Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Spanish National Parks (NPs) are protected areas for biodiversity conservation, including two Maritime–Terrestrian NPs: The Atlantic Islands of Galicia, PNIA (NW Spain) and Archipelago of Cabrera, PNAC (Balearic Islands). This study was aimed to conduct a 3-year genetic survey of syngnathid fish species (i.e. seahorses and pipefish) identified in both NPs and nearby unprotected areas, using mitochondrial and microsatellite markers. A diversity of species was identified with differential distribution among NPs and adjacent areas studied. Pipefish (Syngnathus acus, S. abaster, S. typhle, Entelurus aequoreus, Nerophis lumbriciformis, N. maculatus, and N. ophidion) predominated, while seahorses (Hippocampus guttulatus) were much less abundant. Genetic data and phylogenetic analysis clarified in situ morphological identification. Mitochondrial haplotypes for each species clustered into monophyletic groups, supporting the identification of a cryptic lineage of S. abaster in PNAC distinct from eastern Mediterranean populations of this species. Intraspecific genetic diversity was evaluated at spatial and temporal scale for population samples recorded during the survey period, providing valuable information for individual resampling traceability and delineating management units. Temporal stability in genetic diversity and gene flow with adjacent areas were observed for dominant species within each NP in the 3-year period studied. However, significant intraspecific differentiation was detected between populations identified in Atlantic and Mediterranean NPs. This study provides valuable reference genetic data for future monitoring and to identify distribution or research gaps for further studies towards the conservation of syngnathid populations in Spanish marine NPs, which serve as umbrella species for the preservation of vulnerable coastal ecosystems and habitats.

Environmental DNA methodologies are constantly being developed and optimized for specific purposes. This paper summarizes 3 years of water-sampling and filtering method development, with the aim to reliably detect and quantify eDNA from great crested newts and smooth newts from established monitoring ponds, using species-specific assays and droplet digital PCR (ddPCR). Both newt species were caught in traps from all ponds during the three sampling years. For the first year, water was collected from three separate positions within each pond and filtered individually through a 0.45-μm PES filter. Overall, the pond replicates resulted in 26% false negatives, including three ponds where only one-third of the samples were positive. Positive results within sites also showed high variance in DNA concentration (the highest variance across three filters and nine ddPCRs: 1987 ± 1789). For the second year, subsamples of water from different positions were collected and mixed before being filtered through two 0.45-μm PES filters. This sampling approach reduced the overall variation in eDNA concentration from replicates filtered from each water batch (the highest variance: 7355 ± 4147). However, a few samples did still not reliably detect newt eDNA (9%–10%). For the third year, to test for potential effects of stratification and seasonal variation on the probability of detection, subsamples were collected from both the surface layer and 30 cm below the surface four to five times through the main mating period. In addition, the filter type was changed to a 2.0-μm glass fibre filter to increase water volume. Despite filtering on average 1 L more through each filter compared to the second sampling year, this method produced a higher number of false negatives.

Optimizing filtering methods to reliably detect newts from ponds in the mating season is needed before applying the method in managemental monitoring.

Coral diseases have contributed to the decline of coral populations in the Colombian Caribbean. One of the main causes is the infection of pathogenic bacteria, which are transported through marine currents and deposited in the sediment, making it a potential vector and reservoir. In the Torín sector of Isla Aguja, there is an important reef formation of Acropora palmata influenced by river discharges with possible impacts on their condition. To evaluate whether signs of the disease were reducing the population, in 2019, the formation was delimited, and monthly surveys were performed in 65 tagged colonies to calculate the incidence and prevalence of white pox in the population. Samples of water, sediment, healthy mucus and disease mucus were collected to isolate bacterial members and characterize them through amplifications of the V1–V3 hypervariable region of the 16S gene. Because of pandemic restrictions, monitoring was restarted in September 2020 and ended in December 2021, recording only the appearance of signs of disease. Nineteen bacterial strains were isolated. Enterobacter cloacae was found in water and disease mucus, Klebsiella variicola was found in healthy mucus and disease mucus, Klebsiella pneumoniae was found in water and healthy mucus, and Staphylococcus aureus was common in sediment and healthy mucus. Escherichia coli was found only in water. Signs of disease were frequent, with low prevalence but a rapid and evident natural recovery of the colonies, thus not constituting, yet, a threat to the reef formation of A. palmata. In contrast, the gillnets registered on four occasions between 2019 and 2021 caused the breakage of large colonies that impacted the population. It is urgent to establish management strategies for this local formation or strengthen surveillance activities that ensure good fishing practices to protect and prevent impacts on these species.

