Relative species abundance of benthic diatoms across three oligotrophic lakes of varying nutrient composition

Abstract

Trophic states can be useful indicators as to the health and composition of a system in particular reference to algal communities. Much is known regarding relationships between trophic states and algal productivity and distribution. This study focused on the impacts of nutrient levels on three oligotrophic lakes in Northern Lower Peninsula Michigan on benthic diatom communities. Diatoms were assessed for species richness, abundance, biodiversity, and similarity between community composition. While each we classified each lake as oligotrophic, nutrient levels varied within the classification boundaries. We found that Lancaster Lake had the highest nutrient levels (total phosphorus: 5.75 ug/l) and the highest biodiversity score (1.0208). Walloon Lake had median nutrient levels (total phosphorus: 3.99 ug/l) and the lowest biodiversity score (0.756). Wildwood had the lowest nutrient levels (total phosphorus: 1.98 ug/l) and the highest biodiversity score (1.00). Jaccard's Similarity Index revealed that across all lakes 20.00% of the community composition was shared. Values varied between each lake with the highest scoring relationships being between Wildwood and Lancaster (44.22%) as well as Wildwood and Walloon (44.22%) while the lowest scoring relationship was between Walloon and Lancaster (29.78%). Navicula radiosa and Cymbella affinis were the dominant species in all three locations. As harmful algal blooms (HAB) and eutrophication become more common it is important to understand how nutrient composition and other variables impact algal communities in systems that are not undergoing eutrophication. The monitoring and maintenance of these systems can prevent HABs from occurring.