Reef fish drawn to feeding grounds by algal cue


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American scientists have found that a chemical responsible for the smell of the sea is also the substance which some reef fishes use to home in on feeding grounds.

In a study published in a recent issue of the journal Science, Jennifer DeBose, Sean Lema and Gabrielle Nevitt found that some reef fishes are drawn to artificially released plumes of dimethylsulfoniopropionate (DMSP).

DMSP is a metabolite produced by phytoplankton and algae, and the release of DMSP from an area is indicative of zooplankton abundance, since DMSP is released when zooplankton feed on phytoplankton.

DMSP is also a substance that is important in oceanic sulfur cycles and global climate regulation.

DMS and DMSPA product of the breakdown of DMSP is dimethyl sulfide (DMS), which, along with substances produced by algae known as dictyopterenes, is responsible for the smell of the sea.

DMS also plays an important role in global climate by promoting the formation of clouds (its breakdown products such as sulfuric acid form aerosols capable of acting as cloud condensation nuclei).

The authors released DMSP in a down-current plume approximating concentrations that coral reef fish are likely to encounter in nature at four sites on fringing reefs along the coastline of Curaao in the Netherlands Antilles (using polyethylene carboys suspended in midwater and tethered to the substrate).

Attraction to DMSPThey found that planktivorous reef fish species such as Brown chromis (Chromis multilineata), Creole wrasse (Clepticus parrae), and Boga (Inermia vittata) were highly attracted to the DMSP plumes , although other planktivores such as Seargeant major (Abudefduf saxatilis) and Yellowtail snapper (Ocyurus chrysurus) did not respond to DMSP.

The authors conclude: lthough DMSP has been studied primarily in the context of global climate regulation, our results suggest that planktivorous fishes can eavesdrop on trophic interactions that leave residual chemical signatures and point to DMSP as a specific, biogenic compound that they can use to exploit their prey.

Taken more broadly, this work strengthens the hypothesis that, in addition to serving as a climate regulator, DMSP is an important signal molecule in the marine environment.

For more information, see the paper: DeBose, JL, SC Lema and GA Nevitt (2008) Dimethylsulfoniopropionate as a foraging cue for reef fishes. Science 319, p. 1356.