Table of Contents

Executive Summary

Acknowledgments

1.0 INTRODUCTION

2.0 METHODS

2.1 Physical Collection Methods

2.2 Plankton Methods

2.3 Vascular Plant Survey Methods

3.0 RESULTS

3.1 Physical Characteristics

3.2 Plankton

3.2.1 Phytoplankton

3.2.2 Zooplankton

3.3 Vascular Plant Survey

4.0 DISCUSSION

4.1 Physical Characteristics

4.2 Plankton

4.3 Vascular Plant Survey

5.0 GENERAL CONCLUSIONS

6.0 REFERENCES

7.0 APPENDICES

I. Scope of Work

II. RCC Student Observations

III. Plankton Data

IV. Vascular Plant Listing

Figures

I. A map of the Whitehorse Ponds at Crater Lake National Park

Tables

1. Physical Date From Selected whitehorse Ponds

2. August 9, 1993 observations of Whitehorse Ponds with Rogue Community College Students

3. Chemical Concentrations for Several Whitehorse Ponds

4. Ponds sampled for phytoplankton, date sampled, species codes, cell density and biovolumes, and their proportional abundances.

5. Phytoplankton species identified and their corresponding codes, divisions, and individual cell biovolumes.

6. Phytoplankton samples compiled into taxonomic divisions, number of taxa present, and their proportional abundances

7. Zooplankton species list with their corresponding codes and taxonomic division.

8. Zooplankton sample ponds, dates sampled, species identified and cell densities (organisms/m3).

9. Zooplankton species, number of ponds where identified and proportional abundance, total ponds sampled and corresponding proportional abundance based on if species was found in all ponds.

10. Percent similarity between ponds using zooplankton species comparisons.

11. Zooplankton ponds sampled, date sampled, compilation of taxonomic divisions represented and number ot taxa identified in sample.

EXECUTIVE SUMMARY

Crater Lake National Park contains many unique environs. The collection of ponds on the top of Whitehorse Bluff is one such special area. In 1993 the Crater Lake Natural History Association sponsored this environmental research project designed to continue work begun by Roger Brandt in 1992. This study focused on the physical, chemical, and biological characteristics of the ponds themselves and includes a survey of the flora found on the Bluff.

The ponds were visited between July 14 and September 10, 1993. In the first of several field trips the ponds were found to be close to full of water and teeming with life. The ponds were found to support healthy populations of dragon flies, water striders, invertebrates, many types of aquatic insects, frogs, toads, salamander and their tadpoles, moss and other aquatic plants, and many types of plankton. Later in the summer all but two ponds were completely dry. One challenge in surveying the ponds was simply to identify the individual ponds.

The Whitehorse Ponds are located within a mosaic of forest communities of which red fir and lodgepole pine forest were the most important. The dominant overstory tree was Shasta red fir (Abies magnifica var. shastensis) which, in combination with mountain hemlock (Tsuga mertensiana), provided a nearly closed canopy over large areas of the bluff top. 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.

In this brief period the water temperatures varied from 13 to 240 C, the acid concentration or pH varied from 5.55 to 6.20, dissolved oxygen levels were low and varied from 4.5 to 6.7 mg/L and the conductivity of the pond water varied from 7.6 to 16.6 puMHO/cm.

Chemical concentrations paralleled the concentrations of a bulk deposition (precipitation) study completed in September 1988 (Larson, 1993). All chemical species determined were of similar concentration except nitrate and sulfate ions. Nitrate ion was found to be 18 times less concentrated in the ponds than in precipitation. Nitrate ion, an important nutrient, was probably being taken up by plants in and around the ponds. Sulfate ion was also found in very small concentrations in the ponds about 100 times less than in Park precipitation. Total phosphate, sodium, potassium, calcium, magnesium, and chloride were all similar in concentration when compared to precipitation.

When Crater Lake water chemical specie concentrations were compared to pond water concentrations, they ranged from similar, as in total phosphate, to 50 times greater for alkalinity. All the other chemical species were in the 8 to 20 times range greater in the Lake. The ponds are probably fed by precipitation alone. Changes in the quality of the precipitation would certainly affect the ponds.

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 Rm3/L. The single sample from September 10 contained only four taxa but had a biovolume of 14,300,00 Rm3/L. There was a great diversity and biovolume of phytoplankton for such small water bodies. Further study will probably reveal that this study underestimates the true diversity in the phytoplankton community.

A review of all the plankton data suggests 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. Chemical analyses do not support the nutrient suggestion. However, it has been documented that later in the summer the number of phytoplankton species 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 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.

Future study of the Whitehorse Ponds would document changes in the ponds due to changes in this small watershed.

