US Army Corps of Engineers

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The Effects of Suspended Sediment from Western Lake Erie on Walleye (Sander vitreus) Eggs and Fingerlings?Burton Suedel, C.H. Lutz, J.U. Clarke, D.G. Clarke

USACE-ERDC-EL, Vicksburg, MS

C. Godard-Codding and J. Maul

The Institute of Environmentaland Human HealthTexas Tech UniversityLubbock, TX

Dredging 2012San Diego, CA24 October 2012

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Sediment Resuspension

The most frequently cited concern related to restrictions imposed on dredging schedules

Exposures may affect: Spawning or foraging behavior Egg hatching success and larval development Disrupt anadromous fish migrations Physical disturbance of habitat by increased

sedimentation rates

Engbretson Underwater Photography

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Setting Environmental Windows is Controversial

EW: Time periods that allow dredging No consistent, broadly accepted methodology

for objectively setting EWs has emerged Often set without scientific basis Established by negotiations emphasizing

conservative professional judgments Lack of effects data for suspended sediments

on species used to set EW

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Maumee Bay Study Area

SpawningArea

LarvalNursery

Area

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Near-field Plume ConditionsMaumee Bay Study Area

0

100

200

300

400

500

600

700

9:4

8

9:5

5

10

:02

10

:09

10

:16

10

:23

10

:30

10

:37

10

:44

10

:51

10

:58

11:0

5

11:1

2

11:1

9

11:2

6

11:3

3

11:4

0

11:4

7

11:5

4

12

:01

12

:08

12

:15

12

:22

12

:29

12

:36

Time

NT

U (

mg/

L)

Near-field (2.2 m Depth) Near-field (7.0 m Depth) Ambient (7.0 m Depth)

46 m 30 m

15 m LWC Max. Turb. 700 NTU (15 m) < 300 NTU (30m)

Max. TSS 800 mg/l

Plume Width 50 m

Distance from Dredge: 3m

Entrained Air

UWC Max. Turb. 175 NTU (15 m) 50 NTU (30m) Ambient in < 50 m

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Materials and Methods

Flow-through Fish Larvae and Egg Exposure System (FLEES)

3 modules/3 500 L water baths/15 aquaria

Aquaria (15) constructed from 20 L polyethylene carboys

Pump recirculated water and suspended sediment in aquaria

Sediment mixed with water and stored in 375 L tank via double diaphragm pump

Slurry routed through FLEES and reused

Sediment concentrations monitored using OBS

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Materials and Methods

Walleye (Sander vitreus) Four experiments:

northern and southern strain eggs (newly spawned) and fingerlings (45-60 d old)

Sediment: Maumee Bay, Ohio (Lake Erie)

Concentrations: 0, 100, 250, 500 mg/L TSS

Duration: 3 days (72 h) Temp: 10-13°C eggs;

14-17°C fingerlings PVC cups for containment

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Experiments and Endpoints

Two Phases►2010►2011

Northern and Southern Strains►Fingerlings – survival, coiling, scoliosis,

lordosis/kyphosis, gill integrity►Eggs – viability and hatchability, wet and dry mass

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2010 No. Viable Northern Strain Eggs

No significant differences among treatments were observed for viable eggs (Anova, F=0.38, P=0.7678).

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2010 No. Viable Southern Strain Eggs

No significant differences among treatments were observed for viable eggs (Anova, F=3.53, P=0.0681).

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Southern Strain Fingerling Survival

Fingerling survival did not differ significantly among TSS treatments (Anova, F=2.74, P=0.113).

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Northern Strain Fingerling Gill Lamellae

Fingerling gill lamellae did not differ significantly among TSS treatments.

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Percent Hatch of Northern Strain Eggs

No significant differences among treatments were observed for percent hatch (Anova, F=1.15, P=0.386).

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Number of Viable Northern Strain Eggs

No significant differences among treatments were observed for viable eggs (Anova, F=0.56, P=0.6533).

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Wet Mass Northern Strain Eggs

No significant differences among treatments were observed for viable eggs.

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These experimental data can be used with dredge plume characterization data that were obtained for bucket dredging in Maumee Bay to assess potential risk to walleye.

Current EW restrictions in Lake Erie may merit review in light of reduced uncertainty regarding risk associated with effect thresholds within the range of dredging-induced perturbations.

Implications

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