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Understanding Lake Ecology and Aquatic Invasive Plants such as Water Chestnut and Hydrilla Pat Rector Presented to the Swartswood Homeowners Association June 7, 2014 Swartswood Lake, Swartswood, N.J. N.J Lakes N.J. has 870 named lakes Lake Hopatcong, N.J.’s largest lake. Morris & Sussex Counties Origin of Lakes Volcanic Origin Oxbow Lakes • Cutoff from the River NJ Coastal Lakes- 20 Formation of a bar across a depression to form a coastal lake. Wreck Pond Glacial origin • Swartswood is a glacial lake Great Lakes seen from space. Largest example of glacial lake formation. Wikipedia. NJ lakes Other ways lakes are formed • • • • Landslides Tectonic forces Solution Karst lakes In hot arid areas, a playa lake may cover a wide area, but it is never deep. Most water in it evaporates, leaving a layer of salt on the surface. Playa lakebeds • A dry lake is an ephemeral lakebed. A basin that is mostly salt (b/c of evaporation( it is called a salt pan, hard pan or salt flat (what is left of a salt lake). Other ways lakes are formed Great sketch courtesy Dr. Trophic levels • Trophic = feeding Oligo = little. low • Oligotrophic = Low rates of productivity; low nutrients (especially phosphorus); often hypolimnion to epilimnion ratio is high; due to low production slow decomposition slow nutrient release Mesotrophic • Meso=middle http://www.lindyfishingtackle.com/fishingresources/articles/walleye/iceroadwalleyes Eutrophic • Eu=excess Swartswood Lake has a Total Maximum Daily Load (TMDL) for Phosphorus and would be considered Eutrophic. This picture is of a mat algae bloom and this cove by itself might be considered hyper-eutrophic. Eutrophic • Excess phosphorus – which is typically the limiting nutrient in freshwater systems • Excess plant growth • Excess bacterial growth to decompose dead organic material • May lead to anoxic conditions (without oxygen) or low oxygen in the lower levels • Lack of mixing to restore oxygen may lead to fish kill • Loss of species, often influx of aquatic invasive species • Odor problems • Loss of recreation • Loss of aesthetics • Loss of home value • Phosphorus from Phosphorus – Fertilizer– new fertilizer rule has 0 phosphorus in NJ except form some exemptions (establish new lawn) – Weathering of rocks – Lake sediment – Release from organic material (2,788,800 lbs wet wt. 217,526 lbs dry wt. 498 lbs total phosphorus) – Septic or wastewater discharges – Stormwater runoff – Goose, dog, etc. droppings – Atmospheric depositions (small amount) What should it be? – (Standards are 0.1 mgTP/L in stream and 0.05 mg TP/L in lake. Since 2010 “response indicators using a “weight of evidence” approach that will determine whether phosphorus causes non-attainment of the aquatic life use.”…”prohibit nutrient concentrations that cause objectionable algal densities, nuisance aquatic vegetation, or render waters unsuitable for designated uses.” – For Swartswood Lake Total 1,461 kg TP/yr 100% – Margin of Safety 487 33% – 1,938 kg TP/yr reduction to achieve the TMDL with the Margin of Safety. Phosphorus and sediment • Phosphorus is often the limiting nutrient • Sedimentation is an issue in NJ lakes especially those lakes that are simple dammed rivers or ponds that were enlarged. • As lakes become more shallow, issues become greater. • Dredging is a very expensive option that is required for many NJ lakes to become less eutrophic at this point. Sediment Residence Time = 150 years Residence Time = approximately 3 days Residence Time or retention time = the amount of time one molecule of water would spend in the lake. It is basically Retention time = volume of the lake + inflow outflow from the lake Stratification and Turnover http://www.waterontheweb.org/under/lakeecology/05_stratification.html Loon Lake Association Dissolved Oxygen 16°C = 60.8° F 12°C = 53.6° F http://loonlakeassociation.org/lake-conditions/dissolved-oxygen-testing/loon-lake-dissolved-oxygen-profiles/2013-do-profiles/ Nationwide • According to US