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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