PARENT SESSION
Oral Session #57: Aquatic Ecology: Wetlands, Estuaries, Marine. Presiding: T. Klinger.
Wednesday, August 8, 2001. 1:00 PM to 5:15 PM. Hall of Ideas J.
Activated chemical defenses in temperate bloom-forming macroalgae.
Van Alstyne, Kathryn1, 1
ABSTRACT- Many green algae responsible for the formation of harmful macroalgal blooms produce an activated defense system that may allow them to persist in the presence of herbivores. In this defense system, the precursor, DMSP, is converted upon damage to the alga to DMS and acrylic acid by the enzyme DMSP lyase. Our data provide strong evidence that DMSP functions as the precursor in an activated defense system in at least eight species within five genera of temperate macroalgae from the Washington and Oregon coasts. DMSP occurs in all of these species and DMSP lyase activity is present in at least two species, Ulva fenestrata and Polysiphonia hendryi. Our laboratory experiments have shown that both the products of the reaction, DMS and acrylic acid, are feeding deterrents to green sea urchins, whereas DMSP is a feeding attractant. DMSP concentrations varied spatially among populations and were affected by environmental factors such as nutrient concentrations
KEY WORDS: activated defenses, chemical defenses, green algae, plant-herbivore interactions