Aquatic macrophyte management plan facilitation, Lake Moraine, Madison County, NY 2016

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1 Aquatic macrophyte management plan facilitation, Lake Moraine, Madison County, NY 2016 W.N. Harman 1 and M.F. Albright 1 BACKGROUND (From Harman et al. 2010) Located in Madison County NY, Moraine Lake (42 o N, 75 o W) was formed by a deposited glacial moraine damming a valley. The lake, which has been artificially raised, is divided into two basins separated by a causeway and interconnected by a submerged culvert. The north basin is approximately 79 acres, has a mean depth of 1.1m, and a maximum depth 3.7m. The south basin occupies 182 acres, has a mean depth of 5.4m, and a maximum depth of 13.7m. Most of the recreational activities such as fishing, boating and swimming take place in the south basin (Harman et al. 1997). Moraine Lake has been regarded as meso-eutrophic due to the high productivity of algae and macrophytic plants, low transparency, and depleting levels of dissolved oxygen in the hypolimnion during summer stratification. Development of lakeside residences and nearby agricultural activities are believed to have contributed to the current productivity status of the upper and lower basins (Anon. 1991). Nutrient loading as a result of faulty septic systems from the residences are believed to be a significant source of the problem in nutrient introduction (Harman et al. 1998). Many of the systems are out of date, undersized, and extremely close to the lake (Brown et al. 1983). Furthermore, soils surrounding the lake have poor percolation rates, steep slopes, shallow depths to bedrock, and fractured bedrock make the lake vulnerable to nutrient loading (Harman et al. 2008). INTRODUCTION The aquatic macrophyte communities of Moraine Lake have been monitored by the SUNY Oneonta Biological Field Station (BFS) since The purpose of monitoring these plant communities has historically been directed towards controlling Eurasian water-milfoil (), though in recent years the expansion of the exotic starry stonewort (Nitellopsis obtusa) has been a matter of increased focus. Eurasian water-milfoil is an invasive species that grows rapidly and its extensive canopies cause problems for recreation and other species growth (Borman et al. 1999). Numerous methods of control have been applied to reduce the abundance of Eurasian water-milfoil (Harman et al. 2006). Since 1998, efforts have focused primarily on applications of Sonar, which has been demonstrated to control Eurasian watermilfoil with some specificity. Other efforts have involved stocking the weevil Euhrychiopsis lecontei, which had been shown to limit the growth of Eurasian milfoil in some instances (Harman et al. 2002). The goal of managing the Eurasian water-milfoil in the past has been to achieve a balance of species (Lembi 2000, Harman et al. 2008). Most recent activities have 1 SUNY Oneonta Biological Field Station.

2 included a Sonar application in the north basin in 2010 and in the south basin in Copper Sulfate was applied in , and Renovate was used in the north basin in July 2014 MATERIALS AND METHODS Sampling took place 28 June, 26 July and 18 August 2016 (though plant harvesting activities on the last date limited our access to the south basin) Five collection sites were sampled, two in the north basin and three from the south basin (Figure 1). The sampling method used was the Point Intercept Rake Toss Relative Abundance Method (PIRTRAM) (Lord and Johnson 2006). It was evaluated in 2008 by comparing the PIRTRAM and dry weight methods such that the rake toss method could prove useful, if not too much value is placed on actual abundance estimates. an adequate number of replicate samples could provide insight into species dominance and extent related to exotic nuisance species as well as efforts to control them (Harman et al. 2008). For this method two heads of garden rakes were welded together and connected to a 10m nylon cord. At each of the 5 sites, the rake was thrown out randomly 3 times. The rake was allowed to settle to the bottom of the lake and slowly pulled into the boat. Once in the boat, species were separated and each was assigned an abundance category. The 5 abundance categories are no plants (denoted by Z ), fingerful ( T = trace), handful ( S = sparse), rakeful ( M =medium), and can t bring into the boat ( D = dense). Table 1 provides biomass range estimates associated with each category. Each rake toss triplicate sample s category was converted to its corresponding mid-point (Harman et al. 2008). The mid-points were averaged for each species at each site. These species averages were then summed together to look at overall biomass at each site. In each basin at the deepest location, water quality parameters were measured with a YSI multiprobe. From surface to substrate, temperature, dissolved oxygen, conductivity, and ph were measured. A water sample was taken from each basin and returned to the lab to be analyzed using the Lachat QuickChem FIA+Water Analyzer. The ascorbic acid method following persulfate digestion (Liao and Marten 2001) was used to determine total phosphorus. For total nitrogen, the cadmium reduction method (Pritzlaff 2003) was used following peroxodisulfate digestion as described by Ebina et al. (1983). The phenolate method (Liao 2001) was used to measure ammonia and the cadmium reduction method (Pritzlaff 2003) for nitrate+nitrate-nitrogen. (Harman et al. 2008)

