Ecology of Shallow Lakes

Transcription

1 Paul Cunningham Bureau of Fisheries Management Ecology of Shallow Lakes A Primer Management Tools for Rehabilitation Will Rehab Work for my Lake?

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3 SHALLOW LAKE > One third of WI lake acres, > 300k ac WI s largest, 137,708 ac Large littoral zone area(>50%criteria) Aquatic plants = Heart of ecosystem Exist in turbid or clear water state Water column stays mixed User expectations often unrealistic

4 Good Resource Management is Driven by Sound Science and Data. Chlorophyll varies between ~ 10 and 220 ug/l High inter-lake variability in Chlorophyll at a given concentration of TP For TP=200 ug/l

5 Photo Courtesy of MNDNR

6 Shallow Lakes of Northeast South Dakota Photo Courtesy of MNDNR

7 Catastrophic Regime Shifts Kelp Forests Drylands Coral Reefs Shallow Lakes

8 Stable States in Shallow Lakes Clear State clear water low algal biomass high macrophyte biomass Piscivores dominate Turbid State murky water high algal biomass sparse macrophytes Planktivores/benthivores dominate

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12 Clear-water State Turbid-water State Piscivores Planktivores/Benthivores Zooplankton grazing Algae biomass Aquatic plant biomass Sediment Resuspension N. Hansel-Welch & M.B. Butler, 199

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14 Cladocerans, or water fleas vacuum the algae from lake water. When they are abundant, the water is more clear.

15 Spawning Egg 1.5 mm diameter Unguarded Hatch in 3-4 days Common Carp Larvae 5 mm length at first hatching Feed on yolk sac for 2-3 days Weak swimmers Bottleneck at early life stages

16 Bioturbation

17 Biomanipulation

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19 What is the Root Cause of this Regime Shift? Reductions in Piscivores

20 Shallow Lake Management Tools (From Scheffer et al. 1993)

21 Management Tools

22 Management Tools SPOT TREATMENTS CHEMICAL RECLAMATION COMMERCIAL HARVEST STOCK PISCIVORES PROTECT PISCIVORES FISH BARRIERS AERATION

23 Hammering Carp Trap em Net em Nuke em Suffocate the bastards

24 Advances in Fisheries Management

25 Mechanical Removal

26 Rotenone

27 Fry Stocking

28 Aeration to Prevent Winterkill

29 Electrical Barrier

30 Physical Barrier

31 Management Tools PROTECT PISCIVORES STOCK PISCIVORES COMMERCIAL HARVEST CHEMICAL RECLAMATION SPOT TREATMENTS LONG-TERM LEVELS DRAWDOWN

32 Low Water Levels Rejuvenate Wetlands

33 Time Series Relationship between Lake Koshkonong Water Levels and Hydrologic Conditions Palmer Drought Index YEAR Summer Target Water Deviation Summer Palmer Index = ( summer) Summer Water Level Deviation (ft.) Mid 1930 s drought Mid 1990 s Wet Period

34 Koshkonong s Mud Lake Wetland Complex

35 HIGH WATER LEVELS DESTROY HABITAT NOW 1930

36 Management Tools PROTECT PISCIVORES STOCK PISCIVORES COMMERCIAL HARVEST CHEMICAL RECLAMATION SPOT TREATMENTS DRAWDOWN LONG-TERM LEVELS TEMPORARY BREAKWATERS BARRIER ISLANDS BOATING RESTRICTIONS

37 Permanent Breakwater

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39 Boats

40 Boats

41 Boating Weekday to Weekend Turbidity Change Turbidity Change (NTU) Mid-lake Near-shore Shallow lakes Deep lakes

42 Management Tools PROTECT PISCIVORES STOCK PISCIVORES COMMERCIAL HARVEST CHEMICAL RECLAMATION SPOT TREATMENTS DRAWDOWN LONG-TERM LEVELS TEMPORARY BREAKWATERS BARRIER ISLANDS BOATING RESTRICTIONS EXTERNAL LOADS NUTRIENT INACTIVATION

43 BMPs Buffers Settling basins Flow diversion External Nutrient Loads

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46 Restorations Unstable

47 Thunder Lake Big Muskego Rush Lake Lake Puckaway Fox Lake Beaver Dam Lake Sinnissippi Lake Lake Koshkonong

48 Indian Lake Rehabilitation Carp, Woeful Weather and a Hail Mary Pete Jopke - Water Resources Planner, Dane County LWRD Paul Cunningham, Dave Rowe, Kurt Welke (retired) WDNR Fisheries

49 66 acres drainage lake (40:1) Watershed: Lake area Dane County Parks - Riparian Owner Bass/Bluegill Fishery Popular Recreation Park- Best County Park Wisconsin Trails, acre Dog Exercise Area History of Water Quality Problems

50 Indian Lake Aeration turned on late resulting in winterkill. Flipped from rooted aquatic plants to algae dominated system

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52 2006

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57 Indian Lake Team - Final Preparations Staging

58 Rotenone In-lake Treatment Zone

59 Holy Carp on a Cracker! Aug UWSP Students seine 46 YOY carp September DNR gillnet and electrofish a few adult carp September 2015 DNR population estimate on YOY Carp - Mark Recapture = 5,738 - CPUE Method ( Sorenson ) = 12,591

60 July 4, 2017 Fish Kill-Dissolved Oxygen Crash

61 Indian Lake Aquatic Plant Survey Results using Sonar

62 Big Muskego Lake Rehabilitation 19 Month Drawdown Eradication of Carp-Dominated Fish Population via Rotenone (Fall, 1996) Intensive Fish Restocking Alum Treatment of Bass Bay Electrical/Mechanical Fish Barrier Restrictive Fishing Regulations Nesting Island Construction Controlled Burning and Reseeding Vegetation Management

63 00 Trophic State Index of Big Trophic State Index Big Muskego Lake Muskego Lake TROPHIC STATE Eutrophic Phos ph Mesotrophic Oligotrophic n-88 c-88 c-89 c-90 n-92 c-92 c-93 c-94 n-96 c-96 c-97 c-98 n-00 c-00 c-01 c-02 n-04 c-04 c-05 c-06 n-08 c-08 c-09 c-10 n-12 FISHERIES MANAGEMENT.... we make fishing better

64 1995 Emergent Plants Big Muskego Lake % 56% <25% 27% Big Muskego Lake Levels Water Level Month/Year FISHERIES MANAGEMENT.... we make fishing better

65 Is Shallow Lake Restoration Feasible

66 Is Shallow Lake Restoration Feasible? Attribute Ext. Nutrient Load Inlake TP Sediment Resuspension < 1 g/m 2 /yr 1-2 g/m 2 /yr >2 g/m 2 /yr < 100 ug/l ug/l >250 ug/l < 500 acres 500-5,000 acres > 5,000 acres Hydrologic Connectivity Muti-basinal isolated waterbodies Direct Connection Floodplain/Riverine Macrophyte Potential >50% surface area <20% surface area Fish Biomass Fish Community High (>400 lbs/acre) High Abundance Benthivores/Planktivores Low (<100 lbs/acre) Low Abundance Benthivores/Planktivores

67 Ecology and Management of Shallow Lakes Conference February 7-8, 2017; Horicon Marsh Visitor and Education Center Media Recordings Day one: Day two a.m.: Day two p.m.: