Staghorn Sculpin (Leptocottus armatus) Size and Abundance as a Function of Tidepool Conditions in False Bay, San Juan Island, WA

Abstract

The physical and biological variations in tidepools are essential to the survival of intertidal organisms. These fluctuating sub-habitats provide a refuge for juvenile fish during extended periods of low tide, offering them a place to grow and forage on smaller invertebrates. I examined the effects of these various tidepool conditions on the abundance and size of sculpin (family = Cottoidea) in six different tidepools in the tidal flat of the False Bay Estuary on San Juan Island, WA. The aim of this study was to examine the trends in our results and use them to advise future research into the abundance of fish as an indicator of habitat quality in the estuary. Previous research demonstrated the importance of studying bioindicator species such as sculpin in an effort to examine the health of various ecosystems and the biochemical structures within them. Using net tows and a YSI meter, I quantified the various tidepools conditions: temperature, salinity, dissolved oxygen, Ulva spp. cover, and prey abundance. I found a significant relationship between water temperature and both sculpin size and abundance. Mean sculpin size increased with water temperature while sculpin abundance decreased with water temperature. The standard deviation of sculpin size was significantly increased with salinity. Lastly, the abundance of sculpin was significantly related to the abundance of prey. Additional research should be conducted to further examine fish abundance across larger areas of False Bay over a longer time period to build a more holistic view of the estuary. Supplemental research should also be done into nutrient inputs from False Bay Creek and Forest Creek to determine if agricultural nutrients contribute to any of the variables examined in this study.