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Mechanisms of Ingestion of Protistan Prey by Brachyuran Crab Larvae
EPA Grant Number: U915965Title: Mechanisms of Ingestion of Protistan Prey by Brachyuran Crab Larvae
Investigators: Perez, Margarita F.
Institution: Western Washington University
EPA Project Officer: Boddie, Georgette
Project Period: January 1, 2001 through January 1, 2002
Project Amount: $52,802
RFA: STAR Graduate Fellowships (2001)
Research Category: Fellowship - Oceanography , Aquatic Ecosystems , Academic Fellowships
Description:
Objective:The objective of this research project is to investigate the nature of feeding stimuli and prey discrimination of first-stage brachyuran crab larvae for Cancer magister (Dungeness crab) and Hemigrapsus oregonensis (common shore crab). Brachyuran crab larvae may be an important link in the coastal marine food web, providing food sources for a variety of fish larvae and other organisms. Crab larvae, or zoeae, ingest toxic algae under certain conditions, although the consequences to the larvae or their predators remain unclear. Although zoeae derive optimal nutritional benefit from mesozooplankton, they also feed on bacterially enriched detrital particles and protists. The latter two do not sustain development, but provide measurable nutritional contribution between encounters of sparse but dense, nutritious food patches (Sulkin, et al., 1998; Lehto, et al., 1998). Zoeae do not feed indiscriminately. They demonstrate selective feeding by avoiding ingestion of dinoflagellates of the genus Alexandrium, both toxic and nontoxic strains. Yet, when a preferred diet is present, a positive cue prompts larvae to feed on both the favored and nonfavored prey (Hinz, 2000). In nature, prey fields will most commonly consist of mixed species.
Approach:To investigate the nature of the positive feeding stimulus, I will manipulate dinoflagellate cell-surface constituents using various enzymes and lectins. In this manner, I hope to remove or block the cell-surface signal that notifies the zoea that it is handling a favored or unfavored prey particle. To determine if specific cell-surface proteins, carbohydrates, or glycoproteins prompt ingestion, I will provide larvae with inert particles bound with biomolecules known to exist on dinoflagellate cell surfaces. To further investigate toxic prey discrimination, I will provide larvae with diets of other dinoflagellate genera, both toxic and nontoxic.
References:
Sulkin SD, Lehto J, Strom S, Hutchinson D. Nutritional role of protists in the diet of first stage larvae of the Dungeness crab Cancer magister. Marine Ecology Progress Series 1998;169:237-242.
Lehto J, Sulkin SD, Strom S, Johnson D. Protists and detrital particles as prey for the first larval stage of the brachyuran crab, Hemigrapsus oregonensis. Journal of Experimental Marine Biology and Ecology 1998;230:213-224.
Hinz S. Effects of feeding on toxic and non-toxic strains of the dinoflagellate Alexandrium sp. by larvae of four crab species. Presented at the Huxley College of Environmental Science, Western Washington University, Bellingham, WA, 2000.
Supplemental Keywords:fellowship, brachyuran crab larvae, zoeae, Cancer magister, Dungeness crab, Hemigrapsus oregonensis, common shore crab, dinoflagellate, protistan prey.