环境科学与生态学最新文献

Habitat edges are often considered environmentally stressful areas, and as such, research has largely focused on the impacts of physical factors in shaping these edges. However, less is known about the relative importance of biotic disturbance agents and bottom-up drivers in shaping habitat edges. Here, we used intertidal seagrass beds as a model system to test how the independent and combined effects of stingrays-a disturbance-generating forager in seagrass beds-and nutrient addition affect the upper elevation edge of seagrasses. A two-season long manipulative experiment with stingray exclusion × nutrient addition revealed that shoreward seagrass edges experienced heightened loss in percent cover when exposed to stingrays (p = 0.037) but were not impacted by nutrient additions to marine sediments (p = 0.13). Additionally, transplant experiments designed to test whether stingrays could limit intertidal seagrass establishment in higher elevation found that transplanted seagrass had a higher chance of survival when stingrays were excluded (p < 0.01), suggesting that seagrass could live higher in the intertidal and that stingrays may limit shoreward expansion. Finally, a multi-site observational survey demonstrated that stingray pit abundance was a strong predictor of the distance between seagrass edge and shoreward habitats. Combined, these results challenge current understanding in plant ecology that seagrass edges are controlled mainly by physical factors and instead suggest that the structure of the seagrass shoreward edge is controlled by both physical and biotic drivers. Our results also indicate that the relative effects of consumer disturbance and physical factors in controlling edge limits are likely predicated on consumer density: in areas with higher densities of large consumers, biotic forcing is likely to be more important. Furthermore, these results could have implications for restoration in areas with high densities of disturbance-generating foragers and align with calls for greater inclusion of animal impacts into restoration schemes. Biotic drivers along environmentally stressful edges are likely not limited to seagrasses and the generality of biotic control of habitat edges deserves further exploration across diverse ecosystems.

How communities are structured into functional groups and trophic layers is key to understanding ecosystem functioning. Nonetheless, we lack insights about spatiotemporal variation in guild composition of communities and its causes. To investigate spatial and temporal patterns and drivers of variation in insect feeding guilds, we combined data from a nationwide survey of Swedish insects using Malaise traps and DNA metabarcoding with a comprehensive trait database. We assigned species into one of three feeding guilds (phytophages, saprophages, predators) or into one of three associated parasitoid guilds. We then analysed patterns in species richness for each guild. Species richness declined with latitude in all guilds. Beyond this gradient, local variation in species richness matched between hosts and their parasitoids. Yet, hosts and their parasitoids responded differently to habitat. The phenological peak of parasitoid species richness appeared later than the peak of their hosts, but the length of time lags varied among guilds. Spatiotemporal patterns were driven by guild-specific responses to temperature, though much variation remained between seasons and locations even when controlling for temperature. Overall, these patterns suggest that shifts in both climate and land use may alter the synchrony of insect trophic layers, with unknown consequences.

This study evaluated the effects of Moringa oleifera (MO), chitosan, and alum as adsorbents on the physicochemical properties of water collected from Lake Florida in Johannesburg, South Africa. The lake water was subjected to three different treatments using jar tests at concentration dosages of 25, 30, and 35 mL and settling times of 30, 60, and 90 min. The water treated with adsorbents significantly reduced turbidity (p < 0.05) with removal efficiencies of 99.33% for MO (30 mL, 30 min), 99.22% for chitosan (35 mL, 60 min), and 99.60% for alum (25 mL, 60 min). Dissolved oxygen increased significantly (p < 0.05) from 2.06 ± 0.02 mg/L to 3.24 ± 0.01 mg/L with chitosan (25 mL, 90 min) and MO (35 mL, 90 min), and to 3.15 ± 0.01 mg/L with alum (25 mL, 60 min). Sulfate levels increased with MO from 65.00 ± 1.00 mg/L to 200.67 ± 0.58 mg/L (35 mL, 90 min), while alum caused an initial decrease to 49.67 ± 0.58 mg/L (25 mL, 30 min), followed by an increase to 71.33 ± 0.58 mg/L. Furthermore, total dissolved solids and conductivity increased with MO, whereas chitosan and alum caused no significant changes. However, a slight pH reduction was noted, with no significant nitrate alteration. Based on principal component analysis, the key factors driving water quality variations in the dataset were treatment type and retention time, with parameters such as pH, conductivity, and sulfate being strong indicators of treatment efficiency. Dissolved oxygen and nitrate were more dependent on treatment time. These findings provide insights into the performance of different adsorbents and their impacts on lake water quality.

Heavy metal (HM) pollution poses serious risks to ecosystems and human health because of its toxicity, persistence, and ability to accumulate in living organisms. Conventional remediation methods, including chemical precipitation and adsorption, are often effective but remain costly and can produce secondary waste. Microbial bioremediation provides a more sustainable alternative by using microorganisms to transform or immobilize toxic metals. In this review, we critically evaluate the main microbial mechanisms (biosorption, bioaccumulation, and biotransformation) focusing on their efficiency, limitations, and the challenges of applying laboratory findings in real environments. Case studies and applications in wastewater treatment, groundwater remediation, mining, agriculture, and the textile industry are examined to illustrate both their potential and constraints. A comparative discussion of microbial species highlights their advantages and weaknesses under different conditions. Particular attention is given to lactic acid bacteria (LAB), which combine bioremediation capacity with probiotic and food-related benefits. Finally, we consider recent advances in genetic engineering, microbial consortia, computational modeling, and nanotechnology, which together point toward promising strategies for enhancing the scalability and effectiveness of microbial HM remediation.