Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Coral restoration is a critical but costly endeavour, and the selection of appropriate outplanting materials plays a key role in both the effectiveness and cost-efficiency of these projects. This study aims to evaluate and compare the suitability of seven adhesive materials for coral outplanting, focusing on their adhesion performance, operability, biocompatibility and cost-effectiveness. The study emphasises the importance of selecting adhesives with optimal curing time and tensile strength to ensure successful coral fixation, with Portland cement, the mixture of Portland cement and quick-setting cement, and epoxy putty adhesive emerging as the most effective materials in this regard. Subsequently, the three materials were tested for more than half a month for underwater coral outplanting. The results indicate that adhesives, particularly epoxy putty adhesive and Portland cement, are viable and cost-effective alternatives to traditional outplanting nails, offering superior underwater operability and stability. Portland cement is highlighted for its affordability and ease of use, making it increasingly favoured in large-scale restoration efforts. However, the potential biocompatibility issues associated with Portland cement-based adhesives necessitate further investigation. These findings suggest that adhesives can serve as an efficient and cost-effective technique for underwater coral fixation during coral restoration, although careful consideration of environmental factors and additional field testing are essential to validate their effectiveness across varied conditions.

The Patagonia Frog (Atelognathus patagonicus) is endemic to a lagoon system in northwestern Argentine Patagonia. Laguna Blanca National Park includes 10 of the 23 lagoons historically known to harbour the species. During summer, we conducted surveys within the park in nine of these lagoons that retained water, sampling a total of 176 sites across three repeated visits. To develop occupancy models, we measured four site covariates (rock cover, vegetation cover, shore distance and water depth). Shore distance was categorized into three fixed values representing sites located in the water, on the shoreline and on land. We detected individuals in 10% of the surveyed sites and in eight of the nine lagoons. Sites in the water and along the shoreline showed the highest occupancy probability values, consistent with the species' aquatic lifestyle. The best-supported model included all four covariates, showing a positive relationship with rock and vegetation cover, and a negative relationship with depth and distance from the shoreline. Among all covariates, rock cover showed the strongest positive relationship with occupancy. Therefore, conservation actions should prioritize the protection of existing rock structures, while also addressing other key threats such as exotic fish and livestock grazing. Our findings provide key insights into habitat use and offer recommendations for strengthening habitat-based conservation strategies that promote the long-term persistence of the Patagonia Frog.

The brown macroalga Rugulopteryx okamurae, identified as invasive in the Strait of Gibraltar a decade ago, is rapidly expanding across the NE Atlantic and the NW Mediterranean, displacing native assemblages and disrupting coastal ecosystems. However, the capacity of native herbivores to regulate this invasion remains poorly understood, especially under climate-driven extreme events such as marine heatwaves (MHWs). In this study, we conducted a mesocosm experiment to test the feeding response of the sea urchin Paracentrotus lividus on R. okamurae and two native macroalgae, Dictyota fasciola and Ulva sp., across a simulated MHW gradient. Consumption rates declined significantly with rising temperatures, indicating that warming reduces overall grazing activity, and R. okamurae was always the least consumed species. Feeding preference was consistent across treatments: D. fasciola was the first preference, followed by Ulva sp., and R. okamurae as the last option. Our findings show that R. okamurae is only partially grazed under lower temperature conditions, with consistently lower consumption than native macroalgae, and that rising temperatures progressively suppress overall herbivory, further reducing top-down control on the invader and facilitating its spread across Mediterranean and Atlantic reefs.

The blue whale has been the focus of considerable research effort worldwide, yet significant gaps remain in the understanding of this species' ecology, behaviour, distribution and resilience to anthropogenic pressures. This review synthesizes insights from an international workshop held during the 25th Biennial Conference on the Biology of Marine Mammals 2024 hosted in Perth, Western Australia, which convened over 40 scientists specializing in blue whale research. The workshop aimed to consolidate the current state of knowledge, identify key research gaps and develop collaborative strategies to advance blue whale science with a focus on the local population of blue whales, the eastern Indian Ocean pygmy blue (EIOPB) whale. With research efforts into the species intensifying in recent years, there exist considerable opportunities for collaboration across research groups to avoid unnecessary duplication of effort and maximize the value of research efforts. Further, filling critical knowledge gaps that limit conservation and effective population management will require holistic studies focused not only on blue whales but on their prey species, krill and the mechanistic links between environmental drivers, krill and blue whales.

Detecting rare fish species across extensive river systems can be challenging due to their low abundance. However, detection probability may increase when individuals aggregate within localised areas during the spawning season. This study investigates whether environmental DNA (eDNA) detection probability can be improved for the threatened Australian grayling (Prototroctes maraena) by concentrating sampling effort in the putative spawning grounds (lower freshwater reaches) during the spawning season. Eight replicate water samples were collected from each of three sites in the Tuross and Deua rivers in New South Wales (NSW), where Australian grayling occur in very low abundance, and from three sites in the Bunyip River in Victoria (positive field control)—one of the last rivers supporting a relatively high abundance of this species. Sampling was conducted on six occasions between April and June 2023 to coincide with the species' downstream migration to spawning grounds. A species-specific quantitative PCR (qPCR) assay targeting the Australian grayling COI gene was developed and applied to detect the species using six replicate qPCR reactions per sample. Australian grayling were detected or putatively detected in 78% of sampling occasions in the Tuross River and 100% of sampling occasions in the Deua and Bunyip rivers. The proportion of positive qPCR replicates was much higher in the Bunyip River, consistent with the species' higher abundance in this location. Nevertheless, there was a peak in detection probability in the NSW sites from May to early June, confirming the efficacy of a targeted sampling strategy coinciding with spawning aggregations in the lower reaches. The study's findings demonstrate the benefits of incorporating knowledge of behaviour into eDNA survey design for improved detection of low-abundance species, which can assist in informing threatened fish recovery actions.

Water resource managers need Streamflow Duration Assessment Methods (SDAMs) to predict if streams are ephemeral, intermittent or perennial. Although SDAMs exist for some regions of the United States, no validated SDAM has been developed for Puerto Rico and the US Virgin Islands. This review lays the foundation for a US Caribbean SDAM that will be accurate and practical by characterizing trends in stream research and identifying flow class documentation, candidate indicators of streamflow duration and a hydrogeographic framework. We screened 2081 titles and abstracts and 750 full-text documents. Despite many Caribbean islands having only non-perennial streams or a mixture of perennial and non-perennial streams, our review identified only 10 studies that evaluated stream characteristics between reaches with different flow duration. Candidate indicators include drainage area, riparian herbaceous cover, two fish metrics and 19 aquatic invertebrate metrics. A total of 235 documents provided localities for 2282 stream reaches, 94.7% in Puerto Rico and 5.3% in the US Virgin Islands. Eighty-two documents classified streamflow duration, but only 45 provided flow class and locality. From these, we identified 425 candidate SDAM study reaches, of which 308, 103 and 14 were perennial, intermittent and ephemeral, respectively. Hydrology, chemistry and geomorphology topics dominated the stream research literature. The ecological life zones framework is the most suitable of 13 hydrogeographic frameworks for a US Caribbean SDAM. The subtropical dry forest zone contained most of the documented intermittent reaches, whereas documented perennial reaches dominated the subtropical moist forest and subtropical wet forest zones.