ACKNOWLEDGMENTS

This study was supported by the Crater Lake Natural History Association. Observing and trying to understand the special features of the Whitehorse ponds can be an exciting challenge. The CRNHA helped continue a study begun by Roger Brandt in 1992. His work on many ponds in the Park initiated many park researchers to look into the intricate systems present in these delicate environs.

The authors of this report enjoyed their small part in putting this study together. The principle investigator, John Salinas, would like to thank Bob Truitt for his painstaking work with the phytoplankton and zooplankton. Bob did not have many samples to work with, however he did observe some very interesting trends and has asked for more samples from more ponds at more frequent intervals. The seeds for another very interesting study have been planted. Bob Truitt would like to thank the major investigator, John Salinas, for his interest, financial help, and his patience.

Thanks also to David Hartesveldt who walked the bluff as if he lived there. He inventoried the many plants and suggested that the flora should be more completely studied in the near future. A single day on the bluff in August began a study which should continue through spring, summer, and autumn.

The physical characteristics of the ponds themselves were also very interesting. Further in situ measurements along with grab samples would surely clarify some of the trends identified in this study. This study will continue in one of many forms. Hopefully these authors will be involved in these future studies.

Finally, thank you to the CLNHA for their support and encouragement. Also thanks to Cam Jones of the Cooperative Chemical Analytical Laboratory who completed the chemical determinations. Cam has supported many of us with his fine laboratory work. This report would have been years in the writing without this great support.

1.0 INTRODUCTION

The study of the Whitehorse Pond Complex began in 1992 with the work of Roger Brandt (Brandt, 1992). Whitehorse ponds are located in Crater Lake National Park on Whitehorse Bluff just south of Highway 62 and west of the Pacific Crest Trail. From the top of the bluff one can see the highway. From the highway the bluff is seen above a one-hundred foot gray wall of rock to the south. The current study was initiated because of the author's keen interest in both the Crater Lake environs as well as the quality of water in the High Cascades. His research proposal is included in Appendix I.

The White Horse Ponds are located on White Horse Bluff in Crater Lake National Park approximately 0.25 to 0.5 miles south and west of Highway 62. White Horse Bluff is a conspicuous outcrop of what appears to be andesitic lava achieving elevations of 6,300 to 6,350 feet national geodetic vertical datum (NGVD). Previous studies have identified 12 ponds (Brandt 1992). Some of the numbered ponds should be referred to as pond complexes, because more than one pond are associated with them. For example, Pond 7 includes four interconnected ponds. These ponds occupy topographic depressions in the lava with spill elevations two to four feet above the invert elevations of the pond bottoms. Ponds of only one to two feet of depth often become dry late in the summer, although the deepest ponds (e.g. Pond 3) remain inundated through most summers.

The Whitehorse pond area was visited five times during the summer of 1993. The author was accompanied on most trips by field researchers working in or around the Park on similar research. Studies included field and taxonomic observations of the flora surrounding the pond area, in situ aquatic monitoring of temperature, and pH. Grab samples included the collection water for the determination of dissolved oxygen, nutrient chemical concentrations, phytoplankton, and zooplankton. The chemical analyses were completed by the Cooperative Chemical Analytical Laboratory (CCAL) in Corvallis headed by Mr. Cameron Jones. This lab was established by memorandum of understanding no. PNW-82-187 between the USDA Forest Service and the Department of Forest Science, Oregon State University.

A survey of the flora in the Whitehorse ponds area was completed by Mr. David Hartesveldt. The observations documented in this report were limited by the single survey undertaken in August of 1993. The flora of Whitehorse Bluffs and, possibly, the ponds themselves, is almost certainly more diverse than is indicated in this report. Due to the varied phenology of the montane flora of Crater Lake, one field survey conducted late in the summer necessarily misses plants blooming earlier or later in the summer. No effort was made to collect or identify any of the various bryophytes (e.g. mosses and liverworts) associated with the White Horse Ponds. Yet, mosses were an important component of several ponds, particularly those which were dry at the time of the field survey. For a more complete understanding of the floristic relationships and successional processes of the White Horse Ponds, a more comprehensive floristic study of the ponds that includes the bryophytes would be warranted.

Eight ponds on White Horse Bluff, were sampled for zooplankton and phytoplankton. John Salinas collected 14 total samples, 11 zooplankton and 3 phytoplankton, during a period from July 14 through September 10, 1993. Mr. Robert Truitt analyzed pond water samples for phytoplankton and zooplankton.

This project also exposed students of Rogue Community College to field research. This was accomplished on the August 9th field day. About a dozen students recorded observations and collected pond samples for later analyses. Several of their reports are included in Appendix II.

