Levin, L. Marine Life Research Group, Scripps Inst. Oceanography, llevin@ucsd.edu

 
UNTANGLING THE ROLES OF OXYGEN AND ORGANIC MATTER IN STRUCTURING COMMUNITIES: INSIGHTS FROM BATHYAL MACROFAUNA
 
Macrofauna are highly sensitive to their geochemical environment at the individual, population and community level. In particular, oxygen and organic-matter availability, which often vary inversely, strongly influence patterns of infaunal abundance, taxonomic composition, diversity and lifestyle. The mechanisms by which these parameters affect community structure remain poorly understood. Studies of macrofauna in oxygen minimum zones (OMZs) off Mexico, Peru and Oman, at seeps and vents, and in naturally and experimentally enriched margin settings, provide insights into the relative effects of oxygen and organic matter. These studies suggest: (1) Organic-matter (food) availability supercedes oxygen as a structuring agent at all but the lowest oxygen levels (<0.4 ml/l), contributing to high density and low diversity in enriched settings. (2) Annelids dominate macrofauna in low-oxygen, enriched systems, but within the taxon, community parameters are highly sensitive to geochemical variation. Taxa typically responsive to enrichment are not necessarily tolerant to low oxygen. (3) Together, oxygen and organic-matter concentrations may explain much of the variation in dominance and species richness of bathyal macrofauna, particularly within OMZs. However, sulfide concentrations and symbioses are likely to mediate the influence of oxygen and organic matter.
 
Day: Thursday, Feb. 4
Time: 09:15 - 09:30am
Location: Hilton of Santa Fe
 
Code: SS30FR0915S