Aquatic Ecology最新文献

The lane snapper (Lutjanus synagris) is a valuable fishery resource vulnerable to various threats in the Mexican Atlantic, including coral reef degradation, damage to seagrass beds, massive influxes of sargassum, decline of other commercially important species, as well as its slow growth rate and late sexual maturity. Various studies have reported genetic differences and low genetic diversity in lane snapper populations; however, no information is currently available for populations along the Mexican Atlantic coast. Hence, this study aimed to assess the genetic connectivity levels among L. synagris populations across four sites spanning 1400 km of coastline in the Mexican Atlantic. Results showed that allele frequencies are statistically different across populations, yet no relationship was found between genetic flow and geographical distances. Additionally, low genetic diversity was observed in all populations compared to Atlantic-wide studies. The Garza-Williamson index suggested that the studied populations experienced a size reduction. This study highlights the need to regulate the fishing of this species.

Island ecosystems, characterized by isolation and vulnerability, are subject to natural and human-induced pressures. Rapid and effective biodiversity monitoring is crucial for tracking these impacts and adapting conservation efforts. This study focuses on Reunion Island (South-West Indian Ocean), where aquatic biodiversity is threatened by habitat loss, invasive species, and climate change. Stressors, both environmental and human-caused, can affect aquatic community structures. To test this hypothesis, a comprehensive dataset was compiled from various aquatic habitats, including rivers, ponds, reefs, and coastal waters. Biodiversity data for bacteria, diatoms, invertebrates, and fish were collected using eDNA metabarcoding, while environmental and anthropogenic parameters were recorded through field measurements and local databases. Redundancy analysis was used to identify the spatial distribution patterns of aquatic communities and their variations in response to these parameters. Results showed a significant distinction between freshwater and marine communities, with rivers and ponds hosting fewer taxa than marine environments, reflecting unique ecological patterns. In freshwater systems, fish and invertebrate communities are significantly driven by conductivity, temperature, and metals such as arsenic and barium, while diatoms and bacteria are primarily influenced by oxygen levels, atrazine, and perfluorooctanesulfonate. In marine environments, community composition is primarily affected by turbidity and conductivity. This study demonstrated that eDNA methods are effective for routine monitoring of large taxonomic groups, enabling the detection of biodiversity changes related to water chemistry in watersheds. These approaches, commonly used on continents, are also effective in monitoring biodiversity on tropical islands threatened by human activities.

Knodus moenkhausii is a small characid widely distributed and abundant in the Doce River basin, which experienced the largest socio-environmental disaster in Brazil. This species is also recognized for its broad dietary response to various levels of degradation, making it a potential indicator of the ecosystem's impacts resulting from the rupture of the Fundão iron mining dam in 2015. Thus, the objective of this study was to investigate the trophic ecology of K. moenkhausii in the Doce River basin by analyzing its carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic compositions. Samplings of K. moenkhausii individuals and their potential food resources were conducted at three sites affected by the rupture of the ore tailings dam and at three unaffected (control) sites, which were distributed across the upper, middle, and lower regions of the basin. Within each evaluated region, no differences were observed in the δ¹³C values of K. moenkhausii between the affected and their respective control sites. The δ¹⁵N was different between regions for the control sites, but similar between the affected sites, indicating possible homogenization of the river channel conditions due to the impact. In control sites, K. moenkhausii individuals fed on more nutritious resources, such as invertebrates, while in affected sites, they assimilated more algae and periphyton. We also confirmed the importance of the regional context when assigning control sites and verified that the δ¹⁵N values were more effective in reflecting the degradation of the Doce River basin.

The mole crab, Emerita analoga, is found on the sandy beaches of the Pacific coast and is the primary food resource for various populations, particularly shorebirds. Along the Peruvian coast, E. analoga has been reported as a hydrobiological resource used for human consumption, which raises potential public health concerns due to its role as an intermediate host for different groups of parasites. The aim of this study was to determine the prevalence and parasitic load in E. analoga, as well as the relationship with sex and cephalothorax length (LC). The study was conducted on the Mollendo beach circuit (Arequipa, Peru) during October and November 2023. It was found that of the 548 E. analoga individuals sampled, 51.64% were infected and exhibited larger LC sizes, with females showing a greater mean size (x̄ = 20.06 mm). Fisher's test revealed no significant differences between sex and parasitic infection; however, significant differences were observed between LC and infection (r = 0.32, p < 0.001), especially in females (r = 0.31, p < 0.001). Two parasite species were identified: Profilicollis altmani (Acanthocephala), with a prevalence of 41.61%, and Proleptus sp. (Nematoda), with 4.74%. A survey conducted among the local population highlighted the current use of E. analoga in fishing and human consumption (e.g., omelet and ceviches), which poses an increased health risk given that more than 50% of the individuals were found to be infected.