3 Figure1. Bathymetric map of Moraine Lake, Madison County, NY. Contours in feet. WQ1 and WQ2 represent were water quality data were collected, sites 1-5 represent where plant biomass and rake toss methods were performed (Harman et al. 2008). Table 1. Categories, field measurements, midpoint of each category (g/m 2 ) and dry weight ranges applied for the rake toss method and used to generate Tables 2-6 (Harman et al. 2008). Abundance Categories Field Measure Total Dry Weight (g/m^2) mid low high "Z" = no plants Nothing "T" = trace plants Fingerful "S" = sparse plants Handful "M" = medium plants Rakeful "D" = dense plants Can't bring in boat

4 RESULTS Plant Biomass Tables 2-6 proved biomass estimates, by species, during 2016 for sites 1-5 at Moraine Lake. Eurasian water-milfoil was essentially absent from the south basin sites throughout the summer (Tables 2-4). However, it was abundant in the north basin throughout June and July (Tables 5 and 6). Of particular note is the dominance by starry stonewort (Nitellopsis obtusa) at sites 1, 2 and 3; the biomass estimates given in Tables 2, 3 and 4 undoubtedly underestimate actual values because masses of this plant would collapse and fall off the rake as it was being pulled into the boat. Beds of this plant were often so thick that the perception was that a false bottom existed over 1 m from the actual bottom was the first year that it was noted at site 2, and by summer s end it dominated there. However, stonewort has not been so aggressive in the north basin. In 2014, starry stonewort was first documented in the north basin, and by September it was established at both sites there (Tables 5 and 6). It was actually less common over 2016 than it had been the previous few years. Milfoil was prevalent throughout that basin over the summer, as was coontail. Figures 2-6 graphically summarize the plant biomass contributed by starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species between 2008 and While not the original focus of study, starry stonewort is highlighted along with milfoil because it is also an exotic nuisance species and management efforts ought to focus upon control both species. Starry stonewort has come to dominate throughout the south basin throughout much of the summer, while milfoil, coontail and, to a lesser extent, a few native species have comprised the community of the north basin.

5 Table 2. Mean biomass (g/m 2 ) category mid-points for each species found at Site 1 during 2016 sampling events. Megalodonta beckii Zosterella dubia Najas spp. Ceratophyllum demersum Site 1 6/28/2016 7/26/2016 8/18/2016 Chara vulgaris Vallisneria americana Elodea canadensis Ranunculus aquatilis Ranunculus trichophyllus Stuckenia pectinata Potamogeton crispus Potamogeton zosteriformis 0.3 Potamogeton pusillus 0.7 Nitellopsis obtusa Total Table 3. Mean biomass (g/m 2 ) category mid-points for each species found at Site 2 during 2016 sampling events. Site 2 6/28/2016 7/26/2016 8/18/2016 Megalodonta beckii Zosterella dubia Najas spp. Ceratophyllum demersum 24.0 Chara vulgaris Vallisneria americana Elodea canadensis Ranunculus aquatilis Ranunculus trichophyllus Stuckenia pectinata Potamogeton crispus 47.7 Potamogeton zosteriformis Potamogeton pusillus Nitellopsis obtusa Total

