Publication Date

Spring 2026

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Michael Graham; Scott Hamilton; Thomas Connolly

Abstract

Understanding the resilience of foundation species to disturbance, such as the canopy-forming giant kelp (Macrocystis pyrifera), is crucial as these species support diverse communities by provisioning habitat and nutrients. This study investigated sublethal effects of biomass loss on reproductive traits and the recovery of vegetative biomass following simulated disturbance at shallow and deep sites in Stillwater Cove, central California. Initial baseline morphometrics revealed that depth significantly influenced total frond length and blade density but did not predict other vegetative or reproductive biomass metrics. A manipulative experiment varying type and intensity of disturbance—from canopy removal to full frond culls—demonstrated a decoupled response between growth and reproduction. Vegetative biomass was significantly affected by disturbance severity and depth; individuals in deeper sites maintained higher frond abundance while non-disturbed control plants had the greatest number of fronds throughout. In contrast, the density of viable spores was independent of biomass loss and depth, showing a significant temporal decline from the start to the end of the study. These results indicate that reproductive viability is not impacted by biomass loss, despite vegetative biomass determining plant recovery from disturbance. Given the variable results in this study, differences in regional vegetative biomass should be noted by coastal managers and restoration efforts, particularly when assessing seasonality and the Macrocystis harvesting in vulnerable areas.

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