memo Project Name Little Lake Point Intercept Survey 2017 Date 9/5/17 To / Contact info Cc / Contact info From / Contact info Regarding Jerry Spetzman Greg Graske, PE Joe Pallardy, Mike Majeski Little Lake Aquatic Plant Community Little Lake Survey Results A point-intercept aquatic plant survey was completed on August 24, 2017 at Little Lake. The pointintercept method is considered the standard protocol by MnDNR for sampling macrophytes because it offers a methodology that is quantitative (e.g., frequency of occurrence), repeatable (can be used to track trends in aquatic plant communities over time), and georeferenced (can be used to compare plant communities within different areas of a lake). From this data, a Floristic Quality Index (FQI) was calculated that measures the diversity and health of the aquatic plant community. The FQI calculation is based on both the quantity of species observed (species richness) as well as the quality of each individual species. Every aquatic plant in Minnesota has been assigned a coefficient of conservatism value (c-value) ranging from 0 to 10. The c-value of all aquatic plants sampled from a lake is used to determine the FQI for a given lake. Species with a c-value of 0 include non-native species such as curly-leaf pondweed (Potamogeton crispus) that are indicative of a highly disturbed environment. In comparison, the native species Oakes pondweed (Potamogeton oakesainus) has a c-value of 10 because this species is extremely rare and only found in undisturbed, pristine environments. The average FQI score for Minnesota Lakes in the North Central Hardwood Forest (NCHF) ecoregion is 23.7±8 with a median of 22.5 (Radomski and Perleberg, 2012). A study of 41 Minnesota lakes surveyed across the state, as part of the EPA s National Lakes Assessment Project, yielded a maximum FQI score of 30. In 2016, the MNDNR developed a robust geodatabase of aquatic plant surveys and associated FQI scores from more than 3,600 lakes across the state. FQI scores ranged from 0 to 49 with a median of 25.1±9. The FQI score of 21.3 for Little Lake was lower than the median FQI score for assessed lakes in the DNR geodatabase and the NCHF ecoregion average. The results of the Little Lake survey and associated FQI score are summarized in Table 1. Included in Table 1 is a list of all native aquatic plants sampled and their associated c-values and frequency of occurrence values. Table 2 includes introduced species which have been assigned a c-value of 0. FQI scores from the MN DNR geodatabase exclude introduced species from their FQI calculation; therefore, Table 1 provides the best means of comparison with the DNR geodatabase. Table 2 is useful in that introduced species are both an indication of anthropogenic stress and a stressor themselves in terms of their direct impacts to the surrounding plant community. Shoreline species associated with the wetland habitat (e.g., jewelweed) were also excluded from the FQI calculation. The distribution and density ranking for each individual species with a frequency of occurrence 5% is mapped within Appendix A. For each data point mapped, a density ranking of 1 indicates only a few individual plants were observed while a ranking of 4 indicates an abundance of plants were observed. EOR is an Equal Opportunity Affirmative Action Employer Emmons & Olivier Resources, Inc. 7030 6th Street N. Oakdale, MN 55128 T/ 651.770.8448 F/ 651.770.2552 www.eorinc.com
Table 1. Little Lake Point-Intercept Survey Results- Native Species Only. Common Name Scientific Name C- Value Frequency of Occurrence Broad-leaf arrowhead Sagittaria latifolia 3 3.4% Canada waterweed Elodea canadensis 4 21.8% Clasping-leaf pondweed Potamogeton richardsonii 5 2.8% Coontail Ceratophyllum demersum 2 25.1% Fern-leaf pondweed Potamogeton robbinsii 8 7.8% Flatstem pondweed Potamogeton zosteriformis 6 0.6% Floating-leaf pondweed Potamogeton natans 5 3.9% Greater duckweed Spirodela polyrhiza 5 8.4% Lesser duckweed Lemna minor 5 3.4% Northern watermilfoil Myriophyllum exalbescens 7 0.6% River bulrush Schoenoplectus fluviatilis 4 0.6% Sessile-fruited arrowhead Sagittaria rigida 7 6.2% Small pondweed Potamogeton pusillus 7 1.7% Softstem bulrush Schoenoplectus tabernaemontani 4 2.2% Water smartweed Persicaria amphibia 4 0.6% White water-lily Nymphaea odorata 6 26.2% Yellow pond-lily Nuphar lutea ssp. Variegata 6 12.3% Summary Table FQI = C* S Average C-Value 5.18 C= Mean coefficient of conservatism value Number of species 17 S= Number of species in sample FQI* 21.3 * FQI calculation does not include narrow-leaf cattail and Eurasian watermilfoil which have a C-value of 0.
