Aquatic Ecology最新文献

Parasites are facing a loss in biodiversity in a changing climate. In this context, the present study aimed to evaluate the influence of climate change on Hoplias malabaricus and its species of monogenetic and digenetic parasites. The models were developed for South America and the species occurrence data were obtained from databases and digital platforms. The bioclimatic, edaphic, elevation, and slope variables were obtained from specialized platforms. Thus, to generate species distribution models, Support Vector Machine, Random Forest and Generalized Linear Model algorithms were used. All predictions of the model for a species were combined to obtain its final model (Ensemble) for the present and future scenarios. As a result, definitive hosts of the parasites showed high climatic suitability. The broad niche of these species indicated that these organisms can show certain opportunistic and generalist characteristics. Unlike their parasites that revealed a more restricted distribution than their host. Also, in a future scenario, endoparasite species will generally reduce 99% of their populations, ectoparasites 93%, while some hosts will increase their populations. In conclusion, the study assumed that future climatic events can influence parasites and their hosts differently, whereas anthropization can influence parasite extinction even without directly affecting their hosts.

Sediments, waters and vegetation work together and cooperate mutually to maintain normal function of mangrove wetland ecosystem. To gained a comprehensive understanding of the response strategies existed by the leaf traits of Aegiceras corniculatum and to identity the key factors that drive leaf traits variation in the response to shrimp aquaculture wastewater, we sampled leaves of A. corniculatum, sediments and interstitial water from non-discharge area (CK), direct discharge area (DDA) and landfill restoration area (LRA) in Qinzhou Bay in southeast coast of China. We established a correlation between leaf vein traits and stomatal traits and abiotic conditions such as pH, nutrient content in sediment. In comparison to CK and LRA, leaf vein traits (primary vein diameter, secondary vein diameter, tertiary vein diameter, enclosed circular area, vein spacing, and tertiary vein density) exhibited a decrease in DDA. This observation suggests that the persistent discharge of shrimp aquaculture wastewater exerts a detrimental impact on the leaves’ mechanical support, nutrient, and water transport capacity. Furthermore, a marked negative correction emerges between stomatal density and length. In contrast, within LRA, an increase in stomatal density and a corresponding reduction in stomatal length indicate a heightened transpiration function of the leaves, thereby enhancing the efficiency of water and inorganic salt transport. Subsequently, the leaf vein traits in LRA are observed to be higher than in CK, suggesting that the leaf traits of A. corniculatum has undergone pre-adaptation to DDA and possesses high phenotypic plasticity. Through the analysis of leaf vein and stomatal traits in diverse shrimp aquaculture wastewater discharge habitats, this study demonstrates that such pre-adaptation and elevated phenotypic plasticity facilitates the adaptation of A. corniculatum to the challenging shrimp aquaculture wastewater environment.

Malacostracans are significant in several environmental processes, making them a major biotic component in aquatic ecosystems. An investigation on the spatio-temporal variations in the diversity and abundance of malacostraca was carried out in the Kallada River for a period of two years from 2019 to 2021. The malacostracan community was represented by 35 species in 17 families and 4 orders during the investigation period. Decapods (24 species), amphipods (7 species), isopods, and tanaids (2 species each) were identified from the Kallada River. Seasonally, PoM (Post-monsoon) witnessed the presence of 33 species closely followed by PrM (Pre-monsoon) and MoN (Monsoon) with 32 species each. The amphipod species Melita zeylanica belonging to the family Melitidae dominated in terms of abundance throughout the study period. Diversity, richness, and dominance indices were increased from the upstream to downstream sites. Contrarily, the highest values of evenness were recorded the upstream and lowest recorded downstream. Diversity analysis values were maximum at downstream sites during the PrM season while the abundance was maximum during the PoM season. Multivariate tools such as CCA (canonical correspondence analysis) and hierarchical clustering were applied to investigate the co-existence of various malacostracan taxa and the relation between the species and water quality parameters. Similar feeding habits and water quality requirements allowed the co-occurrence of malacostracan species. CCA indicates the freshwater and estuarine influences on malacostracan diversity and abundance. The study also assessed the detrimental effects of sewage and municipal effluents on malacostraca at the midstream stations. However, the low diversity at the upstream stations was attributed to the natural environmental conditions.