Roger Brandt's pond numbering system was used to identify individual ponds (Figure 1). A shallow pond far to the east on the plateau was unnamed in Roger's work and has been numbered Pond #0 in this report. A pond to the east of the Pond #9 complex has been called Pond #9 east or Pond #13. There also seem to be two ponds to the extreme southwest of the main pond group, these were called Ponds #14 and #15 and were not visited in this study. East of Ponds 10, 11, and 12 was another unnamed pond which was called Bear Tree pond because a bear had stripped a tree of its bark to about ten feet high.

Ground truthing of Roger's map began as soon as this pond study began. Every effort was made to accurately document each sample with respect to pond location and name. However Roger's map needs to be updated and each pond identified with a simple marker.

A Hach One pH meter probe was used to quantify in situ temperature and acid concentration, pH. This probe is used to measure pH in low conductivity waters. It was calibrated with low ionic strength pH buffers following a similar protocol used in the Crater Lake field lab (Salinas, 1992). An Perstorp in situ multiparameter probe was used to measure temperature, pH, and conductivity in addition to the Hach meter.

Pond water samples were collected in a Scott-modified Van Dorn collecting bottle for nutrient chemical concentrations, dissolved oxygen concentration, and phytoplankton. Water was collected in acid rinsed plastic bottles for analyses in the Cooperative Chemical Analytical Laboratory in Corvallis (Jones, 1992). This is the same laboratory used by the Crater Lake monitoring team. Analyses included pH, alkalinity, conductivity, total phosphorus, nitrate/nitrite, sodium, potassium, calcium, magnesium, chloride, and sulfate ions. These ions were only those dissolved in the water since the water was passed through a pre-rinsed glass fiber filter before it was cooled and shipped to Corvallis.

Water samples were preserved in dark plastic bottles for phytoplankton speciation and enumeration. Lugol's iodine solutions was used for this purpose making the sample one percent iodine before storage.

2.2 Plankton Methods

Each phytoplankton sample was preserved with 1% Lugol's solution in the field. In the laboratory, each phytoplankton sample was homogenized by shaking and poured into a 1 L graduated cylinder and settled for 72 hours. The sample was concentrated to 100 ml by aspirating off the top and split into 2-50 ml aliquots. One aliquot was put aside for archiving and the other was rinsed into a Hydro-bios Kiel 50 mL settling chamber and allowed to settle for 24 hours. The settled sample was then placed on a Nikon DIAPHOTTMD inverted microscope fitted with a Javelin color camera and Sony color printer and monitor. The first 200 cells encountered were counted and identified at 1500 X oil on phase contrast. A digital photomicrograph was taken of the major algal taxa encountered and are included with this report. The cell density was calculated in cells per liter (cells/L) using the following:

N = [n(A/WL)] / [V/1000] cf,

where      N = the number of cells per liter;

n = the number of cells counted;

A = the area of the chamber (cm2);

W = the field width (cm);

L = the total length of the transect counted (cm);

V = the volume of the chamber (mL);

cf= the volume of the concentrated sample divided by the volume of the original field sample.

Zooplankton were collected with al2-centimeter diameter 64 uM mesh sized zooplankton net. It was towed 9.5 meters through the water for each sample. It was kept between the surface and the pond's bottom for each tow. No attempt was made to keep the net at the pond's surface or bottom. All ponds sampled for zooplankton were wide enough and deep enough to accomplish this type of tow. Samples rinsed from the net were preserved with formalin and placed in plastic sample bottles.

Zooplankton samples (ca. 50 mL) were preserved in the field with a 10%/vol. formalin solution to a 4% final concentration in the sample. In the laboratory, all samples were stained with Eosin Y prior to processing to facilitate counting. The samples were diluted to acceptable concentrations using a Folsom Plankton Splitter. One collecting tray, from the splitter, was designated as the counting (C) tray, the other as the picked (P) tray. The sample was placed in the splitter and rocked 5x to randomize sample, then poured into the trays. The splitter was rinsed with 0.22 gm filtered Crater Lake water, rocked 5 more times and poured into the trays. The C tray was poured back into the splitter and the procedure repeated until an approximate density of zooplankton were obtained to facilitate counting (ca. 250-350 organisms/sample), by observing the tray under a stereo microscope. All other remaining organisms were retained in the P tray. Both tray samples were then filtered through 0.10 gum nitex cloth to reduce volume and remove sugar formalin, then rinsed into 25 mL liquid scintillation vials. The P vial was preserved with 1 mL of 10% sugar formalin, used for identification of zooplankton and archived. The C vial was rinsed into a Hydro-bios Kiel 50 mL settling chamber, allowed to settle undisturbed for 24 hours and the sample counted at 4x (for crustacean zooplankton) and 20x (for rotifers) with phase contrast on a Nikon Diaphot-TMD inverted microscope fitted with a Javelin color camera and Sony color printer and monitor. A digital photomicrograph was also taken of the major zooplankton taxon encountered and are included with this report. The counts were used to estimate the number of organisms per cubic meter (organisms/m 3) of lake water filtered:

N = (ndf) / VL,

where      N = number of organisms per cubic meter;

n = number of organisms counted;

df= dilution factor of sample (splits);

VL= volume of (m 3 ) of lake water filtered.

