Aquatic Conservation-Marine and Freshwater Ecosystems最新文献

Sustainable preservation and management of sturgeon habitats in the Caspian Sea (CS) require sound knowledge of habitat suitability (HS). Here, the MaxEnt model was applied to map the HS and distribution of HS of Acipenser persicus, Acipenser stellatus and Acipenser gueldenstaedtii using 11 environmental variables. The model showed high predictive performance, with training AUC values exceeding 0.91 and TSS above 0.70 for all species. The most powerful environmental drivers were sea surface salinity (SSS), particulate inorganic carbon (PIC) and water depth, although their impact varied somewhat among species. Geographical analysis indicated that A. persicus and A. stellatus had higher HS in the southern CS, while A. gueldenstaedtii was more associated with the northern CS. The middle CS exhibited low HS for three species. Relative proportions of highly suitable habitats were less than 1.5% for all species, whereas moderate suitability was 65.6%, 63.7% and 62.7% for A. persicus, A. stellatus and A. gueldenstaedtii, respectively. Climate change exacerbates rising sea surface temperatures (SSTs) and low water levels, which severely threaten sturgeon populations, especially in the shallow northern regions. Habitat loss and poaching also endanger these species, and region-specific conservation efforts are strained. The findings highlight the need for targeted management of sturgeon in the CS. Conservation efforts should prioritize the southern CS as a key HS area for A. persicus and A. stellatus and the shallow northern area for A. gueldenstaedtii. Combined with transboundary cooperation and effective fisheries regulations, these measures are vital for the sustainable conservation of each species.

Coptodon zillii is one of the most dangerous invasive fishes in the world. To develop management plans to effectively prevent its further spread in global aquatic ecosystems requires an understanding of the change in suitable habitat under future climate scenarios. In this study, we develop a Maximum Entropy Model (MaxEnt model) based on the current distribution data of C. zillii and the current WorldClim ecological database to generate a global habitat suitability model for C. zillii. This model was then used to predict the future habitat suitability for C. zillii based on the SSP3-7.0, SSP5-8.5 future climate scenarios. We found that the mean temperature of the coldest Quarter (Bio11) was the environmental variable limiting the distribution of C. zillii. Under the current climatic conditions, the global range of suitable area for C. zillii was mainly concentrated in the tropical and subtropical regions (with a total area of about 40,862,654 km²). Among them, the projected suitable habitat areas reached 304.12 × 10⁴, 933.05 × 10⁴, 66.29 × 10⁴, 845.85 × 10⁴, 1412.58 × 10⁴ and 407.13 × 10⁴ km² in North America, South America, Europe, Asia, Africa and Oceania, respectively. Under the SSP3-7.0 climate scenario, the global areas of suitable habitat for C. zillii in the 2030s and 2050s expanded by 13.84% (315.47 × 10⁴ km²) and 20.78% (408.76 × 10⁴ km²), respectively. Under the SSP5-8.5 climate scenario, the global areas of suitable habitat for C. zillii in the 2030s and 2050s expanded by 16.55% (383.33 × 10⁴ km²) and 21.26% (460.97 × 10⁴ km²), respectively. These findings will help the governments of countries and regions at high risk of C. zillii invasion to develop biological invasion management plans, such as prioritizing enhanced border quarantine measures, strictly regulating potential introduction pathways, and establishing early monitoring and warning systems in predicted suitable habitats.

The Nayar River serves as a home to the fry, fingerlings and juveniles (residents) of Golden Mahseer, Tor putitora, where the brooders ascend annually for spawning (migrants) in search of suitable breeding cum nursery grounds from their abode in the Ganga. Here, we statistically explored the relationship of residents and migrants to ecologically relevant water parameters, land use land cover, and anthropogenic variables in the Nayar River. From July 2021 to June 2022, the samples of river water and Golden Mahseer were collected from six sampling stations at monthly intervals. Concurrently, a stretch of 44.54 km² of the immediate river valley was examined for the basin land cover. Based on variability within the respective stations, the clustering analysis classified the sampling stations into three clusters. The chi-square value (p < 0.05) of the observed variables supported the use of canonical correspondence analysis (CCA) for selected variables in both residents and migrants. The Cos² metric, an extension of the CCA biplot, identified the relation of the examined variables with different Mahseer inhabitants. The Cos² metric showed a strong correlation of migrants with current velocity, electrical conductivity, water temperature, pH, fishing pressure and riverbed substrates, while mining, rural areas, vegetation cover and electrical conductivity strongly correlated with residents. The study suggests a need for strict regulation on fishing, mining, and other anthropogenic activities along the river as the aggregate effects are negatively impacting the habitat quality for both residents and migrants of Golden Mahseer in the breeding cum nursery grounds of the Nayar and its Western and Eastern tributary.

