Effects of a Non-indigenous Bryozoan on the Recruitment of the Native Olympia Oyster, Ostrea lurida.

Leeza-Marie Rodriguez and Danielle C. Zacherl, Biology Department, California State University- Fullerton, 800 N. State College Blvd. Fullerton, CA 92831-3599.

Non-indigenous fouling organisms that settle onto piers, seawalls, and natural hard substrata in estuaries can negatively impact native species via space competition, predation, or other mechanisms. We studied the effects of the invasive bryozoan, Zoobotryon verticillatum, and other fouling organisms on the recruitment of the native Olympia oyster, Ostrea lurida, to determine whether their presence, biomass, and abundance affect oyster recruitment. Terracotta tiles acting as a proxy for available hard substrata were deployed in Upper Newport Bay, California at tidal elevations ranging from -0.4 to +0.1 feet MLLW for five months throughout the oyster spawning and recruitment season between April and October, 2020. We established five treatment groups (n= 5 replicates per tile) to examine the effects of Z. verticillatum and of other fouling organisms on recruitment of O. lurida: unmanipulated controls, Z. verticillatum removals, Z. verticillatum plus other fouler removals, other fouler removals with Z. verticillatum additions, and other fouler removals with 2X Z. verticillatum additions. The tiles were surveyed and treatment groups were maintained monthly by removing foulers and adding or removing Z. verticillatum as appropriate per treatment; all removals were quantified via volume displacement as a proxy for biomass. Upon retrieval of the tiles, the volume displacement and wet weight of all remaining Z. verticillatum and other foulers were recorded. Oysters recruiting to the tiles were measured for length and width, identified, and counted. We also recorded percent cover of all species recruiting to the tiles using point contact techniques. Preliminary results suggest that Z. verticillatum is potentially facilitating Olympia oyster recruitment as Z. verticillatum removals resulted in lower oyster recruitment. Some common non-indigenous fouling organisms may not be as problematic as predicted when restoring native species in estuarine communities.

Additional Abstract Information

Presenter: Leeza-Marie Rodriguez

Institution: California State University - Fullerton

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4089