Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

This study used a novel approach combining stable isotope data and condensed multivariate fatty acid data to define comparative niche space and overlap of six sympatric sharks from the south-west Indian Ocean: Galeocerdo cuvier, Sphyrna zygaena, Sphyrna lewini, Carcharias taurus, Carcharodon carcharias and Carcharhinus obscurus. G. cuvier had the smallest fatty acid niche space but exhibited the largest range in δ¹³C, suggestive of foraging across multiple environments (habitat generalist) but on nutritionally similar prey in a narrow trophic band (nutritional specialist). The remaining five species had comparatively higher δ¹⁵N, pelagic-based fatty acids and larger fatty acid niche spaces, suggesting they are nutritional generalists with a preference for higher trophic level prey. Niche space was not associated with conservation status despite declining populations for half of the species studied. This suggests that resource availability is not a limiting factor for these species and that their mobile nature provides them access to diverse habitats and resources, while exposing them to a broad range of anthropogenic threats, muting the relationship between conservation status and resource use. The combined approach allowed for a comprehensive representation of niche space, distinguishing species based on trophic level, basal carbon sources and pelagic and coastal prey consumption. The presented integrated approach provides greater detail and resolution of elasmobranch trophic ecology that could not be achieved with either fatty acid or stable isotope analysis alone.

Understanding how invasive species affect the stability and function of ecosystems is critical for conservation. Here, we quantified the effect of an actively suppressed invasive species on the Yellowstone Lake ecosystem using a food web energetics approach. We compared energy flux, functional state, and stability of four food web states: a pre-invasion network and three post-invasion networks undergoing active invasive species suppression, namely, initial invasion, expansion, and decline. Invasion caused ≥ 25% change (±) in energy flux for most consumers, and total flux increased twofold post-invasion. Flux to the species of conservation concern, Yellowstone cutthroat trout (Oncorhynchus virginalis bouvieri), was 2.8 times less post-invasion versus pre-invasion, whereas invasive lake trout (Salvelinus namaycush) flux was up to 17.3 times higher compared to the initial invasion network. The dominant functional state and food web stability did not change post-invasion, likely due to introduction of a generalist predator and the stabilizing effect of suppression. Lake trout invasion in Yellowstone Lake caused large changes to energy flux, shifting dominant fluxes away from the species of conservation concern, despite not changing functional state or stability. We demonstrate that changes in energy flux may signal invasions in ecosystems, but functional state or stability may not necessarily reflect the magnitude of invasion influences. For invaded fish communities, a better understanding of how the invasive species control the food web beyond just the direct influence on prey can be achieved by investigating energy flux, functional state, and food web stability. Furthermore, evaluating the effect of suppression beyond the invasive species can demonstrate the far-reaching value of suppression management actions for conservation.

Because coral reef ecosystems face threats from human activities and climate change, coral reef conservation programmes are implemented worldwide. Monitoring coral health provides references for guiding conservation activities. However, current labour-intensive methods result in a backlog of unsorted images, highlighting the need for automated classification. Few studies have simultaneously utilized accurate labels along with updated algorithms and datasets. This study aimed to create a dataset representing common coral reef conditions and associated stressors in the Indo-Pacific. Concurrently, it assessed existing classification algorithms and proposed a new multilabel method for automatically detecting coral reef conditions and extracting ecological information. A dataset containing over 20,000 high-resolution coral images of different health conditions and stressors was constructed based on the field survey. Seven representative deep learning architectures were tested on this dataset, and their performance was quantitatively evaluated using the F1 metric and the match ratio. Based on this evaluation, a new method utilizing the ensemble learning approach was proposed. The proposed method accurately classified coral reef conditions as healthy, compromised, dead and rubble; it also identified corresponding stressors, including competition, disease, predation and physical issues. This method can help develop the coral image archive, guide conservation activities and provide references for decision-making for reef managers and conservationists. The proposed ensemble learning approach outperforms others on the dataset, showing state-of-the-art (SOTA) performance. Future research should improve its generalizability and accuracy to support global coral reef conservation efforts.

The northern Gulf of Mexico is home to several species of corals that provide a wide range of ecosystem services to other organisms. Oil and gas infrastructure, such as platforms and pipelines, form an extensive network throughout the northern Gulf of Mexico. Detrimental impacts associated with oil and gas exploration and extraction have been recorded in this area at depths where corals are found. Due to these ecosystems' vulnerability to long-term impacts, it is necessary to determine areas of interest that would benefit from further exploration and informed spatial planning. This study aimed to identify potential areas of interest for coral studies in the northern Gulf of Mexico. Ensemble species distribution models for 13 species of corals including scleractinians, black corals, and octocorals were produced based on seafloor characteristics and combined to identify areas with relatively higher coral diversity potential than others. The ensemble modelling approach produced robust outputs, as evaluated by the area under the curve, Cohen's kappa coefficient, sensitivity, specificity and the proportion of correct predictions. The proximity of suitable habitat to active and proposed oil and gas infrastructure was evaluated; this spatial analysis showed that oil and gas infrastructures potentially impact 23.5% of all predicted suitable coral habitat in the study area and contribute to benthic habitat fragmentation. Twelve areas of interest greater than 100 km² and located outside a 4-km zone of potential influence from oil and gas infrastructure were delineated and deemed of interest for further exploration and spatial planning, and hypothetical prioritization scenarios for spatial planning are presented. The maps produced can inform discussions among stakeholders to reach the best spatial planning outcomes while considering other ecological, social, economic and governance factors.

Coralligenous, a typical Mediterranean mesophotic habitat, is a highly diverse assemblage, severely threatened by several stressors, including fishing litter. To characterise the coralligenous of the upper mesophotic of the Portofino Promontory (Ligurian Sea, Italy), video transects at 35 and 50 m depth were performed at four sites. Benthic assemblages and lost fishing gears were recorded, and the two depths compared. A higher coverage of taxa with complex 3D structures was found at 50 m, mainly due to the gorgonian Paramuricea clavata. However, the overall low density of this species (0.4–6.6 colonies/m²), together with the impact caused by 120 fishing lines found along the transects, highlights the need for tailored conservation measures. With climate change moving further down the water column and fishing impacts being a major cause of degradation, the design of marine protected areas needs to be extended to include mesophotic depths, contributing to the 30 × 30 targets agreed upon at the COP15.

The use of environmental DNA (eDNA) as a tool for monitoring represents a major innovative advance in environmental science, one that enables the detection of species without the need to observe or capture them. This article assesses the state of play of eDNA research targeting crayfish. We found a total of 41 peer-reviewed articles published between 2014 and 2023 on both native and invasive species. Most studies focused on invasive species (or a native/invasive species co-detection assessment) (65.8%). There was also a clear geographical bias across studies, with more than half conducted in Europe (51.2%) and a quarter in the United States (26.8%). In contrast, there were none conducted in Africa. The relatively large number of published studies has led to an interesting diversity of protocols designed or utilized, with most favouring the development of their own assays (69.33%). That said, filtration (as an eDNA capture method) was common (80.5%), along with the use of commercially available eDNA extraction kits (69.8%). The COI gene also appeared to be the preferred target region (89.33%). Such range of protocols is interesting, but is it optimal? Are the best protocols always being utilized? Or is the chance for novel application hampering our ability to explore larger trends across studies?