of SP can be readily extracted from C. crispus and more importantly based on the animal model used in this study, SP extracted from C. crispus can rapidly induce health enhancing activities in Mytilus spp. at a cellular, humoral and molecular level and with a prolonged effect up to ten days post treatment.
Assuntos
Adjuvantes Imunológicos/farmacologia , Chondrus/química , Mytilus/imunologia , Extratos Vegetais/farmacologia , Polissacarídeos/farmacologia , Animais , Mytilus/efeitos dos fármacos , Sulfatos/químicaRESUMO
In this study, the ability of oyster larvae, brooded in the pallial cavity of the parent oyster, to become infected in the pallial fluid, which is influenced by the brooding oyster and surrounding environment, was investigated. Larvae were collected over three summers from three areas around Ireland. Samples were screened for the presence of Bonamia ostreae DNA using PCR analysis. Four samples of larvae were found to be positive for B. ostreae DNA, though the parent oysters were negative for infection. Larvae may be able to acquire the pathogen from the water column during filter feeding or elimination of pseudo-faeces by the brooding adult.
Assuntos
Larva/microbiologia , Ostrea/microbiologia , Infecções por Protozoários/transmissão , Animais , Haplosporídios , Interações Hospedeiro-Parasita/fisiologia , Irlanda , Reação em Cadeia da PolimeraseRESUMO
During October and November of 2011 and 2012, 229 hermit crabs, Pagurus bernhardus, were randomly collected from the intertidal shore at three locations along the southwest coast of Ireland. This is the first survey to assess the health status of this crustacean in Ireland. Carapace length and the sex of each crab were recorded. Crabs were screened for parasites by histology and the intensity and prevalence of infection was determined. Crabs of varying carapace length were screened. The only parasite observed in the crabs was Microphallus sp., the first record of this digenetic trematode in P. bernhardus in Europe.
Assuntos
Anomuros/parasitologia , Animais , Irlanda , Prevalência , TrematódeosRESUMO
Organisms of the genus Bonamia are intracellular protistan parasites of oysters. To date, 4 species have been described (B. ostreae, B. exitiosa, B. perspora and B. roughleyi), although the status of B. roughleyi is controversial. Introduction especially of B. ostreae and B. exitiosa to naïve host populations has been shown to cause mass mortalities in the past and has had a dramatic impact on oyster production. Both B. ostreae and B. exitiosa are pathogens notifiable to the World Organisation for Animal Health (OIE) and the European Union. Effective management of the disease caused by these pathogens is complicated by the extensive nature of the oyster production process and limited options for disease control of the cultured stocks in open water. This review focuses on the recent advances in research on genetic relationships between Bonamia isolates, geographical distribution, susceptible host species, diagnostics, epizootiology, host-parasite interactions, and disease resistance and control of this globally important genus of oyster pathogens.
Assuntos
Haplosporídios/fisiologia , Ostreidae/parasitologia , Animais , Haplosporídios/genética , Interações Hospedeiro-Parasita , FilogeniaRESUMO
The protistan pathogen Bonamia ostreae was first detected in Ostrea edulis at Rossmore, Cork Harbour, on the south coast of Ireland in 1987. A selective breeding programme commenced in 1988 by Atlantic Shellfish Ltd. to produce B. ostreae-resistant oysters using 3 to 4 yr old survivors as broodstock for controlled spawning in land-based spatting ponds. On-growing of oyster spat settled on mussel cultch was carried out on designated beds within Cork Harbour. Oyster production subsequently increased successfully, resulting in 3 yr old Rossmore O. edulis being marketed from 1993 onwards and a record tonnage of 4 yr old oysters being produced in 1995 and 1996. O. edulis production, B. ostreae prevalence and oyster mortalities have been monitored and recorded at Rossmore for over 30 yr. The collation and analysis of this data from 52 samples and 3190 oysters demonstrate the introduction and progression of bonamiosis and subsequent interventions to ameliorate disease effects during this period at Rossmore. Results suggest that O. edulis mortalities are now negligible during the first 4 yr of growth, prevalence of B. ostreae infection is low, and no correlation exists between prevalence of infection and oyster mortalities. This study, when compared to other studies of bonamiosis-infected oyster populations, suggests that an intervention in the form of a selective breeding programme is required to reduce the impact of the disease.
