Major Long-Term Objective:

1. Experimentally examine interactions of suspended sediment and nutrient loading on receiving freshwater food webs.

2. Examine the complex role of suspended sediments in controlling algal species and promoting or depressing noxious algal blooms.

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Major Short-Term Objectives:

1. Conduct large-scale enclosure experiments to test system response to gradients of P loading, suspended sediment loading, and crossed P x sediment loading.

2. Assess microscale effective "competition" between phytoplankton and sediments for P.

3. Examine survival of noxious algal species after they have coflocculated with sediments and settled out of the water column.

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Accomplishments:

1. Discovered an entire new group of freshwater dinoflagellates that mimics clay particles in appearance, with many mechanisms for capturing prey.

2. Determined that the base of the food web in shallow turbid reservoirs can consist of mixotrophic algae that survive using animal-like as well as plant-like nutritional modes.

3. Experimentally demonstrated that suspended sediments can be beneficial at small concentrations, but that they are generally detrimental to desirable phytoplanlcton species.

4. Experimentally demonstrated that suspended sediments can mitigate the effects of P enrichment in stimulating algal blooms.

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Significance:

Early journal accounts indicate that North Carolina's waters were once ~crystal clear.~ This research has shown that even small amounts of suspended sediment loading adversely affects algal species that are considered beneficial for higher trophic levels. Although our waters receive nutrient loading that would support noxious algal blooms in clear systems, these studies have also demonstrated that suspended sediment loading imposes light reduction that takes precedence over nutrients as the primary limiting resource, and mitigates growth of noxious algae.

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Future Plans:

1. Examine the influence of N loading on algal growth across P and sediment gradients.

2. Determine how abundant mixotrophic dinoflagellates affect higher trophic levels in the food webs of turbid reservoirs.

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