Aquatic Ecology最新文献

This study shows how YouTube™, a popular video website, is a powerful tool to document and improve our ability to manage freshwater pet release in Brazil. Based on a series of 24 videos chosen randomly using 19 standardized keywords posted by pet-keeping YouTubers between January 1, 2020 and March 20, 2023 (650 h of searching time), we documented the intentional release of 12 translocated and five non-native species involving 11 fish species, two freshwater stingray species, two freshwater turtle species, one freshwater crab species, and one crayfish species in multiple watersheds/ecoregions of Brazil. This is the first record of intentional introduction for 17 species in Brazilian inland waters. The main drivers behind pet release were excessive growth, “agreeableness” (i.e., compassion, pet owner's reluctance to euthanize the animal), and aggressive behavior. The videos documented the release of multiple freshwater pets in numerous freshwater ecosystems. Pet releases were predominantly into rural freshwater ecosystems rather than urban, with an introduction hotspot identified in the Southeast region. This finding is important because pet release is more common in urban than rural areas. While colonization pressure (i.e., number of translocated/non-native species that each pet owner released) was high, overall propagule pressure (i.e., number of individuals of a translocated/non-native species released into a region) was low with a total of 49 individuals released over the monitored period. Proactive management is key in reducing the incidence of pet release in Brazil, attainable through transforming pet shop owners into disseminators of correct information about species traits. Environmental authorities should create “Non-native Pet Amnesty Day” to provide the opportunity for people to surrender their non-native aquatic pets; YouTubers can engage in awareness actions on YouTube™ such as show the negative effects that aquatic pets can cause if introduced into the wild; Brazilian scientists turn into “science YouTubers” and provide arguments that can be used to disseminate reliable scientific messages about freshwater pet release.

Surface water inhabiting crayfish are well-known for the impact on their surroundings. This impact has been related to loss of biodiversity and deteriorating water quality for invasive crayfish. Crayfish dig burrows for various reasons like lack of natural shelters, avoiding an upcoming drought, or high crayfish density and this may lead to increased sediment transport and accelerated bank instability. All crayfish are considered to have burrowing capability, but not all species have been observed burrowing. Studies comparing this behaviour among different species in standardized ways are scarce. Crayfish burrowing was investigated under standardized laboratory conditions to reveal differences among species and their sex. All studied species occur in the Netherlands and were the native Astacus astacus (Linnaeus, 1758), the Eurasian Pontastacus leptodactylus (Eschscholtz, 1823) and the invasive North American Faxonius virilis (Hagen, 1870), F. limosus (Rafinesque 1817), Pacifastacus leniusculus (Dana, 1852), Procambarus acutus (Girard 1852), and P. clarkii (Girard, 1852). As burrowing triggers were evaluated presence of shelter, increased light intensity, increased water temperature, and increased crayfish density. Results showed species-specific and sometimes sex-specific differences in burrowing behaviour among crayfish. The response to burrowing triggers was also species-specific and no two species reacted identical to all triggers. Absence of shelter was a strong driver to burrow for A. astacus, F. limosus and F. virilis, while increased light intensity triggered burrowing behaviour in P. leptodactylus, P. acutus and P. clarkii and lowered activity of F. limosus. Burrowing behaviour of P. clarkii was mostly influenced by increased water temperature. Significant differences between females and males were observed for P. leptodactylus, P. leniusculus and P. acutus in the shelter, increased density and increased water temperature treatment, respectively. Understanding the triggers that invoke burrowing may help managing populations of these invasive species.

Ocean acidification (OA) arises as a consequence of excessive carbon dioxide (CO₂) inputs into the ocean, a situation further exacerbated by anthropogenic gas emissions. Predictions indicate that seawater surface pH will decrease by 0.4 by the end of the twenty-first century. Notably, studies have observed significant alterations in molluscan assemblages due to OA, leading to a substantial decline of 43% in species richness and 61% in overall mollusc abundance. Moreover, OA has been associated with a 13 ± 3% reduction in the skeletal density of massive Porites corals on the Great Barrier Reef since 1950, particularly affecting marine invertebrates. Given these impacts, this review aims to comprehensively assess the research status and main effects of OA on the physiology and ecology of marine invertebrates over the past two decades, employing bibliometric analysis. Additionally, this review aims to offer valuable insights into potential future research directions. The analysis reveals that research on OA and its influence on marine invertebrates is predominantly conducted in Europe, America, and Australia, reflecting the local extent of acidification and the characteristics of species in these regions. OA significantly affects various physiological aspects of marine invertebrates, encompassing the calcification process, oxidative stress, immunity, energy budget, metabolism, growth, development, and genetics, consequently impacting their behaviour and causing disruptions in the population structure and marine ecosystem. As a result, future research should aim to intimately connect the different physiological mechanisms of marine invertebrates with comprehensive ecosystem evaluation, such as investigating the relationships between food webs, abiotic factors, energy, and matter flow. Furthermore, it is crucial to explore the interactive effects of OA with other stressors, assess the potential for adaptation and acclimation in marine invertebrates, and evaluate the broader ecological implications of OA on entire marine ecosystems. Emphasizing these aspects in future studies will contribute significantly to our understanding of OA's impact on marine invertebrates and facilitate effective conservation and management strategies for these vital biological communities within marine ecosystems.

