Faculty Profile: Gary Lamberti
Chair, Biological Sciences

The wild salmon runs in the streams and rivers of the Pacific Northwest are rapidly declining because of impassable hydroelectric dams, degraded water and habitat quality, over fishing in the ocean, and competition with hatchery fish.

The net result is that the tremendous salmon migrations to traditional spawning grounds have greatly declined and with them the millions of tons of salmon biomass that historically moved upstream. The critical question is what this decline means for the entire watershed that may depend on the successive waves of migrations of Chinook, Coho, Chum, Pink and Sockeye salmon.

For the past ten years, Lamberti and his team of Notre Dame graduate and undergraduate researchers, have traveled to Alaska’s incomparable Tongass National Forest on the southeastern coast to take precise measurements designed to answer that very question.

“Salmon put on 95 percent of their growth in the ocean. When they swim upriver to spawn it’s a one-way street for them. They spawn and then they die, leaving all of their ocean-derived biomass in the river,” states Dr. Lamberti. It is one of the most impressive migrations in the natural world. The annual migration of 100 million salmon through the Alaskan waterways produces a vast transferal of nutrients from the saltwater ocean to the ecosystems and even up onto the land. "Our hypothesis is that this biomass fuels the growth of many other aquatic and terrestrial organisms."

The team, which includes Jennifer Tank and Dominic Chaloner at Notre Dame, is conducting experiments in Alaskan waterways to take exacting measurements in order to trace salmon nutrient pathways through the entire watershed. Here chemistry gives them an important tool to make these precise measurements. Certain stable, non radioactive isotopes of both carbon and nitrogen come from the sea. These “heavy” isotopes, carbon 13 and nitrogen 15, are incorporated within the salmon as they gain body mass prior to maturation.

“Not only do we find elevated nutrient levels wherever we find salmon, we can also trace these heavy isotopes all the way through the aquatic food chain from the algae to the invertebrates, and then right into the young salmon developing in the streams,” Lamberti said. "Our next goal is try to trace these chemicals into the terrestrial ecosystem." Therefore, both the carcasses trapped in the stream and those that bears and floods scatter on the land may be essential nutrient sources for these unique ecosystems.

This project has been generously funded by the US Department of Agriculture - National Research Initiative.

More:

Gary Lamberti talks about his research and the environment.

 

Stream Ecology Lab Web Page.