A 20-year comparison of shrimp populations in the Opunohu Valley of Moorea, French Polynesia

Global change is a central issue in many fields of science, particularly related to climate. One impact of climate change is changing weather patterns. This study focuses on the effects of changes in rainfall on freshwater stream ecosystems. Streams on small tropical islands are extremely fragile ecosystems. On the South Pacific volcanic island of Moorea, French Polynesia, lies the Opunohu Valley watershed. The Opunohu valley watershed is inhabited by three species of shrimp: Macrobrachium sp., Atyoida pilipes, and Caridina weberi. These shrimps are key components of their ecosystem because they break down organic material that falls into the stream thereby creating habitat for many other living organisms. Thus, they are a good measure of stream ecosystem health. This study focused on nine different sites throughout Opunohu valley. These sites had been surveyed in 1996 by C. Feldman. Comparisons to survey data collected in 1996 revealed no significant changes over time, demonstrating that shrimp populations have not declined or increased significantly in the last two decades.