The influence of water chemistry on copper neurotoxicity in fish

Transcription

1 The influence of water chemistry on copper neurotoxicity in fish Photo by Morgan Bond SWASSW Jenifer McIntyre Dec David Baldwin, Nat Scholz - NOAA-Fisheries, NWFSC

2 Copper is neurotoxic Peripheral sensory system Gustation (taste) Olfaction (smell) Mechanosensation (lateral line)

3 Olfaction begins at olfactory rosettes Anguilla anguilla Kuhlia sandvicensis Lepisosteus platostomus Eleotris sandwicensis Hansen & Zielinski J.Neurocytol. 34

4 Olfactory Sensory Neurons Nonsensory Microvillous Ciliate d Hansen & Zielinski J.Neurocytol. 34

5 Cross-Species Cu Toxicity All sensitive to olfactory toxicity at low ppb dissolved Cu

6 Bioavailability Is copper in PNW salmon streams bioavailable to the salmon nose?

7 Copper Bioavailability - Fish Gill Biotic Ligand Model (BLM) = classic metals toxicity in fish water Cations Gill tissue DOM Cu + Na + transporter Anions Metals compete with cations at the biotic ligand Metals complex with anions & DOM Water chemistry determines bioavailability

8 Copper Bioavailability Fish Nose water Nose tissue Odour molecules Cations G olf AC Odour Receptor ATP DOM Cu +? K + Na + 2+ Cation channel Anions Cl - Cl channel Do ions & DOM protect nose against Cu?

9 Copper Bioavailability in Different Waters Low-ion Control 0.2 mm Ca 0.2 mm HCO 3 0 mg/l DOM + Hardness Alkalinity Dissolved Organic Matter One of 3 increases [Ca] [HCO 3 ] Hi ph Low ph [Fulvic Acid] [Natural Organic Matter] 10

10 Bioavailability Study Design pre-exposure to artificial test water (24-h) Fish placed on rig Test water over nose Measure electrical response to odours 15 min acclimation 30 min Cu exposure (20 μg/l) Odour exposure L-serine, TCA: 10 s each Alternating odour pulses every 2.5 min.

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12 % Relative Olfactory Response 120 Hardness [Calcium] mm Alkalinity Normal ph Low ph [HCO3-3 ] mm 120 Dissolved Organic Carbon Fulvic Acid NOM No-copper control 95% L.C.L. control Water Quality on Copper Neurotoxicity 20 μg/l Cu (30 min) significantly inhibits olfaction of L-ser (and TCA) Olfaction improves with calcium, bicarbonate, and DOC DOC has strongest effect [DOC] mg/l McIntyre et al ES&T. 42

13 Fathead minnow corroboration ppb Cu mm Ca Green et al ES&T 44

14 Hardness & Alkalinity in PNW Streams 5 Puget Sound Willamette Yakima Sacramento Calcium (mm) HCO 3 - (mm) Calcium (mm) Bicarbonate (mm) Copper nontoxic Copper toxicity reduced 50% Puget Sound Willamette Yakima Sacramento 95% SER Copper nontoxic Copper toxicity reduced 50% 50% SER No streams contain enough calcium for even 50% protection Only 1 stream sample (<1%) had enough bicarbonate for 50% protection 0 McIntyre et al ES&T. 42

15 DOC in PNW Streams Puget Sound Willamette Yakima Sacramento DOC (mg/l) Copper nontoxic Copper toxicity reduced 50% 6% of samples 19% of samples 0 McIntyre et al ES&T. 42 DOC should be measured along with dissolved copper concentrations in streams of concern

16 Water Chemistry Comparison: Gill vs Nose Hardness effect similar at: Gill Nose Alkalinity Very protective at fish gill Little protection at: Nose DOC protective at: Fish gill Less protective at: Nose McIntyre et al EST 42

17 Copper Toxicity to Lateral Line Danio rerio larva A B Control Fish Hair cells Copper-exposed No hair cells C Linbo et al ET&C

18 Copper Toxicity to Lateral Line 1. Hardness Linbo et al ETC? CaCl 2 MgSO 4 CaCl 2 :MgSO 4 2. Sodium NaCl NaHCO 3 3. Dissolved organic matter (DOC)