Sagartaal is located in Budaun with geographical coordinates 28.0512°N and 79.1305°E in Nawada region, Uttar Pradesh, Uttar Pradesh, India. Understanding the composition, diversity, and abundance of the zooplankton is vital for better utilization of such waterbodies. The present study was carried out from October 2022 to September 2023. A total of 24 species belonging to 16 species of Rotifera, 4 species of Cladocera, 2 species of Copepoda, and 2 species of Ostracoda were recorded. The prominent species were Brachionus forficula, B. calyciflourus, Keratella cochlearis, Simocephalus sp., Cyclops sp., and Mesocyclops sp. Zooplankton showed seasonal variations in their species composition, abundance, and diversity concerning water temperature, pH, total alkalinity, dissolved oxygen, and hardness. The zooplankton density was recorded as maximum in winter and minimum in monsoon. Statistically, zooplankton shows significant correlations as Rotifera with EC, BOD (r =− 0.50; − 0.58, respectively); while with total hardness (r = 0.75); Cladocera with DO (r = 0.53), alkalinity (r = 0.57), nitrate (r = 0.56), and phosphate (r = − 0.49). The highest Shannon index (2.83) was obtained for summer, due to the lowest value of the dominance index (0.07) for this season. More studies are warranted on Monitoring such ecosystems as Sagartaal to understand the effects of anthropogenic pressure on zooplankton's community structure, can help in identifying the indicator species to formulate effective conservation planning.

Periphyton is an important basal food source for many aquatic consumers by directly or indirectly providing long-chain polyunsaturated fatty acids (LC-PUFA). Although periphyton LC-PUFA content is highly sensitive to aqueous nutrients, the majority of prior studies have been conducted in low-nutrient aquatic environments. Less is known about how periphyton LC-PUFA content may change in response to higher nutrient concentrations in rivers. We conducted a periphyton culturing experiment by manipulating a gradient of aqueous nutrient concentrations from 0.002 to 0.18 mg P/L to investigate how aqueous nutrients affected periphyton FA from oligotrophic to eutrophic waters. Our results showed a significant curvilinear relationship between aqueous water nutrients and periphyton FA. In oligotrophic conditions, periphyton LC-PUFA increased as aqueous nutrients increased, whereas in eutrophic waters, periphyton LC-PUFA decreased as aqueous nutrients increased. The change of taxonomic composition, especially the increase of diatom density, was a significant factor influencing periphyton LC-PUFA content. Additionally, periphyton biomass experienced a significant increase with elevated aqueous nutrients, which differed from periphyton LC-PUFA. Our study detected the response of periphyton FA to aqueous nutrients from oligotrophic to eutrophic conditions, and provided a reference for the protection of river ecosystems.

Gastropoda assemblages were investigated for four seasons in 2016–2017 (autumn, winter, spring, and summer) near Umm Al-Namil Island in Kuwait in rocky and sandy habitats to study the effect of season and habitat type on species richness, abundance, evenness, and diversity. A total of 28 gastropod species belonging to 14 families were identified (26 in sandy, 20 in rocky, 18 in common between both habitats). Clypeomorus bifasciata (31.07%) and Trochus erithreus (21.43%) were the most abundant species in the rocky habitat. Pirenella arabica (27.51%), C. bifasciata (26.15%) and Mitrella blanda (15.66%) dominated the sandy habitat. At the rocky habitat, total abundance ranged from 6.5 ± 4.71 to 40 ± 45.17 ind m⁻² in autumn and summer, respectively. As for the sandy habitat, total abundance varied from 53.0 ± 22.60 to 294.0 ± 316.67 ind m⁻² in summer and winter, respectively. The results of the rocky habitat showed that diversity and evenness were strongly affected by season more than habitat type. Species richness and abundance were strongly influenced by habitat type rather than the season. However, the sandy habitat had a higher value of abundance, diversity, species richness, and evenness throughout the sampling period than the rocky habitat. There was almost a distinction between the species resident in both habitats throughout the study. These findings could be attributed mainly to the feeding habits of these gastropods and their burrowing nature.

Rivers interlinking by transposition projects have multiplied in the world, altering the landscape and flow regime of continental water systems. Recently, an intermittent river in northeastern Brazil has been artificially connected to the São Francisco River basin in a water transfer project. Thus, this study aims to provide an inventory of the fish parasites from the Jaguaribe River basin in the scenarios of pre- and post-transposition, and to evaluate the short-term impacts on the parasite fauna. Of the analyzed fishes, belonging to 31 species, about 30% were parasitized. A total of 47 parasite taxa were recovered, including monogeneans (17), digeneans (9), nematodes (9), acanthocephalans (3) and crustaceans (6), and unidentified cysts of Acanthocephala, Cestoda and Digenea, representing the description of 30 new geographic records and 104 new parasite-host associations. By expanding the range of the geographic distribution of fish parasites and increasing the list of hosts, the study contributes to the knowledge of fish parasites biodiversity in the semi-arid region of Brazil and in the Caatinga domain. Considering all parasite species, significant differences were observed in total prevalence, total mean abundance, diversity index and host specificity index; the highest values of total prevalence and total mean abundance were observed in the post-transposition, while the diversity index and host specificity index was higher in the pre-transposition period. This is the first study evaluating fish parasites before and after a major water transfer event and the results will allow further evaluation of middle and long-term changes in the specific composition of fish and parasites from the receiver drainages.