Here, VL= net opening area (m 2 ) X length of tow (m) X filter factor (a 100% factor was used).

Sample Analysis

The data were recorded on computer coding sheets according to a standard format required by the programs selected for data analysis (AID 1 and AIDN). Each data file was organized into a series of blocks, each of which represented the counts of species occurring in a particular sample (i.e. ponds), the phytoplankton were not analyzed because there were only 3 samples taken. The general approach to the quantitative analysis of distributional patterns in the zooplankton involved: 1) estimation of community composition parameters (AID 1 program); 2) calculations of similarity measure for comparing the species compositions of sample pairs (AIDN program); and 3) calculations of a similarity measure for comparing the species compositions of pooled sample pairs (AIDN program).

Two indices of species diversity, the information measure and Simpson's index were used to express community structure, H" and SDI respectively. A measure of dominance (R) for selected taxa was included. A similarity measure (SIMI [a,b]) was used to compare taxonomic similarity between samples a and b. For completeness all statistical outputs are contained in this report (Appendix 3-8).

2.3 Floral Survey

A single survey of the White Horse Bluffs and associated ponds was conducted by David J. Hartesveldt on August 21, 1993. The focus of the survey was the ponds themselves. Most of the twelve ponds were visited and all vascular plants observed in them were noted to species or were collected for later identification. A meander survey was conducted throughout the area of White Horse Bluffs and all vascular plants observed were noted to species. Unknown taxa were keyed to species within two weeks of collection.

3.0 RESULTS

3.1 Physical Characteristics

The ponds were found to be full of water and teeming with life early in the summer season. However, later in this wet year all except two ponds were dry. The following describes the several field days

The first attempt to visit the ponds was not successful. Beginning on the Pacific Crest Trail, the author and his son, Garrett, walked west and were lead over a series of hilltops and valleys. The ponds were actually farther south and west than the map suggested. This first trip on July 5th did not produce any samples or observations of the ponds directly.

The second trip to the ponds was on July 14. Scott Swarts of the Crater Lake stream survey team accompanied the author to Whitehorse Bluff. On this field trip we climbed the bluff on the north side and arrived at Pond #7 first. Few observations were taken there in hopes of finding larger ponds. Pond #6 was encountered next and its temperature at 1700 hours was 130 C (Table 1). Pond #8 was encountered next and was determined to be about 7 meters in diameter, grass covered the bottom, and it was 140 C. In addition there were mosquito larvae and water bugs in the water. It was a foot lower than full on this date.

Walking west we arrived at one of the largest ponds on this date, Pond #9. We called it Frog Pond as it is referred to in Bob Truitt's report. We collected two zooplankton samples. The first at 1800 hours on the north side of Pond 9A and the second tow at 1825 hours was collected on the south side of Pond 9A. The tows were made by holding the 12 cm diameter net at surface level as the other walked a semicircle with the cord to a spot on the other side of the pond. The net was pulled through undisturbed water about 50 cm deep and 10 cm off the bottom. Any shrimp collected were trapped in the vertical portion of the tow which occurred at the end of the horizontal tow.

Frog tadpoles were noticed and were about one inch in length. Also noticed was a campfire ring on the southeast side of Pond #9A.

Turning south we encountered Ponds #10 and #11. Pond #11 was 160 C and was down from full by about 30 cm. Pond #12 was found by walking further south and was covered with a grass bottom.

The final pond group observed on July 14th was east of Ponds #10, 11, and 12. There is no number for this group but we identified it by a tree striped of its bark by a bear. We called it Bear Tree Pond. A single small pond was found north of a larger pond complex. Moss covered the southern side of the smaller pond. Salamander egg masses covered the north side of the larger pond. An adult frog was photographed in the larger pond. Two zooplankton tows were made at 1900 and 1920 hours in the larger pond.

This was a very special research trip. Several students from Rogue Community College accompanied the author. The day was spent observing the ponds and collecting samples for later study. Some of these student reports are included in Appendix II.

