Chronic / Sublethal Bioassays

Transcription

1 Chroic / Sublethal Bioassays Tab N Dr. Todd S. Bridges KEY WORDS: Chroic Sublethal Toxicity, Neathes, Leptocheirus, Hyalella, Chiroomus Why Chroic Sublethal Toxicity Tests? Required by Federal regulatios To address likelihood for loger-term impacts Evaluate potetial for sublethal effects Defiitive method for evaluatig margially cotamiated dredged material

2 Federal Regulatios 103 of MPRSA Materials shall be deemed evirometally acceptable for ocea dumpig oly whe...o sigificat udesirable effects will occur due either to chroic toxicity or to bioaccumulatio... [40 CFR 227.6(c)(3)] Materials will ot cause ureasoable acute or chroic toxicity or other sublethal adverse effects [40 CFR (b)] 404 (b) (1) of the Clea Water Act The permittig authority shall determie i writig the potetial short-term or log-term effects [40 CFR ] Acute vs. Chroic Toxicity Acute toxicity Short-term exposure (hrs-days) Adults Lethality edpoit Higher levels of cotamiatio Chroic toxicity Respose Loger-term exposure (days-weeks) Early life stages Sublethal edpoits (growth, reproductio) Lower levels of cotamiatio Dose/Exposure

3 Marie/Estuarie Tests Curretly Uder Developmet Neathes areaceodetata (28-day, survival, growth, >25 ) Polydora coruta (14-day, survival, growth) Leptocheirus plumulosus (28-day, survival, growth, reproductio, 5-20 ) Muliia lateralis (10-day, survival, growth,7-32 ) Freshwater Tests Curretly Uder Developmet Chiroomus tetas (10-day, survival, growth, <1 ) Chiroomus tetas (>40-day, survival, growth, & reproductio, <1 ) Hyalella azteca (10 ad 28-day, survival, growth, <1 ) Hyalella azteca (42-day, survival, growth, ad reproductio, <1 )

4 Selectig a Chroic Sublethal Test Factors to cosider: Ecologically relevat exposure sceario Represetative test orgaism Adequate iterpretive guidace Test edpoits Defied potetial for o-cotamiat effects Ecologically Relevat Exposure Scearios Water colum exposure durig ope water disposal is most commoly a short-term evet Chroic elutriate tests are ot relevat to evaluatig the potetial for water colum effects Exposig a test orgaism to media it s ulikely to ecouter i ature does ot provide relevat toxicity data Pore water tests with epifaual/pelagic orgaisms are ot appropriate for evaluatig dredged material

5 Neathes areaceodetata Natural history Marie polychaete (>20 ) Ifaual, 3-7 cm adult size Omivorous deposit-feeder 12-week life cycle Sexes form moogamous pairs Male provides the paretal care, female dies; direct developmet Adult worms are aggressive ad territorial Distributio Worldwide i shallow, sedimetary habitats Siblig species have bee idetified Neathes Chroic Toxicity Test Test Parameter Coditio Age/size Emerget juveiles (<7 d) Test duratio 28 d Saliity Exposure chamber 250-ml glass beaker Aimals/beaker 1 Reps/treatmet 10 Feedig 2 mg TetraMari & 1 mg alfalfa 2x weekly Edpoits Survival, growth (mg/day) Test acceptability >80% cotrol survival

6 Leptocheirus plumulosus Natural history Estuarie amphipod (5-20 ) Ifaual, U-shaped burrows 8-10 mm adult size Suspesio ad deposit feeder 4-week life cycle Females produce multiple broods Media life spa about 4 moths, females live loger tha males Distributio East coast U.S., Cape Cod to orther Florida Leptocheirus Chroic Toxicity Test Test Parameter Coditio Age/size µm (1-2 wks) Test Duratio 28 d Saliity 5-20 Exposure chamber 1-L glass beaker Aimals/beaker 20 Reps/treatmet 5 Feedig 1.0 mg Tetrami/aimal - 3x weekly (MWF)- first 2weeks; 2.0 mg/aimal thereafter. Edpoits Survival, growth, reproductio Test acceptability >80% cotrol survival, repro. i all reps Guidace maual:

7 Leptocheirus Compariso of Acute ad Chroic Tests d Compoud LC 50 LOEC LC 50 LOEC DANT DDT PCB Lead Fluorathee Hyalella azteca Natural history Freshwater amphipod Bethic, 3-7 mm adult size Grazer ad deposit-feeder 5-wk life cycle, 1-yr life spa Amplexus, mate guardig Females ca produce multiple broods of 1-30 youg Distributio North ad South America Shallow, letic ad lotic systems

