Change in aquatic insect abundance: Evidence of climate and land-use change within the Pawmpawm River in Southern Ghana

Abstract

Insects are key indicators of change in the landscape. They are known to be sensitive to the environment and climate in both terrestrial and aquatic ecosystems. A systemic way of monitoring river ecosystems response to land-use and climate change is critical although lacking in most West African countries. This study explored the taxonomic composition of insect assemblages within the Pawmpawm River to quantify the level of change (if any) in biodiversity of aquatic insects as evidence of a land-use and climate change in a 40-year interval. We collected insect larvae from river shores, edges, and riffles and compared diversity indices of collected samples with that of previous study conducted within the same study area 40 years earlier prior to the current study. Our results show that there were no significant differences in taxonomic diversity of aquatic insects between the two studies. This indicates that diversity of insects in the Pawmpawm River and its environment has not changed significantly in the past 40 years. However, there were significant reductions of individual insect numbers or abundances within the river and its environment giving an indication of a possible climate and land-use change in the study area. We recommend using change in aquatic insect diversity and abundance as monitoring tools for change in environment and land-use within the Pawmpawm River and other such rivers in Ghana.