The plan was to allow a student to study a single pond. In this way several ponds would be studied in detail. An in situ probe was used to measure pH, temperature, and conductivity. Water samples were taken and analyzed for dissolved oxygen and phytoplankton (Table 1). The temperatures of the ponds ranged from 23.7 to 16.60 C, the conductivity from 7.6 to 16.6 uMho/cm, the pH from 5.23 to 5.69 units, and the dissolved oxygen concentrations from 4.50 to 6.69 mg/L (Table 2). Ponds observed on this field day included #0, 3, 4, 6, 9, 10, and 11. Notes on special conditions follow.

Pond #0 SE is not shown on any map. However two students selected it for study. Surrounded by tall trees, it was well shaded. The bottom was covered with grass and had only about an inch of water in it. Several zooplankton were collected and drawn in the lab at Rogue Community College (RCC). No chemical sampling was completed here since it was so far away from the main group of ponds. It lies far to the south east on the bluff.

Ponds #1 and 2 were not observed. Pond #3 was a tea brown color. This pond had the coolest water and the temperature changed little in the sun or in the shade. The conductivity of this water was less than 10 uMho/cm.

Pond #4 was observed and had several parameters recorded for it (Table 1). Pond #5 was not observed. Pond #6 had dried into two basins by this date. The north and south basin were not similar in many respects. Pond #6 north was a reddish color and had many pollywogs with shrimp and animal tracks around it. Pond #6 south was clear and had numerous elk and deer tracks along the shore as well as the tracks of grouse and quail. There were shrimp in this south pond but no pollywogs. These two basins were very different from each other on this date.

Ponds #7 and 8 were not observed on this date. Pond #9 was sampled and another pond to the east of the main pond was discovered. We called the unmapped pond, #13 or Pond #9 east. Pond #9 was a root beer color. It had elk tracks as well as pollywogs and frogs in evidence. There were logs in the pond and it was half shaded by 50 foot tall hemlock trees.

Pond #10 was the warmest pond observed and had a temperature of 23.70 C. It also had the highest conductivity of 16.6 uMho/cm. This pond was clearer than most ponds and was observed to contain shrimp. It was about one third of its filled size.

Pond #11a also had shrimp. It was quite warm with a temperature of 22.80 C. Pond #12 was not observed on this date.

The author was accompanied by Mr. David Hartesveldt and Mr. Larry Beard and family on this field trip. The Beards and the author worked together to sample the ponds for chemical and biological specimen as well as physical and chemical parameters. Mr. Hartesveldt crisscrossed the Bluff several times observing the flora in and around the ponds.

The tour began at Pond #7C. Pollywogs were noted in great numbers. They had bodies about one centimeter in diameter and tails of about 2.5 cm. They also had external gills. A zooplankton tow was completed on the pond's surface. The pH was measured at 5.98 at 15.10 C at 1150 hours. The depth of the pond was 35 cm. Several egg clusters were seen on the shore with 50 or more 0.5 mm eggs per cluster.

Pond #7A had about 80 cm of water in it with a pH of 6.20 at a temperature of 13.20 C. There were two types of pollywogs in this pond, the first type had external gills and the other had no external gills. This second pollywog was round with a white belly and iridescent. A pond sample was taken from this pond for chemical nutrient analyses at CCAL (Table 3).

Pond #6 was observed. It was turbid and about 12 cm deep. There were few pollywogs in this pond. It appeared to be drying fast.

Pond #4 was grass covered and had one centimeter long dark toads all around it. These toads numbered about 30/m2. What water there was looked turbid. The bank was covered with elk tracks in the wet mud.

Pond #3 was 18.30 C and had a pH of 5.56. There were water striders and dragon flies at this pond. A chemistry nutrient sample was taken for CCAL. The pond was 95% exposed to direct sunlight. Grass was found high out of the water, under the water, and rooted at the bottom of the pond but floating on the surface. There were young salamanders with all four legs and about 8 cm long. An 8 to 10 cm frog was found. It had blue ear areas. This pond measured 60 cm deep and the bottom was covered with rocks and branches.

Pond #2 was 70% shaded and had a temperature of 17.40 C and a pH of 5.55. The pond was tea colored. Salamander pollywogs with external gills were observed.

Ponds #MA and B were discovered to be dry and covered with moss. This made a very soft bed on which to lie.

Pond #9 was sampled for chemistry nutrient analyses for CCAL. It had salamander pollywogs which were 5 cm long. There were other salamander pollywogs evident with external gills. The temperature was 22.30 C and the pH was 5.59.

Pond #9 East or Pond #13 had shrimp and was very dark in color. The temperature was 22.0° C and the pH was 5.55.

