Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Luciobarbus esocinus (mangar), a critically endangered mega-fish species (≤ 140 kg) endemic to the Euphrates and Tigris river systems, faces severe threats due to habitat fragmentation. To assess its spatial ecology in the Keban Reservoir, 30 individuals were acoustically tagged and monitored for 218–437 days using 18 receivers deployed in the reservoir. The tagged fish exhibited low site fidelity, with station residency indices (RI) ranging from 0.00 to 0.46 and detection periods lasting 59–153 days. Depth and temperature data (115,318 and 112,789 records, respectively) revealed seasonal habitat shifts: individuals occupied deeper waters in winter (mean 10.1 m), shallower depths in spring (4.4 m) and summer (3.8 m), and tolerated temperatures of 7.4°C–28.4°C. Although depth use was weakly correlated with temperature, trends indicated shallower occupancy during warmer periods. Home range analyses showed a maximum linear home range (LHR) of 36.5 km and the areal home range estimated via minimum convex polygon (MCP) was 6422.8 ha. In addition, kernel density (KD) analysis revealed the 95% KD area was 2877.0 ha, the 75% KD area was 67.7 ha and the 50% KD area was 33.8 ha. Seasonal migrations spanned 25–30 km upstream/downstream from release sites, particularly toward tributaries in spring. Around the Keban Reservoir, 14 hydroelectric power plants (HPPs) present and most of these HPP are not designed suitable fish passages. Urgent conservation measures are needed, including Fish Conservation Zones in critical habitats and connectivity restoration via functional fishways, to safeguard this imperilled species in fragmented river-reservoir ecosystems.

Seahorse populations in Rio de Janeiro State are distributed throughout the territory, but they are threatened by human activities such as trawling, aquarium trade, traditional medicine, religious purposes and unsustainable tourism. They had a significant decline observed in the Lake Region in the last 13 years. Their conservation relies on targeted public policies addressing coastal management, efficient wastewater treatment, climate change mitigation and strict enforcement of regulations against industrial fishing, intentional capture and illegal trade. Given the threats and the absence of data for the whole Brazilian coast, the present policy brief aims to recommend local strategies to protect seahorses.

Freshwater ecosystems in biodiversity hotspots face unprecedented threats from climate change, yet endemic species—often the most vulnerable—remain understudied. Using species distribution models (MaxEnt), we project habitat shifts for 10 riverine fishes (six endemics) in Iran's Central Zagros, a critical freshwater biodiversity hotspot, under optimistic (RCP 2.6) and pessimistic (RCP 8.5) scenarios (2050–2080). Our results reveal stark disparities: While generalists like Sellal bleak Alburnus sellal may gain > 130% habitat, endemic taxa such as killifish Esmaeilius vladykovi and Large scale scraper Capoeta aculeata face near-total losses (> 90%). Notably, the Near Threatened Capoeta ferdowsii (endemic) declines across all scenarios, underscoring the heightened risks for range-restricted species. Temperature and land use emerged as dominant drivers, with endemic fishes disproportionately affected by climatic stressors. These findings challenge assumptions of uniform climate impacts and provide a replicable framework for prioritizing conservation in fragmented freshwater ecosystems. We highlight three actionable insights: urgent protection of thermal refugia for endemic species, habitat connectivity restoration to facilitate climate-driven range shifts and integration of SDM projections into IUCN Red List assessments. By quantifying divergent fates—from expansion to collapse—our study equips conservationists with data to safeguard freshwater biodiversity in one of the Middle East's most vulnerable regions.

