Bioaccumulation Of Metal Substances by

Aquatic Organisms Part 2

Bill Adams

OECD Meeting, Paris

September 7-8, 2011

Bioaccumulation – Another Fish Story

Presentation Overview

• Biomagnification summary for metals

• Trophic transfer factors (TTF)

• Proposed approach to assessing metal

bioaccumulation

Trophic Transfer Factors (TTF)

Definition

Tissue Concentration in Predator

TTF = --------------------------------------------

Tissue Concentration in Prey

TTF are used to assess food chain accumulation, i.e.,

Potential for secondary poisoning

Trophic Transfer & Biomagnification

Trophic Transfer

•Transfer of metal from one level in the food chain to the next higher level

•Trophic transfer factor TTF = concentration at level 2 divided by level 1

Biomagnification

•Biomagnification = an increase in tissue concentration across three trophic levels (i.e., phytoplankton to zooplankton to fish)

•Factors greater than 1 are given significance

Differentiating Biologically Available

vs. Bound Metal in Tissue

• Important issue in assessing effects and

trophic transfer

• Three basic physiological models for

metal bioaccumulation in aquatic

organisms

• Regulation, Regulation-Storage, Storage

• Regulation-Storage is by far the most

common model

Biomagnification – Clear Example

DDT residue BAFs for various trophic levels in the Carmans River

Estuary, Long Island, (data from Woodwell et al. 1967)

1

10

100

1,000

10,000

100,000

1,000,000

10,000,000

Pla

nkto

n

Shrim

p

Mum

michog

Atlan

tic nee

dle fish

Com

mon

tern

Her

ring

gul

l

Cor

mor

ant

Rin

g-bi

lled g

ull

BA

F

Inverse Relationship Between Diet and TTF

Dietary Cd g g-1 dw

0.001 0.01 0.1 1 10 100 1000 10000

TTF

0.001

0.01

0.1

1

10

100

1000Annelid

Arthropod

Fish

Mollusc

Dietary Cu ( g g-1 dw)

0.1 1 10 100 1000 10000

TTF

0.001

0.01

0.1

1

10

100

1000Annelid

Cladocera

Fish

Amphipod

Cadmium Copper

Inverse Relationship Between Diet and TTF

Dietary Zn ( g g-1 dw)

1 10 100 1000 10000

TTF

0.001

0.01

0.1

1

10

100

Annelid

Amphipod

Cladocera

Fish

Zinc

Are TTFs Predictive of Effects?

Dietary Cd ( g g-1 dw)

0.01 0.1 1 10 100 1000 10000

TTF

0.001

0.01

0.1

1

10

100

1000Toxicity Not Assessed

Controls

No Effects

Effects

Cadmium

Dietary Cu ( g g-1 dw)

0.1 1 10 100 1000 10000

TTF

0.001

0.01

0.1

1

10

100Toxicity Not Assessed

Controls

No Effects

Effects

Copper

Freshwater TTFs – Empirical Lab

0.08

0.04

0.05

0.02

0.1

1

10

100

1000

10000

Phyto

plant

on

Cladoc

era

Fish T

L3

Phyto

plant

on

Cladoc

era

Fish T

L3

Food Chain 1 Food Chain 2

Cadmium,

µg/

g dry

wt.

0.05 0.7

0.05 0.5

1

10

100

1000

10000

Phyto

plant

on

Cladoc

era

Fish T

L3

Phyto

plant

on

Cladoc

era

Fish T

L3

Food Chain 1 Food Chain 2

Lead,

µg/

g dry

wt.

Freshwater TTFs – Empirical Lab

0.1

0.02

0.1

1

10

100

1000

Phytoplankton Cladocera Insect TL3

Nickel, µ

g/g

dry

wt.

Freshwater Field Data - Zinc

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Mixed

inverts

Midge Mayfly Midge Mayfly Midge Mayfly Midge Mayfly

Arctic

cod

Sacramento

sucker

Threespine

stickleback

Sacramento

pikeminnow

Chinook

salmon

Tro

phic T

rans

fer

Fact

or REF

EXP

Evaluation of Field Studies

Cd Cu Pb Ni Zn

Num

ber

of S

tudies

0

3

6

9

12

15

18

No Biomagnification

Possible Biomagnification

Clear Biomagnification

Cardwell, DeForest, Brix, & Adams – 2011

Marine Field Data TTFs – Predatory Gastropods

0

2

4

6

8

10

12

14

Morula musiva Thais clavigera Thais clavigera

Clearwater Bay Butterfly Bay

Tro

phic T

rans

fer

Fact

or

Cd

Cu

Zn

Cheung and Wang 2008

Biomagnification

• The majority of data from lab and field

indicates that biomagnification of many

metals ours only in select food webs and

is not the common case.

