PARENT SESSION
Oral Session 76: Biodiversity V: Marine.
Presiding: AA Sabor
Wednesday, August 4, 1:30 PM to 5:00 PM, Meeting Room B 110.
Is algal species identity or diversity related to primary production in benthic marine communities?
Bruno, John*,1, Lee, Sarah1, Kertesz, Johanna1, Carpenter, Robert2, Boyer, Kathy3, Duffy, Emmett4, 1 The University of North Carolina at Chapel Hill, Chapel Hill, NC2 California State University at Northridge, Northridge, CA3 San Francisco State University, San Francisco, CA4 Virginia Institute of Marine Sciences, Gloucester Point, VA
ABSTRACT- Influential research in terrestrial habitats has shown that several ecosystem processes are related to plant diversity, yet these links remain poorly studied in marine ecosystems. We conducted a series of field and mesocosm experiments to explore the relative effects of macroalgal identity and diversity on primary production in hard-substratum subtidal communities in North Carolina and Jamaica. We measured primary production as the net accumulation of algal biomass in the absence of consumers and also as photosynthetic rate using an oxygen probe in sealed aquaria. In contrast to previous results from grasslands and microbial microcosms, our manipulations of algal diversity did not strongly support the predicted diversity-productivity relationship. Algal identity had consistently strong effects on both measures of net primary production while richness generally did not. In one case we found slightly higher rates of production in more diverse algal assemblages (i.e., 6-10 species), but this was largely due to the presence of highly productive species (i.e., the sampling effect). However, similar experiments that included simultaneously manipulated herbivore diversity indicate that plant diversity could increase plant standing biomass by reducing herbivory via several mechanisms. Additionally, our results do not preclude a potential role of algal diversity in different environmental conditions, across larger spatial and temporal scales, or when additional ecosystem processes are considered.
Key words: marine, productivity, algae, diversity