Nutrient Pollution and Effects on the Water, Sediment, and Ulvoid species creating Green Tides in False Bay, San Juan Island, WA

Abstract

False Bay in San Juan Island, WA (N48.4865°, W123.0680°) is a biological preserve on the southwest side of San Juan Island. The watershed includes Trout Lake, the main supply of water for the town of Friday Harbor. Ulvoid blooms have been common which produces a stench as well as possibility for research into the cause. Sampling of the biomass, nitrate concentrations, oxygen saturation, salinity, and temperature at both high tide of August 14, 2012 and low tide on August 15, 2012 revealed small impact of creek or possible agricultural runoff than previously expected. Small amounts of nitrate did not appear to correlate with biomass readings and differences in oxygen saturation. It suggested possible uptake of ulvoids instead. This study provides a jumping off point for future research into causes of ulvoid blooms and nutrient cycling in the bay as well as the unique ecology of this system.