Does Fencing Protect Aquatic Macroinvertebrate Diversity in Temporary Ponds Within a Livestock-Grazed, Semi-Arid Landscape?

Abstract

Protecting the diversity of aquatic macroinvertebrates in ponds requires maintaining their habitat integrity. In areas with livestock grazing, fencing ponds effectively protects aquatic vegetation from grazing and prevents livestock from trampling. In this study, we investigated how fencing affects both α-diversity (species richness and diversity within a pond) and β-diversity (species turnover between ponds) by sampling macroinvertebrates and environmental variables from 10 temporary ponds near Palapye, central Botswana. Among these, six ponds were unfenced, and four were fenced. To ensure accurate comparisons, we rarefied species richness and estimated diversity using Hill numbers. We calculated both incidence and abundance-based β-diversity indices. We analysed the relationship between environmental variables and macroinvertebrate communities using redundancy analysis and employed variation partitioning to determine the influence of environmental and distance-related factors on macroinvertebrate variability. Our results showed that fenced ponds exhibited significantly higher Shannon diversity, Simpson diversity and species richness compared to unfenced ponds. Conversely, unfenced ponds experienced greater taxa turnover, while fenced ponds displayed higher abundance-based nestedness. Variation partitioning revealed that environmental factors primarily drove macroinvertebrate variability. These findings support fencing as an effective management strategy to protect macroinvertebrate diversity in temporary ponds within semi-arid, livestock-grazed landscapes. Although fencing enhances α-diversity, it is unnecessary to fence all ponds to maintain β-diversity. The increased nestedness in fenced ponds indicates that macroinvertebrate taxa respond sensitively to habitat disturbances, highlighting the importance of preserving the integrity of fenced ponds to support higher α-diversity.