Assessment of Macrophyte and

Sediment ConcernsJess Hesley, Tyler Jack, Christina Leid

University of IdahoLimnology Service Learning Project

December 7th, 2011

Outline Background Methods• Sampling• Analysis

Results Recommendations

The OX Ranch near Council, ID

Photo Credit: Frank Wilhelm

Sampling Methods: Macrophytes

• Site Selection

• Collection

Sampling Methods: Sediment• Site Selection

• Collection

Analysis Methods: Macrophytes

• Preparation

• Drying

Analysis Methods: Sediment

• Preparation

• Drying

ResultsMacrophytes

Species ID Biomass

Sediment Water Content Deposition

Vegetative Culprits • Ceratophyllum demersum

Coontail

• Ceratophyllum echinatumSpiny Hornwort

• Myriophyllum spp.Milfoil

Biomass Determination

A B C0

0.1

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Macrophyte Biomass

Polygon

Bio

mas

s (k

g/m

2)

Water Contents

20 40 60 80 1000

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Core ACore BCore C

Water Content (%)D

epth

(cm

)

Sediment DepositionPond Wide

Total: ~787 m3 Annual: ~44 m3

By PolygonA: 107 m3 B: 462 m3

C: 215 m3

Photo Credit: Frank Wilhelm

A B C0

50

100

150

200

250

300

350

400

450

500

Deposition

Polygon

Tota

l Sed

imen

t (m

3)Deposition by Polygon

Review of Concerns

MacrophytesBiomassInvasive nature

SedimentDepositionAltering pond

structure

RecommendationsControl Method Use at OX Ranch

Extended Drawdown Recommended to allow for dredging.

Dredge Recommended down to a depth of 3 m in center of pond, removing 5 400 m³ of sediment and 4 600 kg of dried macrophytes.

Benthic Barriers Recommended in areas with significant re-growth. Application of 190 m² of 8 mm perforated black plastic covered with 10 y³ of pea sized gravel .04 m thick.

Hand Pulling Recommended in select areas.

Determining factors for - DredgingPositive Impacts:

Reduction of suitable habitat for rooted macrophytes.

Removal of nutrients stored in the plant structures.

Swimming and fishing will be greatly improved for 2013 summer season.

Negative Impacts:

Fragmentation and threat of re-colonization.

Determining factors for – Drawdown, Benthic Barriers, and Hand-pulling

Positive Impacts:• Drawdown mitigates fragmentation re-colonization.

• Placement of benthic barriers proven to reduce growth of macrophytes.

Negative Impacts:• May require fish capture and transport to avoid fish kill.

• Requires restocking of fish.

Determining factors against – Herbicides and ShadingHerbicides• Do not address the cause or source of the problem.• Short lived and may require re-application.• The long term impact of herbicides on humans,

non-targeted plants, and animals is relatively unknown.

Shading• While non-toxic it will impact aesthetics and all

species within the pond.

Dark blue – area dredged to a depth of 3 m.

White – area recommended for the placement of benthic barriers.

Yellow – area of intensive use recommended for potential hand-pulling treatment.

Red – Installation of docks for fishing accessibility.

Other Considerations

Impacts of nutrient addition from adjacent fields of agricultural use.

Installation of additional docks to provide improved fishing access.

Estimated ExpensesDate Action Cost

Labor ?mid October

Equipment Rental $1000 – $2000 / day for 5 days

mid October

Gravel Purchase $900

mid October

Plastic Purchase $80

mid June Dock Purchase $1000 eachmid June Fish Stocking $300

Total $13 280 + labor

TimelineYear Treatment Type Schedule

2012 Extended drawdown mid June

2012 Dredging mid October

2012 Installation of benthic barriers late October

2013 Re-filling of pond Spring run-off

2013 Re-stocking of fish June

2013+ Hand-pulling As needed

ConclusionSediment accumulation is the ‘root’ of the

macrophyte growth problem.

Mitigate macrophyte growth through: Drawdown Dredging Benthic Barriers Hand-pulling

Photo credit: www.crappielake.com

References Center for Aquatic and Invasive Plants. (2011). University of Florida

IFAS Extension. Retrieved from http://plants.ifas.ufl.edu/ Fewless, G. Invasive Plants of Wisconson. (2011). Retrieved from

http://www.uwgb.edu/biodiversity/herbarium/invasive_species/myrspi01.htm

Krebs, C. J. (1998). Ecological methodology. (2nd ed.). Menlo Park,CA:Benjamin/Cummings.

Maine's interactive field guide to aquatic invaders and their native look alikes. (2009). Retrieved from http://mainvolunteerlakemonitors.org/ mciap/ herbarium/Hornworts.php

Susan, B. (1998). Through the looking glass: A field guide to aquatic plants. Madison, WI: University of Wisconson Press.

TroutLodge (2011). Troutlodge price list. Received via personal contact with TroutLodge. www.troutlodge.com

Species Size No./ac.Alt (1) Trout 5-10 cm. 100-175Alt (2) Trout 12-15 cm. 90-150Alt (3) Trout 22-25 cm. 80-130

Cold Water Pond Stocking Recommendations

Guide illustrating stocking recommendations that have been successfully applied in the United States. Other combinations and rates may be used, depending upon the owner’s objectives and site suitability.

Organic Content4 6 8 10 12 14 16 18 20 22 24

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Core ACore BCore C

Organic Matter Content (%)

Dep

th (

cm)