Dynamic Nature of Algal Symbioses: Consequences for Host Fitness in an Intertidal Alga-Anemone Association.

Western Washington University, Bellingham WA

Investigators

Abstract

Anthopleura elegantissima is the most abundant sea anemone in intertidal communities of the northeast Pacific Ocean. This dominant invertebrate plays an important role in the ecology of these systems. Because of the unique symbiotic relationship A. elegantissima has with two distinct photosynthetic algae, it is also important as a model to help us better understand symbiotic partnerships and how they respond to a changing environment. The relative abundance of the two algae in A. elegantissima populations along the outer coast of Washington State will be assessed. This will provide a barometer for climate change; the distributions and abundances of the two symbiont species are predicted to shift if, for example, temperature or light levels change. This prediction is based on the different physiological tolerances of the algal symbionts (one prefers cooler, low-light environments while the other does better in warmer, high-light environments). In laboratory studies, the relative value of each symbiont will be tested by measuring their impact on growth and reproduction of the anemone host. Anemones will be exposed to different levels of natural sunlight, and sexual reproduction, asexual division, and body growth will be monitored. Health of the symbionts will also be measured in terms of photosynthetic productivity and division rate. Results of the work will provide valuable insights into the ecology of an important and abundant intertidal species. Results will also be important for developing testable hypotheses about how other long-lived species with multiple symbiotic partners (e.g., lichens and corals) will be affected by climate change-related shifts in symbiont complements. This project will engage in symbiosis research 14 undergraduate and 2 graduate students, including members of groups underrepresented in science. Elements of the project will be incorporated into existing undergraduate courses and an elementary school outreach program, and also disseminated through public lectures.