Download Understanding Lake Ecology and Aquatic Invasive Plants such as

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]