133 Macrobenthic invertebrate survey of Waneta and Lamoka Lakes, Schuyler County, New York, September, 1996. Matthew Albright Willard N. Harman INTRODUCTION Schuyler County encompasses 331 square miles of the Appalachian Plateau in the Finger Lakes region (Curatolo, 1991). The county's economy is largely tourism-based, relying heavily upon its aquatic natural resources. The eutrophication of some of these water bodies, including Waneta and Lamoka Lakes (Figure 1), has had detrimental impacts on traditional lakes uses. Macrophyte growth and algal blooms have negatively impacted swimming. fishing, boating, and the perceived aesthetic qualities of theses areas. These changes are believed to have lead to a decline in both tourism activities and in lakeside property values. In order to address these concerns, Schuyler County initiated an aquatic vegetation control program in 1986 (Curatolo. 1991). This program was to serve as an integrated approach to manage the county's aquatic resources through monitoring, research, macrophyte harvesting, upland treatment. and public education. In 1990. a comprehensive study was undertaken in order to provide baseline iniormation upon which lake management plans would be based (Curato 10. 1991). This work included a characterization of the physical qualities of local lakes. surveys oftheir macroinvertebrate benthic populations. a description of macrophyte harvesting activities, a determination of the feasibility of conducting dredging operations in selected areas. and addressed means of reducing nutrient inputs to these lakes. This document describes the tirst of a two part benthic survey of Waneta and Lamoka Lakes. conducted 16 September. 1996. A second sampling is planned for May, 1997 in order to ensure that various life stages of organisms are represented. This database. when compared to previous work (i. e. Curatolo. 1991) and future works, will indicate the impacts of macroph}te management on the benthic faunal communities. The background material for this report is derived almost exclusively from Curatolo. 1991. BACKGROUND Waneta Lake (Figure 2) covers 781 acres in surface area. of which over 90% is located in Schuyler County. The lake occupies a volume of approximately 10.860 acre-feet and has about 6.8 miles of shoreline. This eutrophic lake has a maximum depth of <30 feet. Approximately 450 year-round and seasonal dwellings and a Boy Scout camp line the shore. The substrate varies
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133
Macrobenthic invertebrate survey of Waneta and Lamoka Lakes, Schuyler County, New York, September, 1996.
Matthew Albright Willard N. Harman
INTRODUCTION
Schuyler County encompasses 331 square miles of the Appalachian Plateau in the Finger Lakes region (Curatolo, 1991). The county's economy is largely tourism-based, relying heavily upon its aquatic natural resources. The eutrophication of some of these water bodies, including Waneta and Lamoka Lakes (Figure 1), has had detrimental impacts on traditional lakes uses. Macrophyte growth and algal blooms have negatively impacted swimming. fishing, boating, and the perceived aesthetic qualities of theses areas. These changes are believed to have lead to a decline in both tourism activities and in lakeside property values.
In order to address these concerns, Schuyler County initiated an aquatic vegetation control program in 1986 (Curatolo. 1991). This program was to serve as an integrated approach to manage the county's aquatic resources through monitoring, research, macrophyte harvesting, upland treatment. and public education.
In 1990. a comprehensive study was undertaken in order to provide baseline iniormation upon which lake management plans would be based (Curato10. 1991). This work included a characterization of the physical qualities of local lakes. surveys oftheir macro invertebrate benthic populations. a description of macrophyte harvesting activities, a determination of the feasibility of conducting dredging operations in selected areas. and addressed means of reducing nutrient inputs to these lakes.
This document describes the tirst of a two part benthic survey of Waneta and Lamoka Lakes. conducted 16 September. 1996. A second sampling is planned for May, 1997 in order to ensure that various life stages of organisms are represented. This database. when compared to previous work (i. e. Curatolo. 1991) and future works, will indicate the impacts of macroph}te management on the benthic faunal communities. The background material for this report is derived almost exclusively from Curatolo. 1991.
BACKGROUND
Waneta Lake (Figure 2) covers 781 acres in surface area. of which over 90% is located in Schuyler County. The lake occupies a volume of approximately 10.860 acre-feet and has about 6.8 miles of shoreline. This eutrophic lake has a maximum depth of <30 feet. Approximately 450 year-round and seasonal dwellings and a Boy Scout camp line the shore. The substrate varies
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LAMOKA LAKE
Figure I. The location of Waneta, Lamoka, and Seneca Lakes in Schuyler County, New York (modified from Curatolo, 1991).
i , \I .~ I ;I~ !/~ I I~ i ~ i~1 ~ !~, rT\ \c.,) Q.7
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'/
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Figure 2. Waneta Lake, Schuyler County, New York, showing sampling stations (modified from Curatolo, 1991).