September 10, 1993, Fifth Trip

We expected that at some time the ponds would be dry. On this field day all ponds were quickly visited and found to be dry except Pond #7A and D, and Pond #1. The ponds were visited between 1540 and 1810 hours. The temperature of Pond #7a was 23.50 C, pH was 5.92, and the dissolved oxygen concentration was 7.29 mg/L. A chemistry nutrient sample was taken for CCAL. A zooplankton tow was completed at Pond #7D. Although there was no water, there was an elk wallo in Pond #12.

3.2 Plankton

3.2.1 Phytoplankton

Three phytoplankton samples were obtained from three different ponds (Table 4). Pond WH9 was sampled on August 9, 1993, as was pond WH11A. Nine alga taxa were identified in both ponds. Pond WH7A was sampled on September 10, 1993, and only 4 taxa were identified. The species number and their corresponding division, individual species biovolume and species name are arranged in Table 5.

Ponds WH9 and WH11A, both collected on the same date, show many similarities quite different from pond WH7A (Table 4). Nine taxa were identified in WH9 and WHl lA, both had similar total cell densities (5289.54 and 4768.45 cells/L, respectively) and biovolumes (224928.79 and 348983.87 gm3/L). Pond WH7A, with 4 taxa, had a total cell density of 155900.31 cells/L and total biovolume of 14288870.0 [tm 3/L.

The dominant taxa varied for each pond (Table 4). Pond WH9 was dominated by Diogenes sp. and Synechocystis sp., both cyanobacteria with combined cell density of 79.1% and the cryptophyta were 10.9%. In cell biovolume the cryptophta were dominate (65.4%) and the cyanobacteria were greatly reduced (15.4%). Pond WH1 lA was dominated by a statospore (or cysts) and Chromulina sp., both chrysophytes and had a combined cell density of 82.0% and euglenaophyta had 0.5%. The cell biovolume was 12.7% and 56.0% for chrysophta and euglenaphyta, respectively. Pond WH7A had only one taxa dominate (both in cell density and biovolume), Chlorella sp., in the division chlorophyta (Table 4).

On a divisional level, all ponds had a fairly even distribution (Table 6). Pond WHi 1A had two taxa each of Chlorophyta, Chrysophyta, Cryptophyta, and Cyanobacteria; and one taxon of Euglenophyta. Pond WH7A had one taxon in Chlorophyta, Chrysophyta, Cryptophyta, and Cyanobacteria. Pond WH9 was slightly different with three Chrysophyta, two Chlorophyta and cyanobacteria, one Bacillariophyta and one Cryptophyta.

3.2.2 Zooplankton

The zooplankton exhibited more diversity than did the phytoplankton, probably as a result of the greater number of samples and the larger period of time over which the zooplankton samples were obtained.

There were eleven zooplankton samples taken over a period from July 14 - Sept. 10, 1993 (Table 8). From those samples, 18 different organisms were identified; 8 rotifers, 3 cladorcerans, 2 calanoid copepods, 2 cyclopoid copepods, 1 nauplii (combined both calanoid and cyclopoid), 1 fairy shrimp, and 1 seed shrimp (Table 7). The number of species identified within each sample, ranged from a low of two in FROG 1 (7/14/93) to a high of 8 species in 4 ponds; BEARI (7/14/93, a surface tow), WH3 (8/21/93), WH7C (8/21/93), and WH7D (9/10/93) (Table 8). In comparing the proportional abundance, the dominate species was Diaphanosoma brachyurum Lieven (25.6%), a cladoceran, and the lowest was the seed shrimp and Hexarthra mira at 0.3% (Table 9). On a divisional basis, the cladocerans had the highest proportional abundance (39.8%) and the seed shrimp the lowest (0.3%).

The percent similarity, in which all species identified within a sample are used in comparing between all samples, showed that ponds FROG1 and WH11A had the greatest similarity at 92.4%, and the two BEAR samples at 80.2% (Table 10). Sample BEAR2 had no percent similarity (0.0%) with three other samples , FROG 1, WH11 A, and WH13. Nine other sample combinations had similarities over 50%. Of the total different possible similarity combinations (55), 31 were less than 25% similar.

Table 11 shows the compilation of zooplankton taxa into divisions. The sample BEARI, with eight taxa, had the greatest number of divisions, six. Two samples, FROG 1 and WH1 1A had only 2 divisions and 2 and 3 taxa, respectively.

3.3 Flora Survey Results

Other trees observed included lodgepole pine (Pinus contorta ssp. murrayana), western white pine (Pinus monticola) and subalpine fir (Abies lasiocarpa).