Assuntos
Cruzamento , Haplosporídios/fisiologia , Ostrea/genética , Ostrea/parasitologia , Animais , Interações Hospedeiro-Parasita/genética , Irlanda , Estações do Ano , Fatores de TempoRESUMO
The spread of the protozoan parasite Bonamia ostreae is of major concern to the European flat oyster Ostrea edulis industry. Many studies have looked at the sensitivity of individual methods available to screen for B. ostreae, but in this study, 3 separate laboratories examined 4 methods of diagnosis currently used routinely in laboratories: heart imprints, histology, polymerase chain reaction (PCR) and in situ hybridisation (ISH). The results were compared to estimate interlaboratory variability. Heart imprints and histology had the highest reproducibility amongst the 3 laboratories, with greatest agreement between detection of infected and uninfected individuals. PCR had the highest detection level in every laboratory. These positives were related to the presence of confirmed infections but also in unconfirmed infections, possibly due to the presence of traces of B. ostreae DNA in oysters where clinical infections were not observed. PCR, in combination with histology or ISH, provided the most reliable detection levels in every laboratory. Variation in results for PCR and ISH observed between laboratories may be due to the different protocols used by each laboratory for both methods. Overall, the findings from the 3 laboratories indicated that at least 2 methods, with fixed protocols, should be used for the accurate detection and determination of infection prevalence within a sample. This combination of methods would allow for a clearer and more precise diagnosis of B. ostreae, preventing further spread of the disease and providing more accurate detection levels and epidemiological information.
Assuntos
Haplosporídios/isolamento & purificação , Haplosporídios/fisiologia , Laboratórios/normas , Ostrea/parasitologia , Animais , DNA/genética , Haplosporídios/genética , Interações Hospedeiro-Parasita , Variações Dependentes do Observador , Reação em Cadeia da Polimerase , Reprodutibilidade dos TestesRESUMO
This study aimed to examine the pathobiology of a haplosporidian-like infection in juvenile (pre-recruit) edible crabs (Cancer pagurus) from two locations in South West Wales, UK. Infected crabs showed no external symptoms of the disease but dissection revealed an infected and hypertrophic antennal gland. Histological examination showed extensive parasitisation of the antennal gland overlying the hepatopancreas. Heavily infected crabs also showed the presence of parasites with morphological similarities to Haplosporidia in the labyrinth of the antennal gland and in the gills. The spread of the infection from the antennal gland to the gills suggests that these parasites are released into the haemolymph. Attempts to characterise the haplosporidian-like organism using several primers previously shown to amplify members of the phylum Haplosporidia failed. The prevalence of infection in juvenile edible crabs varied throughout the sampling period of November 2011 to July 2012 with the lowest level of ca. 15% in November peaking at 70% in March. This parasite may represent a threat to the sustainability of edible crab fisheries in this region if the damage observed in the antennal gland and gills results in host mortality. The identification of these parasites as members of the phylum Haplosporidia based on morphology alone must be seen as tentative in the absence of sequence data.
Assuntos
Braquiúros/parasitologia , Haplosporídios/fisiologia , Interações Hospedeiro-Patógeno , Animais , Braquiúros/crescimento & desenvolvimento , Haplosporídios/isolamento & purificação , País de GalesRESUMO
Parasite species richness is influenced by a range of drivers including host related factors (e.g. host size) and environmental factors (e.g. seawater temperature). However, identification of modulators of parasite species richness remains one of the great unanswered questions in ecology. The common cockle Cerastoderma edule is renowned for its diversity and abundance of parasites, yet drivers of parasite species richness in cockles have not been examined to investigate the association of both macro and microparasite communities. Using cockles as a model species, some of the key drivers of parasite prevalence and parasite species richness were investigated. Objectives of this 19-month survey were to determine the influence of the environment, host-parasite dynamics and parasite associations on parasite species richness and prevalence at two different geographic latitudes, chosen based on environmental differences. The highest parasite species richness was recorded in the northern sites, and this was potentially influenced by a range of interactions between the host, the pathogens and the environment. Parasite prevalence increased with host size and age, and parasite species richness increased with reduced salinity. A number of interactions between parasites, and between parasites and pathologies may be influencing parasite infection dynamics. New and concerning information is also presented regarding interactions between parasites and their environment. A number of parasites and potential pathogens (bacteria, Trichodina ciliates, metacercariae, trematode sporocysts) may be advantaged under climate change conditions (warming seas, increased precipitation), increasing disease incidence, which may prove detrimental not just for cockles, but for other bivalve species in the future.
