Bioaccumulation of mercury and organochlorines in the

food web of Lake Washington

Jenifer K. McIntyre and David A. BeauchampSchool of Aquatic and Fishery Sciences

University of Washington

• Large urban system

• Popular for fishing

• Elevated levels of Hg in 1970s

• Elevated PCB and DDT in tributary sculpin (McCoy & Black 1998)

Lake Washington

Main Project Objectives

1. Determine current levels of mercury and organochlorines in Lake Washington biota

2. Explore major pathways governing bioaccumulation in food web

3. Evaluate whether contaminant levels are of regulatory concern

4. Develop bioenergetics models to simulate bioaccumulation of Hg and OCs in top predator fishes

Talk Structure

2. Regional Comparisons

3. Historical Comparison

1. Bioaccumulation in L. Washington• Age-related accumulation?

• Lipids in OC bioaccumulation?

• Benthic versus pelagic pathways?

• Is biomagnification significant?

TrichopteransChironomid

Cutthroat Pikeminnow

Zooplankton

Perch

Neomysis

Sockeye SmeltPeamouth

juv. coho

juv. chinook

Bass

Other fish

CrayfishMolluscs

Oligochaetes

Sculpin

Stickleback

Sample Processing

Total and fork length, weight

Scales and/or otoliths

~0.1 g dorsal muscle tissue

Wrapped in aluminum foil, plastic bags

-20 C until analysis

Whole bodies ground

Basic Metrics:

Ageing:

Stable Isotopes:

Storage:

King County:

Fillet : Whole BodyMHg: binds to protein groupsOCs: lipophylic

MHg: higher in muscle tissue OC: higher in fatty tissues

[MHg]: =1.44WBF

WBF[OC]: =0.68

Chemical AnalysesMethylmercury – Frontier Geosciences - CVAFS

Total Mercury – King County ELD - CVAA

Organochlorines – King County ELD – GC-ECD

Total DDT = ΣDDT,DDD,DDE

Total PCB = ΣAroclor 1254,1260

Total Chlordane = Σα,γ chlordanes

Not detected: Aroclors 1016,1221,1232,1242,1248

β, γ BHC (aka HCB)

1. Bioaccumulation

[g]

(μg

g)

0

100

200

300

400

500

600

700[Hg]

Perch

Pikeminnow

Cutthroat

2 4 6 8 10 12

0

100

200

300

400

500

0

500

1000

1500

2000

2500

2 4 6 8 10 12

0

20

40

60

80[∑DDT] ppb ww

[∑PCB]

[∑CHL]

Fish Age (years)

Fish age = 42-94% of [x] ppb ww

82-94%

66-83%

59-84%

42-82%

0.3590.1120.3940.10813PS

0.7070.3730.8030.64125YP

0.5280.3300.3610.42812NP

0.6340.7230.6590.64918CT

Ln[CHL]

Ln[PCB]

Ln[DDT]

Ln[MHg]

NSp.

Correlations with Lipids? p0.05

Lipids as correlated with Hg as with OCsLipids more correlated with Length than [X]

Ln(TL)

0.774

0.551

0.827

-0.108

Oct 2002 Mar 2003 Oct 2001 Mar 2002

Σ DD

T (p

pb w

w)

(SD

)

0

50

100

150

200

% L

ipid

(wet

wei

ght)

2

4

6

8

10

12

Oct 2001 Mar 2002

Σ DD

T (p

pb w

w)

(SD

)

0

20

40

60

80

% L

ipid

(wet

wei

ght)

3

4

5

6

7

8

Lipids and OCsin forage fishes

• Lipids may co-vary with OC, but not causal

Stickleback

Sockeye

Longfin Smelt

0+

1+1+

2+

•Lipids track OC in smelt

• Lipids trends opposite OC in stickleback and sockeye

Benthic vs. PelagicUsed δ13C and diet analysis to separate benthic and pelagic feeding guilds

Compared [X] as a function of trophic position

Bioaccumulation similar among habitats

Location of feeding not significant to bioaccumulation in L.Washingtonδ15N (‰ ) ~ Trophic Position

ΣChlordane

11 12 13 14 15 16 17 18 19

Ln[Σ

CH

L]

-1012345

ΣPCB

Ln[Σ

PC

B]

2

4

6

8

10

ΣDDT

Ln[Σ

DD

T]

1234567

MercuryLn

[Hg]

-6-5-4-3-2-10

BenthicPelagic

Biomagnification?

