Microplastics are ubiquitous in aquatic ecosystems globally, with tropical freshwater systems underrepresented in the literature. The ubiquity of microplastics may affect the feeding, growth, reproduction, and survival of organisms in aquatic systems; however, the data on the potential effects of microplastics on aquatic organisms is tentative. In the current study, I conducted a meta-analysis using published data to examine the impacts of microplastic exposure on functional traits (i.e., feeding, growth, reproduction, survival) of fish and aquatic invertebrates. The data revealed that while there were within-taxa negative effects on traits such as reproduction and growth some effect sizes were low, suggesting that the exposure to microplastics may vary across taxa. Globally, negative effects on growth, reproduction, and even survival were evident in some taxa (e.g., bivalves, crustaceans). Considering feeding habits, negative effects of microplastic were more pronounced in bacterivores, omnivores, predators, and filter feeders compared to shredders. In tropical freshwater systems, microplastics had no significant effects on the feeding, growth, reproduction, and survival of aquatic organisms. It is worth noting that organisms that are passive feeders (e.g., bivalves) may be particularly susceptible to microplastic pollution, which in turn may have long-lasting effects on the stability of lacustrine and lotic food webs. Because microplastics may impart more chronic effects than acute effects, future works must include understudied regions of the world (e.g., freshwater systems) and must emphasize the subtle role that microplastics may play on the physiology and behavior of organisms in the long term.

The Kowie River, a relatively pristine system in South Africa, was sampled on four occasions over one year to determine if relative abundances of functional feeding groups (FFGs) of invertebrates changed along the longitudinal gradient, and if these changes matched predictions of the river continuum concept (RCC). The results revealed that gatherers and filterers dominated in the Kowie River, and together represented 50–83% of the invertebrate assemblages. There was a general paucity of shredders (relative abundance was <10% at all sites and times). The changes in relative abundances of the different FFGs did not always follow the predictions of the RCC, as there were no correlations of community structure with river width or canopy cover in some seasons; however, some predictions of the RCC were supported, as a dominance of filterers (with relatively small contributions from shredders and grazers) and a consistent presence of predators were recorded. The FFG abundances were correlated with water velocity and total dissolved solids. Broadly, shifts in relative abundances of FFGs along the river continuum could not be explained by physical attributes alone, and were probably influenced by the availability of food and the chemistry of the river. Our findings highlight the need for theoretical and field studies across a broad array of African systems to refine the applicability of the RCC and FFG classifications to further develop models of ecosystem function.

Globally, wildfires and prescribed fires are becoming more prevalent and are known to affect plant and animals in diverse ecosystems. Understanding the responses of animal communities to fire is a central issue in conservation and a panacea to predicting how fire regimes may affect communities and food webs. Here, a global meta-analysis of 2581 observations extracted from 208 empirical studies were used to investigate the effect of fire on aboveground and belowground fauna (e.g., bacteria, fungi, small mammals, arthropods). Overall, results revealed that fire had a negative effect on biomass, abundance, richness, evenness, and diversity of all faunas. Similarly, when considering wildfires and prescribed fires the data revealed that both fire regimes have negative effects on fauna. Similarly, fire had negative impacts on aboveground and aboveground fauna across most biomes and continents of the world. Moreover, there was little evidence of changes in pH, moisture and soil depth on soil organisms suggesting that other factors may drive community changes following a fire disturbance. Future research in fire ecology should consider the effects of fire across several species and across larger geospatial scales. In addition, fire effects on faunal community structure must be studied under contrasting global fire regimes and in light of the effects of climate change.