Whitehorse Pond – 5.0 GENERAL CONCLUSIONS

Crater Lake National Park Whitehorse Pond Limnological and Vascular Plant Study, 1993



This study of the ponds on Whitehorse Bluff was proposed to be an introduction to the many features exhibited by the ponds. The water quality was documented as well as the phytoplankton and zooplankton communities. An initial floral survey was made. It is evident now that there are many aspects of these ponds which would make very interesting studies in the future.

Phytoplankton were sampled three times. The two samples taken on August 9 from two separate ponds were very similar in population with nine taxa identified in each and biovolumes of 225,000 and 350,000 ,um3/L. The single sample from September 10 contained only four taxa but had a biovolume of 14,300,00 Jim 3/L. There was a great diversity and biovolume of phytoplankton for such small water bodies. Further study will probable reveal that this study underestimates the true diversity in the phytoplankton community.

Reviewing all the plankton data suggest that the Whitehorse ponds were eutrophic in quality with a high amount of organic material present. The pond color supports this as well as the presence of the euglenoids that require certain organic materials to live. Phytoplankton cell densities increased 30 times in September due to a reduction in nutrients, higher temperatures, and greater light intensities as Bob Truitt has suggested. However chemical analyses do not support the nutrient suggestion. However, it has been documented that later in the summer the number of phytoplankton specie decrease and the cell densities increase. More study into this trend would reveal interesting relationships.

Zooplankton were more diverse than the phytoplankton. Similarity indices indicated that different ponds also had unique zooplankton communities. Zooplankton seem to feed on the smaller phytoplankton. There was a documented difference in the zooplankton assemblages on a pond’s surface and on the pond’s bottom. This was seen to be true even in very shallow ponds about 1 m deep. The large diversity in zooplankton depended little on the date of collection. A greater number of samples through time and for each pond would also document very interesting trends in zooplankton community structure.

The single day’s floral survey documented twenty-nine taxa in and around the ponds. Study of plants in the Whitehorse Bluff area over a summer would surely add to the listing begun by David Hartesvelt. He suggested that the bryophytes alone are deserving of a more complete survey. The bryophytes were observed but not documented here.