19 Ca Mg Chemistry Comparison Hardness effect similar at: Gill Nose Lateral line Alkalinity Very protective at fish gill Little protection at: Nose Lateral line (Na effect) McIntyre et al EST 42 Linbo et al ETC 28 DOC protective at: Fish gill Less protective at: Nose Lateral line

20 Freshwater Cu Bioavailability Cu Toxicity at Fish Gill Cu Toxicity at Fish Nose (and LL) Hardness Hardness DOC Cu + DOC Cu + Alkalinity Alkalinity Important to measure DOC and alkalinity in receiving waters

21 Fresh vs Seawater Cu Bioavailability Freshwater Cu Toxicity Ca 2+ Mg 2+ Na + Hardness DOC Cu + Saltwater Cu Toxicity Ca 2+ Mg 2+ Na + DOC Cu + Alkalinity CO 3 2- OH - HCO 3 - SO 4 2- CO 3 2- OH - HCO 3 - SO 4 2- Does saltwater protect against copper sensory toxicity?

22 Seawater Cu Bioavailability Important uncertainties relative to toxicity in freshwater Salinity - changes in copper complexation, etc. DOC influence - changes in copper/doc interaction Physiology - changes in fish upon smolting Olfactory toxicity of copper to seawater-phase salmon

23 Seawater Cu Bioavailability Baldwin et al. Unpublished results. No olfactory toxicity up to 100 ppb in seawater (35 ppt)

24 Sodium protective against Cu? Copper toxicity to lateral line neurons Copper toxicity (EC50 ppb) Linbo et al ETC 28 (NaCl, NaHCO 3 ) EC50 >500 ppb 436 mm

25 Measuring Olfactory Response: EOG & EEG Perfusion Recording electrode Electro-olfactogram (EOG) Measures changed in electrical current at olfactory epithelium in perfusion water EEG measured at olfactory bulb Measures changed in electrical current at olfactory bulb no water chemistry interference with recording

26 Olfaction important to salmon behaviors Olfaction required for natal stream Cu homing Cu Reproductiv e priming & behaviour Copper may be developmentally neurotoxic Cu Cu Olfactory predation cues can alter egg hatch timing Cu And/or fry emergence Cu May interfere with imprinting

27 Cu Sensory Toxicity: Research Needs What are current water chemistry conditions (esp. DOC)? What changes in water chemistry are predicted? Is olfactory toxicity in adult salmon similar to juveniles? Species specific measurements for SOC (e.g. sockeye) Consequences of Cu toxicity to other olfactory behaviors Homing Reproductive priming and behaviors Better understanding of mechanosensory toxicity Testing in salmonids Functional impairment vs cell death Survival consequences of mechanosensory impairment

28 Acknowledgements Funding Sources: NOAA Coastal Storms Program EPA S.T.A.R. Graduate Fellowship NOAA Oceans & Human Health Technical & Field Assistance James Meador (NOAA Fisheries - Montlake) Julann Spromberg NOAA Fisheries Montlake) Dave Rose (University of Washington) Gordy George (University of Washington) Matt Gilman (WA Dept. Fish & Wildlife) Chris Tatara (NOAA Fisheries - Manchester) Barry Berejikian (NOAA Fisheries - Manchester) Sarah McCarthy (King County DNR) Evan Malczyk (King County Environmental Lab)

29 Olfactory Neuroanatomy Stimulated By: Bile salts Amino acids Steroids ciliated microvillous crypt Olfactory Sensory Neuron Types Behaviours: Alarm Feeding Reproductive

30 Copper impacts olfactory receptors Rosett e Epithelium Dendrites with odour receptors Axon reaching olfactory bulb Number olfactory neurons 4 hr (Hansen et al ETC 18) Copper can destroy olfactory receptors

31 Copper inhibits olfaction Baldwin et al ET&C. 22:2266 Sandahl et al ES&T 30 min in 10 μg/l Cu 70% inhibition Relative EOG = 0.3 Recording electrode Electro-olfactogram (EOG) Inhibition of olfaction: Dose-dependent Short exposures Low concentrations