The reproductive strategies of species play a fundamental role in formulating effective management plans and maintaining local community structure and ecological balance. This study investigated the reproductive characteristics of two sympatric species, Callinectes danae and Callinectes ornatus, in Atlantic waters. Monthly sampling was conducted from July/12 to June/14 in the coastal (sites: S1, S2, S3 and S4) and estuarine-lagoon (sites: S5, S6 and S7) areas of Cananéia-Iguape, Brazil. Significant differences in allometric coefficients were observed, particularly in the relationships chelipod length vs. carapace width (CW) for males and abdominal width vs. carapace width (CW) for females. Morphological sexual maturity was estimated at 58.8 mm CW for C. danae males, 54.5 mm CW for females, 45.0 mm CW for C. ornatus males, and 41.2 mm CW for females. Gonadal sexual maturity sizes were identified at 69.4 mm CW for C. danae males, 61.4 mm CW for females, and 58.4 mm CW for C. ornatus males, 46.9 mm CW for females. Both species spawn predominantly during the austral summer, with higher prevalence in site S5 for C. danae and S1 for C. ornatus. Recruitment occurred in austral spring and summer, with C. danae concentrated in estuarine-lagoon regions and C. ornatus along the coast. Reproductive patterns of C. danae were associated with temperature and salinity, while C. ornatus exhibited correlations with temperature and organic matter. This study highlights the influence of environmental factors on species' life cycles. Furthermore, it contributes to the evaluation of management and monitoring strategies, recognizing the economic and ecological significance of these species for sustaining these ecosystems.

Salinity is one of the main factors influencing the early life stages of fish along an estuary, which shows great temporal and spatial changes. Recently, remote sensing has been widely applied to map salinity changes and fuzzy logic is identified as a suitable and strong tool for modeling complex systems. Based on collections of fish larvae and juveniles and water parameters in May, September, November, and December during 2019 along the Ba Lat estuary of the Red River, northern Vietnam, the present study attempts to predict the mapping and monitoring of the salinity using multispectral satellite imagery from Landsat 8 OLI satellite. The study determined that the NFS machine learning model, when improved by PCA, achieved a higher performance in displaying different salinity levels. The present study also confirms that using high spatial resolution or hyperspectral images would have increased the accuracy of spatial variation in similar modeling and mapping. Fuzzy rule–based modelling suggests that the occurrence of fish larvae and juveniles depended on salinity levels, with an R² > 0.9, compared to the field surveys. This finding further confirms the accuracy data obtained by artificial neural network models.

Early stages of fish are easily sensitive to any alteration of environments, thus understanding their dispersions in a dynamic system like estuaries are important in protection and conservation of fish diversity and fishery resources. Especially, it is more significant for a mangrove-associated mudskipper, Periophthalmus modestus, which are distributed in mudflats along the Northwest Pacific, and now are listed as near threatened due to climate change and human activities. In the present study, a hybrid model, Extreme gradient boosting (XGBoost)-Artificial neural networks (ANN), was applied to forecast the distribution of P. modestus larvae and juveniles collected from a large estuary in northern Vietnam, which are driven by temperature and mangrove changes. Present results demonstrate the usefulness and applicability of ANN-XGBoost model in ecological studies, with an excellent estimation accuracy. Furthermore, employing Generative adversarial networks (GANs) model, this study exhibits a decrease in mangrove areas due to human activities between 2010 and 2023. This change with a rise in temperatre during this period would have impacted on P. modestus larvae and juveniles, which tend to be distributed in mangroves and avoid human-affected areas. Thus, it is concluded that changes in P. modestus’ environment like mangroves have a significant influence on their distribution and survival. Applying a novel model in ecological research, this work further indicates the importance of mangrove forests for aquatic organisms, especially mudskippers. This research will allow scientists and biological managers to make more precise forecasts regarding the spread of P. modestus, while also helping to the protection of this mudskipper and other species. Protecting and developing mangrove forests are the first and crucial action to supply a suitable habitat for any fish species. The models employed in this work will be helpful for other relevant studies when obtaining a highly accurate performance.