EPA • Nutrients are the number 1 pollutant reported by states • Followed by mercury as evidenced by fish tissue samples. Another minor problem Aquatic Invasive Species • Dabbling and diving ducks prefer native pondweed and eel grass. • Dense submerged vegetation impacts birds that must swim through water to catch prey. • Dense floating vegetation impacts birds that hunt by sight. Aquatic Invasive Species Aquatic invasive species (AIS) are organisms introduced to marine or freshwater ecosystems to which they are not native and whose introduction causes harm to human health, the environment, or the economy. (EPA Economic Impacts of Aquatic Invasive Species Workshop Washington, DC, July 20-21, 2005 ) Curly leaf pond weed Lake Musconetcong, NJ Photo Pat Rector Aquatic Invasive Species • Have been introduced from outside the region. • Have no natural controls or competitors. • Reproduce better and outcompete regional native species. • Disrupt balance of regional ecosystem. Without control growth can be aggressive Water chestnut Kitchell Pond, Morris County Parks. Photo Pat Rector. Eurasian Watermilfoil 2238.97500000 Harvested in 1 year 2,239 tons (4,478,000 lbs) of weeds in Lake Hopatcong; mostly Eurasian watermilfoil Eurasian watermilfoil Removal of 1,600 tons in 2007. Trapa natans Water Chestnut Not confused with Asian cusine • Trapa natans should not be confused with the water chestnut sold in stores or served with Asian cuisine. • That particular edible water chestnut is Eleocharis dulcis, pictured at right. Why Focus on Water Chestnut? • Recent invasive to NJ, not yet fully established (“horse not all the way out of the barn”). • Spreads aggressively. • Highly disruptive. • Easy to find and identify. • With early detection can be successfully managed. Flower of water chestnut, 2009. Photo courtesy of Lauren Theis, Senior Scientist Upper Raritan Watershed Association. Air bladder of water chestnut, 2009. Photo courtesy of Lauren Theis, Senior Scientist Upper Raritan Watershed Association. Fruit of water chestnut Control Methods • Aquatic herbicides – Such chemical treatment requires a NJDEP permit and must be conducted by a NJDEP Category V licensed applicator. – Costs vary, but can be expensive when treating large expanses of water chestnut. • Biological controls – Grass carp not effective; do not prefer water chestnut and cannot be stocked in flowing waters or ponds/ lakes greater than 10 acres in size. – A beetle, Galerucella birmanica has been investigated but may not be species specific. Chemical management • Must be applied by a licensed applicator • Must be applied according to permit requirements • Common aquatic herbicides: 2,4-D, diquat, endothall, glyphosate. • When vegetation is heavy, treat ½ of the area at one time and the remainder 10 days later. • Many will be marked as to when swimming or contact use can be resumed, or if the product can be used near a water supply. • Label directions specify exact dosage and use. • Treatment must be posted. Mechanical harvesting using specially designed Control machines. No permit is required for hand pulling, hydro-raking, mechanical weed harvesting or disposal. Key to success is rapid response, vigilance, consistency, and continued monitoring. Methods Water Chestnut research Germination of Water Chestnut Seeds 90.00 80.00 70.00 Germination rates (%) 60.00 50.00 40.00 30.00 20.00 10.00 0.00 Treatment No Treat Treatment No Treat DD DD ND ND Drawdown (DD) and Control (ND); Treated area versus Untreated Area An ounce of Prevention • Prevention is the best management measure. • Know the plant and its habitat preferences. • When leaving a lake, conduct a thorough inspection of your boat, boat bilge, live wells and trailer to prevent any “hitchhikers”. • Before you re-launch wash your boat (or better, steam clean) it and the trailer. • Do not empty bait buckets in a lake. • Do not import or plant any non-native aquatic plant species for use in water gardens and back yard fish ponds. Water lettuce • Probably dumped from