Tuesday, June 5, 2007
530

Seasonal dynamics of periphyton and nutrients in urban vs. rural streams

Susan E. Gresens, Biological Sciences, Towson University, 8000 York Road, Towson, MD 21252-0001

Periphyton biomass was measured in twenty-five streams in the Baltimore, MD area during 2002, to assess its relation to nutrients, and to quantify seasonal variation in food resources for macroinvertebrates.  Surveys were conducted ten times during the year, and used a visually-based scoring system to categorize the thickness of the periphyton layer.  A regression relationship (R2= 81%) was developed between chlorophyll a of periphyton samples of known area and their thickness score; this relation was then used to estimate chlorophyll a concentration of periphyton from field data.  Algal biomass estimates ranged from 1 – 2,220 ug chlorophyll /cm2.  Peak algal biomass occurred in April, and then declined to a minimum at the end of a prolonged drought.  Mean periphyton biomass was almost always greater in urban streams.  Mean total phosphorus (TP) concentration was ca. twice as high in urban than in rural streams, whereas total nitrogen (TN) concentration showed much less variation seasonally, or between urban and rural streams.  Correlations between algal abundance, TP and TN were stronger in rural streams, but changed seasonally.  The highest correlation between TP and biomass (r=.858) occurred in rural streams during summer drought, when algal biomass was low. 

See more of Poster Session - Periphyton
See more of Contributed Sessions

See more of The NABS 55th Annual Meeting