alga or cyanobacterium (Table 4) . Mosses and/or watercress made 

 up the bulk of the periphyton samples collected at the upper two 

 sites. Some water buttercup {Ranunculus sp . ) was also present at 

 Burleigh's Easement. 



Competition for resources by mosses and vascular plants may 

 be responsible for the low algal diversity in upper Big Spring 

 Creek. Constant flows and cold water temperatures originating 

 from the Big Spring probably contributed to the low diversity of 

 non-diatom alge in this reach. 



Green algae, which prefer cool but not extremely cold 

 waters, appeared at the Carroll Trail site and were abundant at 

 all three stations on the lower creek (Table 4) . Cladophora was 

 the dominant alga at the Carroll Trail site and near the mouth. 

 Oedogonium and Spirogyra, which prefer warmer, nutrient -rich 

 waters, were also present at Carroll Trail. 



Stigeoclonium, often an indicator of organic enrichment, 

 appeared at the Carroll Trail site and peaked in abundance at the 

 Spring Creek Colony (Table 4) . Periphyton samples collected at 

 the lower two sites contained large amounts of sediment . 



DIATOM ALGAE 



Seven species dominated the diatom associations in Big 

 Spring Creek (Table 5) . All but one of these species- -Navicula 

 cryp to tenel la -- is sensitive to organic enrichment (Lange-Bertalot 

 1979). This species, along with other pollution- tolerant taxa 

 {Navicula reichardtiana, Navicula capitatoradiata, Nitzschia 

 palea) tended to peak in abundance at the three downstream sites. 

 Even with increases in pollution- tolerant species at these sites, 

 pollution index values were all within acceptable limits (Table 5 

 and Table 3) . 



