Research Technical Report

Shipwrecks on Sanctuary Shores: Disturbance and Recovery Along a Height Gradient in the Rocky Intertidal Zone

McConnico, L., M. Foster, R. Walder, and A. DeVogelaere (November 2003)

Oral Presentation at the Western Society of Naturalists Meeting, Long Beach, CA

ASBTRACT

The shipwreck and subsequent salvage of a fishing vessel in Monterey Bay, California (1996) caused physical and chemical damage over a gradient from the low to high rocky intertidal. Recovery from this anthropogenic disturbance was monitored and data were used to examine patterns of recovery and variability in recovery rates across the range of tidal heights. Disturbed and control (undisturbed) plots were established in a mid/high intertidal red algal (dominated by Endocladia muricata and Mastocarpus papillatus), mid intertidal mussel (Mytilus californianus), and low intertidal surfgrass (Phyllospadix torreyi) assemblage. Percent cover of sessile organisms in 0.25 x 0.25-m plots in each of the assemblages was assessed between 1996-1998 and 20012002. Results indicated recovery varied over the exposure gradient. Ephemeral seaweeds initially colonized all disturbed plots, but were replaced by later successional species within 2-12 months. Contrary to expectations, recovery rates did not vary inversely with tidal height. Instead, relative recovery was greatest in the high intertidal red algal assemblage, followed by surfgrass, and Mytilus assemblages. The patterns of recovery suggest that assemblages characterized by a few dominant species that recruit rapidly and grow quickly will recover faster than those dominated by organisms with variable, episodic recruitment, or those that have limited success with sexual reproduction relative to vegetative propagation.