6 8 10 12 14 16 18 20-3

-2

-1

0

Log10[Hg]=0.1589*δ15N - 3.514

r2=0.674

Age may confound biomagnification assessment

Large fishes

Small fishes

Invertebrates

δ15N ~ Trophic Position

Log 1

0[MH

g]

Σ PC

B (p

pb w

w)

0500

1000150020002500

Hg

(ppb

ww

)

0100200300400500600700

δ15N (‰) ~ Trophic Position8 10 12 14 16 18 20

Biomagnificationpikeminnow perch

cutthroat

Piscivory dominates

Piscivory coincides with increased [X]

δ15N (‰) ~ Trophic Position6 8 10 12 14 16 18 20

[Mer

cury

] (pp

b w

w)

0

20

40

60

80

100

Biomagnification

InvertebratesFishes

2. Regional Comparisons

Total Length (mm)100 200 300 400 500 600

Met

hylm

ercu

ry (p

pm w

w)

0.0

0.1

0.2

0.3

0.4

2. Regional Comparisons: Hg

Mercury concentration is similar in cutthroat trout from L.Washington and adjacent L.Sammamish

L.Washington

L.SammamishL.WaL.Wa L.SamL.Sam

2. Regional Comparisons: Hg

Mose

s L.

pper

Long

L.Te

rrel L

.

Okan

agan

R.

Bank

s L.

alla W

alla R

.Pa

lmer

L.

Neum

an L.

Black

L.De

er L.

Was

hingto

nKit

sap L

.Sa

mish

L.Lo

omis

L.Fa

zon L

.

Vanc

ouve

r L.

Duck

L

Merid

ian L.

0

100

200

300

400

500

Mercury concentrations in L.Washington bass are similar to bass across Washington State

Bass

F/WB = 1.44

Tota

l Mer

cury

(ppm

ww

fille

t)

DOE. 2003.

THg

550 ppb dw

Mercury in sediments is evenly distributed throughout the lake

Mercury source is atmospheric deposition

Dat

a fro

m K

ing

Cou

nty

2. Regional Comparisons: Hg

Tot

al D

DT

(ppb

ww

fille

t)

0

100

200

300

400

500

600

700

800

2. Regional Comparisons: DDT

Non-agricultural

L.W

hatc

om S

MB

L.W

hatc

om K

OK

Can

al L

. LM

B

LwrD

uwam

. ES

L.S

amm

amis

h C

T

Fish

trap

Cr.

RT

Cle

ar C

reek

CT

Cow

litz

R. M

WF

Cow

litz

R. C

T

Van

couv

. L. L

MB

Pal

ouse

R. N

P

Roy

al L

. SM

B

Sco

ot. R

es. L

MB

Sco

ot. R

es. S

MB

Cra

b C

reek

MW

F

Red

rock

L. L

MB

L.W

ashi

ngt.

SM

B

L.W

ashi

ngto

n C

T

L.W

ashi

ngto

n N

P

Lake

Che

lan

RT

Lake

Che

lan

KO

K

Lake

Che

lan

SM

B

Yak

ima

R. S

MB

Cow

iche

Cr.

RT

∑DDT (ppb ww fillet)

F/WB=0.68

Agricultural

**

Historical DDT Spraying in L.Wa.Basin

Spraying smoke and DDT for mosquitos in Union Bay, L.Washington in 1957 (photo appeared in Seattle Times, Aug. 6, 1988)

2. Regional Comparison: PCB

KOK SMB NP MWFSMB RT KOK LMB SMBCarp CT SMB CT NPE.SoleMWF RT

[PC

B] p

pb fi

llet

0

200

400

600

800

L.Whatcom

PalouseR.

Crab Cr.

L.Chelan

Vancouver L.Yakim

a R.L.Sam

mam

ishL.W

ashingtonDuwam

ish R.Spokane R.

No PCB Superfund association

PCB Superfund association

*

*

F/WB=0.68

PCB Source to L.Washington?

PCB Superfund Site 3 miles south of L.Washington

Expect to see S-N gradient of PCBs in sediments?

Sediments show patchy hot spots, highest associated with King County CSOs from Seattle

ΣPCB

ND at 38 ppb/Aroclor

577 ppb dw

Dat

a fro

m K

ing

Cou

nty

Cedar River

3. Historical Comparison

3. Historical – Hg in sediment

Sediment [Hg] is half what it was during 1970s

0.5x

[Hg] ppm dw

‘70 ‘90‘50‘30‘10

1970s

1990s

3. Historical Comparison: Hg

Internal recycling of mercury?

