Effect of low level fertilization on microplankton in Arctic LTER lakes

• Main Authors: Boyko, Alison Lisa, NC DOCKS at The University of North Carolina at Greensboro
• Language: English
• Published: 2006
• Subjects: Lake ecology > Arctic regions; Arctic
• Online Access: http://libres.uncg.edu/ir/uncg/f/umi-uncg-1123.pdf

"Many studies have examined the effects of high level nutrient additions (up to 10x ambient loading rate) to lake ecosystems. This study examined microplankton response to low-level nitrogen and phosphorus additions (nominally 2X ambient loading rate) in lakes with and without fish at the Arctic LTER site. Annual variation in microplankton abundance in experimental and reference lakes was high. Lakes with fish had fewer large microplankton taxa. Overall, the response of microplankton to fertilization was unremarkable except for Vorticella whose average total biomass at 1 meter in the experimental lake containing fish increased significantly over the experimental period (regression coefficient = 1.264; F = 18.27; p = 0.007; d.f. = 5). Microplankton biomass trended downward in reference lakes while remaining relatively stable in experimental lakes, thus a subtle positive response may have occurred. Assessing changes in intermediate trophic levels in response to low-level fertilization is difficult because of high inter-annual variation in temperature and rainfall and a high coefficient of variation in direct count data (range 2 - 244%). Long term experiments and observations (10 years or greater) may be required to definitively assess such subtle impacts."--Abstract from author supplied metadata.