Judith Orser

Publication Date


Advisor(s) - Committee Chair

Gary Dillard, Jeff Jenkins, Robert Hoyt

Degree Program

Department of Biology

Degree Type

Master of Science


Periodic collections were obtained from Sloan’s Crossing Pond, Mammoth Cave National Park, for one year to analyze, quantitatively and qualitatively, the periphyton community and determine patterns of periodicity. Productivity was measured by dry and ash-free dry weights and chlorophyll a content.

Productivity was lowest during the winter months and highest between July and September. Dry weight showed a range of 3.0-243 mg/m­2/day, the peak occurring in August. Ash-free dry weight also reached its annual peak in August at 92 mg/m2/day. Chlorophyll a followed the pattern of dry weight except its peak was obtained in July at 584 mg/m2/day. This difference was attributed to the fact that in July blue-green algae were dominant while in August diatoms became subdominant. Therefore, biomass was higher in August, but chlorophyll a content was lowered. Low productivity in the winter was due to low light and temperature which caused reduced growth.

Diversity was poorest during the winter months, January and February, due to low productivity, and richest in April. During the summer months when the nutrient levels were low and the temperature was high, variety again reached a minimum. In fall, it increased and then dropped for the winter. The Chlorophyta, represented primarily by Chlorococcales, Mougeotia sp., Chlorella vulgaris, and Chlamydomonas sp., appeared in their greatest numbers during the spring and fall. The Chrysophyta showed the same basic pattern, except that their relative abundance was approximately 10% lower. Naviculoid spp. and Synedra ulna were the most abundant members of the Chrysophyta. The Cyanophyta, especially Oscillatoria sp., O. Subbrevis, and O. tenuis, dominated the summer flora and also appeared in great abundance in December. Euglenophyta, especially Euglena sp. and Trachelomonas volvocina, were highest in frequency in January and November and lowest during the summer.


Biology | Life Sciences

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