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Ecosystem processes - challenges for radioecology Clare Bradshaw Dept. of Ecology, Environment and Plant Sciences (EMB) Stockholm University, Sweden [email protected] CERAD kick-off meeting, Oscarsborg Fortress, Oslofjord, April 17-19 2013 Who am I?! My particular interest / focus • Understanding the role of ecology in determining the fate/effects of contaminants, including radionuclides/radiation – Mainly through experiments using ecologically relevant scenarios, but also field studies • Raising the profile of / critically addressing such issues and looking for ways to incorporate such knowledge in a practical way into risk assessment, management – e.g. IUR Ecosystems Approach Task Group ”Environmental protection” Are we protecting ecosystems? ICRP 2007: Aim: “… preventing or reducing the frequency of such radiation effects to a level where they would have a negligible impact on the maintenance of biological diversity, the conservation of species, or the health and status of natural habitats, communities and ecosystems”. IAEA 2003: “…to safeguard the environment by preventing or reducing the frequency of effects likely to cause early mortality or reduced reproductive success in individual fauna and flora to a level where they would have a negligible impact on conservation of species, maintenance of biodiversity, or the health and status of natural habitats or communities”. Ecosystems are complex! Resources Physical conditions organisms/populations Current situation Ecosystem processes: include effects and fate/exposure • In both cases, often a lack of ecological and/or environmental realism • We base legislation and guidelines aimed at protecting ecosystems on data from – single species/individuals – equilibrium conditions – and/or (even worse ) purely physics and chemistry • Bottom up thinking (small scale to large scale, simple to complex, extrapolation) – why not the reverse? State of the art: fate/exposure • • • • • Lots of field measurements (esp Cs)! Lots of chemistry, not much biology/ecology Heavy focus on using (e.g.) Kd, CR...in predicting/modelling Lab studies rarely include biological/ecological factors Some steps being made to include more complexity – BLM to take into account a range of physicochemical factors – More studies appearing on trophic transfer as a pathway – Modelling taking into account ecological, spatial and temporal aspects of RN distributions Kumblad et al 2003, 2004 An example of how ecological processes can affect RN uptake: Daphnia magna 14C assimilation 20 18 3 days of feeding on 14C labelled phytoplankton DPM/ug Daphnia 16 14 12 10 8 6 4 C A5 A50 Daphnia take up more C from irradiated phytoplankton A100 B5 B50 B100 Daphnia take up less C the more they are irradiated D5 D50 D100 Intermediate situation where both are irradiated? State of the art: effects • Wealth of data on single species, cellular level effects, not so much of populations, ecosystems • Problems with extrapolation from these studies to population/ecosystem level • Current attempts to improve the situation – More experiments addressing population-relevant endpoints – Population models, dynamic models – Species Sensitivity Distributions (SSDs) + = H. Kautsky An example of how ecological processes can influence effects of radioactivity: Indirect effects on interspecies competition Monoraphidium:Dunaliella ratio relative to original ratio on Day1 Dunaliella tertiolecta vs. Monoraphidium contortum 10 9 8 7 6 5 4 3 2 1 0 0 25 50 200 1000 0 2 4 6 8 10 12 Day 2 phytoplankton species, acute gamma up to 1000 Gy at day 0 Reflections on RA2 (from an ecosystem perspective) • To specify how speciation, cocontaminants, climate conditions and biological factors influence radionuclide transfer through ecosystems in a Nordic context, and to replace equilibrium transfer constants with time and temperature dependent functions… • Uptake in organisms – influence of environmental factors…great! • Uptake in organisms - influence of ? biological factors (not so well developed in the text) Reflections on RA3 • To identify responses induced in biota exposed to … radiation … in combination with other stressors … under varying temperature/climate conditions • Mention of importance of indirect effects in introduction...though this is not much expanded • Field work mentioned briefly, (...’impacts at individual/ population/ community and ecosystem levels’) but not expanded on. • Many single species tests mentioned (of different trophic levels), but I lack the link between these. • Multispecies exposures mentioned - not many details, careful planning needed!) ? Reflections on RA4 • To evaluate and improve impact, risk and benefit-cost assessments … scientifically based set of decision criteria for handling radiation and multi-stressors within an environmental and societal perspective….ecosystem approach • Benefit Cost Analysis , Damage Function Approach…in the last step of DFA - estimate the economic value of damages from radiation and multi-stressors, using valuation techniques for public health and ecosystem services . If this is achieved it would be a huge step forward, but unclear how it will be done • Analyse community-level responses in form of species sensitivity distributions… SSDs say NOTHING about community level responses!! ?! ?! Challenges • Complexity! – Difficult to study – Difficult to understand – Even more difficult to implement in risk assessment etc • Finding good ways to extrapolate from simple to complex (or start looking at the complexity!) • Finding good ways to reduce or deal with – variability – uncertainty • Challenging the status quo H. Kautsky GOOD LUCK CERAD! What about ecosystems? • Single species are usually considered. • Existing methods do not usually take into account biological and ecological processes – these can strongly influence uptake and exposure to ionising radionuclides – indirect effects MarLin H. Kautsky Model ecosystem experiments Potamogeton Ruffe Smelt Idotea Roach (juv) Fucus Theodoxus Zooplankton Pilayella Phytoplankton Particulate matter Dissolved matter Hydrobia Cerastoderma Macoma Sediment 0-3cm Sediment 3-6cm 1.5 MPB1 Mn Co V Fe Cl Ti As Ni Al VP2 Zr VP1 VP3 Br SED361 PIL1 Th SED031 Li PIL3 I SED033 Cu SED032 PIL2 Pb SED362 Mg Si SED363 FUC3 Cr FUC1 Rb FUC2 F Ba Cs THEO4 THEO3 Na MAC3 MAC1 MAC2 Mo S Cd Nd C Zn Ce Gd Pr N3 N2 K N Yb Sm N1 G3 Eu Ho Tb Dy M2 P G1 Er Tm Lu M1 G2 M3 Ca POM3 POM1 Hg POM2 Se -1.5 PC2 MPB2 -1.0 PC1 3.0 Lots of assumptions Doses to organisms have been estimated in a rather generalised way, e.g. based on: – activity concentrations in the surrounding environment, – bioconcentration factors, transfer factors – reference organisms – organism geometry H. Kautsky Distribution (106 g) and annual flux (106 g y-1) of C Next step: adapt C flow models to element / radionuclide flows with radionuclidespecific data Kumblad et al 2003/4 • Easy – just measure the water • Assume equilbrium (but this is rarely the case) • Don’t take into account biological processes • Vary widely with time, space, type of organism, element... • Lack of data means extrapolation necessary (between types of organism, elements, ecosystems...) Using CRs Concentration in water (mg/L) x CR (mg/kg)/(mg/L) = Concentration in organism (g/kg) An example of CR variability: brackish/marine benthophytes GM, 90% CI Nordén et al., 2010 / Konovalenko unpublished Difficulties with existing data • Most data are from – Individuals – Single species – Mortality rather than reproduction endpoints – Acute radiation exposure – High doses – External irradiation – Laboratory – Radiation alone (and these are the least relevant!) + = Savannah River Ecology Laboratory accuracy, reliability single species experiments Low Dose-Rate Irradiation Facility mesocosm / model ecosystem studies ecosystem / field studies environmental relevance H. Kautsky