Managing Aquatic Plants and Algae in Ponds and Lakes Bryan Swistock - - PowerPoint PPT Presentation

Managing Aquatic Plants and Algae in Ponds and Lakes

Bryan Swistock Water Resources Specialist Penn State Extension School of Forest Resources brs@psu.edu 814-863-0194

Plant/Algae Problems are Common

52 34 26 9 8

20 40 60

Plants/Algae Nuisance Wildlife Leaks Water Quality Fish Kills

percent

• Native species
• Diverse mixture
• Moderate density (20-30%)

Desirable Aquatic Plant Communities

Why do Aquatic Plants Grow?

Water + Sunlight + Nutrients + (Transport?) Balanced ecosystem = 20 to 30% plant coverage Problems occur with:

• Nitrogen and phosphorous inputs
• Sedimentation (decreased depth)
• Increased transport

Factors Causing Plant/Algae Growth

• The pond or lake “watershed”
• Land uses, nutrients, sediment
• Source of pond/lake water
• Groundwater better than surface water
• More consistent flow, fewer nutrients and sediment
• Pond or lake depth
• Shallow water promotes more growth

Proper Identification is the First Step to Control !

Algae Submerged Plants Emergent Plants Floating Plants

Filamentous algae Planktonic algae

Common Type of Pond Algae

Harmful Algae Blooms (HAB)

• Some blue-green algae can produce dangerous toxins
• Avoid human and animal contact if water has these

symptoms:

• Floating layer looks like paint
• Surface scums, mats or films
• Discolored water or colored streaks
• Floating material below the water surface

HABs Anna McCartney

Common Submerged Plants

Bladderwort Coontail Naiad Elodea

Photos courtesy of Amy Smagula, New Hampshire Department of Environmental Services

Potamogetons

Common Floating Plants

Duckweed Watermeal Watershield

Water Lily

Common Emergent Plant

Cattail Water Plantain Arrowhead Bulrush

Exotic Invasives – Watch Out for These !

Yellow Floating Heart Parrot Feather Purple Loosestrife

Photos courtesy of Amy Smagula, New Hampshire Department of Environmental Services

Based on Annual Chemical Control Requests

Algae

52% 35% 11% 2%

What are the Problem Plants ?

Control Starts with Measurements

• Surface area (acres)
• GPS units work nicely for this
• Volume (acre-feet)
• PSU Survey – 75% of pond owners have never measured their

pond – most only estimate size

• Water quality
• pH, alkalinity, total dissolved solids, nitrate, temperature, dissolved
• xygen, phosphate
• 80% of PA pond owners have never tested pond water quality

Pond and Lake Testing

• Simple test strips available at pet and pool stores OR
• Certified testing through accredited labs
• Penn State Lab Results (2007-2014)

10 20 30 40 % of Ponds with Problem

Nutrient Reduction

Sediment ponds Buffers Aeration Stabilize banks Septic maintenance Reduce fertilizer Control animals

Physical Control Methods

Dredging Drawdown Raking, Pulling Harvesting

BE CAREFUL – harvesting can make some problems worse (naiad, elodea, etc.)!

Dredging photo courtesy of Ed Molesky, Aqua Link, Inc. & Hydro Logic Products

Other Biological Options

• Grass Carp
• Control some rooted aquatic plants
• Permits and use vary by state
• Bacteria / enzyme products
• Marketed as water quality enhancers
• Out compete algae & plants for nutrients
• Water chemistry important, re-treatment necessary
• Aeration
• Reduces nutrients in water column
• Barley straw
• Preventative for algae
• Must be applied in fall or early spring
• Mixed results

Aquatic Herbicides

• Widely used and abused
• Consider all alternatives first!
• Many pond owners quickly turn to aquatic herbicides because:
• Products are available for any plant
• Most work quickly
• Easy to apply
• Cheap (in some cases)
• They work !

Herbicide Considerations

• Cost – varies from <$100 to >$1,000 per acre
• Time of year
• Toxicity to pond ecosystem (i.e. copper versus dyes)
• Permit – may not be granted for certain herbicides in

certain cases

• Selective or broad spectrum – target plants
• Water use restrictions – what do you use the water

for?

Herbicide Problems

• Failure to acquire permit(s)
• Overdose of herbicide (Poor measurement, application, timing)
• Failure to follow label !
• Ignoring water use restrictions
• Treating too much vegetation at one time
• Common cause of fish kills
• Some algae developing resistance
• Accumulation in sediment
• Band-aid approach (perpetual treatment)
• May trade one problem for another

i.e. remove duckweed and get curly leaf pondweed

Survey of PA Pond Owners: Aquatic Plant Management Reality

• 46% felt a healthy pond should have

essentially no aquatic plants or algae

• 39% thought some non-native aquatic

plants were good for a pond

• 30% felt a buffer strip around a pond

provided no benefits

Survey of PA Pond Owners: Aquatic Plant Management Reality

• 40% regularly attempt to control aquatic

plants or algae

• 49% felt pulling, raking or cutting aquatic

plants and algae was always a good idea

• 47% felt copper sulfate was not toxic at all to

pond fish

• 23% thought aquatic herbicides should only

be used late in the summer when plant growth was most abundant

• 65% were unaware of the state permit for

aquatic herbicide use

• Fewer than 20% of those who had used a

herbicide had obtained a permit 20 40 60 80 100 Of those who control plants, what methods do they use?

Penn State Extension Pond Website

http://extension.psu.edu/water/ponds