Assuntos
Cardiidae , Parasitos , Trematódeos , Animais , Cardiidae/parasitologia , Interações Hospedeiro-Parasita , PrevalênciaRESUMO
Global shipping facilitates the introduction of invasive species and parasites via ballast water and hull fouling. Regional management of invasives may be strengthened by identifying the major routes in a network, to allow for targeted ship inspections. This study used cargo shipping records to establish the connectivity of shipping routes between ports in Ireland and other nations. 9291 records were analysed, investigating vessel residence and journey times. On average, vessels spent up to five days in port and less than five days at sea. However, there was strong variation, with general cargo ships recording up to 13 days in port. A horizon scan for species likely to invade in Ireland was incorporated for five species and their associated parasites: American razor clam, Asian shore crab, Brush clawed shore crab, Chinese mitten crab and American slipper limpet. Routes of concern are highlighted and a general framework for effective management is outlined.
Assuntos
Espécies Introduzidas , Navios , Irlanda , ÁguaRESUMO
Two commercially available fluorescein isothiocyanate (FITC) -conjugated anti-Escherichia coli antibodies, tested for immunofluorescence were assessed for their suitability in screening E. coli using flow cytometry. Staining efficacy was initially tested using immunofluorescent microscopy; and further optimization was carried out using flow cytometry. Initially, an acetone fixation step was utilized; however, it was determined statistically that the step could be omitted without impacting the assay and thus reduce the time involved. There was no statistical difference between the staining proficiency of the two antibodies employed. The percentage staining was quite low, approximately 10% for the two antibodies, which indicated that both were equally sensitive but ultimately, more specific antibodies are required for the detection of E. coli. Known proportions of target-E. coli (105, 106, and 107 cells/ml) were mixed with large quantities of non-target bacteria; there was a significant correlation among all the antibodies at the different bacterial cell concentrations. Therefore, despite the low staining percentage achieved on the bacterial cultures, there is a representative and comparative level of staining occurring, between samples and between bacterial strains.
Assuntos
Anticorpos Antibacterianos , Técnicas Bacteriológicas/métodos , Escherichia coli/isolamento & purificação , Citometria de Fluxo/métodos , Microscopia/métodos , Técnica Direta de Fluorescência para Anticorpo/métodos , Sensibilidade e Especificidade , Manejo de Espécimes/métodos , Coloração e Rotulagem/métodosRESUMO
Shellfish, including the key species the common cockle Cerastoderma edule, living and feeding in waters contaminated by infectious agents can accumulate them within their tissues. It is unknown if microbial pathogens and microparasites can subsequently be transmitted via concomitant predation to their consumers, including shorebirds. The objective of this study was to assess if pathogens associated with C. edule could be detected seasonally in the faeces of shorebirds that feed on C. edule and in the physical environment (sediment) in which C. edule reside, along the Irish and Celtic Seas. Two potentially pathogenic global groups, Vibrio and Haplosporidia, were detected in C. edule. Although Haplosporidia were not detected in the bird faeces nor in the sediment, identical strains of Vibrio splendidus were detected in C. edule and bird faecal samples at sites where the oystercatcher Haematopus ostralegus and other waders were observed to be feeding on cockles. Vibrio spp. prevalence was seasonal and increased in C. edule and bird faecal samples during the warmer months, possibly due to higher seawater temperatures that promote the replication of this bacteria. The sediment samples showed an overall higher prevalence of Vibrio spp. than the bird faecal and C. edule samples, and its detection remained consistently high through the sites and throughout the seasons, which further supports the role of the sediment as a Vibrio reservoir. Our findings shed light on the fact that not all pathogen groups are transmitted from prey to predator via feeding but bacteria such as V. splendidus can be. As most of the wading birds observed in this study are migratory, the results also indicate the potential for this bacterium to be dispersed over greater geographic distances, which will have consequences for areas where it may be introduced.