The Sailfin Catfish of the genus Pterygoplichthys is a popular aquarium pet distributed and sold globally through the ornamental pet trade. Pterygoplichthys spp. have established stable populations in various freshwater ecosystems following aquarium pet owners’ deliberate introduction in the regions outside their native range (South America). Colonisations of Pterygoplichthys spp. in multiple areas of India and Bangladesh were reported along with frequent catches with the aquacultural fish hauls and subsequent adverse effects on the socio-economy and ecosystem functions. In the present study, we identified the suitable habitats of Pterygoplichthys spp. using species distribution modelling (SDM) based on global and regional occurrence data considering India and Bangladesh as focal areas. Along with literature surveys and online databases, we used social media platforms to gather additional occurrence data for SDM. In addition, the social media platforms were used to conduct an online survey to assess the public perception regarding using Pterygoplichthys spp. as an aquarium pet and subsequent release to natural waterbodies. The results of SDM indicated that several areas of India and the whole of Bangladesh are high to moderately suitable for Pterygoplichthys spp. colonisation and range expansion which can be prioritised for effective restoration and management. It is evident from people’s perception that raising awareness among the public about the potential impacts of invasive species on the concerned ecosystems may help reduce or stop further deliberate non-native species introductions to natural habitats.

Flooding, a sudden disturbance, is considered to affect negatively the survival of fish by causing shock and growth, especially for species living in headwaters of a river. Neolissochilus benasi is a freshwater fish that prefers living in clean, flowing water and rocky bottoms with sands and gravels. Based on a segment in mtDNA obtained from eight specimens collected from northern Vietnam, the present study applied a hybrid novel, genetic algorithm (GA)–artificial neural network (ANN) to understand impacts of floods on N. benasi. The GA–ANN hybrid model was successful in mapping flood susceptibility, which correlates with river density, altitude, and rainfall, being typical in lowlands, along rivers and streams. Strong correlations were found between fish and urban density, agriculture, and land use/land cover, which contribute to the decrease of N. benasi. Habitat destruction, hydropower dams, pollution, overfishing, and using destructive gears are probably the main causes of the N. benasi decline. Importantly, based on GA–ANN model, flooding had a significant impact on N. benasi, which performs a low genetic diversity in the studied regions. Thus, this endangered freshwater fish species would have been easily affected by flooding since very high and high susceptibility of N. benasi was abundant in the province, particularly along the Red River and urban areas. This is the first study to examine the link between flooding and genetic diversity of an aquatic organism in Vietnam applying deep learning models. Accordingly, these results recommend significant suggestions to protect N. benasi in its habitats from northern Vietnam under flooding.

The study of macroinvertebrates using computer vision is in its infancy and still faces multiple challenges including destructive sampling, low signal-to-noise ratios, and the complexity to choose a model algorithm among multiple existing ones. In order to deal with those challenges, we propose here a new framework, dubbed 'MacroNet,’ for the monitoring, i.e., detection and identification at the morphospecies level, of live aquatic macroinvertebrates. This framework is based on an enhanced RetinaNet model. Pre-processing steps are suggested to enhance the characterization propriety of the original algorithm. The images are split into fixed-size tiles to better detect and identify small macroinvertebrates. The tiles are then fed as an input to the model, and the resulting bounding box is assembled. We have optimized the anchor boxes generation process for high detection performance using the k-medoid algorithm. In order to enhance the localization accuracy of the original RetinaNet model, the complete intersection over union loss has been integrated as a regression loss to replace the standard loss (a smooth l1 norm). Experimental results show that MacroNet outperforms the original RetinaNet model on our database and can achieve on average 74.93% average precision (AP), depending on the taxon identity. In our database, taxa were identified at various taxonomic levels, from species to order. Overall, the proposed framework offers promising results for the non-lethal and cost-efficient monitoring of live freshwater macroinvertebrates.

