Population dynamics and mechanisms for persistence of the red alga, Gracilariopsis andersonii, in central California

The purpose of this project was to examine and compare the mechanisms for growth and reproduction of Gracilariopsis andersonii found along an exposed rocky coast and within an estuarine sand flat. Biomass and reproductive capacity were measured within permanent plots at Pigeon Point (Pescadero, CA) and in the Elkhom Slough (Moss Landing, CA) for one year and while cultivated in the laboratory for 40 days. The rocky coast population relied heavily upon sexual fertilization while the estuarine population relied almost solely upon vegetative fragmentation for propagation, clearly indicating life history plasticity within this species. Additionally, I investigated the sediment size frequency in areas with and devoid of algae and found evidence indicating the alga as a sediment stabilizer. The results of this study indicate that variations in environmental conditions may control the life cycles and therefore demographics of these organisms.