Assuntos
Aves/microbiologia , Cardiidae/microbiologia , Interações Hospedeiro-Patógeno , Ração Animal , Animais , Biodiversidade , Ecossistema , Face/microbiologia , Sedimentos Geológicos , Modelos Teóricos , Estações do AnoRESUMO
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.
RESUMO
BACKGROUND: The common cockle Cerastoderma edule plays an important ecological role in the marine ecosystem both as an infaunal engineer (reef forming and bioturbation) and a food source for protected bird species in its European range. Cockle beds are found in close proximity to aquaculture and fisheries operations, which can be "hot spots" for infectious agents including viruses and bacteria. Ostreid herpesvirus-1 microVar (OsHV-1 µVar) has spread to many Pacific oyster Crassostrea gigas culture sites globally, where it has been associated with significant mortalities in this cultured bivalve. Knowledge on the impact of the virus on the wider ecosystem, is limited. As the likelihood of released virus dispersing into the wider aquatic ecosystem is high, the plasticity of the virus and the susceptibility of C. edule to act as hosts or carriers is unknown. METHODS: In this study, wild C. edule were sampled biweekly at two C. gigas culture sites over a four-month period during the summer when OsHV-1 µVar prevalence is at its highest in oysters. C. edule were screened for the virus molecularly (PCR, qPCR and Sanger sequencing) and visually (in situ hybridisation (ISH)). The cockle's ability to act as a carrier and transmit OsHV-1 µVar to the oyster host at a temperature of 14 â, when the virus is considered to be dormant until water temperatures exceed 16 â, was also assessed in laboratory transmission trials. RESULTS: The results demonstrated that OsHV-1 µVar was detected in all C. edule size/age cohorts, at both culture sites. In the laboratory, viral transmission was effected from cockles to naïve oysters for the first time, five days post-exposure. The laboratory study also demonstrated that OsHV-1 µVar was active and was successfully transmitted from the C. edule at lower temperatures. CONCLUSIONS: This study demonstrates that OsHV-1 µVar has the plasticity to infect the keystone species C. edule and highlights the possible trophic transmission of the virus from cockles to their mobile top predators. This scenario would have important implications, as a greater geographical range expansion of this significant pathogen via migratory bird species may have an impact on other species that reside in bird habitats most of which are special areas of conservation.
Assuntos
Cardiidae/virologia , Crassostrea/virologia , Vírus de DNA/fisiologia , Especificidade de Hospedeiro , Animais , Aquicultura , EcossistemaRESUMO
European populations of the native flat oyster, Ostrea edulis, have been heavily depleted by two protozoan parasites, Marteila refringens and Bonamia ostreae, with mortalities of up to 90% reported in naïve populations. However, in studies carried out over a 10-year period, researching the parasite-host relationship of B. ostreae and O. edulis in several age cohorts within a naïve O. edulis population from Loch Ryan (LR), Scotland, 1364 specimens were challenged and only 64 (5%), across multiple testing protocols, screened positive for B. ostreae. This article presents a case for the development of S-strategy life traits in the LR population that coincide with enhanced immune function and survival. Oysters are considered typical r-strategists (small in size with fast development and high fecundity) while S-strategists, as outlined in Grime's (1977) competitor-stress tolerant-ruderal (C-S-R) triangle theory, are characterized by slow growth and investment in the durability of individuals. This study hypothesizes that slower growth and reduced reproductive output in LR oysters has resulted in the investment of an enhanced immune function and reduced susceptibility to B. ostreae that is, r-strategists with S-strategy life traits equates to protection from significant pathogens. The findings presented here within provide a strong case study for local adaptation of energy allocation and provides empirical support for the C-S-R triangle theory in a marine organism.
