Meeting Abstract

77.3  Wednesday, Jan. 6  Food falls, feeding attractants, and organization of complex chemical signals ZIMMER, Richard; Univ. of California, Los Angeles z@biology.ucla.edu

Organic food falls play critical roles in structuring communities within coastal ocean, estuarine and deep sea environments. The aggregation of carrion feeders over time near enrichment sites can invite higher-order consumers, thus causing trophic cascades while increasing species richness and altering pathways of energy flow and community metabolism. Over the last 20 years, we have performed experiments on the chemistry of organic food falls and on the attraction of crustacean and molluscan scavengers and predators to enrichment sites. Across field sites (California, Alaska, South Carolina New Zealand), there was surprising concordance among results. Chemical composition of leachates from a wide range of carrion was extremely dynamic following animal sacrifice and introduction into each ocean habitat. Many of these changes could be attributed directly to microbial decomposition, but autolytic degradation also contributed to the overall signatures, especially in a growing correlation over time among dissolved-free (DFAA) and –combined (DCAA) amino acid pool compositions. Scavenger recruitment to food falls covaried positively with DFAA and DCAA fluxes from carrion, but did not scale according to either the flux of carbohydrates or lipids. For DFAAs, variation in scavenger abundance ultimately was attributed to the relative magnitude of release and not to differences in mixture blends. In summary, organic nitrogen often is a limiting dietary factor in ocean habitats, and thus, is a prized commodity. The combined strength of DFAA/DCAA release is, however, a reliable cue for scavengers tracking scents towards finding organic food falls and valuable nitrogen rewards.