someone’s aquarium. This was about 4-6 weeks growth. Hydrilla Photo from Wikipedia downloaded http://upload.wikimedia.org/wikipedia/commons/a/ab/Hydrilla_USGS.jpg 4_1_13 Hydrilla • Hydrilla is often confused with common waterweed (Elodea canadensis). • It can be distinguished from common waterweed by counting the number of leaves in each whorl: hydrilla generally has five to eight leaves per whorl and common waterweed has three leaves per whorl. • In the southeastern United States Hydrilla causes major problems with navigation in waterways. In some instances entire stretches of rivers and lakes are completely choked with the plant and beneficial native plants are out competed. • Hydrilla is difficult to manage once it attains nuisance densities. • It is another recent invasive species to come to NJ. Thus far it seems to be found in the southern part of the state. IF you see hydrilla PLEASE contact me at [email protected] Algae Blooms Filamentous Algae Mat Blue-green algae bloom • Technically cyano-bacteria, not Blue-green algae blooms algae. • • • • • • • • Can deplete oxygen, Prevent the growth of beneficial algae Produce toxins that are harmful May be triggered by excess nutrients, low-water or low flow conditions, calm water and warmer temperatures. Most are harmless Some can produce toxins which are harmful to people and animals. Hard to tell the difference. Best to stay out if unsure and not allow pets to swim or drink. Symptoms can include nausea, vomiting, diarrhea, skin or throat irritation, allergic reactions or breathing difficulties. Blue-green algae can also produce toxins that affect the liver and nervous systems when water is consumed in sufficient quantities. Water test is required to determine if toxins are present. Barley straw Costs (EPA Economic Impacts of Aquatic Invasive Species Workshop Washington, DC, July 20-21, 2005 ) THE ECONOMIC SIGNIFICANCE OF LAKE HOPATCONG Table 1: Summary of Findings (2007 $) Component of Annual value Present value Total Economic Value $MM/yr $MM* Recreational value $ 1.2 - 1.3 $ 40 – 43 Econ. activity value (pvt. sector) 2.7 90 Consumption goods value 0.1 – 0.2 2–5 Water supply reserve value 2.3 – 2.6 77 – 87 Property enhancement value 2.1 – 6.9 71 – 230 Other ecoservice values ? ? Non-use values ? ? Total $ 8.4 – 13.6 $ 280 – 455 NEW JERSEY DEPARTMENT OF ENVIRONMENTAL PROTECTION DIVISION OF SCIENCE, RESEARCH & TECHNOLOGY BUREAU OF NATURAL RESOURCES SCIENCE Nov. 2008 http://www.lakehopatcong.org/Pubs/Reports/Economic%20Report%20DEP.doc Dredging • Dredging removes sediment built up on the bottom of a lake. • This helps to reduce nutrients and increase the depth of the lake back to “an earlier time”. • A deeper lake also helps to reduce the amount of available habitat for macrophytes. • Dredging requires a bathymetric survey conducted at close intervals across the lake with sediment analysis to determine if the soil has any contamination. • If sediment exceeds the standards the soil needs to be disposed of properly. • Disposal and transportation of sediment is expensive. • Dredging costs are in the millions of dollars and years to receive permit. • UNLESS THE SOURCE OF THE SEDIMENT IS ADDRESSED THIS IS A USELESS ENDEAVOR AND WITHIN A DECADE OR SO THE LAKE WILL BE BACK WHERE IT WAS PRIOR TO DREDGING. Buffers Lakes • Provide a wonderful recreational opportunity to residents of NJ • Provide ecosystem services and habitat for fish, birds and other organisms. • Lakes in NJ are stressed and the majority of NJ lakes are impaired. • Of the 200 state lakes, most have some issues with water quality, sedimentation or aquatic invasive species. Due to lack of funding most of these are not being addressed. • Private lake communities are only recently becoming aware of the costs of lake stewardship and frequently look to the state or municipality to help shoulder the costs. Questions? Questions? Contact Pat Rector Rutgers Cooperative Extension Environmental and Resource Management Agent Morris/Somerset Counties [email protected]