Allison Burke

Two masters theses projects from the zoology department at Miami University could provide valuable information for fisheries across the country.

The research revealed that the effects of nutrients and light on aquatic plants eventually impact fish populations through energy transfer through the food chain for fisheries across the country.

The research completed by María González, associate professor of zoology, and Michael Vanni, professor of zoology, along with masters students Beth Mette and Jennifer Newell, tested degrees of light exposure and nutrient level in aquatic environments. The goal was to determine what produced the best plant quality. The energy and nutrients stored in algae would be transferred through the food web, ultimately affecting the growth rate of fish, Gonzalez said.

“The conditions of light and nutrients in the aquatic system can influence the transfer of energy through the food web,” Gonzalez said. “This means that depending on the light and nutrient conditions under which algae grow, their nutrient content can be low or high.”

Gonzales said this can dictate the nutritional value of the fish because they consume organisms in the water.

According to Gonzalez, the group set up four different experimental treatments that mirrored real aquatic habitats using the mesocosm facility at the Miami Ecology Research Center, which is located approximately two miles from campus, north of Oxford.

Gonzales said the group had a hypothesis that low light and high nutrients would produce the best fish growth rate.

“Our results match our initial predictions,” Gonzalez said. “Low light and high nutrients produced the best quality algae and under these conditions we observed the highest fish production.”

Although previous research has shown that light and nutrient conditions can affect nutrition content of algae, this is the first study that tested the effect on energy transfer to fish, according to Gonzales.

Also, the effects of algae quality on fish are indirect since the fish do not consume the algae themselves but instead consume zooplankton that eat algae, according to Gonzalez.

This experiment has the potential to provide valuable information for the management of fisheries around the country. For example, aquacultural fish production facilities will be able to adjust light and nutrient levels in order to have the largest fish possible, according to Gonzalez.

Ultimately, the research has important implications since light and nutrient inputs to aquatic systems can be affected by environmental modifications and climate change, according to Gonzalez. This includes the possible cloud growth in certain areas, which will affect fish growth simultaneously.

The experiment was funded by the United States Department of Agriculture and the National Science Foundation.

Mette and Newell needed to do research to earn their masters degrees.

“The zoology masters degree requires a research based thesis,” Mette, a 2007 graduate from Miami’s masters zoology program, said. “During the execution of the research project, graduate students work very closely with an adviser and several undergraduate students are also involved in research activities.”

Mette said she and Newell were in Oxford in the summer of 2005 and available to participate in this project.

“The project came up and we were both very interested in it,” Mette said. “Neither of us could have done it by ourselves so we were able to collaborate.”

Gonzalez said Mette’s research focused on algae while Newell’s centered on zooplankton.