Cross-Reef Transport of Invasive Macroalge on the Northern Reef Flat of Coconut Island in Kane'ohe Bay, Hawai'i

Abstract

Cross-reef transport of invasive macroscopic algae may be significant to algal accumulation at downstream sites. On the northern reef flat of Coconut Island in Kane’ohe Bay, Hawai’i there is a substantial population of Gracilaria salicornia and Acanthophora spicifera, with algal accumulation on the leeward reef slope. The goal of this project was to study possible modes of algal transport across the reef flat. Algae were measured at several sites along the leeward edge of the reef flat and compared to weather data from Coconut Island. There is no linear correlation between algal biomass and wind speed, and seasonality appears to be the best predictor for algal transport. However, multiple regression analysis shows that maximum wind speed and water temperature are significant (P < 0.05). This suggests that algal accumulation is dependent on productivity and wind events.