Geology topics

Musa C. Mlambo

Publications and source records attributed to Musa C. Mlambo.

3 recordsLinked to original sources

USGS2025

Challenges and solutions for measuring taxonomic richness of aquatic invertebrates in wetlands

Measurements of biodiversity are crucial to assessing the ecological integrity of ecosystems. However, adequately describing the range of organisms existing in habitats can be challenging, especially for the taxonomically rich invertebrates. We analysed six large datasets designed to describe the taxonomic richness of aquatic invertebrate assemblages in depressional freshwater wetlands from various regions or locations (in North America, southern Africa and South America). Three of the datasets targeted large numbers of wetlands (57–163 sites), sampled once and the other three datasets repeatedly sampled over longer time periods (5–23 years), but targeted a smaller number of wetlands (10–18). We estimated the total number of invertebrate taxa that likely existed for each target area (Chao estimator), as opposed to how much of that richness was actually collected by each effort (using taxon-accumulation curves). The most ambitious effort (17 wetlands, 23 years, 5–6 samplings per year) captured 95% of the aquatic invertebrate taxa projected to occur in the study area; none of the other five efforts captured appreciably more than 80% of the projected total richness per study area. Findings suggest that capturing 90% or more of regional taxa is truly laborious and should not be a primary goal for efforts to sample the invertebrate fauna in wetlands. Objectives for sampling wetland invertebrates should be tailored to address what is realistic, knowing that as much as 30% of taxa may be missed by even ambitious efforts. As a potential solution, we suggest setting feasible objectives for wetlands macroinvertebrate assessments. We recommend researchers try to reach a 70% study area richness target by sampling 60–80 wetlands once or smaller sets of wetlands for 2–3 years.

Freshwater Biology↗

USGS2024

A global assessment of environmental and climate influences on wetland macroinvertebrate community structure and function

Estimating organisms' responses to environmental variables and taxon associations across broad spatial scales is vital for predicting their responses to climate change. Macroinvertebrates play a major role in wetland processes, but studies simultaneously exploring both community structure and community trait responses to environmental gradients are still lacking. We compiled a global dataset (six continents) from 756 depressional wetlands, including the occurrence of 96 macroinvertebrate families, their phylogenetic tree, and 19 biological traits. Using Bayesian hierarchical joint species distribution models (JSDMs), we estimated macroinvertebrate associations and compared the influences of local and climatic predictors on both individual macroinvertebrate families and their traits. While macroinvertebrate families were mainly related to broad-scale factors (maximum temperature and precipitation seasonality), macroinvertebrate traits were strongly related to local wetland hydroperiod. Interestingly, macroinvertebrate families and traits both showed positive and negative associations to the same environmental variables. As expected, many macroinvertebrate family occurrences were positively associated with temperature, but a few showed the opposite pattern and were found in cooler or montane regions. We also found that wetland macroinvertebrate communities would likely be affected by changing climates through alterations in traits related to precipitation seasonality, temperature seasonality, and wetland area. Temperature increases may negatively affect collector and shredder functional groups. A decrease in precipitation could lead to reductions in wetland area benefiting drought-tolerant macroinvertebrates, but it may negatively affect macroinvertebrates lacking those adaptations. Wetland processes may be compromised through broad-scale environmental changes altering macroinvertebrate family distributions and local hydroperiod shifts altering organism traits. Our complementary family-based and trait-based approaches elucidate the complex effects that climate change may produce on wetland ecosystems.

Global Change Biology↗

USGS2022

Perils of life on the edge: Climatic threats to global diversity patterns of wetland macroinvertebrates

Climate change is rapidly driving global biodiversity declines. How wetland macroinvertebrate assemblages are responding is unclear, a concern given their vital function in these ecosystems. Using a data set from 769 minimally impacted depressional wetlands across the globe (467 temporary and 302 permanent), we evaluated how temperature and precipitation (average, range, variability) affects the richness and beta diversity of 144 macroinvertebrate families. To test the effects of climatic predictors on macroinvertebrate diversity, we fitted generalized additive mixed-effects models (GAMM) for family richness and generalized dissimilarity models (GDMs) for total beta diversity. We found non-linear relationships between family richness, beta diversity, and climate. Maximum temperature was the main climatic driver of wetland macroinvertebrate richness and beta diversity, but precipitation seasonality was also important. Assemblage responses to climatic variables also depended on wetland water permanency. Permanent wetlands from warmer regions had higher family richness than temporary wetlands. Interestingly, wetlands in cooler and dry-warm regions had the lowest taxonomic richness, but both kinds of wetlands supported unique assemblages. Our study suggests that climate change will have multiple effects on wetlands and their macroinvertebrate diversity, mostly via increases in maximum temperature, but also through changes in patterns of precipitation. The most vulnerable wetlands to climate change are likely those located in warm-dry regions, where entire macroinvertebrate assemblages would be extirpated. Montane and high-latitude wetlands (i.e., cooler regions) are also vulnerable to climate change, but we do not expect entire extirpations at the family level.

Science of the Total Environment↗