Metal pollution of aquatic ecosystems continues to be a worldwide concern, and many studies have previously been conducted evaluating metal toxicity to aquatic organisms. However, these studies have mainly been focused on temperate species and only evaluated aqueous exposure, whereas aquatic organisms under real-world conditions are also exposed to metals through their diet. Toxicity tests were conducted evaluating the effects of Cr on cell density and biochemical composition of the microalga Chlorella vulgaris. Additionally, the toxic effects of Cr on the temperate Ceriodaphnia dubia and the tropical Ceriodaphnia silvestrii cladocerans were investigated through three contamination routes: contaminated medium (CM), contaminated food (CF; C. vulgaris), and the combination of both situations (CMF; contaminated medium and food). The toxicity tests with the cladocerans evaluated the metal effects on survival, number of newborns, and feeding activity. Exposure to 48 µg L⁻¹ total dissolved Cr reduced cell density and increased protein, carbohydrate, and lipid content in C. vulgaris. The increase in the biochemical composition and hence food quality of the microalgae after Cr exposure have contributed to the absence of toxic effects to the cladocerans in the CF treatment. No toxic effects were observed to the temperate cladoceran at any treatment. The tropical cladoceran C. silvestrii showed reduced filtration, ingestion and reproduction rates in the CM and CMF treatments at a Cr concentration below national and international standards. Implications for considering different exposure pathways in ecotoxicological studies, (tropical) risk assessments and indications for future research are discussed.

Beira Lake, in the heart of Colombo City in Sri Lanka, is a prominent landmark, serving a variety of important services such as flood control, and providing habitat and nesting grounds for the city’s wildlife. During the past decades, Beira Lake has become highly polluted due to anthropogenic activities. The majority of the past restoration attempts failed, revealing a lack of understanding of the pollutant intricacies. The objective of this study is to investigate the trophic status of all four basins of the lake to investigate the pollution status. Thirty-nine sampling locations were randomly selected based on a 100 × 100 m grid covering the entire lake for water quality sampling. Water quality index (WQI) and trophic level index (TLI) were calculated to further investigate the pollution scenarios. WQI, total nitrogen, total phosphorous, Secchi depth, and Chlorophyll-a were considered to calculate the TLI of the lake. As per the WQI, more than 93% of the lake’s surface area is in poor condition. The TLI reveals the hypereutrophic status of the lake water. According to principal component analysis, eutrophication and algal bloom index observed can be due to the heavy anthropogenic activities and land use patterns around the catchment indicating a high possibility of untreated effluent entering the lake through the active inlets. The effluent entering the lake should be managed immediately to prevent further deterioration of the entire lake. Immediate restoration of the lake is recommended, as the hypereutrophic state may lead to irreversible an imbalance in the lake ecosystem.

To effectively address biodiversity loss, it is essential to prioritize conservation efforts by identifying areas of high conservation value. Ecological uniqueness is a valuable metric for this purpose that decomposes beta diversity into local contributions to beta diversity (LCBD), thereby measuring the contribution of each site within a region to overall biodiversity variation. LCBD has been used extensively to evaluate ecological uniqueness from community composition data, but biodiversity is a multifaceted concept, and community-based ecological uniqueness may not capture the full range of ecological uniqueness occurring at other levels of biological organization. We investigated ecological uniqueness estimates derived from community and species population levels in a watershed of south-central Chile and analyzed their responses to water and habitat quality variables. Ecological uniqueness was estimated at the community level from fish and macroinvertebrate assemblages and at the population level using genetic and morphological data gathered for two invertebrates, the gastropod Chilina dombeiana and the water bug Aquarius chilensis. Our results revealed low spatial congruence between the levels of ecological uniqueness calculated for these different biodiversity components, with mismatches occurring among sites with high LCBD values. Water and habitat quality were major drivers of beta diversity in this watershed, accounting for 43.8% to 74.3% of the spatial variation in LCBDs, and their effects differed among the ecological uniqueness estimates. Overall, our results underscore the idiosyncratic nature of ecological uniqueness metrics, emphasizing the importance of using multiple components of biodiversity to guide conservation actions.

Air pollution and lake eutrophication have led to a reduction in incident total radiation and water transparency in many lakes, resulting in a decrease in available underwater light. This reduction in available light depends significantly on the dynamics of spring phytoplankton communities. However, the process and mechanisms behind these effects are not yet well understood. In this study, we conducted a field mesocosm experiment to observe the responses of the phytoplankton community to varying levels of light intensity (100%, 85%, and 65% photosynthetically active radiation, PAR). Our study revealed that reducing PAR resulted in an earlier peak of cyanobacterial biomass in spring, while the biomass of chlorophytes and bacillariophytes declined with decreasing light intensity. The weakening of light intensity promoted the recovery of photosynthetic activity in cyanobacteria but reduced the photosynthetic activity in chlorophytes and bacillariophytes. Additionally, the decrease in light intensity reduced the diversity of phytoplankton communities, accelerating the rate of species turnover. However, the rate of species turnover slowed down as the dominance of cyanobacteria was established in the later stages of the experiment. Therefore, the weakening of light intensity is beneficial to the early establishment of the dominance of cyanobacteria in the phytoplankton community structure, accelerating the succession process of phytoplankton community. These findings contribute to the exploration of the effects of reduced light intensity on the establishment of cyanobacterial dominance in spring, providing valuable insights for the management of lake ecosystems.