Aquatic Ecology最新文献

Dinotefuran possesses promising prospects, but poses a threat to the health of organisms in aquatic environment. In this study, the enantioselective toxicity effects of dinotefuran on Rana nigromaculata tadpoles were investigated. Acute toxicity tests for 96 h showed that R-(−)-dinotefuran had a more significant toxic effect on tadpoles than Rac-dinotefuran, which was greater than that of S-(+)-dinotefuran. In the toxicity assays with 0.2 and 2 mg/L dinotefuran for 28 d, noticeable changes in oxidative stress induced by Rac-dinotefuran and the two enantiomers were observed. The results of the growth parameters indicated that the development of R. nigromaculata tadpoles was inhibited to a certain extent, and the order was R-(-)-dinotefuran > Rac-dinotefuran > S-(+)-dinotefuran. Furthermore, the determination of triiodothyronine (T3) and thyroxine (T4), and the expression levels of corresponding genes (dio2, dio3, trα and trβ), demonstrated that R-(-)-dinotefuran and Rac-dinotefuran caused endocrine disruption of the thyroid system and delayed the development and metamorphosis of tadpoles, but S-(+)-dinotefuran had little effect, which was basically consistent with the results of acute toxicity and growth parameter assays. The results provide a new theoretical basis for assessing the environmental risk posed by chiral pesticides to aquatic nontargeted organisms.

Graphical abstract

Anthropogenic eutrophication continuously degrades aquatic ecosystems and has led to a high frequency of massive cyanobacterial blooms in Taihu Lake since 1980. After bloom-forming cyanobacteria begin to disappear, substantial cyanobacterial scum accumulates and is degraded by microorganisms along the lakeshore. Several studies have revealed that cyanobacterial decomposition alters bacterial composition. However, the differences in responses among free-living and particle-attached bacteria to lake microbial community succession and the transition mechanism from one life strategy to another during cyanobacterial biomass and cyanobacteria-derived dissolved organic matter degradation remain unclear. This study investigated the microbial dynamics of cyanobacterial organic matter degradation over 61 days and revealed that complex interactions between particle-attached bacteria and cyanobacterial organic matter resulted in stage-specific changes in the chemical properties of water and a significant succession of the particle-attached bacterial community structure. As cyanobacteria biomass decayed, partial particle-attached bacteria transitioned into free-living bacteria. Successive free-living and particle-attached bacterial communities play important roles in driving dynamic variations in the chemical properties of water. This study provides new insights into the ecological processes and mechanisms governing the shift in bacterial community assembly between free-living and particle-attached bacteria during the post-bloom period in the Lake Taihu watershed.

As a major parts of marine organism, seagrass exhibit crucial role in sustaining balance of marine ecosystem. However, the escalating development of urban industry may bring potential pollution risk to seagrass. In order to make a comprehensive understand of the pollution level of heavy metals and their environmental risk in seagrass, totally four seagrass beds from seashore of Yellow Sea were selected in this study. The concentration of typical heavy metals in seagrass, seawater, and sediment were determined and their ecological risk in different seagrass beds were further evaluated. In regards to the concentration of heavy metals in sediments and seawater, our results indicated that Zn exhibits the highest concentration and then decreased in order of Cu, Pb and Cd. However, the average concentration of these metals are not exceed the first-class national quality standard of sediments and water. Significant differences of heavy metal concentration in seagrass are found among different sampling sites. Furthermore, the heavy metals accumulated in the aboveground tissues of seagrass are found higher than those in underground tissues. The risk assessment in the study area show that although no significance pollution risk is found for each element, a high risk level of Cd with E_i (ecological hazard index of element i) value of 156.9 in seagrass beds is observed, which was also proved by the value of risk indices (IR). The value of I_geo (Geoaccumulation index) in seagrass beds decrease in order of Cd > Pb > Zn > Cu. The results of this study are of considerable significant for the protection of seagrass ecosystem in Yellow Sea.

This study aimed to analyse the microbial biodiversity in ceriantharian tubes through shotgun metagenomics, to enhance the understanding of ecological dynamics in these microhabitats. We sampled two tubes of Ceriantheomorphe brasiliensis in Florianópolis (SC), and two tubes of Ceriantheopsis lineata in Alcatrazes archipelago (AK), South and Southeast Brazil, respectively. The environmental DNA from the tubes was extracted, amplified, and submitted to shotgun metagenomics sequencing on the Illumina HiSeq platform, and the biodiversity analysis was run using the Kraken2 software. Our results indicate that Ceriantharia-associated microbiomes likely harbour novel microbial diversity, as roughly only 8% of metagenomic reads were classified. Microbial composition was highly similar in both locations, with the Bacteria domain predominating, particularly the phyla Pseudomonadota and Actinomycetota. Nitrososphaerota was consistently the most common archaeal phylum in all samples. The bacterial classes Betaproteobacteria and Planctomycetia, and the archaeal class Nitrososphaeria were present in all four tubes, as were the bacterial family Pseudomonodaceae and the archaeal family Nitrosopumilaceae. Roseobactereaceae dominated alphaproteobacterial families from AK tubes, while Streptomycetaceae prevailed among actinobacterial families from SC tubes. The α-diversity indicates similar values between AK and SC samples, with slight distinctions favouring SC. β-diversity results show higher similarity within the same locations (AK or SC) than between different locations, highlighting spatial influence on microbial composition. To the best of our knowledge, this study is the first to address microbial composition found in ceriantharian tubes, using shotgun metagenomics, and our findings set up the scenario for a wider comprehension of these cnidarians as key holobionts in marine ecosystems.

