Year Established: 2011 Start Date: 2011-03-01 End Date: 2012-05-31
Total Federal Funds: $30,000 Total Non-Federal Funds: $62,297
Principal Investigators: Gretchen Rollwagen-Bollens, Stephen Bollens
Abstract: Seasonal blooms of cyanobacteria and other algae are natural occurrences in lakes, and may naturally increase in frequency as lakes evolve from oligotrophic states (deep, clean and unproductive) to eutrophic states (shallow and infested with aquatic plants and phytoplankton). However, increasing evidence demonstrates that the eutrophication process in lakes is being accelerated by human activity, and is contributing to an increase in frequency and intensity of cyanobacteria blooms. Excessive abundance of cyanobacteria may have detrimental effects on lake ecosystems and water quality, including development of surface scums, depleted oxygen levels, and (in some cases) production of toxins that can negatively affect aquatic life and humans. This phenomenon is of great concern to water resource managers, particularly with respect to human health, as well as to the public whose use and enjoyment of these environments may be prohibited as a result. Vancouver Lake, in Clark County, WA, is a large, shallow lake in the lower Columbia River floodplain that is popular with the local community for swimming, boating, fishing and other recreational activities. Vancouver Lake has experienced numerous summertime blooms of Anabaena and Aphanizomenon cyanobacteria over the past 20 years, often necessitating closure of the Lake to swimming and other recreational use. In this proposal our goal is to better understand the dynamics of toxin production by cyanobacteria in Vancouver Lake, in particular the influence of biological (e.g. grazing pressure by planktonic consumers) and environmental (e.g. temperature, nutrient levels, and turbidity) factors on both the diversity of cyanobacteria and the stimulation of toxin production by particular cyanobacteria taxa. We have three specific objectives designed to meet our goal for this project: 1) Quantitatively measure toxin concentrations, cyanobacteria taxonomic composition and abundance, and the presence and activity of toxin-producing genes from samples collected in 2009-2010 and new samples to be collected in 2011, using molecular genetic techniques (ELISA assays, qPCR). 2) Apply these molecular genetic approaches to quantitatively measure cyanobacteria diversity and toxin production in specially-preserved samples from a series of microzooplankton grazing (dilution) experiments conducted over the full cyanobacteria bloom cycle in 2009. 3) Conduct a multivariate statistical analysis of these samples to test for the relative influence of biological and environmental factors on cyanobacteria taxonomic composition, abundance and toxin production. The results of these analyses will allow us to more accurately define cyanobacteria diversity in Vancouver Lake and to better predict the conditions that may lead to toxic cyanobacteria blooms. This information will be critical for assisting Clark County Public Health in determining whether restrictions must be imposed on Lake usage during bloom periods. In addition, these results will complement the suite of biological and chemical data currently available to Clark County Public Works and Environmental Services to inform management decisions that may mitigate or prevent cyanobacteria blooms in the future. Finally, what we learn about Vancouver Lake will have broad implications for other lakes in Washington as well as shallow, temperate lakes around the globe.