Stachowicz Lab University of California, Davis

Amy Larson

Graduate Student in the Joint Doctoral Program in Ecology
University of California, Davis
San Diego State University (advisor: Brian Hentschel)
CV [pdf/ doc]

Research interests

I am interested in how habitat complexity affects species distributions and can facilitate distinctive communities. More specifically, I am working to better understand the roles of positive interactions, biogenic habitat modification, foundation species and chemical ecological processes in soft-sediment systems.

I have chosen to work primarily in marine soft-sediment systems because they are extremely important and complex environments that are among the most extensive habitats on earth. Estuarine environments, particularly, play important roles as feeding grounds for migrating shorebirds and nurseries for juvenile fishes. Soft-sediment organisms are not only important as trophic links in many systems, but they also play key roles in nutrient cycling and pollutant detoxification.

P. viridis collected from a 10 cm diameter core in Bodega Harbor.

Phoronid transplant experiment. Phoronids and phoronid mimics were transplanted into the mudlfat to determine potential impacts on the infaunal species assemblage. Sediment was sieved prior to transplanting.

To transplant the phoronids, straws were used to keep them in place until the sediment was replaced around the tubes.

P. viridis occur in very high densities and can be the primary subsurface structure in many sandy mudflats within the harbor.

Current projects

  • Very dense populations of Phoronopsis viridis (syn. P. harmeri) are found throughout the intertidal sandy mudflats of Bodega Harbor. P. viridis is a chemically defended invertebrate that also produces tubes which are a distinctive structural element in the mudflats. P. viridis appears to be a foundation species in the mudflat that is associated with a distinct species assemblage when compared to similar areas without P. viridis. These attributes make P.viridis an ideal organism in which to look at the relative importance of chemical and structural complexity in determining community structure. In addition to describing the community associated with P. viridis, I am also conducting experiments to determine the effects of P. viridis structure and chemistry on foraging by common predators including juvenile fishes and shorebirds.

  • P. viridis (Hilton) has been determined to be the same species as the seemingly more widely distributed P. harmeri (Pixell) (Marsden 1959). However, there may be some populations that do not fit the description of P. harmeri on the basis of spermatophore, larval, and pigment differences (Zimmer 1974, 1991). We are collecting individuals from a number of populations of intertidal phoronids to determine if there are genetically distinct species of Phoronopsis on the Pacific coast from San Diego, California up to Friday Harbor, Washington. This work is being conducted in conjunction with Dr. Andrew Bohonak and Sharon Barkwill.