Presentation: Developing Science-Informed Policy Responses to Curb Endocrine Disruption in Freshwater, Minna Saaristo - Senior Scientist – Emerging contaminants, EPA Victoria, Australia

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Ecosystem impacts: direct and indirect effects of endocrine
disrupting chemicals
Dr Minna Saaristo
Developing science-informed policy responses to curb endocrine disruption in freshwater,
OECD, Paris, France;
18 Oct – 19 Oct 2022

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Introduction to the topic
Case studies (I –II)
Problems of scale and complexity
Take home-messages
Outline of the talk

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Endocrine disrupting chemicals (EDCs)

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Behaviour, an early indicator of chemical
contamination

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Direct effects on behaviour: are caused by contaminants acting on the
physiology of an animal.
Indirect effects on behaviour: changes to animal behaviour in one
organism or species have cascading effects on other organisms and species
in the exposed system.
Credit: Plymouth Marine Laboratory

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What about feedback loops?

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Conceptual framework:
the effects of chemical contaminants on communities
manifest in the interactions within and among populations.

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Simply monitoring changes in the abundance of
key predators is likely to underestimate the risks.
Feedback loops

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Move away from the ‘one chemical - one species – one
endpoint’

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Case study I – direct
effects
Credit: UnderWater Tribe

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Case study I.
The effects of 17α-ethinyl estradiol
on the reproductive behaviour of
the sand goby (Pomatoschistus
minutus).

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Methods
Study site:
• Baltic Sea (Finland)
• brackish water

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Methods
Exposure design:
• Flow-through exposure (ng/L)
• Short-term exposures (1-4 weeks)
• LC-MS (HS 1100-Waters Quattro II)

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17α-ethinyl estradiol (EE2)
EE2 is a synthetic estrogen used in oral contraceptive pills.

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Sand goby (Pomatoschistus minutus)
A small, marine fish with a one-year life cycle
Resource-defence mating system
Male competes for females: strong sexual selection for
increased male size

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Behavioural assays

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Female choice experiment

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Courtship behaviour decreased
Saaristo et al. (2009b) Hormones and Behavior, 56, 315-321.

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21 females out of 30
mated with control males

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Mating system experiment

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Mating system changed: females preferred
smaller males
Saaristo et al. 2009a. Hormones and Behavior, 55, 530-537.

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Nest competition experiment

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Exposed males lost the nest competition:
males were not able to acquire or defend a nest site
Saaristo et al. (2009b) Hormones and Behavior, 56, 315-321
Control Control
EE2 EE2
Stage1
Stage 2

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Male-male competition experiment

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Exposed males were less
aggressive
Saaristo et al. 2010. Chemosphere, 79, 541-546.

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Changes in nest building, courtship and
aggressive behaviour of EE2-exposed males:
negative implications for male reproductive
success.

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Case study: Indirect effects
Study species: e.g. fathead minnow
(Pimephales promelas)
Model compound: EE2
Study design: A whole lake exposure, 4-year
study.
Kidd et al. 2007. Collapse of a fish population after exposure
to a synthetic estrogen. PNAS, 104, 8897-8901.
Kidd et al. 2014. Direct and indirect responses of a
freshwater food web to a potent synthetic oestrogen. Phil.
Trans. Royal Soc. B., 369, 20130578.

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By 2002, age-0 fathead minnow were virtually absent in the lake.
By 2004 the adult fathead minnow biomass had declined by two
orders of magnitude, to less than 1% of the biomass in the previous 4
years.

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Increases in zooplankton, Chaoborus, and emerging insects after 2-3 years of EE2
additions, strongly suggesting indirect effects mediated through the reduced
abundance of several small-bodied fishes.

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Biomass of top predator lake trout declined by 23-42% during and after EE2 additions, most
probably an indirect effect from the loss of its prey species, the fathead minnow and slimy
sculpin (Cottus cognatus).

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This study demonstrates that small-scale studies
focusing solely on direct effects are likely to
underestimate the true environmental impacts
of chemical contaminants.

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1) Susceptibility differences between species
• Differences in the rate and extent of
chemical being taken up, metabolized and
concentrated.
• Mating system plays a role
• Bioconcentration in fish tissues differ by
several orders of magnitude (Lagesson et
al. 2016).
Problems of scale and complexity:
Predicting effects in the wild from effects in the laboratory

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1) Susceptibility differences between species
• Differences in the rate and extent of
chemical being taken up, metabolized and
concentrated.
• Mating system plays a role
• Bioconcentration in fish tissues differ by
several orders of magnitude (Lagesson et
al. 2016).
Therefore, two species inhabiting the same polluted system can be
exposed to very different internal concentrations of contaminants!!
Problems of scale and complexity:
Predicting effects in the wild from effects in the laboratory

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Problems of scale and complexity: wild vs lab species
• Differential behavioural responses to chemical contaminants in laboratory-
reared versus wild species
• The distribution of behavioural traits studied should be characterized within
each test group.
Saaristo et al. (2018) Proc. R. Soc. B, 285, 20181297.

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Conclusion
• Effects can vary dynamically within the same individuals and
populations - ‘All species are the same’ argument does not
hold
• Sublethal effects can be both ‘positive’ and ‘negative’ for
individuals, populations and communities.
• Risk assessment should consider both direct and indirect
effects of exposure to EDCs.

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Take-home message
Understanding the behavioural and ecological
mechanisms underpinning contaminant-induced
population changes is the key for environmental risk
assessments.

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Questions?
Contact
Email: minna.saaristo@epa.vic.gov.au
Twitter:#minnasaaristo