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from silty to organic clay. Eurasian milfoil (Myriophyllum <spicatum) dominated most of the shallows, with plant diversity being considerably higher at the southernmost shore. At the time of sampling (16 September), all substrates were oxygenated.
Lamoka Lake (Figure 3) is interconnected with Mill Pond, located in western Schuyler County at 1099 feet in elevation. These shallow «47 ft) eutrophic lakes together occupy 826 acres in surface area, 16.410 acre-feet in volume, and have approximately 11.3 miles of shoreline. In 1990, about 325 seasonal and year-round houses occupied the shoreline. Recreational activities include swimming, fishing, and boating (Curatolo, 1991). Substrates were dominated by anaerobic organic muds; a notable exception was observed at a drop-off at the northeastern shore, where compact sand was encountered. Here, evidence ofUnionid clams (i.e. shells) were seen. The predominating macrophytes ~ncountered were the nonindigenous Eurasian milfoil (Myriophyllum <spicatum) and curly leafed pondweed (Potamoge/on crispus). Toward the southern, shallower end of the lake diversity was considerably higher, with Nuphar. Ceratophyllum demersum, He/eran/hera. and Vallisineria being well represented. Interestingly, at the time of sampling milfoil was absent from the Mill Pond area. Similar flora were encountered along the channel connecting Waneta and Lamoka Lakes.
Access is provided to both lakes by boat launch sites maintained by the New York State Department of Conservation (NYSDEC). Neither lake is used as a potable water supply. Both lakes have been rated as moderately impaired on the NYSDEC 1989 Priority Problem List (NYSDEC, 1989).
Despite inclement weather encountered throughout the day of sampling (45°-50° F, steady rain), bird activity was considerable. Large numbers of tree swallows (lridoprocne hieolor) were active on Waneta Lake, presumably feeding on emerging aquatic insects. Two ospreys (Pandion haliae/us) and parasitic jaeger (S/ercorarius parasi/icllS) were seen over Lamoka Lake; the latter seabird is extremely rare in this region and was likely displaced by recent tropical storms (Butts, 1996).
MONITORING AND WATER QUALITY
Temperature, dissolved oxygen, pH. and conductivity were measured using a Hydrolab Scout II multiparameter water quality monitoring instrument which had been calibrated the day of data collection following manufacturer's operating manual (Hydro lab Corp., 1993). Readings were taken at I meter (m) intervals from the surface to the bottom. The maximum depth encountered at Waneta Lake was 8.1 meters (26.6 feet); that for Lamoka Lake was 12.2 meters (40.0 feet). Waneta was undergoing fall overturn, although slight. presumably temporary stratification was observed below 8 m. Here, temperature was approxin1ately 0.3 ° C less than the rest of the water column and dissolved oxygen was over 2 mg/lless than overlaying waters. Conductivity was between 198-202 mmho/cm throughout. Temperature, dissolved oxygen. and pH profiles are graphically presented in Figure 4a.
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/000 ft t
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CREEK
POND
FLEET
•
o•~ -. _.- EXTENT OF VEGETATION
ffi SAMPLING STATION
N
BOAT LAUNCH SITES
PUBLIC ACCESS
UNLOADING SITES
Figure 3. Lamoka Lake, Schuyler County, New York, showing sampling stations (modified from Curatolo, 1991).
A
1
2
3
4
5 -.,
a '-' 6 oS 0. II)
Cl 7
8
9
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138
B 2 4 6 8 10 12 14 16 18 20 2 4 6 8 10 12 14 16 18 20 l -----1._.J __ L-..--L_J._ I _L~....L_l_..L-l __ .l.----.l.-_.l
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9
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- Temperature -pH
_ Dissolved Oxygen
Figure 4. Profiles of temperature, pH, and dissolved oxygen for Waneta (A) and Lamoka (B) Lakes, 17 September, 1986.
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Lamoka Lake was stratified at the time of sampling, with the thermocline located between 6 and 7 m. Hypolimnetic waters were essentially anoxic «0.3 mg/l), a situation similar to that reported by Curatolo (1991) for corresponding dates in 1988, 1989 and 1990. Conductivity was approximately 190 mmho/cm through the epi1imnion and increased below the thermocline to 213 mmho/cm at the bottom. Temperature, dissolved oxygen, and pH profiles are graphically presented in Figure 4b.
Water transparency was measured using a standard 20 cm Secchi disk. Transparency was 1.9 m (6.2 ft) in Lamoka and 2.0 m (6.6 ft) in Waneta. Values reported by Curatolo (1991) indicate that Lamoka was somewhat more transparent and Waneta twice as transparent in 1996 compared to similar dates in recent years.
