Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

The Olympia oyster (Ostrea lurida) is the only oyster native to the west coast of the United States. Its populations are less than 5% of what they were historically, and although restoration efforts have re-established some populations, the long-term viability of the species will depend on its capacity to resist environmental threats. Shell-boring polychaetes have recently been reported for the first time in the Salish Sea, infesting both Pacific (Magallana gigas) and native oysters. These parasitic worms are pervasive aquaculture pests that can jeopardize oyster health and growth. It remains unknown whether these polychaetes are new to the Salish Sea ecosystem, or if they have long been present but were previously unreported. We take advantage of the fact that traces of infestation are preserved in oyster shells to generate a timeline for shell-boring polychaetes in the region. We collected 996 native oyster shells from four populations (Modern, Archaeological, Recent Fossil, and Fossil) across three different time periods (Modern, Holocene and Pleistocene). Infestation prevalence ranged from 9% to 55% in the past populations, and from 18% to 96% in the Modern populations, suggesting that prevalence is higher today than it was in the past. Radiocarbon dating and prior studies allowed us to determine that shell-boring polychaetes have coexisted with native oysters for at least 80,000 years. We end by providing some recommendations for managers and practitioners on how to monitor for this parasite if it were to pose threats for native oyster populations undergoing restoration.

Representativity within marine protection and planning refers to the principle of ensuring that the full range of biodiversity and ecosystems (and the species that they support) in a particular region is included in a network of marine protected areas (MPA). The New Zealand Seafloor Community Classification (NZSCC), which was developed to support MPA planning and reporting at a national scale, depicts compositional turnover of 1716 taxa (demersal fish, reef fish, benthic invertebrates and macroalgae) classified in 75 groups representing seafloor communities. Here, we use the NZSCC to evaluate representativity of benthic communities within current spatial management areas across New Zealand's marine environment based on the extent of each group within spatial management areas, estimates of within- and between-group similarities and taxonomic richness. Results suggest that while offshore, deep-water communities in general are well represented within current spatial management areas (notably those communities predicted to occur below fishable depths), 46 of the 75 groups, predominantly coastal and continental shelf groups, were inadequately represented. The use of within- and between-group similarities is a significant improvement on assessments that only look at extent protected because they allow the identification of those areas that are the most representative of each group but also consideration of which groups are most dissimilar (unique) to all other groups already protected.

Internet and social media use have increased significantly over the past decade, resulting in huge volumes of biodiversity data that are potentially cost-effective means to better inform biodiversity conservation and resource management. We examine the role of digital conservation in a data-poor context of the Global South, using sharks and rays in India as a case study. India is a top shark fishing nation characterised by few, disconnected species-specific research and conservation projects but lacks nation-scale conservation insights. We analysed 1293 elasmobranch-related posts and recorded 83 species from six social media and citizen science platforms. We identified two key dimensions of data—ecological and social (including politics and governance)—and tested the effectiveness of these data in mirroring or complementing scientific research. We found that digital platforms were (i) spatio-temporally better representative than scientific research, because they included 96 underrepresented regions and spanned 18 years, despite some biases; (ii) useful to detect the presence of data-poor and rare species; and (iii) effective to detect human–elasmobranch interactions and public perceptions towards sharks and rays, topics which are poorly represented in the scientific literature. We find that digital conservation can therefore be utilised to generate national-scale insights in regions with limited resources and site-specific data. It is also useful to fill socioecological data gaps to drive better management and increased public participation/awareness for conservation. The multidisciplinary nature of data emerging from digital conservation has high relevance for current and future conservation of species.

Since the early 1980s, the recruitment of the European eel (Anguilla anguilla L.) to the European continent has declined dramatically. There is a lack of research utilizing biotic variables to determine European eel habitat selection, particularly in short karstic coastal catchments. This study provides the first reference on the habitat preferences of European eels in the Croatian karst region. The research was conducted at six lotic waterbodies within the Adriatic Basin in Croatia. A total of 380 European eel specimens were sampled. Environmental parameters were recorded at each sampling location, including water quality, bottom substrate, instream cover and the degree of anthropogenic alteration. Individuals were classified into three length classes: Class 1 (< 20 cm); Class 2 (20–45 cm) and Class 3 (> 45 cm). Multivariate analysis identified habitat degradation, instream cover, conductivity and sea distance as key factors influencing European eel habitat preferences. Class 1 was associated with lower altitude, proximity to the sea and coarse bottom substrate. Class 2 exhibited a strong association with greater distance and higher altitudes, water depth and channel width. Class 3 was primarily associated with conductivity, instream cover and heterogeneity of bottom substrates. All three length classes show high sensitivity to modifications of the riverbanks or riverbed. These alterations, along with the loss of instream cover, may lead to a significant decline of the species and local extirpation. This study could help prioritize areas for habitat protection and support conservation efforts aimed at restoring European eel habitats in short, isolated Mediterranean rivers.

Biomagnification of environmental toxins is influenced by food chain length, which in turn is shaped by habitat connectivity and food web dynamics. Dam removals are increasingly used as restoration measures, yet their role in reducing contaminant exposure has rarely been quantified. We tested if mercury concentration in pike (Esox lucius) muscle tissue was reduced by removals of lake outlet dams in five oligotrophic, boreal lakes, using a before-after design. For pike of average size (50 cm), mean mercury concentration decreased from 843 to 598 μg Hg per kg muscle tissue following dam removal, which corresponds to a 29% reduction. These results show that dam removal can lower mercury bioaccumulation in apex predators, providing an additional conservation benefit of restoring natural aquatic connectivity, with positive implications for both ecosystem integrity and human health.