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Title Diversity of Algae Slows Growth of Microcystis
Publication Date
Date Accessioned
Degree MS
Discipline/Department Natural Resources and Environment
Degree Level masters
University/Publisher University of Michigan
Abstract As harmful algal blooms (HABs) have expanded in both size and scope, there have been increased efforts to design models that try to predict which ecosystems are at the greatest risk for a bloom. However, predicting blooms is a difficult process that has had limited success which we believe partly stems from the fact that efforts to date have considered a relatively small set of variables that influence algal growth. In particular, the focus on hydrology and abiotic conditions fails to consider biotic interactions that ultimately control the final composition of ecological communities. In this study we examined how species richness of resident green algae influenced the growth and carrying capacity of Microcystis in both low and high nutrient environments. We found that when either nitrogen or phosphorous were reduced, competition with green algae had a significant negative impact on the growth rate and final biomass of Microcystis, but the species richness of the green algal assemblage had no discernible effect on outcomes. However, in a high nutrient environment, a species rich community of green algae had a greater negative impact on the invasion success of Microcystis than a species-poor community. These results suggest that biotic interactions with phytoplankton can be important in limiting the establishment and proliferation of HAB species like Microcystis, and diverse communities can be more resistant to proliferation of HABs under nutrient conditions that favor blooms. In the future, the inclusion of biotic variables that influence bloom formation, in addition to the physical and abiotic requirements of a HAB species, could more accurately predict HAB events allowing for more effective management of our freshwater resources in the future.
Subjects/Keywords microcystis; harmful algae; species richness; Lake Erie
Contributors Cardinale, Brad (advisor); Allan, J. David (committee member); Johengen, Thomas (committee member)
Language en
Rights Unrestricted
Country of Publication us
Record ID handle:2027.42/113075
Repository umich
Date Retrieved
Date Indexed 2019-06-03
Grantor University of Michigan
Note [thesisdegreename] Master of Science; [thesisdegreediscipline] Natural Resources and Environment; [thesisdegreegrantor] University of Michigan; [bitstreamurl] http://deepblue.lib.umich.edu/bitstream/2027.42/113075/1/M_Nolan_Thesis_2015.pdf;

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…to focus on species from the genus Microcystis because it is one of the most common and widespread cyanobacterial HAB species (Paerl and Otten 2013). This genus of cyanobacteria is particularly problematic due to the production of the toxin…

…that the water was shut off for the entire city for 3 days (Frankel 2014). In order for Microcystis to bloom, the species must first be introduced into the water column, which generally occurs when hydrologic mixing re-suspends overwintering…

Microcystis? And do higher levels of species diversity intensify these competitive interactions? In this paper, we attempt to answer these questions with the results of two laboratory experiments in which we looked at how the species diversity of resident…

…quantified how the growth rate of Microcystis varied as a function of dissolved N or P concentrations to determine levels at which Microcystis maintained positive growth and maximized its growth rate. In the second experiment we examined how species richness…

…reduced the growth rate and carrying capacity of Microcystis regardless of nutrient condition. Prediction 2 was also only partially supported. We found that species richness of green algae did reduce Microcystis growth and carrying capacity, but this only…

…occurred in the high nutrient environments. Our work suggests that biotic interactions with phytoplankton can be important in limiting the establishment and proliferation of HAB species 6 like Microcystis, and that diverse communities can be more…

…𝜇𝜇 is the average growth rate of Microcystis at each nutrient concentration, µMax is the maximum growth rate that the species can achieve at unlimited nutrient concentrations, α is the initial rate of change showing how growth rates respond at low…

…might reasonably be interacting with Microcystis. In a 1998 survey of Lake Erie performed by Barberio and Tuchman (2001), 22 green algae species were classified as dominant: defined as species comprising at least 5% of the sampled biomass. From…