Presentation Title

Antibiotic and Nutrient Mixtures Influence Phytoplankton Abundance and Community Composition in Flowing Waters

Location

Nessmith-Lane Atrium

Session Format

Poster Presentation

Research Area Topic:

Natural & Physical Sciences - Biology

Abstract

Rivers and streams transport essential freshwater, nutrients, and organisms, including phytoplankton, to coastal systems. Phytoplankton exhibit sensitivity to contaminants that enter rivers in agricultural runoff and wastewater effluent, including antibiotics such as tetracycline (TC) and excess nutrients. Ecologically relevant concentrations of TC decreased phytoplankton abundance under flowing conditions in previous artificial stream experiments, while nutrients are known to alter competitive interactions between species, leading to dominance by species unpalatable to grazers or bloom-forming species. Although TC and excess nutrients are likely to be present simultaneously in the environment, how the combination affects phytoplankton communities remains unclear. We conducted two artificial stream experiments to test whether nutrients (nitrate and phosphate) and TC together affect phytoplankton communities differently than each contaminant alone. For both experiments, communities of three phytoplankton species were exposed to treatments of nutrients (nitrate and phosphate), TC, both, or no addition control for a minimum of one week. Both TC and nutrients increased total abundance relative to the nutrient-only and TC-only treatments due to increases in Navicula sp. and Scenedesmus sp. Abundance of Navicula sp. increased by 50-90% in the contaminant combination relative to nutrient-only and TC-only additions in both experiments, potentially due to reduced competition with aquatic bacteria. Microcystis aeruginosa trended toward increased abundance in the contaminant combination relative to the nutrient-only addition, but only in the first experiment. Our results suggest that simultaneous TC and nutrient inputs alter phytoplankton community composition in streams, which could ultimately change the abundance and quality of phytoplankton subsidies reaching coastal waters.

Presentation Type and Release Option

Presentation (Open Access)

Start Date

4-16-2016 10:45 AM

End Date

4-16-2016 12:00 PM

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Apr 16th, 10:45 AM Apr 16th, 12:00 PM

Antibiotic and Nutrient Mixtures Influence Phytoplankton Abundance and Community Composition in Flowing Waters

Nessmith-Lane Atrium

Rivers and streams transport essential freshwater, nutrients, and organisms, including phytoplankton, to coastal systems. Phytoplankton exhibit sensitivity to contaminants that enter rivers in agricultural runoff and wastewater effluent, including antibiotics such as tetracycline (TC) and excess nutrients. Ecologically relevant concentrations of TC decreased phytoplankton abundance under flowing conditions in previous artificial stream experiments, while nutrients are known to alter competitive interactions between species, leading to dominance by species unpalatable to grazers or bloom-forming species. Although TC and excess nutrients are likely to be present simultaneously in the environment, how the combination affects phytoplankton communities remains unclear. We conducted two artificial stream experiments to test whether nutrients (nitrate and phosphate) and TC together affect phytoplankton communities differently than each contaminant alone. For both experiments, communities of three phytoplankton species were exposed to treatments of nutrients (nitrate and phosphate), TC, both, or no addition control for a minimum of one week. Both TC and nutrients increased total abundance relative to the nutrient-only and TC-only treatments due to increases in Navicula sp. and Scenedesmus sp. Abundance of Navicula sp. increased by 50-90% in the contaminant combination relative to nutrient-only and TC-only additions in both experiments, potentially due to reduced competition with aquatic bacteria. Microcystis aeruginosa trended toward increased abundance in the contaminant combination relative to the nutrient-only addition, but only in the first experiment. Our results suggest that simultaneous TC and nutrient inputs alter phytoplankton community composition in streams, which could ultimately change the abundance and quality of phytoplankton subsidies reaching coastal waters.