Transitional between the aquatic habitat of some ponds (e.g. Ponds Four and Seven) and the more xeric upland habitat of the greater portion of the bluff top were the mesic embankments. These embankments supported dense stands of grouse whortleberry (Vaccinium scoparium) and sparse stands of big whortleberry (Vaccinium membranaceum). Other species occasionally observed included western wintergreen (Gaultheria humifusa) and dwarf bramble (Rubus lasiococcus). Much of Pond Four has been filled from sedimentation such that little aquatic habitat remains. Narrow-spiked reedgrass, western wintergreen, alpine everlasting (Antennaria media) and mountain spiraea (Spiraea densiflora) all contributed to the turf of the developing meadow.

4.0 DISCUSSION

4.1 Physical Characteristics

The Whitehorse Ponds were visited several times in 1993. Compared to Crater Lake itself, these ponds experience great physical extremes. In winter they are covered with several feet of snow and in spring the fast melting snow flushes each pond and fills it with seasonal water. The quality of the ponds depends completely on the quality of the precipitation.

This study included physical, chemical, phytoplankton, zooplankton, and floral studies. Observations were included on each pond visited. The ponds were visited between July 14 and September 10, 1993. In this brief period the water temperatures varied from 13 to 240 C, the acid concentration or pH varied from 5.55 to 6.20, dissolved oxygen levels were low and varied from 4.5 to 6.7 mg/L and the conductivity of the pond water varied from 7.6 to 16.6 ,MHO/L.

Comparing pond chemical concentrations with a bulk deposition study (precipitation and dryfall) completed in 1988, a caldera spring study 1984/89 and chemical species in the Lake itself 1982/90, interesting relationships are revealed (Table 3). Chemical concentrations paralleled the concentrations of a bulk deposition study completed in September 1988 (Larson, 1993). All chemical species determined were of similar concentration except nitrate and sulfate ions. Nitrate ion was found to be 18 times less concentrated in the ponds than in Crater Lake precipitation. Nitrate ion, an important nutrient, was probably being taken up by plants in and around the ponds. Sulfate ion was also found in very small concentrations in the ponds about 100 times less than in Park precipitation. Total phosphate, sodium, potassium, calcium, magnesium, and chloride were all similar in concentration when compared to precipitation.

When Crater Lake water chemical specie concentrations were compared to pond water concentrations, they ranged from similar, as in total phosphate, to 50 times greater for alkalinity. All the other chemical species were in the 8 to 20 times range greater in the Lake. The ponds are probably fed by precipitation alone. Changes in the quality of the precipitation would certainly affect the ponds.

4.2 Plankton Discussion

With only three phytoplankton samples, it is difficult to interpret much. However, with six of the eight freshwater algal divisions represented, the population data suggest the possibility of more eutrophic, than oligotrophic, systems. It is also known that euglenoids require particular organic inputs (i.e. B-12) and therefore, further leads towards more organically rich systems. The greater diversity of taxa, during the August samples, as opposed to the much reduced taxonomic number, but thirty fold increase in cell densities of the September sample, suggests a reduction in nutrients (i.e. available nutrients bound up), higher water temperatures (the dominance of cyanobacteria and the Cholorella sp.), and light intensity. The herbivory by the zooplankton is surely of some effect upon the phytoplankton also.

The two Frog Pond (Pond #9) samples are both "surface tows", with FROG 1 from the shore and FROG2 from the central part of the pond. Both FROG samples are dominated by a large filter feeding cladoceran, Diaphanosoma brachyurum Lieven and a selective feeding copepodid, both herbivores. FROG2 sample contained Scapholeberis kingi Sars, a small cladoceran filter feeder and nauplii, also a small filter feeder. All these taxa represent a propensity toward feeding on small phytoplankton, as represented by the majority of phytoplankton identified. The D. brachyurum can also select larger and more motile phytoplankton (as the smaller Rhodomonas and the Chromonas sps. identified). The copepodid, an intermediate stage between nauplii and adult calanoid or cyclopoid copepoda, have the ability to individually select and manipulate food and as more active swimmers are adapted to exploiting the niche held by those areas of higher phytoplankton concentrations and largest of the species (the larger Rhodomonas sp. and Synedra sp.).

The BEAR samples (BEARI and BEAR2) are shown to be >80% similar, even though BEAR1 is a surface tow, and BEAR2 is a bottom tow. The most unique difference in zooplankton between them is the presence of the fairy and seed shrimp, identified from BEARI, the surface tow. Both of the shrimp species typically swim upside-down and filter feed just below the surface. The seed shrimp will also feed on the periphyton of submerged aquatic macrophytes.