Table 2. Little Lake Point-Intercept Survey Results w/ Introduced Species Common Name Scientific Name C- Value Frequency of Occurrence Broad-leaf arrowhead Sagittaria latifolia 3 3.4% Canada waterweed Elodea canadensis 4 21.8% Clasping-leaf pondweed Potamogeton richardsonii 5 2.8% Coontail Ceratophyllum demersum 2 25.1% Eurasian watermilfoil Myriophyllum spicatum 0 6.7 Fern-leaf pondweed Potamogeton robbinsii 8 7.8% Flatstem pondweed Potamogeton zosteriformis 6 0.6% Floating-leaf pondweed Potamogeton natans 5 3.9% Greater duckweed Spirodela polyrhiza 5 8.4% Lesser duckweed Lemna minor 5 3.4% Narrow-leaf Cattail Typha angustifolia 0 15.1% Northern watermilfoil Myriophyllum exalbescens 7 0.6% River bulrush Schoenoplectus fluviatilis 4 0.6% Sessile-fruited arrowhead Sagittaria rigida 7 6.2% Small pondweed Potamogeton pusillus 7 1.7% Softstem bulrush Schoenoplectus tabernaemontani 4 2.2% Water smartweed Persicaria amphibia 4 0.6% White water-lily Nymphaea odorata 6 26.2% Yellow pond-lily Nuphar lutea ssp. Variegata 6 12.3% Summary Table FQI = C* S Average C-Value 4.63 C= Mean coefficient of conservatism value Number of species 19 S= Number of species in sample FQI* 20.2
Little Lake 2014 Survey Results The MN DNR conducted a Biological Survey on Little Lake in June of 2014 (MN DNR, 2014). The area surveyed was limited only to the northeast shore of the lake. Individual species observed, coefficient of conservatism values, and associated FQI scores from the 2014 survey are provided in Table 3. The plant communities observed during the 2014 and 2017 surveys are comparable, with 15 of 17 species recorded during the 2014 survey also observed in 2017. The average c-value and number of species observed in 2017 was slightly higher than those reported in 2014, resulting in a slightly higher FQI score in 2017. While the 2017 survey found a greater number of in-lake species (excluding shoreline species) and higher average c-value, results from both the 2014 and 2017 survey indicate an aquatic plant community with FQI scores that are below the median FQI score for assessed lakes in the DNR geodatabase and the NCHF ecoregion average. A healthy aquatic plant community can help to maintain a clear-water, aquatic plant-dominated state which is the ecologically preferred state. Currently, the aquatic plant community is being hindered by poor water clarity resulting from algae growth and excess nutrient inputs from the surrounding watershed. Results from the 2014 and 2017 surveys should be compared with future surveys to determine if an increase in the number and quality of species observed is occurring along with a concomitant increase in water clarity and quality. Table 3. 2014 DNR Survey Results. Common Name Scientific Name C- Value Found in 2017 Broad-leaf arrowhead Sagittaria latifolia 3 Yes Canada waterweed Elodea canadensis 4 Yes Coontail Ceratophyllum demersum 2 Yes Fern-leaf pondweed Potamogeton robbinsii 8 Yes Flatstem pondweed Potamogeton zosteriformis 6 Yes Greater duckweed Spirodela polyrhiza 5 Yes Leafy pondweed Potamogeton foliosus ssp. Foliosus 6 No Northern watermilfoil Myriophyllum exalbescens 7 Yes River bulrush Schoenoplectus fluviatilis 4 Yes Small pondweed Potamogeton pusillus 7 Yes Softstem bulrush Schoenoplectus tabernaemontani 4 Yes Turion-forming Duckweed Alisma triviale 1 No White water-lily Nymphaea odorata 6 Yes Yellow pond-lily Nuphar lutea ssp. Variegata 6 Yes Summary Table FQI = C* S Average C-Value 4.93 C= Mean coefficient of conservatism value Number of species 14 S= Number of species in sample FQI 18.44* * Additional introduced and shoreline species were sampled but not included in the FQI calculation.
Little Lake Shoreline Species Comparison The 2014 DNR survey included a reconnaissance of the shoreline aquatic plants. Shoreline species were not included in the 2014 or 2017 FQI calculation because they were not found within the lake itself; rather, they were associated with the wetland fringe that surrounds Little Lake. Shoreline species were also recorded in the 2017 survey at the point-intercept sampling points located closest to shore; however the primary focus of the 2017 survey was on the in-lake aquatic plant community. Additional shoreline species observed in the 2017 survey included greater water dock and blue flag iris. Table 4. Little Lake Shoreline Species 2014 DNR Survey Common Name Scientific Name Found in 2017 Bulb-bearing water hemlock Cicuta bulbifera No Bur-Marigold / Beggar-Ticks* Bidens sp. No Bur-reed* Sparganium sp. Yes** False Cyperus Sedge Carex pseudocyperus No Jewelweed Impatiens capensis Yes Narrow-leaf cattail Typha angustifolia Yes Northern bugleweed Lycopus uniflorus No Northern marsh fern Thelypteris palustris Yes Porcupine-like Sedge Carex hystericina No Purple Loosestrife Lythrum salicaria Yes Rattlesnake grass Glyceria canadensis No Speckled Alder Alnus incana ssp. rugosa No Steeple-bush Spiraea tomentosa var. rosea No Swamp Milkweed Asclepias incarnata No Water Plantain/ Mud Plantain* Alisma sp. No * Not identified to species. **Likely Giant Bur-reed
Appendix A: Little Lake Aquatic Plant Species Distribution Figure 1. Eurasian watermilfoil distribution and abundance August, 2017.
Figure 2. Narrow-leaf cattail distribution and abundance August, 2017.
Figure 3. Sessile-fruited arrowhead distribution and abundance August, 2017.
Figure 4. Coontail distribution and abundance August, 2017.
Figure 5. Canada waterweed distribution and abundance August, 2017.
Figure 6. Yellow pond-lily and white water-lily distribution and abundance August, 2017.
Figure 7. Fern-leaf pondweed distribution and abundance August, 2017.
Figure 8. Duckweed species distribution and abundance August, 2017.