The Semporna Priority Conservation Area (PCA), located on the southeast coast of Sabah, Malaysia, spans 7680 km² within the Sulawesi Sea and is part of the Coral Triangle, known for its rich marine biodiversity. Despite its ecological significance, the area faces multiple anthropogenic threats. The study aimed to (1) evaluate reef health by assessing live coral cover, indicator fish and invertebrate density in six locations in Semporna; (2) examine the survey team's threat rankings with the vulnerability factors perceived by experts; and (3) compare vulnerability scores for 10 identified threats. Underwater surveys were conducted using the Reef Check methodology, supplemented by in situ observations from SCUBA divers and boat attendants in May–June 2017. Marine biologists or scientists familiar with Semporna assessed coral reef vulnerability factors based on scales, frequency, functional impact, resistance, recovery time and certainty towards different threats. The main threats identified include fish bombing, marine debris, commercial fishing and artisanal fishing. Results indicate reef degradation, particularly from destructive fishing practices, and highlight differences between local observations made by the field team and expert assessments gathered through interview surveys. Tourism activities were significant in the Centre to Southwest and Northeast to Southwest regions, necessitating site-based management. This integrated approach provides a comprehensive understanding of threats in the Semporna PCA and underscores the importance of combining empirical data with local insights to guide management prioritisation and develop effective conservation strategies, such as establishing new marine protected areas.

Sharks are important species that occupy different niches and trophic levels due to their biological and behavioural variability. It makes them a key element for conservation measures in marine environments. Among several stressors, climate changes put pressure on species in different ways (direct and indirect) and intensities. Understanding how changes may affect shark species is essential to evaluate measures that reduce the impact on shark populations and help them to adapt to a future climatic scenario. The aim was to identify the levels of vulnerability for Northern and Northeastern Brazil sharks to climate change based on a semiquantitative method of ecological risk assessment. Temperature and UV light were, respectively, the most concerning direct and indirect effects for sharks. In general, most of the assessed species have moderate chances of surviving the pressure caused by climate change. Carcharhinus porosus, Mustelus higmani and Isogomphodon oxyrhyncus were the most vulnerable assessed species. Coastal and estuarine sharks had high rates of exposure and high vulnerability indexes to climate change. Coastal and inshore species generally has high habitat specificity and latitudinal limitation, which worsens its ability to adapt to the new climate scenario. Both parameters may be a crucial factor in preserving coastal shark populations. Continental shelf habitats are commonly affected by other human stressors, such as fishing, waste contamination and destruction of tidal vegetation. In this way, region-specific conservation measures can reduce bycatch and increase reproductive efficiency, increasing the likelihood of coastal sharks surviving climate change. There is still little knowledge about the synergistic effect between human pressure and climate change. However, it is necessary to take measures to preserve the coastal and estuarine environments, so that the biota of these areas show favourable conditions for survival.

Behavioural and acoustic plasticity allow cetaceans to exploit a variety of habitats developing strategies to overcome increasingly demanding anthropogenic pressures. Bottlenose dolphins are known to compete with artisanal fishing along the southwestern coast of the Gulf of Mexico, but the extent of marine traffic impacts on the species is unknown. We investigated dolphin behavioural dynamics through unmanned aerial vehicles (UAV) and acoustic recordings in two zones off Alvarado, Veracruz, Mexico, with high (HVP) and low-vessel presence (LVP). Within the HVP zone (at the mouth of a lagoon) known for its greater abundance of prey, dolphins focused their behavioural budget on feeding (mostly individually), with higher emission rates for echolocation trains. Conversely, at the LVP zone (located northwest and southeast of the lagoon mouth), groups were larger and their behavioural repertoire was more varied (dolphins travelled, fed, socialized and rested equally), emitting not only high emission rates for echolocation trains but also for whistles. Our findings suggest that dolphins have developed a zoning strategy through a compensatory mechanism that allows tolerance to a certain level of fishing activities and marine traffic, especially within their feeding areas, by reducing group size to individual interactions, while prioritizing certain surface and acoustic behaviour when in the presence of vessels. By using this trade-off strategy, dolphins may remain at the site and continue taking advantage of the resources, at the expense of potential long-term effects, which remain to be investigated.