There are three pond comparisons, based on the zooplankton identified, in which there was no similarity. All three comparisons involved BEAR2 sample. The first, is between BEAR2, a bottom sample, with FROG1, a surface sample. Suggesting a strong difference between zooplankton assemblages throughout the water column, even in depths as shallow as 1.5-2 meters. This was further suggested by pond sample WH13, in which the fairy shrimp was again identified, an indication that WH13 is also a surface sample. Pond sample WH11A was the third comparison with no similarity and again, with BEAR2. Indicating that WH11A was either a surface tow or a similar, but more shallow pond.

This short study, even with a scarce number of samples, does suggest possible trends within the water column and seasonally, over time. Greater sampling within several ponds over time would be more helpful and highly suggested.

4.3 Flora Discussion

Twenty-nine taxa of vascular plants were identified during the floristic survey of the White Horse Ponds conducted on August 21, 1993. This survey effort was sufficient to generally characterize the flora of the ponds and their immediate vicinity. It is likely, however, that the vascular flora of this region is considerably more diverse than these survey results indicate. Additional surveys in July, September, and, even, October would be useful in fully assessing the diversity of vascular plants of the White Horse Bluffs.

5.0 GENERAL CONCLUSIONS

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.

The Bluff contained several environments including ponds, wet shores, moist forest, and xeric or dry forest floor. The plants observed were as varied as these environments. The forest contained the Shasta red fir, mountain hemlock, and lodgepole pine, western white pine, and subalpine fir. In the pond area aquatic plants included western quillwort, small burweed, water sedge, and narrow-spiked reedgrass. Further from the ponds the more xeric plants were documented and included whortleberry, pinemat manzainta, and sulfur flower.

Finally, the authors of this report have each suggested that these ponds are each very unique and exhibit great changes in water quality and plant and animal diversity through the seasons. It would be difficult to establish trends and relationships given this limited data set. However, it would be very interesting to begin a study of the ponds at snow melt and continue through the entire summer season to the snows of winter the following winter in any of these areas. Actually the pond study could continue through winter with sampling continuing using snow boring equipment. The results of this type of study would lead to a wealth of information documenting the health and quality of these shallow water bodies.

The significance of this single study has been to document the chemical, physical, and biological conditions of the Whitehorse Ponds area through a single short summer season. By continuing this study, the National Park Service at Crater Lake can make a significant contribution to our understanding of three major environmental concerns:

1. How is the airshed affecting the water shed on Whitehorse Bluff? Is the Cascades themselves changing in water quality?

2. Before chemical analyses can identify without doubt a change in water quality, the plants and animals living in a around a water body have changed noticeably. By continuing to monitor the biota associated with these ponds the NPS may detect early warnings of a change in Southern Oregon waters.

3. Finally, this initial survey could have been directed in several directions. Here the physical, chemical, and biological areas of study were used to document pond conditions. Future work should include a survey of the bryophytes and the amphibians associated with each pond. It has been suggested an increase in UV radiation may be causing a drastic decrease in amphibians ( , 1994). A herpetological survey in the future would document the present condition of these indicator species.

If the NPS and the CRLA-NHA can continue this and similar water quality studies in and around the Park, there will be a great resource of information documenting water quality, population characteristics of phytoplankton and zooplankton, plants, and animals of wetland and pond areas. Returning to the ponds in the future would further document changes in the ponds due to changes in precipitation and its effect on this small watershed. These studies will eventually become a very significant resource documenting major trends in aquatic ecosystems in the Southern Oregon region.

6.0 REFERENCES

APHA. 1990. Standard Methods for the Examination of Water and Wastewater Brandt, Roger. 1992. Survey of ponds in Crater Lake NP and their response to the lowest record of precipitation in the history of this park. National Park Service, Crater Lake National Park. 16 pp.

Hickman, James C. Ed. 1993. The Jepson manual. University of California Press, Berkeley, CA. 1400 pp.

Hitchcock, C. L., and A. Cronquist. 1973. Flora of the Pacific Northwest. Univ. Washington Press, Seattle. 730pp.

Jones, C. 1993. In Crater Lake Limnological Studies Final Report., Cooperative Park Studies Unit, Technical Report NPS/PNROSU/NRTR-93/03. 722 pp.

Larson, G.L, 1993. Crater Lake Limnological Studies Final Report, Cooperative Park Studies Unit, Technical Report NPS/PNROSU/NRTR-93/03. 722 pp.

Natural History Magazine, Sept 1994, Munz, Philip A. 1968. A California flora with supplement. University of California Press, Berkeley, CA. 1905 pp.

Salinas, J. 1992. Standard operating procedures for the monitoring program at Crater Lake, Oregon. U.S. Department of Interior, crater Lake National Park, Crater Lake, Oregon. 43 pp.

7.0 APPENDICES

Appendix I. Scope of Work

Appendix II. RCC Student Observations

Appendix III. Plankton Data

Appendix IV. Vascular Plant Listing