Assuntos
Haplosporídios/fisiologia , Interações Hospedeiro-Parasita , Características de História de Vida , Ostrea/parasitologia , AnimaisRESUMO
Knowledge mobilisation is required to "bridge the gap" between research, policy and practice. This activity is dependent on the amount, richness and quality of the data published. To understand the impact of a changing climate on commercial species, stakeholder communities require better knowledge of their past and current situations. The common cockle (Cerastoderma edule) is an excellent model species for this type of analysis, as it is well-studied due to its cultural, commercial and ecological significance in west Europe. Recently, C. edule harvests have decreased, coinciding with frequent mass mortalities, due to factors such as a changing climate and diseases. In this study, macro and micro level marine historical ecology techniques were used to create datasets on topics including: cockle abundance, spawning duration and harvest levels, as well as the ecological factors impacting those cockle populations. These data were correlated with changing climate and the Atlantic Multidecadal Oscillation (AMO) index to assess if they are drivers of cockle abundance and harvesting. The analyses identified the key stakeholder communities involved in cockle research and data acquisition. It highlighted that data collection was sporadic and lacking in cross-national/stakeholder community coordination. A major finding was that local variability in cockle populations is influenced by biotic (parasites) and abiotic (temperature, legislation and harvesting) factors, and at a global scale by climate (AMO Index). This comprehensive study provided an insight into the European cockle fishery but also highlights the need to identify the type of data required, the importance of standardised monitoring, and dissemination efforts, taking into account the knowledge, source, and audience. These factors are key elements that will be highly beneficial not only to the cockle stakeholder communities but to other commercial species.
Assuntos
Conservação dos Recursos Naturais/métodos , Disseminação de Informação/métodos , Participação dos Interessados/psicologia , Animais , Cardiidae , Europa (Continente) , Pesqueiros , Alimentos Marinhos/análise , Frutos do MarRESUMO
Host size and age are generally assumed to play a pivotal role in digenean trematode infection patterns, accounting for much of the variation found within intermediate host populations. However, knowledge is based on a limited number of studied host-parasite systems. We investigated the shell length class distribution of Meiogymnophallus minutus infections within populations of the first intermediate host Scrobicularia plana and second intermediate host Cerastoderma edule. Infections occurred very early in the life of the two intermediate hosts. Both prevalence and intensity of infections increased with host shell length and displayed extremely high values amongst large individuals. Whilst metacercarial infection patterns in juvenile C. edule could be best explained by differences in host shell length, in adult cockles, the effect of host age on infection levels prevailed. The microsporidian hyperparasite Unikaryon legeri, occurring in the metacercarial stage of M. minutus, was particularly abundant in aged cockles, strongly influencing infection patterns of the gymnophallid. Our results are consistent with the intrapopulational distribution reported from other digenean trematode parasites. The relative influence of both host size and age and the underlying mechanisms as well as the impact of hyperparasitism on M. minutus infection patterns are discussed.
Assuntos
Cardiidae/parasitologia , Trematódeos/isolamento & purificação , Infecções por Trematódeos/veterinária , Fatores Etários , Animais , Tamanho Corporal , Contagem de Ovos de ParasitasRESUMO
The Comet assay was used to investigate the potential of the biotoxin microcystin (MC) to induce DNA damage in the freshwater zebra mussel, Dreissena polymorpha. Mussels maintained in the laboratory were fed daily, over a 21-day period, with one of four strains of the cyanobacterium, Microcystis aeruginosa. Three of the strains produced different profiles of MC toxin, while the fourth strain did not produce MCs. The mussels were sampled at 0, 7, 14, and 21 days by withdrawing haemocytes from their adductor muscle. In addition, a positive control was performed by exposing a subsample of the mussels to water containing cadmium chloride (CdCl(2)). Cell viability, measured with the Fluorescein Diacetate/Ethidium Bromide test, indicated that the MC concentrations, to which the mussels were exposed, were not cytotoxic to the haemocytes. The Comet assay performed on the haemocytes indicated that exposure to CdCl(2) produced a dose-responsive increase in DNA damage, demonstrating that mussel haemocytes were sensitive to DNA-damaging agents. DNA damage, measured as percentage tail DNA (%tDNA), was observed in mussels exposed to the three toxic Microcystis strains, but not in mussels exposed to the nontoxic strain. Toxin analysis of the cyanobacterial cultures confirmed that the three MC-producing strains exhibit different toxin profiles, with the two MC variants detected being MC-LF and MC-LR. Furthermore, the DNA damage that was observed appeared to be strain-specific, with high doses of MC-LF being associated with a higher level of genotoxicity than low concentrations of MC-LR. High levels of MC-LF also seemed to induce relatively more persistent DNA damage than small quantities of MC-LR. This study is the first to demonstrate that in vivo exposure to MC-producing strains of cyanobacteria induces DNA damage in the haemocytes of zebra mussels and confirms the sublethal toxicity of these toxins.