8 Hyalella Chroic Toxicity Test Test Parameter Coditio Age/size 7-8 days old Test Duratio 42 d (10- ad 28-d versios) Saliity < 5 Exposure chamber 300-ml glass beaker Aimals/beaker 10 Reps/treatmet 12 Feedig YCT, 1 ml daily (1800 mg/l stock)/beaker Reewal 2X daily Edpoits Survival, growth, reproductio Test acceptability >80% cotrol survival o day 28 Chiroomus tetas Natural history Larvae of o-bitig midge 4 istars, 2-15 mm Deposit feeder 23- to 30-d life cycle Pupatio 25 d old Females produce 1 egg mass ( eggs) withi 24 h of matig Adult midges die withi 7 d of emergece Distributio Holarctic, commo i mid-cotietal North America Shallow letic ad lotic systems

9 Chiroomus Chroic Toxicity Test Test Parameter Coditio Age/size < 24-h-old larvae Test Duratio d (10- ad 20-d versios) Saliity Fresh water Exposure chamber 300-ml glass beaker Aimals/beaker 12 Reps/treatmet 16 Feedig 6 mg Tetrafi/beaker/d Reewal 2X daily Edpoits Survival, growth, reproductio Test acceptability >70% cot. surv. at day 20, >0.6 mgdw/aimal What is the Ecological Meaig of Chroic ad/or Sublethal Toxicity? The meaig of acute toxicity test results is prescriptively defied e.g., 20% plus statistical sigificace The meaig of chroic toxicity test results is curretly udefied e.g., what does a 10% reductio i growth mea i terms of populatio viability?

10 Statutory Requiremets The Marie Protectio, Research ad Sactuaries Act of 1972, Sectio 102 Effects o marie life icludig...chages i marie ecosystem diversity, productivity, ad stability; ad species ad commuity populatio chages The Clea Water Act of 1977, Sectio 404 Effects o potetial chages i marie ecosystem diversity, productivity, ad stability, ad...species ad commuity populatio dyamics Extrapolatig Effects Biochemistry- geotoxicity Tractability Developmet- fertilizatio, teratogeicity Histopathology- tumor formatio Life history- survival, growth, reproductio Populatio- extictio risk Commuity- structure Ecological Relevace Ecosystem- fuctio

11 Evaluatig Chroic Results: Itegratig Effects Sedimet Survival Growth Reproductio x x x x x x x Matrix Populatio Modelig Idividual >>>>>>>>>> Populatio - Survivorship - Growth - Reproductio Number Time

12 A A (t + 1) (t) (t + 1) (t) F F F F F P P P P s s s s = = Age-Classified Populatio Projectio Matrix Model Populatio Growth λ - The fiite rate of populatio icrease λ > 1, populatio icreasig λ = 1, populatio statioary λ < 1, populatio decliig to extictio

13 Populatio Growth (λ) Ref A B C D E Sedimets Leptocheirus plumulosus

14 Percet Survival Leptocheirus plumulosus 0% BRH-1X 0% BRH-2X 3% BRH-1X 3% BRH-2X 6% BRH-1X 6% BRH-2X Weeks 12 Leptocheirus plumulosus Body Legth (mm) % BRH-1X 0% BRH-2X 3% BRH-1X 3% BRH-2X 6% BRH-1X 6% BRH-2X Weeks

15 Offsprig/Survivor Leptocheirus plumulosus 0% BRH-1X 0% BRH-2X 3% BRH-1X 3% BRH-2X 6% BRH-1X 6% BRH-2X Weeks Leptocheirus plumulosus Populatio-level Effects Fiite Rate of Icrease (λ) * * Percet BRH Sedimet 1X Ratio 2X Ratio

16 Stochastic Matrix Populatio Modelig A (t + 1) (t) s = F1, σ F2, σ F3, σ F4, σ Fs, σ 1 P , σ 2 0 P2, σ P3, σ Ps 1, σ 0 s (t + 1) = A(t) X σ 1.00 Daphia maga Probability CONT-2 GH-1 GH-2 GH-4 SJ-2 SJ Populatio Size

17 Is the Test Ready? Test developmet* Ratioale Selectio of test orgaism Experimetal/statistical desig Evaluatio of ruggedess Field trials Iter-laboratory studies Iterpretive guidace Trasitio to multiple users Verificatio/validatio Stadard method developmet Evaluatio by user groups Overlyig Water Test Orgaisms Sedimet *Dillo 1994 Why Use Chroic Tests? Direct meas of assessig log-term exposures Especially relevat to highly hydrophobic cotamiats Exposures ca be more represetative of field coditios i.e., loger tha 10 days Sublethal edpoits are ecologically relevat Ca provide greater discrimiatory ability

18 Why Not Use Chroic Tests? They cost more Which is better, usig a chroic test or gettig twice the spatial coverage with a acute test? They are more likely to fail to meet performace stadards Necessitatig retestig They are ot always more discrimiatig tha acute tests e.g., sublethal edpoit variability ad role of feedig Disagreemet o the ecological cosequece of sublethal effects The ifluece of o-cotamiat iflueces o edpoits is problematic Coclusios Biological tests are a ecessary, but ot exclusive, elemet of sedimet assessmet Chroic toxicity tests offer utility Need for process-level research Challeges cofrotig the use of chroic tests iclude establishig The reliability of the tests Iterpretive guidace