The impact of contaminated pilings on nudibranchs at the docks of Friday Harbor

Abstract

Docks in the Friday Harbor Island have been observed to have many nudibranchs present on them. One hypothesis for this is the creosote, a chemical used to help preserve the wood from wear, is attracting them to the pilings. Creosote has been shown to have negative effects on the environment, and because nudibranchs’ rinophores are sensitive chemoreceptors that are used to help find food, navigate, and find mates, an interaction could be harmful to these animals. Our study looked at the preference of location in a tank with one side having creosote-treated wood and one side having non-treated wood samples. We used Triopha catalinae (Clown Dorid) and Archidoris montereyensis (Sea Lemon) as our two species. We found there was no significant preference to creosote. We also saw no preference to creosote during the day or evening, but saw a trend in T. catalinae to prefer the sides of the tank especially during the afternoon runs. There was also a trend to avoid the drain in the tank for both species. Nudibranchs therefore show no attraction to creosote in their environment.