Many different types of algae can be found in the creek. Green algae tends to be the most prolific (grows the fastest). The most commonly observed green algae is seen in large mats floating on the surface (below left) and attached to the creek bottom. These large mats are a filamentous variety formed of clong chains of cells. The growth of this type of algae is most rapid in late spring and summer when temperatures are high and nutrient levels rise as a result of fertilzer runoff and increased rates of decomposition. The growth at this time significantly exceeds the rate of consumption by algae eaters leading to stagnation, an accumulation of decomposing organic matter, a decrease in dissolved oxygen levels below the mats of algae as a result of increased rates of decomposition, and a decline in the diversity of creek organisms. Spirogyra, having characteristically sprial arrangements of chloroplasts within its cells, is the most common of all the filamentous green alagae that we see in the study site.