Hydrobiologia最新文献

Despite the ecological importance of riparian forests to streams, the specific scale at which forest cover most significantly influences fish assemblages remains poorly understood. To address this issue, we measured the percentage of forest cover at 11 spatial scales across 12 streams. These scales were categorized into: “local riparian”, which includes circular buffers around the sampled sections, and “riparian network”, which consists of buffers surrounding the stream network upstream of the sampled sections. We developed linear models using species diversity, based on Hill numbers, and the percentage of forest cover at each scale. Additionally, we included the terrain slope and the dominant type of land use in the watershed (rural or urban) as covariates. The results indicated that the 100-m buffer of the local riparian scale was the most effective for assessing fish diversity. The percentage of forest cover in this buffer had a positive and significant relationship with the diversity metrics, though terrain slope significantly influenced this relationship. Therefore, we recommend that studies evaluating the influence of landscape on fish assemblages in streams adopt a multiscale approach to avoid missing the true impact of the landscape on the assemblages.

As plastics undergo degradation, they give rise to microplastics (MPs), such as polyester microfibers (PMFs), which are increasingly recognized for their potential impact on microbial communities. Despite a growing body of the literature on MP effects, there is a gap in understanding prolonged PMF exposure (≥ 1 month) on stream periphyton across an extensive concentration gradient. This study addresses this gap by investigating the response of periphyton exposed to increasing PMF concentrations (0–22,000 PMF L⁻¹) in stream mesocosms. As PMF concentrations increased, total periphyton biomass remained unaffected, while algal and bacterial biomass decreased and increased, respectively. Higher PMF concentrations also modified coarse algal community structure (measured as changes in chlorophyll b:c) and decreased light harvesting efficiency. Increased bacterial abundance was accompanied by elevated respiration, shifting the system from net autotrophy to net heterotrophy at 10,000–12,000 PMF L⁻¹. Additionally, bacterial community composition was altered along with reductions in β-1,4-glucosidase activities. Despite reduced algal biomass, higher PMF concentrations appeared to support bacterial growth. Many periphyton attributes, including nutrient composition, phosphorus removal, gross primary production, and maximum electron transport rate of photosystem II, were unaffected. This study underscores the multifaceted implications of PMF contamination on the structure and function of periphyton in stream ecosystems.

Hypersaline Great Salt Lake’s (GSL: Utah, USA) pelagic food web is dominated by the herbivore, Artemia franciscana. Artemia demographic responses (survival, developmental transition, and reproduction) to GSL salinities, temperatures, common phytoplankton and yeast, and food levels were examined by factorial experiment. Survival across developmental stages was best at 90 ppt salinity, and decreased as temperature increased. Transition between life stages was best at 45 ppt salinity, and increased as temperature increased. Food was most important with both survival and transitioning responding similarly to food types and increasing with amount of food. Artemia reproduce in two ways (diapausing cysts – oviparity, live young – ovoviviparity): ovoviviparous and total reproduction were greatest at 90 ppt salinity and 20 °C, while oviparous reproduction was weakly affected by salinity and greatest at 20 °C. Oviparity was greatest at low food availability, while ovoviviparity and total reproduction increased with food availability, so reproduction shifted from oviparity to ovoviviparity as food increased. Maternal effects were observed for cyst hatchability, and ovoviviparous nauplii survival and transitioning to the juvenile stage. Combinations of salinity, temperature, food taxa and food amount strongly affect demography, making single factor studies of limited value. Results explain Artemia abundance in different parts of GSL and among years.

Solar photovoltaic (PV) generation is burgeoning as global economies pursue decarbonization goals. To meet the surge in solar energy demand, deployment of PV panels on water surfaces has emerged as an attractive option. Despite the potential advantages associated with floating PV (FPV) systems, current understanding of their impact on aquatic life remains scarce. Here, we use the Preferred Reporting Items for Systematic Review and Meta-analysis methodology to provide a systematic review of FPV effects on aquatic organisms. Our search yielded 24 studies selected for qualitative analysis—most of which were performed in small-scale artificial ecosystems. We identified 39 variables across 12 artificial taxonomic groups. The most commonly reported effect was the reduction of chlorophyll-a in the water. Additionally, there is growing evidence that FPV has indirect effects on various groups of aquatic organisms. Enhancing current understanding of ecological consequences of FPV systems on aquatic biodiversity is urgent given the industry’s rapid expansion, and developing strategies for monitoring, controlling and predicting water quality impacts is necessary. This review provides a foundation for future studies and can assist in the development of strategies for balancing impacts and benefits of FPV systems.