BENTHIC INVERTEBRATE ANALYSIS METHODS
Macroinvertebrates were collected from nine sites on Waneta Lake and nine sites on Lamoka Lake. These sites included eulittoral, littoral benthic, littoral vegetative, and profundal areas. The objective was to obtain taxa diversity and density data for comparison with previous (e.g. Curatolo, 1991) and future surveys in order to ascertain any effects of macrophyte and algae control programs, as well as other changes in water quality, on these organisms.
Benthic samples were collected in triplicate using either a 23X23 cm2 or a 15X15 cm2
Ekman dredge. Larger dredges, using a conventional cable and messenger, were used in deeper locations; in shallower areas, smaller dredges were employed using extension handles. Eulittoral samples, where the substrate tended to be stony, were acquired by manually gathering all material within a 23X23 cm2 quadrangle. Vegetative samples were collected by sweeping the macrophytes with a triangle net five times and rinsing the contents from the net. Effort was made to include the entire depth distribution of the macrophyte bed. Each sample was collected in quadruplicate. While it is recognized that these vegetative samples cannot be interpreted as truly quantitative. the attempt was made to standardize the method as much as possible so that future comparisons may be made.
Upon retrieval, multiple samples were composited and passed through a #30 mesh brass screen. thus retaining all particles over 583 microns. This material was transferred to one-gallon plastic jars, to which 95% ethanol was added until a final concentration of approximately 70% ethanol was reached. Several milliliters of rose bengal were added to each sample to later aid in the recognition of benthic organisms.
Upon return to the laboratory. organisms were separated from the substrate by transferring each sample. spoonful at a time, into a white enamel pan and rinsing with adequate water to distribute the material. All benthic organisms were plucked and transferred to 6 dram vials containing 70% ethanol. Taxonomic identifications were made according to Pennak (1989), Peckarsky et al. (1990), and Merritt and Cummins (1996).
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Organisms were enumerated and weighed by taxa. Wet weight was taken by removing the organisms from their vials and setting on blotting paper for 15 minutes prior to weighing to the nearest 0.1 mg on an electronic balance (Wheat, 1993). No attempt was made to count Oligochaetes, as they tended to fragment during processing. For benthic sites, where sample size was more standardized, data were converted to units per mete~
RESULTS AND DISCUSSION
A description of each sample site, including sample type, sampling method, substrate characterization, and dominant macrophytes, is summarized in Table 1 (refer to Figure 1 for site locations). This survey revealed a total of 58 taxa; 44 and 45 taxa were encountered in Waneta Lake and Lamoka Lakes, respectively (Table 2). Generally, diversity was greater in Lamoka, where the number of taxa per site averaged 15.0, compared to 12.2 taxa per site found in Waneta. The southernmost reaches of Lamoka Lake (sites L6-L9) exhibited the greatest diversity. Here, 32 taxa were discovered, with each site averaging 22.0. This area is relatively shallow and macrophytes were likewise diverse. OveralL the Order Trichoptera (caddis flies) showed the greatest diversity, with 7 genera representing 3 families being encountered.
Tables 3-20 describe the macrobenthic invertebrates for each site visited, including numbers and wet weights of each taxa found in Waneta and Lamoka Lakes. For benthic sites, abundance and biomass have been projected to units/mete~. A more intensive interpretation of these data will follow a second sampling to occur in May, 1997. This later survey will complement the present data in that larval aquatic stages not present in the fall will be included.
REFERENCES
Butts, W.L. 1996. Personal communication. Biological Field Station, Cooperstown, NY.
Curatolo, J. 1991. Final Report. The aquatic vegetation control program in Schuyler County, 1990. 66 p. Schuller County Soil and Water Conservation District, Montour Falls, NY.
Merritt, R.W., and K.W Cummins (eds.). 1996. Aquatic insects of North America. Kendall/Hunt Publishing Company. Dubuque, IA.
New York State Dept. Of Envir. Cons., 1989. New York State water quality, 1989. Bureau of Monitoring and Assessment. Division of Water. NYSDEC. Albany, NY.
Peckarsky, B.L., P.R. Fraissinet, M.A. Penton, and OJ. Conklin, Jr. 1990. Freshwater macroinvertebrates of Northeastern North America. Cornell University Press. Ithaca, NY.
Pennak, R.W. 1989. Freshwater invertebrates of the United States, 3rd Ed. John Wiley and Sons, Inc. New York.
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Site Sample Type Dominant Vegetation Substrate Characterization Waneta WI Sub., 3 small dredges W2 Sub., 3 small dredges W3 Veg. 4X5 sweeps W4 Sub., 3 large dredges W5 Veg. 4X5 sweeps W6 Sub., 3 small dredges W7 Sub., 1 quadrangle W8 Veg. 4X5 sweeps W9 Veg. 4X5 sweeps