1ESM 202Assessing the Effects of Chemicals on EcosystemsHuman vs. Ecotoxicology Human ToxicologyDeals with acute (e.g. occupational health) and chronic (e.g. cancer, liver damage) human health issuesFocus on individualsGoal: acceptable risk to human receptors EcotoxicologyDeals with effects on all other organisms, including acute and chronic effectsFocus on populationsGoal: minimize loss of biota and ecosystem integrityEffect of ChemicalsMethods Toxicity Tests/BioassaysAcuteChronic Field Assessments/Surveys Bioaccumulation Studies Biomarkers Microcosm & Mesocosm StudiesToxicity Tests Provide a direct measure of biological uptake of the toxicants Establish link between site contamination and adverse ecological effects May provide info on synergistic or antagonistic interactions among chemicals Direct extrapolation of lab to field should be carefully evaluated May do an in situtoxicity test under field conditionsToxicity Tests Toxicity tests can be used for both aquatic and terrestrial systems Aquatic tests are more developed Endpoints are mortality, growth and/or reproduction VertebratesRodentsFishBirdsToxicity Tests InvertebratesInsectsAmphipods (crustacea related to shrimp and krill)Plankton MicrobesLuminescent bacteria (Microtox) PlantsAquatic or terrestrialVascular or non-vascularToxicity Tests Environmental MatricesWater freshwater estuarine/marineSediments freshwater estuarine/marineSoils Used to develop Water Quality Criteria (WQC) for different usesToxicity Tests/Bioassays Standardized methodsEPAUS Army Corps of EngineersASTMOrg. of Economic Cooperation and Development (OECD) Aquatic Toxicity tests for:fishinvertebratesalgaeAcute Aquatic Toxicity Tests Most frequently used (short = less expensive) Relates dose (Cwx time of exposure) to time of death for a particular test organism Produce concentration/response curve Ranges from 1 to 4 days for aquatic tests and up to 10 days for assessment of sediment toxicity Done in laboratory under controlled conditionsAcute Aquatic Toxicity TestsChronic Aquatic Toxicity Tests Longer tests: 7 - 30 days Objective is to expose for at least 1/10th of lifetime  Effect of different Cwon growth, reproduction, behavioral, physiological or other biological function Sub-chronic: only exposed during part of life-cycle (usually early stages) Life-cycle tests have been done for only a few contaminantsChronic Aquatic Toxicity TestsChronic Aquatic Toxicity TestsSediment ToxicitySediment Toxicity USEPACompilation of National Recommended Water Quality Criteria and EPA's Process for Deriving New and Revised CriteriaWATER QUALITY CRITERIA AND STANDARDS PROGRAMToxicity TestsTerrestrial Toxicity Tests Direct exposure of test biota to media samples from a site Indirect exposure to filtered water exposed to soil or sediments samples Exposure to leachates from a site Controlled exposure to a specific contaminant using soil from the siteTerrestrial Toxicity Tests Test biotasoil microbes and fungi - critical role in C, N, S, P cycling, plus production of SOM and other organicsinvertebrates (earthworms and insects): provide essential ecosystem functions These tests are fast, simple and relatively inexpensive, with relevant results to evaluate effects on ecosystem biogeochemical functionsTerrestrial Toxicity Tests Vertebrates:amphibian: survival, growth and reproductive successavian and small mammal: reproductive success and body burden Feeding studies (small mammal and avian toxicity tests) are useful to determine potential uptake and transfer within the food web - potential human exposure route Standard protocols have been derived from veterinary studies and FDA methods, but many are still under development Longer than invertebrate testsTerrestrial Toxicity Tests Vegetationmostly cropsprimary endpoints are: survival: seed germination test growth: seedling growth rate and root elongation test reproduction success: vascular plant toxicity photosynthesis rates: chlorophyll fluorescence assaycan be applied in lab or in the fieldnutrient,water and light limitations can complicate analysis of resultslonger term studiesField Assessments Field surveys link chemical analyses and toxicity tests with actual effects Provide information on extent and patterns of contamination Indicate presence of sensitive plants or animals At larger scale provide info on structure, function and dynamics of populationsTemporal Scale10,000 years1,000 years100 years10 years1 year1 month1 dayPopulation DynamicsRegional DynamicsEcosystemDynamicsMacro-organismResponseMicro-organismResponse1 mm 1 m 1 km 100 km 1,000 kmSpatial ScaleTemporal Scale10,000 years1,000 years100 years10 years1 year1 month1 day1 mm 1 m 1 km100 km1,000 kmSpatial ScaleAcid RainDepositionPhotochemicalOxidantsEffluentReleasesHazardousWaste SitesLocal PesticideApplicationsChemicalspillsBroad ScalePesticideApplicationsField Assessments Survey of some or all the populations in the aquatic or terrestrial community Community structure and/or function are assessedField AssessmentsField Assessments Remote sensing methodscurrent resolution may be at 10m or less depending on quality of satellite data Ground-truthing: direct observation Long-term monitoring Population surveysBiomarkers Biological measure of an organism’s response to a contaminant Analyze biological tissues, fluids or cells to determine if affected by pollution Integrates temporal exposure and multiple exposure pathways Evaluates pollutant and by-productsBioaccumulation Evaluate net accumulation of chemical in organism through ingestion of water or food containing the chemical Measures difference between rate of ingestion and rate of excretion Particularly useful for highly accumulating chemicals:metalsPCBs, some pesticidesMicro and Mesocosm Controlled experiments in lab or field to study changes at any level:populationcommunityecosystem Microcosm are small studies, usually in lab Mesocosm are large, containing many species, usually outdoorsMicro and Mesocosm Advantages of microcosm studies:Better than single-species studiesMore space efficientEasier to maintain controlled conditionsReplication and standardization easierLow chance of contaminating the environmentMicro and Mesocosm Issues with Microcosm:Can’t simulate certain processes (e.g. acid