Similar to microplastics (MPs), pharmaceuticals are recognized as emerging contaminants. In the environment, macrophytes experience simultaneous exposure to a mixture of these compounds. This study aimed to assess the impact of low-density polyethylene MPs (40–190 µm) and medroxyprogesterone acetate (DMPA; synthetic hormone) to determine the toxic effects on Lemna minor. A chronic assay of 168 h was conducted to expose macrophytes to two concentrations of each pollutant: MPs at 0.5 mg L⁻¹ and 1.0 mg L⁻¹, and DMPA at 26 ng L⁻¹ and 26 µg L⁻¹. The concentrations were evaluated both individually and in specific combinations, between both concentrations of MPs and DMPA, resulting in eight treatments, in addition to a negative control containing only plants and culture medium. The exposure effects were analyzed through chlorophyll a and b levels, carotenoids, frond number, and adhesion of MPs. MPs and DMPA did not show a significant impact on the specific growth rate or frond number of the macrophyte. Nonetheless, a deleterious effect on chlorophyll b content was observed in all treatments, in relation to the control. Combinations of MPs and DMPA significantly reduced these pigments, indicating stress caused by exposure to the drug. The number of adhered particles was higher on the roots compared to the fronds, suggesting specific adhesion of MPs to L. minor. This phenomenon underscores the potential role of plants as a pathway for the entry of MPs into food chains, since aquatic plants act as sinks for MPs in the environment. On the other hand, the substantial interaction of MPs with plants suggests a potential application in phytostabilization and eventually for the removal of MPs from the environment. Based on our findings, it is plausible to assert that vascular plants play a substantial role in the dynamics and fate of MPs within aquatic ecosystems.

The study investigates the influence of environmental conditions on redox-regulating enzymes in two freshwater snail species, Lithoglyphus naticoides and Theodoxus fluviatilis, in the Serbian section of the Danube. These species have high population densities and are characterized by their easy accessibility for sampling making them suitable candidates for biomonitoring efforts. Given the increasing concern about pollution of freshwater ecosystems, this study addresses how different concentrations of trace metals (As, Cd, Cu, Hg, Ni, Pb, Zn) at two sites — Stari Slankamen and Novi Sad — affect the antioxidant enzyme responses of snails at different periods of the year. According to the consensus-based sediment quality guidelines, both studied localities show a significant load of trace metals, especially during the summer months. Nickel concentrations are over 36 mg/kg and Zn concentrations are over 200 mg/kg. Furthermore, the NS locality has an additional contamination with Cd of over 3 mg/kg. The study measures key antioxidant enzymes—superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase (GST)—as biomarkers of metal contamination. The results show that enzyme activities are generally higher in spring than in summer, underlining the seasonal influences on physiological responses. Preliminary results indicate that T. fluviatilis is more sensitive to environmental changes than L. naticoides, highlighting the need for species-specific considerations in biomonitoring. Long-term studies are recommended to further investigate the chronic effects of pollution on these species and to improve the understanding of the relationship between environmental conditions and physiological responses in freshwater ecosystems.

The species composition, abundance and distribution of sea cucumbers in the intertidal zone of East Cab-ilan Island, Province of Dinagat Islands, Philippines were assessed using a transect-quadrat method. Sampling was done once at the two identified sampling stations in three replicates. A total of 10 species were found namely Holothuria scabra, H. leucospilota, H. fuscopunctata, H. hilla, H. fuscocinerea, H. pervicax, Actinopyga echinites, A. mauritiana, A. miliaris and Bohadschia marmorata. The most abundant species found were the Holothuria scabra, H. hilla and Actinopyga echinites. A. echinites was the only common species found in both stations. Results revealed that there was no significant difference in salinity between stations (p > 0.05). However, species diversity, temperature and pH differ significantly in East Cab-ilan Island (p < 0.05). The non-metric multi-dimensional scaling (nMDS) based on square-root transformed abundance data showed clear segregation of samples between two stations. Cluster analysis also revealed that there is no close relationship of the samples between Station 1 and Station 2. SIMPER analysis also showed that there was a high dissimilarity percentage in both stations. Some species of sea cucumbers and their distribution were influenced by physico-chemical parameters such as pH and temperature.