Total Length (mm)50 100 150 200 250 300 350 400

0.0

0.1

0.2

0.3

0.4

F/WB=1.44

Total Length (mm)100 200 300 400 500 600 700

Tota

l Mer

cury

(ppm

ww

)

0.0

0.2

0.4

0.6

0.8

1.0

19742002

F/WB=1.44

Tota

l mer

cury

(ppm

ww

)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

Barnes 1973Current study OctoberCurrent study March

ZOOP JUVSOC

STKB LONGSMELT

Conclusions• Mercury and organochlorines present at

detectable levels in Lake Washington biota

• Age the best predictor of contaminant concentration among predatory fishes

• Lipids not causally related to contaminant levels

• Benthic and pelagic foodwebs similar biomagnification potential

• Piscivory important to bioaccumulation

Conclusions• Hg source atmospheric, concentrations in

Lake Washington fishes were similar to other lakes in the State

• Organochlorine source is local, concentrations in Lake Washington fishes were elevated compared with other waters of Washington State

• [Hg] in biota has not changed since the 1970s – internal recycling of contaminants important

AcknowledgementsH. Mason Keeler endowment from UW School of Aquatic and Fishery Sciences

King County Department of Natural Resources

King County Environmental Laboratory

Dr. David Beauchamp (UW, SAFS)

Dr. Jonathan Frodge (KC DNR)

First Winter: Copepods

% Change in Weight-50 0 50 100 150 200 250 300

% C

hang

e in

Hg

Bod

y B

urde

n

0

200

400

600

800

1000

1. Pathways – Forage fishes - Hg

Growth and diet explain seasonal Hg in forage fishes

LS 1+

SSSB

LS 2+LS 0+

Second winter: high [Hg] mysids, ?[Hg] larval fish

First Summer:

High [Hg] Daphnia

Bio

accu

mul

atio

n

Growth

% Change in Weight-100 -50 0 50 100 150 200%

Cha

nge

in O

GC

Bod

y B

urde

n

-200

0

200

400

600

800

1000

1200

1400

1600

1. Pathways - Forage Fishes - OC

SS SB

LS 2+ LS 0+∑CHL∑PCB∑DDT

LS 1+ First Summer: low [OGC] Daphnia

First Winter: Copepods

Second Winter: higher [OGC] mysids, ?[OGC] larval fish

Growth and diet also explain OC dynamics

Bio

accu

mul

atio

n

Growth

Internal Recycling of Contaminants

[X]

= perturbation of sediments by fish and invertebrates

Bioturbation

“In the Great Lakes…it is now accepted that the internal recycling caused by the coupled

processes of bioturbation and resuspensionare responsible for the continuing elevated

concentrations of trace contaminants in fish…”

B.J. Eadie, L.Michigan Mass Balance Project

Internal Recycling of Contaminants

Another example:Lake Hartwell, 10 to 50-fold reduction [PCB] sediment

over ~25 years, no change in fish over 14 years

Brenner et al. 2004. ES&T 38:2328

Lake Washington MeHg (g/yr)

30

5. Biotransport of Contaminants

?

??

??

?

?

? Remineralization? In-situ methylation

? Groundwater

An example of the far-reaching impacts of our chemical legacy on ‘natural’systems

Biotransport likely much less significant than in arctic systems –less fish, more background contamination

5.4

3. Historical Comparison: OC

[∑PCB] ppb dw

[∑DDT] ppb dw

1970s

1990s2x

1970s

1990s3x

[∑PCB]

[∑DDT]

‘70 ‘90‘50‘30

‘70 ‘90‘50‘30

Total Length (mm)100 200 300 400 500 600

δ13 C

~ F

eedi

ng L

ocat

ion

-32

-30

-28

-26

-24

-22

-20 Carbon isotopes indicate feeding location

Benthic vs. Pelagic Uptake

Cannot use carbon isotopes alone to assess bioaccumulation pathways

Ontogeny in feeding location

Benthic

Pelagic

Benthic vs. Pelagic Uptake

Total Length (mm)100 200 300 400 500 600

δ15 N

(‰) ~

Tro

phic

Pos

ition

10

12

14

16

18

20

Trophic position may confound analysis

ContaminationDDE/ΣDDTSystem

50-70%Great Lakes Newsome & Andrews 1993

24%Hong Kong marketsChan et al. 1999

10-25%Coastal ChinaKlumpp et al. 2002

55-98%Columbia R. BasinEPA 2002

59-88%L.WhatcomDOE 1999

54-75%Lake Wa.McIntyre 2004

Historical

Historical

Historical

Historical

Continuing

Continuing