The spread of invasive alien species (IAS) is causing significant ecological, biological and socioeconomic impacts worldwide, making eradication efforts extremely challenging once they become established. The most effective approach is to prioritize prevention by blocking the entry of high-risk species. However, early detection and rapid response (EDRR) is crucial when prevention fails. In the Southern Right Whale Environmental Protection Area (RWEPA) in southern Brazil, EDRR efforts included citizen science through social media. Citizen science reports from a sport fisherman were received about the high-risk invasive species Nile tilapia (Oreochromis niloticus) and red-breasted tilapia (Coptodon rendalli) on Santa Catarina Island (SCI), located north of the RWEPA boundary. We compared the citizen science results with scientific databases and literature. Notably, citizen science contributed significantly more records than all scientific sources combined. The data suggests that tilapias are establishing populations across the SCI, spreading through drainage channels and rivers, even reaching protected areas. This highlights the need to assess drainage systems globally when studying tilapia invasions. Urgent studies are needed in the SCI region to assess the distribution, establishment and impacts of the tilapia invasion, supporting management actions to eradicate or at least control tilapia populations and consequently conserve native species. Effective management should also improve the sanitary conditions of the SCI to reduce the success of invaders. This study demonstrates that, in understudied areas, a simple citizen science initiative in social media can provide crucial information for conservation biology, highlighting the value of this collaborative approach.

Streams and rivers are increasingly threatened by intensifying land cover and land use (LCLU) change and streamflow alteration at a global scale. Stream fishes provide several ecosystem services and thus understanding fish responses to these anthropogenic changes benefits freshwater conservation and management. We compared historical survey data from 1956 to 1957 to replicated surveys conducted in 2023 to assess long-term changes in taxonomic and functional fish assemblage structure brought on by anthropogenic alterations in the Neches River Basin of Texas. We assessed components of temporal beta diversity to find the predominant form of assemblage change, nestedness or replacement, and related the predominant component to LCLU and streamflow change at whole basin and river mainstem extents. We then examined the relationship between temporal beta diversity and functional dispersion for traits related to fish stream size preference, substrate preference, and capacity to host mussels. Replacement was the primary form of temporal beta diversity at both spatial extents. At the basin extent, streamflow alteration was negatively correlated with replacement, while at the mainstem extent, urbanisation was positively correlated with replacement. Taxonomic replacement was positively correlated with functional dispersion change at high urbanisation levels but showed no relationship at low urbanisation levels or across a gradient of streamflow change. This study leverages rare long-term data to test for patterns in temporal beta diversity at taxonomic and functional levels rather than the more commonly used space-for-time substitutions and provides insight for management actions aimed at conserving stream fish assemblages in the face of LCLU and streamflow alterations.

Understanding genetic diversity is essential for conserving and sustainably managing fish populations in riverine ecosystems. However, overexploitation, habitat degradation, pollution, and ineffective fisheries management threaten the genetic integrity of many species, including the bagrid catfish (Rita rita). This study used simple sequence repeat (SSR) markers to assess the genetic diversity and population structure of R. rita across five sites along the Indus River. Genomic DNA was extracted from dorsal muscle tissues, and cross-species microsatellite primers from Bagarius yarrelli were used for polymerase chain reaction (PCR) amplification. Genetic diversity was evaluated using allelic richness (Ar), heterozygosity, inbreeding coefficients (F_IS) and genetic differentiation (F_ST). The results revealed moderate genetic diversity, with allelic richness ranging from 2.400 to 5.800 and expected heterozygosity (He) between 0.617 and 0.699. Lower observed heterozygosity (Ho) across most populations suggests potential inbreeding effects. Significant genetic differentiation (F_ST) indicated moderate population structuring, with a strong correlation between geographic distance and genetic variation. Analysis of molecular variance (AMOVA) showed that 85.72% of genetic variation occurred within individuals, while restricted gene flow (Nm) across certain loci suggested geographical barriers affect genetic diversity. UPGMA clustering and STRUCTURE analysis identified two major genetic clusters, suggesting the presence of distinct evolutionary lineages. These findings highlight the need for targeted conservation strategies to maintain genetic integrity and reduce further genetic loss. This study establishes a molecular framework for future marker-assisted conservation and aquaculture programs to sustain R. rita populations in their natural habitats.