Food Preference of Strongylocentrotus droebachiensis

Abstract

Sea urchins are a prominent herbivore along the Pacific coast and can devastate kelp beds that are home to many species. Urchin barrens are of concern to ecologists and aquaculture groups, especially along the Pacific Coast. Much of the current literature on sea urchins and their feeding preferences refers to Strongylocentrotus purpuratus (purple urchins) and their effects on kelp forests. I wanted to determine if Strongylocentrotus droebachiensis (green urchins) have a preferred food and how this could contribute to the current problem of urchin barrens. Bycollecting S. droebachiensis from the Friday Harbor Lab dock, as well as three different kelps that are abundant in the area, I was able to determine which kelp S. droebachiensis favors as food. For 5 days, every 24 hours, in 3 tanks, I would feed the sea urchins Nereocystis luetkeana, Saccharina latissima, and Costaria costata. After every 24 hours, I would weigh the leftover kelp and determine the amount of each consumed. I found that the S. droebachiensis favored the N. luetkeana which is important because that is an abundant ecological engineer along the Pacific coast and is highly affected by urchin barrens.