A recent study on coral reefs by marine scientists at UCSB has shown that fishing has caused interesting effects on the behavior of prey and the ecosystem.
Elizabeth Madin, a Ph.D. student at UCSB, is lead author on two journal articles on the subject — the first published in American Naturalist and the second in Ecology. Ecology, Evolution and Marine Biology professor Robert Warner, Steven Gaines of Bren School of Environmental Science and Joshua Madin of Macquarie University of Sydney, Australia were co-authors of the publications.
The researchers showed that fishing affects the reefs by reducing predators and changing the movement of smaller fishes throughout the reefs.
“What our results show is that fishing can have surprising, but very clear, effects throughout coral reef ecosystems,” Madin said in a press release. “Hopefully, these results will help conservation practitioners and resource managers move toward true ecosystem-based management, where the full suite of ecological interactions and human impacts guide policy decisions.”
The research took about five years to complete and showed how the declining number of predators, such as sharks, has allowed their prey to move more boldly throughout the ecosystem. Previously, smaller fish had been forced to hide out in the reefs to avoid these predators. However, now that the amount of predators has been reduced, fish can graze more freely throughout the coral reef without the fear of being hunted, allowing them to have more opportunities to feed and mate.
“I think the most important thing is that it turns out that the indirect effects of predators — like inducing prey to hide and feed less — may be more important than direct effects, like predators eating prey,” Warner said.
This freedom directly affects the ecosystem and the amount of seaweed grown, since seaweed directly affects where new coral can grow — an increase in seaweed can decrease the amount of new coral. These feeding habits have resulted in seaweed spreading more evenly across the reefs and prevented new coral from forming as readily.
“I think that it’s interesting that people don’t always anticipate the negative effects, when they interfere with nature,” Dana Fallon, a second-year linguistics major, said. “It seems that there are some positive effects coming out of fishing off the coast, but the real question is whether or not these positive aspects will outweigh the decline in coral production.”
For students wishing to get involved with research, Warner recommends trying to get involved with the research on campus or take a field course. Students should try and attend office hours to see if there are ways they can help out, as well as doing well in classes.