Approach For Assessing

Bioaccumulation

• Regression Approach

– Back-calculation from toxicity threshold to

waterborne metal concentration

Regression Approach

Given a wildlife

dietary toxicity

threshold

Tissue concentration

in prey

What concentration in water

will lead to accumulation that

equals the tissue

concentration in prey?

Ohlendorf and Santalo (1994) Based on Skorupa & Ohlendorf (1991)

Mean Egg Selenium (mg/kg dw)

Stilts

Teratogenic Population (%)

Mallards

Brine Shrimp

Dietary Selenium (mg/kg dw)

100

50

10

1

1

5

100

50

10

500

1000

Waterborne Selenium (mg/L)

100 80 60 40 20 10 1 5 10 50 100

5

Inverse BCF Relationship (Bivalve or Fish)

Question? How do you interpret a tissue concentration in a field collected organism?

Reported tissue effect levels are very unreliable: - Consensus of SETAC Pellston Workshop Concept: 1. Use tissue levels in a non sensitive species to predict effects

in a sensitive organism 2. Non-sensitive organisms can tolerate much higher effects

without mortality 3. Sensitive organisms in the filed are often gone, insensitive

organisms remain

Alternative Approach to Assessing Metal Tissue

levels: Experimental Design

Resistant:

Lymnaea stagnalis 18 juveniles/ beaker (28 d)

Sensitive:

Hyalella azteca 35 (age 2-9 d)/ beaker (28 d)

Common exposure conditions:

[Cd]: 0, 0.4, 0.8, 1.6 & 3.2 µg/L

Water chemistry: Na = 270 µM

Ca = 180 µM

Mg = 98 µM

Chronic Test: Experimental Design

Nish Pais & Jim McGeer

Dept. of Biology, McMaster University

0 5 10 15 20

0

20

40

60

80

100

120

Day of

exposure

Cd

Bu

rde

n (

µg

/g d

wt)

Accumulation 140

Control

0.4 mg/L

0.8 mg/L

1.6 mg/L

3.2 mg/L

Lymnaea

Chronic test: Hyalella

Day of exposure

0 5 10 15 20 25 30 0

50

100

150

200

250

Cd

Bu

rden

(µ

g/g

d w

t)

Accumulation

Control

0.4 µg/L

1.2 µg/L

0.0 0.5 1.0 1.5 2.0 2.5

0

20

40

60

80

Cd Concentration (µg/L)

Survival at d 28

Su

rviv

al

(%)

100

0 5 10 15 20 0

20

40

60

80

100

120

Day of exposure

Cd

Bu

rde

n (

µg

/g d

wt)

Accumulation 140

0.0 0.5 1.0 1.5 2.0 2.5 0

30

60

90

120

150 C

d B

urd

en

(µ

g/g

d

wt)

Cd Concentration (µg/L)

Chronic test: Lymnaea

Lymnaea Cd burden at saturation

Sensitive organism

(Hyalella) effect conc.

0.5 1.0 1.5 2.0 2.5 0

20

40

60

80

Cd exposure (µg/L)

Survival of Hyalella

Su

rviv

al (%

)

100

30

60

90

120

150 Accumulation in Lymnaea C

d B

urd

en

(µ

g/g

d w

t)

Additional Evidence for the tissue

approach

• The CBR50 in Lumbriculus for predicting mortality of C. riparius was 29.1 – 45.7 mg g-1 wet wt, which was consistent within the experimental period; therefore the use of Cu residue in an accumulator species to predict bioavailability of Cu to a sensitive species from the same habitat is a promising approach.

• Recent manuscript abstract

• Tania Y.T. Ng, Nish M. Pais1, Tarun Dhaliwal2, Chris M. Wood

• Dept. of Biology, McMaster University

Conclusions • BCF/BAF/TTFs and other Accumulation Factors for metals

are clearly inversely related to exposure concentrations)

• Hazard and potential for chronic effects cannot be evaluated by magnitude of BCFs or BAFS

• Biomagnification factors for metal are most often <1 indication biomagnification is not the typical case;

• TTFs >1 do exist for several metals in the food chain with predatory gastropods at the top of the food web

• BMFs >1, when observed, are usually in found in low

exposure environments

• Bioaccumulation and potential for effects can be assessed by use of regression models; classic examples are selenium and mercury

• A new approach of using metal tissue levels in non-sensitive organisms to predict toxicity in sensitive organisms show promise.

Smallest Fish Award