6 Table 4. Mean biomass (g/m 2 ) category mid-points for each species found at Site 3 during 2016 sampling events. Megalodonta beckii Zosterella dubia Najas spp. Ceratophyllum demersum Site 3 6/28/2016 7/26/2016 8/18/2016 Chara vulgaris Vallisneria americana Elodea canadensis Ranunculus aquatilis Ranunculus trichophyllus Stuckenia pectinata Potamogeton crispus 0.3 Potamogeton zosteriformis Potamogeton pusillus Nitellopsis obtusa Total Table 5. Mean biomass (g/m 2 ) category mid-points for each species found at Site 4 during 2016 sampling events. Site 4 6/28/2016 7/26/ Megalodonta beckii 0.3 Zosterella dubia Najas spp Ceratophyllum demersum Chara vulgaris Vallisneria americana 61.7 Elodea canadensis Ranunculus aquatilis 0.3 Ranunculus trichophyllus Stuckenia pectinata Potamogeton crispus 0.7 Potamogeton zosteriformis Potamogeton pusillus 0.3 Nitellopsis obtusa 85.7 Total

7 Table 6. Mean biomass (g/m 2 ) category mid-points for each species found at Site 5 during 2016 sampling events. Site 5 6/28/2016 7/26/ Megalodonta beckii Zosterella dubia Najas spp. 0.3 Ceratophyllum demersum Chara vulgaris Vallisneria americana Elodea canadensis 0.3 Ranunculus aquatilis Ranunculus trichophyllus Stuckenia pectinata 0.7 Potamogeton crispus Potamogeton zosteriformis Potamogeton pusillus Nitellopsis obtusa Total Dry Weight (g/m^2) Site 1 Plant Community Nitellopsis obtusa Others Figure 2. Comparison of biomass (g/m 2 ) of starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species present, 2008 through 2016, Site 1 (see Figure 1 for sites).

8 Dry Weight (g/m^2) Site 2 Plant Community Nitellopsis obtusa Others Figure 3. Comparison of biomass (g/m 2 ) of starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species present, 2008 through 2016, Site 2 (see Figure 1 for sites). Dry Weight (g/m^2) Site 3 Plant Community Nitellopsis obtusa Others Figure 4. Comparison of biomass (g/m 2 ) of starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species present, 2008 through 2016, Site 3 (see Figure 1 for sites).

9 Dry Weight (g/m^2) Site 4 Plant Community Nitellopsis obtusa Others Figure 5. Comparison of biomass (g/m 2 ) of starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species present, 2008 through 2016, Site 4 (see Figure 1 for sites). Dry Weight (g/m^2) Site 5 Plant Community Nitellopsis obtusa Others Figure 6. Comparison of biomass (g/m 2 ) of starry stonewort (Nitellopsis obtusa), Eurasian milfoil () and other plant species present, 2008 through 2016, Site 5 (see Figure 1 for sites).

10 Water Quality Analysis Dissolved oxygen concentrations in the south basin extended later into the summer then they typically have, with bottom waters having oxygen of 32% saturation on 28 June. By 26 July, water below about 8 m was essentially anoxic. ph was typically between 7.2 and 8.5. Transparency was between 4 and 6 m over the sampling dates. In the shallower north basin, intermittent mixing was evident. anoxic. ph ranged from 7.4 to 8.9. Transparency was less than 2.5 m. DISCUSSION The spread of starry stonewort continued in the south basin throughout First documented in the north basing in 2014, it has not expanded as aggressively there. In June and July, Eurasian milfoil was dominant in the north basin, with coontail also being common. Starry stonewort was present at all sites in the south basin on all sampling dates. In July and August it dominated all sites. Eurasian milfoil was practically absent from this basin. The reduction in the diversity of the macrophytic community of both basins is marked. Native species, such as Chara vulgaris, Vallisneria americana, Potamogeton zosteriformes and Elodea Canadensis, that were routinely collected as recently as 2006 (Harman et al. 2007) are now rarely encountered. Similar reductions in plant diversity following the establishment of starry stonewort have been described elsewhere (Pullman and Crawford 2010). The continued spread of starry stonewort throughout the lake is worrisome. It has become a serious pest- particularly to the native plant community- in many lakes, and in Moraine Lake it continues to become increasingly common and problematic. It is worth noting that starry stonewort forms dense mats just above the bottom; this suppresses native plant growth, but it seems not to have as big of an impact on recreational activities as Eurasian milfoil canopies. We are not aware of proven methods of selective control of this species.

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