Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Invasive species threaten biodiversity and ecosystems and require global monitoring and management efforts. One such species is the Pacific oyster (Magallana gigas), originally introduced to Europe for aquaculture purposes, and after several decades of establishment, it has become a widespread invasive species in marine ecosystems. In this study, we used genetic tools to investigate the current genetic landscape of M. gigas in Northern Europe. Using a newly developed SNP panel based on a previous study on the species, we analyzed gene flow, genetic diversity and potential local adaptation at both micro- and macro-ecological scales at different sites within Limfjorden and single locations in the Netherlands, Wadden Sea, United Kingdom, Sweden, Norway and Isefjord. Our findings reveal a generally well-connected population across northern European waters, yet with detectable genetic signatures of early establishment events, i.e., Isefjord, and directional gene flow patterns, notably from Denmark to Sweden and Norway. While effective population sizes were large at broader geographic scales, localized cohorts exhibited smaller N_e values, suggesting genetic founder effects at the microgeographical level. No strong evidence of local adaptation was found, though some outlier loci in Limfjorden hint at possible early-stage adaptation to local environments. Our study provides a current genetic snapshot of the invasive Pacific oyster in Northern Europe, highlighting its ongoing expansion and emphasizing the importance of up-to-date genetic monitoring to guide effective population management and mitigate ecological impacts.

The analysis of the genetic structure of populations of the Mediterranean green sea turtle (Chelonia mydas, C. mydas) is essential for the development of sustainable management strategies and in ensuring the effective conservation of the species. In order to obtain more comprehensive data on the genetic connectivity and migratory behaviour of sea turtles, genetic diversity should be evaluated in detail using advanced molecular markers. Maternal genetic diversity based on mitochondrial short tandem repeats (mtSTRs) in the D-loop region of 327 samples was assessed to elucidate the genetic connectivity and population structure of C. mydas in the Mediterranean. Among the 42 haplotypes identified, nine novel haplotypes were found in stranded individuals from Türkiye, four from Cyprus and one from Tunisia. The origins of the stranded individuals were also investigated through mixed stock analysis. The results show that the genetic structure of C. mydas populations in the Mediterranean is more complex than previously thought. In particular, the Turkish coasts stand out as an important migration and feeding area where different genetic groups come together. The findings suggest that protecting nesting and feeding areas, expanding genetic monitoring and enhancing international conservation cooperation are essential for the species' sustainability. In summary, this study enhances our understanding of the genetic structure of Mediterranean C. mydas populations and provides essential insights to support evidence-based conservation strategies aimed at ensuring the long-term viability of regional management units (RMUs) within the Mediterranean.

Spatial–temporal patterns of biodiversity distribution provide critical insights into ecosystem responses to climate change. We chose the Bohai Sea, a temperate shelf sea highly influenced by climate change and human activities, as a case study to evaluate biodiversity dynamics. This study integrates presence–absence data of macrofaunal communities collected from 152 sampling stations (2011–2022) and employs ensemble species distribution models to assess the current and future habitat suitability of dominant species, functional traits and multidiversity. The findings reveal bottom salinity as the predominant factor driving macrofaunal distribution and biodiversity. The predictions indicate diverse responses: (1) no significant trends for species diversity or functional diversity indices; (2) expansion in habitat suitability for carnivorous feeders and species such as Sternaspis scutata, Moerella iridescens, Protankyra bidentata and Emplectonema gracile; and (3) contraction in deposit feeders and Alpheus digitalis. This study highlights the key role of thermal and salinity tolerance in shaping future species distributions, and that of functional redundancy in sustaining ecosystem resilience, and further advocates for adaptive management to support temperate ecosystem conservation amid climate change.

Marine protected areas (MPAs) act as essential conservation tools. However, biological invasions directly undermine the ability of these important conservation areas to meet their objectives by negatively affecting biodiversity, ecosystem functions and service provisioning. Currently, data on the distribution of marine alien species in South Africa are scarce and often outdated, with little known about invasions in MPAs. This reflects the absence of long-term monitoring programmes, a common challenge for many African countries. Recently, crowdsourced data platforms, including iNaturalist, have been used to support large-scale data collection. Beneficial due to their accessibility, these platforms provide data that cover broad temporal and spatial scales while not requiring funding. This study assessed the status of iNaturalist records for species known to be alien in South Africa, with a focus on MPAs. A total of 952 records were recovered, with 568 retained for analysis following the application of a confidence metric. Alien species were documented in 14 of the 29 South African coastal MPAs, with most species (15) recorded in the Table Mountain National Park MPA. This study documented three ascidians (Ciona robusta; Clavelina lepadiformis; Styela plicata) in natural habitats for the first time and extended the known range of the maritime earwig Anisolabis maritima by more than 1500 km, highlighting the pervasive nature of alien species in MPAs. This study presents the first use of iNaturalist data in a marine invasion context in South Africa and demonstrates the potential of this approach to enhance monitoring in resource-restricted under-surveyed MPAs throughout Africa.

Investigating individual home ranges within animal populations is critical to understanding community dynamics and identifying the drivers of population structure and substructure. Anthropogenic impacts such as habitat modification can have significant effects on the home range of marine predators but have rarely been investigated in free-ranging populations on a long-term basis. In environments where habitat quality is degrading, home range size is expected to increase for large predators as they may need to travel farther to find food. Using photo-identification data from 1999 to 2019 and kernel density estimates, we assessed the spatio-temporal dynamics of home range, residency and community structure within a resident population of bottlenose dolphins in Biscayne Bay, a highly urbanized waterway off the coast of Miami, Florida. General and core home ranges were estimated from 95% and 50% utilization distributions (UD), respectively. Two distinct communities were identified: a northern community and a southern community. The southern community exhibited significantly larger home ranges (95% UD = 126.88 ± 93.45 km², 50% UD = 32.54 ± 27.46 km²) compared to the northern community (95% UD = 68.46 ± 56.55 km², 50% UD = 17.0 ± 13.79 km²). A temporal analysis revealed an overall contraction of core home range for both communities over the course of the study period, significantly decreasing by 36.2% in the northern community and 25.7% in the southern community. The contraction in home range is contrary to what we would have expected in a heavily impacted environment experiencing habitat degradation, where expansion might be necessary to locate sufficient prey. In this population, however, continued use of familiar areas may facilitate the exploitation of limited resources and minimize energy costs in expanding into less familiar territory. Additionally, given the confined geography of Biscayne Bay, a contraction may also reduce competitive interaction among communities through resource partitioning.

Traditional vertical slot fishways (VSFs), designed primarily for larger fish species like salmon, often fail to accommodate smaller, weaker-swimming species, leading to low passage efficiency. To address this limitation, a novel V-shaped multi-slot fishway (VMSF) is proposed, offering improved passability for weaker swimmers. A comprehensive comparison between the VMSF and the VSF was conducted, focusing on flow field topology, operational flow rate and key hydraulic performance indicators. Meanwhile, to further optimize the VMSF structure, the design was analysed under different variations of V-shaped baffle angles and positions. Among the eight VMSF designs analysed at a water depth of 1.8 m, VMSF-2 was identified as the optimal solution. Compared to the VSF, VMSF-2 reduced the flow rate by 33.46% and decreased volume- and time-averaged velocity, turbulent kinetic energy, Reynolds shear stress, turbulent dissipation rate and turbulence intensity by 8.65%, 26.32%, 48.77%, 12.20% and 10.76%, respectively. Additionally, under four different operating conditions, VMSF-2 showed significant improvements in overall performance. This optimized design reduces fish fatigue, diversifies migratory routes and significantly improves both fish passage efficiency and hydraulic performance.