Harmful Algal Blooms (HABs) have been a major water quality issue for Ohio, resulting in impacted drinking water supplies, tourism, property values, and ecosystem health. These blooms, which are commonly dominated by cyanobacteria, have traditionally been viewed as being phosphorous driven due to the ability of the cyanobacteria to “fix” atmospheric N<sub>2</sub>. However, in order to fix N<sub>2</sub>, these organisms require the metalloenzyme nitrogenase, a compound which utilizes Molybdenum (Mo) as a main cofactor and Vanadium (V) or Iron (Fe) as alternatives in low Mo environments. Thus molybdenum concentrations may also have a key role in the growth of HABs. To test this hypothesis, two Ohio lakes were sampled that have had past history of HABs: Grand Lake St. Mary’s and Buckeye Lake as well as in three control sites: Griggs, O’Shaughnessy, and Hoover Reservoirs. These samples have been analyzed for Mo, V, and Fe, as well as for dissolved inorganic Nitrogen (diN), major cations and anions, and other dissolved nutrients. Our hypothesis is that the ratio of ΣMo+V+Fe:diN will be higher in the lakes having HAB problems relative to the reservoirs. This hypothesis is supported by our data with HAB prone waters showing ratios one to two orders of magnitude higher than those not prone to HAB activity. However, water with HAB activity had similar Mo and V concentrations as those without (Mo: 1.9 – 10.7 µg/L and 4.1 – 10.3 µg/L, V: 0.6 – 3.8 µg/L and 0.4 – 1.6 µg/L). By analyzing the potential role of these metals in the proliferation of HABs, this work could greatly aid in better management and potentially better water treatment that may help in decreasing bloom intensity and length in the future.

Potential role of dissolved molybdenum, iron, and vanadium in harmful algal blooms in Ohio lakes

255th National Meeting (2018)

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