Bryozoan settlement varies by kelp species

Abstract

Biofouling on kelp by encrusting bryozoans such as Membranipora membranacea can decrease the commercial value of cultivated kelp by restricting blade size and increasing breakage. The presence of M. membranacea on three species of Laminarian marine algae – Saccharina latissima, Costaria costata, and Alaria marginata – was studied in temperate coastal waters at Friday Harbor Laboratories in Washington State, USA, in May 2021. The settlement at two depths, over a one-week period, and the abundance of previously settled M. membranacea were characterized. We hypothesized that settlement of the bryozoan would differ by kelp species. The results supported our hypothesis. Settlement was highest on S. latissima, intermediate on C. costata, and lowest on A. marginata. No significant difference in settlement was detected at 1 versus 3 m. A. marginata is least challenged by issues of biofouling and may produce chemical defenses to deter epifaunal settlement.