Publicação
Initial insights from eDNA metabarcoding in Ria de Aveiro: biodiversity snapshot and detection limitations
| Resumo: | The common cockle, Cerastoderma edule, is an ecologically, culturally, and economically valuable mollusc, with significant importance for the European coastal ecosystems and populations. This species provides a wide range of ecosystem services, including water filtration, biodeposition, and serving as a vital food source for numerous predators. In addition to its ecological role, cockles support local livelihoods through harvesting and aquaculture, making it a culturally and economically valuable resource. In the Ria de Aveiro, a coastal lagoon on the north-west coast of Portugal, cockle harvesting is especially prominent, accounting for 60% of the total bivalve harvest by 2020. By 2023, reported captures reached 2,803 tons, highlighting its relevance to regional fisheries. Despite their natural resilience, cockle populations face mounting pressures from different stressors. Anthropogenic activities that intensified environmental challenges, like temperature and salinity fluctuation, habitat degradation, pollution and the introduction of invasive species. Concurrently, natural ecological factors such as predation, food availability, and parasitism regulate their population dynamics. Particularly concerning are parasitic infections from digenean trematodes like Bucephalus minimus, causing significant damage to the host’s fitness through tissue damage, castration, and increased vulnerability to predation. Traditional methods for the detection of parasites in bivalves present several limitations, often being labour-intensive, lethal to the host, and vary in sensitivity, highlighting the need for new approaches. Environmental DNA (eDNA) metabarcoding emerges as a promising alternative tool for parasite monitoring and biodiversity assessment in aquatic ecosystems. This technique detects genetic material shed by organisms into the environment, allowing the simultaneous detection and identification of multiple organisms without direct observation. Recent studies have already demonstrated the effectiveness of eDNA in detecting various trematode species and tracking the distribution of aquatic parasites. Building on this, the present study explores the application of eDNA metabarcoding for biodiversity assessment and parasite monitoring in the Ria de Aveiro, with particular focus on B. minimus and other taxa relevant to the health of natural cockle banks. Water samples were collected in the São Jacinto channel, an area with historically high prevalence of B. minimus, using the COI gene as the target marker. Beyond species detection, this research also addresses methodological challenges associated with eDNA-based monitoring. By advancing non-invasive approaches for parasite detection in valuable shellfish resources, this study contributes to the development of early warning systems for disease outbreaks in ecosystems facing increasing environmental pressures. |
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| Autores principais: | Santos, Ivan Lopes dos |
| Assunto: | Cerastoderma edule Bucephalus minimus Parasite detection Ria de Aveiro eDNA Metabarcoding Biologic assessment |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | The common cockle, Cerastoderma edule, is an ecologically, culturally, and economically valuable mollusc, with significant importance for the European coastal ecosystems and populations. This species provides a wide range of ecosystem services, including water filtration, biodeposition, and serving as a vital food source for numerous predators. In addition to its ecological role, cockles support local livelihoods through harvesting and aquaculture, making it a culturally and economically valuable resource. In the Ria de Aveiro, a coastal lagoon on the north-west coast of Portugal, cockle harvesting is especially prominent, accounting for 60% of the total bivalve harvest by 2020. By 2023, reported captures reached 2,803 tons, highlighting its relevance to regional fisheries. Despite their natural resilience, cockle populations face mounting pressures from different stressors. Anthropogenic activities that intensified environmental challenges, like temperature and salinity fluctuation, habitat degradation, pollution and the introduction of invasive species. Concurrently, natural ecological factors such as predation, food availability, and parasitism regulate their population dynamics. Particularly concerning are parasitic infections from digenean trematodes like Bucephalus minimus, causing significant damage to the host’s fitness through tissue damage, castration, and increased vulnerability to predation. Traditional methods for the detection of parasites in bivalves present several limitations, often being labour-intensive, lethal to the host, and vary in sensitivity, highlighting the need for new approaches. Environmental DNA (eDNA) metabarcoding emerges as a promising alternative tool for parasite monitoring and biodiversity assessment in aquatic ecosystems. This technique detects genetic material shed by organisms into the environment, allowing the simultaneous detection and identification of multiple organisms without direct observation. Recent studies have already demonstrated the effectiveness of eDNA in detecting various trematode species and tracking the distribution of aquatic parasites. Building on this, the present study explores the application of eDNA metabarcoding for biodiversity assessment and parasite monitoring in the Ria de Aveiro, with particular focus on B. minimus and other taxa relevant to the health of natural cockle banks. Water samples were collected in the São Jacinto channel, an area with historically high prevalence of B. minimus, using the COI gene as the target marker. Beyond species detection, this research also addresses methodological challenges associated with eDNA-based monitoring. By advancing non-invasive approaches for parasite detection in valuable shellfish resources, this study contributes to the development of early warning systems for disease outbreaks in ecosystems facing increasing environmental pressures. |
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