The consequences of biological invasions are often difficult to mitigate because it is challenging to extirpate invasive alien species (IAS) once they have established and spread in a new environment. Conservation actions to control IAS populations at early stages of introduction may help prevent invasions, but they need to be guided by efficient detection tools. Here, we examined the possibility of using a species-specific qPCR-based eDNA method to detect the clown featherback (Teleostei; Notopteridae; Chitala ornata) in the Perai River, Peninsular Malaysia. Chitala ornata is a large, tropical, piscivorous freshwater fish species native to mainland Southeast Asia, which is believed to have been recently introduced into the Perai River drainage. We detected the eDNA of C. ornata at three out of the five surveyed sampling points, whereas recent specimen-based records indicate a widespread distribution. We discuss three potential causes for this partial eDNA detection: (1) the selection of the methodological variables of the qPCR survey, (2) the impact of tropical environmental parameters such as high water temperature and UV exposure and (3) the role of biological factors such as population size and/or seasonal migratory movements of C. ornata possibly linked to its reproductive behaviour. Although qPCR-based eDNA methods offer several advantages over traditional methods for detecting rare species, multiple methodological and environmental factors can affect the outcomes of qPCR-based eDNA studies, especially in tropical environments.

The high economic value and cultural relevance of diadromous fish make them primary targets for traditional fisheries that need effective management to ensure the long-term survival and conservation of their populations. In Portugal, these species are experiencing a marked decline, primarily due to habitat loss and fragmentation, alongside pollution and overfishing. Accurate monitoring is therefore essential to strengthen the management of diadromous fish within Portuguese ecosystems. Advancements in monitoring methodologies could benefit from more sensitive approaches, such as environmental DNA (eDNA) analysis, which is increasingly recognized as a valuable complement to conventional fish monitoring. However, eDNA-based tools remain largely absent and untested in Portugal's monitoring and management of diadromous fish. This study reviews literature on eDNA-based detection of diadromous fish species and discusses key methodological aspects influencing the detection efficiency, including sample processing (e.g., water filtration), DNA extraction methods, marker regions and primers, approach and platforms. A particular focus is placed on diadromous fishes occurring in Portugal, which includes several endangered and commercially important species, and the prospects of using eDNA to monitor them. By consolidating current literature, this work underscores the potential of eDNA to strengthen diadromous fish conservation in Portugal and offers insights to support the integration of eDNA-based tools into national monitoring frameworks. Although our study focuses on Portuguese species, the approaches and insights discussed are broadly applicable and can inform conservation efforts in other regions facing similar challenges.

Aquatic heteroptera, one of the large insect groups, is an important element of aquatic life and the aquatic food chain. Because it spends its entire life cycle in water, its feature of directly reflecting the properties and quality of water draws attention. In this study, the bioindicator role of heteroptera in water quality monitoring was investigated. For this purpose, aquatic heteroptera samples were collected simultaneously from 71 wetlands with different structures and elevations in the Western Black Sea Region and its surroundings (Turkey), and water samples were taken for 15 months in 2022–2024, and pH, temperature, dissolved oxygen, salinity, and electrical conductivity values were recorded. The water quality of wetlands was determined by determining the average values and correlating them with the aquatic heteroptera fauna of these areas. It was determined that the presence of Mesoveliidae and Veliidae species indicated Class I (very good) water quality, the presence of Micronectidae species indicated Class I (very good) and II (good) water quality, and aquatic heteroptera groups with narrow and wide tolerance to water quality changes were defined. In addition, the relationships between some physicochemical parameters in water were determined. As a result, it was clearly demonstrated that aquatic heteroptera species can be used as bioindicators and can be used together with physicochemical parameters in water quality studies.