Nitrogen (N) and arsenic (As) pollution in water environment seriously threaten human life and health. In order to improve the efficiency of sustainable remediation of N and As co-polluted water environment, the migration and transformation of microalgae, N, and As and their interaction were studied. Based on the bibliometric analysis and the research status of remediation for N and As co-polluted water environment, this study focused on the oxidation, reduction, methylation, and absorption of As by microalgae, analyzed the effects of N sources on the physiological and biochemical functions of microalgae, extracellular secretions, and cell growth, and revealed the mechanism of As enrichment by microalgae in the presence of N sources. It was found that the physiological and biochemical characteristics of microalgae showed complex changes under the condition of coexistence of N and As. N sources affect the metabolic pathways and key enzyme activities of microalgae, and affect the absorption and transformation of As. The extracellular secretions of microalgae may also change, and the organic acids and polysaccharides contained in them can be complexed with As, affecting the migration and bioavailability of As. The concentration of N and As and the type of N source affect the growth rate and cell morphology of microalgae. Under the appropriate concentration ratio of N and As, microalgae can adjust their physiological state to achieve the balance between growth and pollutant removal. Clarifying the physiological and biochemical change mechanism of microalgae under the coexistence of N and As and optimizing their ability to remove pollutants are the key to future research. This study can provide new ideas and references for the simultaneous purification of pollutants such as N and As in water environment.

This study aims to identify the C. raciborskii species based on its morphology, examine its morphological variability by tracking its annual life cycle and environmental parameters fluctuations, and assess its toxicity by measuring cylindrospermopsin (CYN) in Lake Oubeira between October 2021 and September 2022. Microscopic observations revealed the existence of straight or slightly curved filaments. Filament ends exhibited various shapes: rounded (39%), intermediate (40%), pencil (16%), and needle (5%). However, only rounded filament ends were present throughout this cycle. Four morphotypes were observed: filaments with heterocytes and akinetes (< 1%), akinetes only (< 2%), heterocytes only (6%), and neither heterocytes nor akinetes (> 90%). Results showed that filaments without heterocytes or akinetes, and those with only heterocytes, positively correlated with nitrates, conductivity, turbidity, atmopspheric temperature, water temperature, and pH, but negatively with transparency and dissolved oxygen. Conversely, filaments with heterocytes and akinetes were positively correlated with precipitation (Preci) (p ≤ 0.001), showing a positive correlation with phosphates while filaments with only akinetes displayed negative correlations with WT and Trans. Only extracellular Cylindrospermopsin was detected during the study period, excluding February and April, with concentrations ranging from 80 to 750 ng/. Four CYN peaks exceeding 500 ng/L were offset from C. raciborskii biomass peaks. The observed morphological variability in filaments sampled from Lake Oubeira confirms the species as C. raciborskii. However, employing additional approaches, such as culturing, and molecular taxonomy, would be necessary to complete the study of this cyanobacteria species.

Ammonia is one of the deleterious water quality parameters that must be managed for successful aquaculture production. The present study evaluated the impact of chronic ammonia exposure on the physio-biochemical and immunological responses of Etroplus suratensis. Fish (n = 120, 24 ± 3 g) were exposed to four different ammonia concentrations (0, 1, 2, and 4 mg L⁻¹ of Total ammonia nitrogen (TAN)) at 27.5 to 29.7⁰C for 30 days. The unionized ammonia concentrations are 0, 0.014, 0.028, 0.057 mg L⁻¹. The lowest haemoglobin (Hb) level was observed in fish exposed to the highest level of TAN (4 mg L⁻¹). The serum glucose, cortisol, liver superoxidase dismutase, catalase activities, enzymes such as alkaline phosphatase, Serum Glutamic- Oxaloacetic Transaminase, and Serum Glutamic- Pyruvic Transaminase were higher in fish exposed to 4 mg L⁻¹ TAN than the control group. The serum total protein and albumin levels were substantially decreased with TAN exposure. Immune parameters such as Immunoglobulin M and Tumour Necrosis Factor—alpha were significantly (P < 0.05) lower in the groups exposed higher ammonia concentrations than the unexposed group. The heat shock protein 70 gene expression was significantly higher at 1 mg L⁻¹ TAN, and the Insulin-like growth factor-1 gene expression was lower (P < 0.05) at 4 mg L⁻¹ TAN. This is the first detailed investigation on the impact of chronic ammonia exposure in the culture fish E. suratensis. This study reveals that a chronic exposure to TAN even at lower concentrations, such as 1 mg L⁻¹ TAN in fresh water can have a negative impact on E. suratensis physico-biochemical and immunological responses. Hence, it is important to manage TAN levels below 1 mg L⁻¹ in the culture system of E. suratensis to ensure good health.