Are We in Hot Water?: Comparing Macroinvertebrate Communities and Water Quality over Time

Abstract

Freshwater ecosystems, which support a significant portion of the world’s biodiversity, are often plagued by pollution, particularly excess nitrogen and phosphorus. Additionally, freshwater ecosystems are strongly impacted by climate change. In 2003, two macroinvertebrate studies were conducted at Mount Holyoke College to investigate the health of different sites according to biotic indices. This project repeats the macroinvertebrate surveys at four stream sites and two lakes sites to compare and analyze how the macroinvertebrate communities and abiotic factors of the freshwater ecosystems have changed over time. Abiotic water quality data has been collected every two weeks since 1996 using probes. Diversity and biotic indices were calculated from the macroinvertebrate samples and the changes in abiotic factors over time were examined. According to the general decrease in the biotic indices, the water quality has improved across all sites since 2003. The species richness was generally higher in the stream sites compared to the lake sites and the restored stream site. Since 1996, the average annual temperature and pH have both increased significantly. Although the health of the freshwater ecosystems on campus seem to be improving, there is some discrepancy between the different sites and the abiotic effects of climate change are alarmingly evident.