Filter-feeding bivalves have strong effects on ecosystem processes and functions. Bivalves may be used for the rehabilitation of eutrophic waters, either by being placed suspended in cages or on chains in pelagic habitats or stocked in benthic habitats. However, the effects of bivalves on the ecosystem may differ between the two habitats. A 5-week mesocosm experiment with bivalves (Sinanodonta woodiana Lea 1834) was conducted to test if filter-feeding bivalves suspended in pelagic habitats would improve water quality more efficiently than stocked bivalves in benthic habitats. Nutrients, suspended solids, light intensity, biomass of phytoplankton in different size fractions, and zooplankton were measured. Bivalves reduced the biomasses of total phytoplankton and nanophytoplankton and decreased the total phosphorus, total suspended solids, and organic suspended solids in both the benthic and the pelagic habitats. Bivalves also increased the light intensity and the biomass of periphyton and benthic algae. However, we found significantly higher ammonium nitrogen concentrations and higher periphyton biomass in the suspended bivalve treatment than in the benthic bivalve treatment. In both habitats, bivalve introduction reduced the abundance of cladocerans, increased the abundance of copepods but had no effect on the abundance of rotifers. The abundances of total zooplankton, cladocerans, copepods, and rotifers were similar in the treatments with suspended and benthic bivalves. These results confirm the strong effect of filter-feeding bivalves on plankton communities and their potential for the improvement of water quality whether suspended or occurring in the sediment, they indicate a potential of using filter-feeding bivalves in lake rehabilitation.

Aquatic and semiaquatic Heteroptera (Insecta: Hemiptera) are globally distributed and inhabit a wide range of lentic and lotic water bodies. Most semiaquatic bugs (Heteroptera: Gerromorpha) live on the water surface, among hydrophytes, or on the margins of limnic habitats. These predatory insects are particularly diverse in the Neotropical Region, but they are still very poorly known in the northeastern region of Brazil, especially in the Caatinga biome. Their distribution and conservation in the area have very recently started being explored. Based on literature data and samples obtained in the northeastern Brazilian states of Alagoas and Sergipe, we present here potential geographic distribution models for 17 species of semiaquatic bugs and a potential species richness map. We designed fieldwork to reduce sampling bias by including different mesoregions of the states and areas both within and outside local protected areas (PAs). Our results reveal that gerromorphan populations exhibit distinct distribution patterns in the study area, with several species showing high habitat specificity. Furthermore, they are generally well covered by the existing PAs and higher potential richness is likely related to the environmental integrity of these areas, which might play a crucial role in locally conserving aquatic insects. Furthermore, we show that a less dense vegetal cover negatively influenced the richness found in lotic systems. This highlights the importance of maintaining and effectively managing the PAs already established in these states.

Freshwater mussels are filter feeders that play an integral role in keeping our water systems healthy. Filter feeding influences the entire ecosystem through the transfer of energy, cycling of nutrients, and purification of water. Freshwater mussels form multispecies assemblages which may lead to food resource competition among species. This study focuses on determining which suspended food resources freshwater mussels consume and evaluates if, and to what extent, mussels in a multispecies bed are partitioning available food resources. We examined the available food resources consumed by four species of freshwater mussels, Bleufer (Potamilus purpuratus), Pistolgrip (Tritogonia verrucose), Texas Pigtoe (Fusconaia askewi), and Yellow Sandshell (Lampsilis teres), from a single mussel bed in the upper Sabine River of East Texas. Using eDNA as a measure of food availability, we found that bacteria were consumed at a higher richness and diversity than phytoplankton or zooplankton. Furthermore, we found low niche overlap of bacteria between mussel species suggesting niche partitioning may be common for freshwater mussels despite being found in a flowing river environment with potentially unlimited resources. We also found that the richness and diversity of bacteria consumed by the Yellow Sandshell is statistically higher than Pistolgrip and that these species have moderate niche overlap (0.556). These data and previous habitat data indicate that the Pistolgrip can be classified as an ecological specialist species and the Yellow Sandshell as an ecological generalist species. Overall, these results support ecological theory that mussels co-exist in the same environment because they utilize different resources.

The relationship between biodiversity and ecosystem functioning (BEF) is one of the central themes of ecological research. Phytoplankton play important ecological functions in aquatic ecosystems. Although the BEF in phytoplankton communities was found in various types of natural aquatic ecosystems, it has not been examined in artificial ecosystems at small scale. Artificial reef, a submerged device built by human, can pump nutrient-rich bottom water to the surface, mimicking natural upwelling to feed phytoplankton. Here we quarterly investigated the phytoplankton communities in the artificial reef zone and its adjacent water in a subtropical bay. Our results showed positive linear relationship of phytoplankton richness to productivity in the artificial reef zone. The slope of richness-productivity relationship increased with water temperature and was relatively higher in the summer. Phytoplankton resource use efficiency (RUE) was positively correlated with richness but negatively correlated with evenness in the artificial reef zone. Compared to the adjacent natural zone, the artificial reef zone had more diverse phytoplankton communities and higher productivity during the growing season. The phytoplankton BEF pattern we found provides evidence for the role of artificial reef in the functioning of subtropical bay ecosystem.

A case of massive fish mortality is reported in an aquatic body in the municipality of Izamal in Yucatan, Mexico. The fish analyzed exhibited signs of hemorrhage and suffocation. Analysis of the phytoplankton samples revealed the presence of a flagellated microalga with characteristics consistent with Prymnesium parvum, particularly due to the presence of the haptonema. The average densities of the microalgae were approximately 16 × 10⁶ cells L⁻¹. The documentation of this species in the Yucatán Peninsula and the observed effects represent an emerging risk for the aquatic ecosystems of the region. This risk is linked to the extensive connectivity between aquatic systems in the region, combined with the significant dispersion capability of the species, which is magnified by the increasing eutrophication conditions in these bodies of water.