Phosphorus Limitation on Periphyton a Study of Three Baltimore County Streams

Phytobenthos (algal periphyton) www.lfu.bayern.de/.../pic/phytobenthos_gr.jpg

Phosphorus Limitation on Periphyton

A Study of Three Baltimore County Streams

May 2008

Prepared by:

Teresa Bartley

Undergraduate Student

Environmental Science and Studies

For:

Dr. Susan Gresens

Associate Professor

Department of Biological Sciences

Towson University

Towson, MD 21252 USA

Introduction

The study of periphyton [benthic algae that grow attached to large rock and plants in streams (Environmental Protection Agency (EPA) 2007)] is beneficial in forecasting the health of stream ecosystems because they respond quickly to changes in the environment and because they exhibit rapid growth potential in nutrient rich streams. The focus of this report is phosphorus-limitation on periphyton. A notable number of field studies indicate that when phosphorus is present in freshwater ecosystems, growth and primary production of periphyton is reduced (Steinman and Mulholland 2006). This report compared observations of phosphorus-limitation and periphyton growth in three Baltimore County Urban Streams. The questions this report will try to answer are how periphyton growth is affected in streams with high total phosphorus (TP) concentrations versus streams with low TP concentrations, is the phosphorus limited or repleted [abundantly supplied (thefreedictionary.com 2000)], does phosphorus limitation increase when the riparian canopy is in full bloom [the stream receives less light], and is phosphorus less limiting to urban streams or rural streams? The three streams observed and sampled to aid in this study were a shady reach of Baismans Run with a low TP quantity, a shady reach of Oregon Branch with a higher TP quantity, and a sunny reach of Roland Run with the highest quantity of TP. The stream reaches of Baismans Run and Oregon Branch that were sampled are located in the Loch Raven Reservoir watershed and the stream reach of Roland Run is located in the Jones Falls watershed. Figure 1.0 shows the Watershed Indicators for Loch Raven Reservoir and Figure 2.0 shows the Watershed Indicators for Jones Falls (Maryland Department of Natural Resources (MDDNR) 2008).

Figure 1.0 Watershed Indicators for Loch Raven Reservoir

Figure