Speaker(s)

Joseph Eilers, MaxDepth Aquatics, Inc. and SolarBee, Inc.
Kellie Vache, Oregon State University, Corvallis, OR
Benn Eilers, Oregon State University, Corvallis, OR

Description

The role of fisheries in promoting cyanobacteria blooms in Oregon lakes was evaluated by (1) targeted surveys of lakes with a range of morphometric, chemical, and biological attributes, (2) examination of intended and unintended manipulations of fisheries in several lakes, and (3) paleolimnological and modeling analyses of selected lakes with introduced fisheries in the 20th century. The results of the surveys indicate that lakes with low concentrations of nutrients and base cations, low temperature, or low hydraulic residence times are least likely to develop problems associated with cyanobacteria following fish introductions. The manipulation of fisheries, either intended or unintended, has the greatest potential to contribute to cyanobacteria in those lakes with relatively low to moderate concentrations of phosphorus. The success of the introduced fish in promoting cyanobacteria blooms is dependent on the ability of the introduced fish species to find a suitable niche to exploit. Paleolimnological reconstructions combined with modeling analyses confirmed that the timing of the development of cyanobacterial blooms coincided with the introduction of new fish species. The CE-QUAL-W2 hydrodynamic model was modified to allow for enhanced representations of trophic interactions within a hydrodynamic framework. The simulations illustrated the importance of fish biomass in increasing the cycling rate of nutrients within the photic zone. Introduced fish play a major role in promoting cyanobacterial blooms for many Oregon lakes.

Conference

Fifth Symposium on Harmful Algae in the U.S.
Ocean Shores, WA, November 2009