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Tuesday, August 3, 2021

Climate related chemical also acts as cue to help fish find food

Scientists are making discoveries about how some fish locate their food and each other.

Jennifer DeBose, a researcher with the National Oceanic and Atmospheric Administration’s Flower Garden Banks and National Marine Sanctuary in the northwestern Gulf of Mexico, is one of the authors of a recent study of a chemical known as Dimethylsulfoniopropionate (DMSP) and its role in affecting aggregation behavior in fishes.

We [didn’t] really know what cues fish can use to actually find each other and find where their food is, find where their habitat is, said DeBose, a UC Davis graduate student.

The study, which was done by DeBoseas well as fellow UC Davis graduate student Sean Lema and neurobiology, physiology and behaviorprofessor Gabrielle Nevitt, set out to fill that void by releasing DMSP into the ocean and observing how fish reacted to the odor.

According to the study, DMSP is produced by phytoplankton and algae associated with coral reefs. It is released when algae are being foraged or when there is an algal bloom a large growth in algae.

DMSP has been investigated at length in several studies. However, it has not been studied in connection with animal behavior.

There’s a lot of research on this chemical. It’s just related to climate, DuBose said.

Derivatives of DMSP evaporate into the atmosphere from the ocean and contribute to the formation of clouds. Thus far, DMSP has been studied from the perspective of how it relates to the environment, especially in connection with how it affects climate change.

DeBose and her colleagues decided that the study was a chance for the researchers to study DMSP from a different point of view.

Not thinking about the atmosphere, not thinking about cloud formation, but just among the animals in this ecosystem – there is a big push to study how aggregations form, DeBose said.

Releasing the chemical into the coral reef allowed the scientists to see how planktivores, fish that eat mainly plankton, respond to DMSP. Some of the fish that were attracted were the Brown Chromis and the Creole Wrasse.

By releasing this chemical, I’m basically just saying to the environment, ‘Something is attacking algal cells right now,’ DeBose said.

DeBose and her colleagues worked along the coast of the island of Curaçao, Netherlands Antilles, which is located off the coast of Venezuela in the Caribbean. The researchers released very small concentrations of DMSP and waited for one hour.

From that small amount, we would get hundreds and hundreds of fish that would come in, DeBose said.

The results were surprising because DeBose said she did not expect large aggregations of fish to form with those small doses.

I expected to get a fish [to] come and check it out, to get some sort of behavior to show that they smelled [the DMSP], she said. That was pretty impressive to me.

What made the results more surprising was that the study was done blind, so that the researchers would not know what they were releasing.

We would do that for 60 minutes, and be really, really freezing. DeBose said. Then they would repeat the procedure at different locations nearby.

The results, according to the study, imply that odors linked more closely to feeding activity than to the presence of prey alert some planktivorous fish species to potential foraging opportunities.

 

VIOLET SALAZAR can be reached at science@californiaaggie.com.

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