Investigating the role of dimethylsulfoniopropionate (DMSP) as an aggregation cue for coral reef and reef-associated fishes

Dimethylsulfoniopropionate (DMSP) is a ubiquitous compound produced by many species of marine algae. The availability of DMSP in the marine environment is directly tied to the rupturing of algal cells and one major contributor to this algal death is through the foraging activities of zooplankton and planktivorous fish. I proposed that fish may eavesdrop on this activity using DMSP as an olfactory cue. Here I present evidence that DMSP may be used by fish to locate transient foraging opportunities, and thereby elicit the formation of fish aggregations. In the Introduction, I review the current knowledge and emerging focus of research on olfactory ecology in fishes and birds. In Chapters 1 and 2, I show that pelagic jacks are positively associated with DMSP levels over the Flower Garden Banks' reefs in the northwestern Gulf of Mexico. In Chapter 2, I present specific evidence that coral spawning could be a mechanism of release of DMSP in coral reef habitats and that the abundance of pelagic fish and squid is correlated with elevated DMSP over the reef. In Chapter 3, I provide experimental evidence that juveniles of two related species of pelagic jack respond to DMSP in controlled behavioral trials in the laboratory. And in Chapter 4, I present results from a field release experiment, where I discharged DMSP over a fringing coral reef in the Caribbean Sea and instigated an aggregation response in several planktivorous coral reef fishes. Overall, this study is the first to document natural relationships between DMSP, fishes and squid over coral reefs, and to use both laboratory and field experiments to provide evidence that DMSP acts as an olfactory cue driving aggregation behavior in coral reef and reef-associated fishes.