The World Register of Marine Species (WoRMS) started in 2007 with the question “how many species live in our oceans?”. Now, a little over 15 years later, WoRMS is able to answer several questions related to marine species discovery rates and provides a dynamic number of existing marine species, based on the information provided by hundreds of taxonomic experts worldwide, who have proven to be diverse and dynamic. We present basic statistics on marine species discovery rates based on the currently available content of WoRMS, as well as insights in the day-to-day activities and dynamics of our editorial board and the progress made so far on the content priorities as defined by the WoRMS Steering Committee. As for all dynamic systems, WoRMS is not complete and faces challenges. As an endorsed project of the UN Ocean Decade, WoRMS aims to tackle a number of these challenges and knowledge-gaps by 2030, including detailed documentation of authorships and original descriptions, and will provide continuous support to all marine initiatives, programs and projects that rely on WoRMS as an authoritative classification and catalogue of marine names.

This study pioneers the evaluation of toxicity in the Coromandel stream, located in the southeastern region of Brazil, highlighting the essential role of ecotoxicology in informing environmental management decisions. We employed bioindicators to assess the water quality across multiple collection points along the stream, focusing on its physical, chemical, and ecotoxicological characteristics. The investigation utilized Allium cepa seeds and Dendrocephalus brasiliensis nauplii to conduct acute ecotoxicological tests, examining cytotoxic and genotoxic effects, including the mitotic index and micronuclei frequency for A. cepa and immobility rates for D. brasiliensis. Our findings reveal significant pollution impacts, particularly in areas affected by residential and industrial activities, where increased immobility in D. brasiliensis and heightened genotoxic potential were observed. These outcomes indicate deteriorating water quality and underscore the urgency for targeted environmental interventions. Real-time monitoring further identified critical alterations in water parameters, underscoring the stream sections with significant anthropogenic influence as hotspots for pollution and toxic risk. This research underscores the importance of integrated ecotoxicological assessments in detecting and addressing environmental threats in freshwater ecosystems.

La Plata Basin, the fifth-largest basin in the world, includes areas of Argentina, Bolivia, Brazil, Paraguay, and Uruguay and is subjected to intensive human activities such as agriculture, mining, and global trade. The basin hosts 83 native bivalves (Hyriidae, Mycetopodidae, Cyrenoididae, and Sphaeriidae), including 29 endemic and at least 3 non-native species (Cyrenidae and Mytilidae). For their role as filter feeders and their dominance in biomass in benthic freshwater ecosystems, freshwater bivalves play a key role in the resilience of aquatic ecosystems. In this review, we discuss the six major global change threats to freshwater ecosystems in the Anthropocene (climate change, flow regulation, pollution, land-use change, invasive species, and overexploitation) using freshwater bivalves of La Plata Basin as a model in South America. Future directions to properly understand the effects of global change and suggestions for the conservation of the freshwater bivalves in the basin are stated.

Exploring the seasonal dynamics of different components of biodiversity (alpha, beta, and zeta) and identifying the factors driving these patterns can help to reveal the health conditions and changes of ecosystems across different seasons. Seasonal differences in coastal fish biodiversity components were determined based on data of species abundance, traits, and mitochondrial genes. We then used multiple models to assess the relative importance of environmental and geographic variables in shaping the spatial patterns of different components of diversity. The results showed that the variation patterns of alpha diversity indices among seasons were inconsistent. All beta diversity indices showed significant seasonal variations. The rate of zeta diversity decline was highest in winter, and the compositional turnover showed no significant variations among the other three seasons. In spring, longitude was the most important factor influencing variations in alpha and beta diversity, while sea surface temperature and distance from mainland were important drivers for fish zeta diversity. Distance from mainland, sea surface temperature, and salinity were the most critical factors shaping the spatial pattern of diversity in summer, autumn, and winter, respectively. Our results suggest that environmental and geographic factors play an important role in shaping the patterns of coastal fish diversity.