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STEM lecture to explore rain forest fish parenting


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The typical person’s typical day doesn’t involve much time spent thinking about the parenting habits of fish on the floors of rain forests. Ronald Coleman is not your typical person.

Coleman, a Sacramento State associate professor of Biological Sciences, lives for such studies. He waxes enthusiastic about working with cichlid fishes, about the harsh realities of their existence and how adept they are at making seemingly coldblooded life-and-death choices.

Coleman will project that zest for his studies when he delivers the first of the University’s spring semester STEM lectures at 6 p.m. Tuesday, Feb. 21, in the University Union Redwood Room. “Underwater Treasures of Costa Rica: Fish Parental Care Below the Rain Forest” will explore what cichlid fishes do as they prioritize the survival of the species at large against that of a single generation. Coleman believes the rain forest to be a magical place, full of sights and sounds found nowhere else. But it’s also an unforgiving environment.

For example, in controlled experiments, Coleman uses a fake fish on a stick as a model of an invader. One parent fish may bite the invading fish 20 times in 30 seconds as it defends its young, but another may bite only once. “Their parental care is relatively straightforward,” he says, in that when their children are threatened, they bite things. What that tells researchers is how much a parent is willing to do for its children.

Circumstances in the wild can affect the situation – perhaps the parents had many offspring and a catfish came along and ate all but two of them (“which happens a lot,” Coleman says). So, do the parents invest in caring for the two survivors? Or do they breed another couple hundred?

“The really interesting thing about these fish is that they are very astute decision-makers, and they will make that decision – and, actually they make it even more fiercely than that,” Coleman says. “They turn around and eat the last two kids – because somebody’s going to eat them. So they’ll eat them and use that energy to make more kids.”

Coleman has been at Sacramento State since 2001. He has been researching Costa Rican rain forest fishes since the late 1980s and has made more than two dozen trips to Costa Rica, where he travels annually during winter break, to study fish parental care. There, he works with the Organization for Tropical Studies at La Selva, a well-noted field station that is near several rivers, where biologists from many fields congregate. As much of a charge as he gets from such expeditions, there’s something to be said for the special gratification a professor gains from reaching students.

“I have many students who work in the lab and a lot of them have never kept a fish,” he says, “and yet I can have them working with these fish and breeding them and doing experiments in a couple weeks. That’s the amazing thing. … They’re actually doing science. That’s the best part.”

Coleman’s lecture is presented by the Center for STEM (Science, Technology, Engineering and Mathematics) Excellence. Find more on Sacramento State’s STEM program on its website, where you’ll also find topics of previous lectures. For media assistance, contact Public Affairs at (916) 278-6156.

– Ahmed V. Ortiz