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| Aurora Alifano
I am interested in species interactions that define the ecology
of a marine community, specifically the dynamics that regulate the
abundance and diversity of species inhabiting the rocky reefs in
California. Few studies have examined the abundance or composition
of detached macroalgal drift or sea urchin ecology on the coast
of central California. My research will examine the variability
of strength and direction of a particular species interaction using
sea urchins and drift algae as a model. In central California, sea
urchins are not as abundant subtidally as in Southern California
or British Colombia. However, certain sites exist in central California
where an extremely high density of sea urchins are observed burrowed
into lower intertidal and shallow subtidal benches at nearly 100%
cover. These high density populations exist adjacent to lush kelp
forests and algae diverse intertidal areas. How do these dense populations
of Strongylocentrotus purpuratus exist in localized, concentrated
areas? This study addresses interaction strength between trophic linkages in intertidal and subtidal systems. If Strongylocentrotus purpuratus relies on drift subsidy to maintain high-density intertidal populations, they may be responding to the biomass of the subtidal algal populations presenting a linkage between the two systems. If the input of subtidal kelp into the intertidal zone provides a vital component of the sea urchins diet in a location with reduced predation, that process may explain the unusually high sea urchin density in a concentrated lower intertidal zone. This study will determine the role that drift algae plays in this system, such as how much detached macroalgae arrives in the intertidal zone among seasons, how much of the drift is available to sea urchins in tidepools and along benches, and if drift algae alone is enough to sustain the population. The impact of location geology, sea urchin foraging behavior, and adult fertility will also be examined. The findings of this study may clarify whether these grazers are controlled by top-down or bottom-up forces, and may influence central California food web theory.
Contact info: Aurora Alifano
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