Published: Mon Mar 3, 2003You can tell a lot about a fish by what it eats. Just ask Tennessee Tech University chemist Martha J.M. Wells.
Through a contract with the West Virginia Division of Natural Resources (WVDNR), Wells, of TTU's Center for the Management, Utilization and Protection of Water Resources, is studying the fatty acid and lipid composition of fish taken from the Ohio River to determine if their diet has changed due to the construction of dams and locks. Dam and lock construction can limit the mobility of fish and lead to problems in overwintering if fish have not developed enough lipids and fatty acids to survive the winter.
Lipids are important to fish survival, growth and reproduction and insulate and protect different parts of their bodies, especially vital organs. Fatty acids are the building blocks of lipids.
"Lipids, which are components of all living cells, can tell us about the environment in which the fish lives," Wells said. If environmental conditions—and, thus, the food supply—change from dam and lock construction, the lipid content and fatty acid distribution, which may vary among age, sex, species, location or season, of the fish are influenced. Data from fatty acid studies help improve fisheries managers’ understanding of the fish’s survival in a given environment.
Wells says studying fish fatty acids and lipids is significant in three main areas. The first involves the nutritional importance of fish and fish oils as part of our regular diet. When we consume fish, our bodies are enriched by certain fatty acids that can reduce the risk of cardiovascular disease; protect against breast, colon and prostate cancer; and influence brain development, learning, memory and visual functions.
The second category entails the forensic uses of fish fatty acids. In certain cases, wild fish are intentionally being portrayed as cultured fish. Since the fatty acid profiles of fish represent the fish’s diet, the fatty acids of a cultured fish will reveal a diet derived from commercial feeds. The fatty acids of a wild fish will show that its diet has come from the environment. This evidence could help protect consumers from eating large quantities of wild fish that may have accumulated pollutants from their respective natural habitats.
The last category involves the use of fatty acids as environmental biomonitors of pollutants. The accumulation of pollutants from their aquatic habitats may be related to the fatty acid profile and percent of lipids in the fish.
Analyzing fatty acids and lipids as monitors of specific pollution concentrations and effects could prove useful in establishing environmental policy, Wells said.
Three different fish species, paddlefish, white bass and sauger, are being tested in this project. Paddlefish, in particular, were chosen for the study because of their potential use as caviar fish and the economic interests involved in their survival. The other species were chosen for their significance in recreational fishing and for their biological diversity. The samples are collected by project personnel with WVDNR and sent to the Water Center to be analyzed by Wells, doctoral student Le-Ellen Dayhuff-Nelson and research assistant Tammy Boles of the Water Center’s Environmental Quality Laboratory.
Wells’ research team will determine the concentrations of the fatty acids and lipids for each individual fish sample collected for this study, and that information will be combined with data gathered on the location, age and sex of the fish samples. They will then perform a statistical analysis to develop a profile showing the variation of fatty acid and lipid concentrations between age-classes over time and location.
Civil engineer Yvette Clark, also with the TTU Water Center, is working with the WVDNR to develop a Geographic Information System (GIS) template of the Ohio River and its major tributaries. In this part of the study WVDNR personnel tag captured fish, and Clark uses GIS technology to mark the location of capture. When the fish are recaptured, Clark notes that location also and measures the distance between those points to understand the fish’s movement throughout the dam and lock system.
Wells’ work on the project, which began in 2001, will be complete by June of this year.