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Population level effects of contaminated sediments on an estuarine fish, Fundulus heteroclitus

Population level effects of contaminated sediments on an estuarine fish, Fundulus heteroclitus Dawn D. Davis and Thomas J. Miller University of Maryland Center for Environmental Science Chesapeake Biological Laboratory Solomons, MD 20688 USA.

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Population level effects of contaminated sediments on an estuarine fish, Fundulus heteroclitus

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  1. Population level effects of contaminated sediments on an estuarine fish, Fundulus heteroclitus Dawn D. Davis and Thomas J. Miller University of Maryland Center for Environmental Science Chesapeake Biological Laboratory Solomons, MD 20688 USA ehpnet1.niehs.nih.gov/docs/ 1996/104-9/innov.html

  2. Many toxicology studies focus on individual- level responses of organisms: • Usually exposed to only one contaminant • Mortality is used as the end point (LC50s) • Most are short-term studies (< I month) njwrri.rutgers.edu/graduate/

  3. If we want to be more realistic in terms of how contaminated sites and organisms interact in the environment, we should examine: • A suite of contaminants that may affect organisms in the environment • Sub-lethal effects from contaminants over a longer period of time • Population-level responses, such as size shifts, production, or population growth rates

  4. This is a five-year collaborative project by scientists from the University of Maryland Center for Environmental Science, the Virginia Institute of Marine Science, and the Academy of Natural Sciences Estuarine Research Center - all of which are members of the Chesapeake Research Consortium (CRC) • The aim is to quantify how low but chronic levels of pollutants affect ecologically important Bay species.

  5. Elizabeth River Chesapeake BayNorfolk,VA • Region of concern identified by • the Chesapeake Bay Program • Water/Sediment quality influenced by: • Highly industrialized, commercial • and military activities • Densely-populated urban areas

  6. Population dynamics Quantifying the response of the mummichog, Fundulus heteroclitus, to exposure to sub-lethal levels of contaminated sediments with respect to: • Population dynamics • Production • Bioenergetic partitioning • Expression of biomarkers • Toxin uptake in fish tissue

  7. ObjectivesI.F1 experiment: Adult mummichogs were exposed to 4 dilutions of Elizabeth River sediment and 2 levels of clean food for 120 days: • Measure growth in length and weight • Quantify reproduction from egg production II. Egg performance experiment (EP) • Measure egg size, yolk size, hatching success, andsize at hatch for larvae under contaminated conditions • Larval performance experiment (LF) • Measure larval traits through size and yolk size at hatch, and growth over 14 days

  8. F1- Experimental design • Fully-factorial design involving 24 50-gallon aquaria • 4 sediment treatments • 6.25% (ERL),12.5 % (ERM)and25 %(ERH)Elizabeth River Dilutions • Control =Fishing Bay (FB) • 2 food treatments: • Low (L): 6% body weight d-1 • High (H): 12% body weight d-1 • 3 replicates • 56 Fundulus added to each tank • 28 ‘small’ fish (< 56 mm) • 28 ‘medium’ fish (56-70 mm)

  9. F1 experiment Adult Fundulus % known mortality (+/- SD) P=0.0036 B AB B B B A A AB

  10. F1 experiment Adult Fundulus mean growth rate over 120 days (+/- SD) p<0.0001 A A B B BC BC C C

  11. F1 experiment Fundulus mean egg production

  12. F1 experiment Fundulus total mean egg production (+/- SD)

  13. ObjectivesI.F1 experiment:Adult mummichogs were exposed to 4 dilutions of Elizabeth River sediment and 2 levels of clean food for 120 days: • Measure growth in length and weight • Quantify reproduction from egg production II. Egg performance experiment (EP) • Measure egg size, yolk size, hatching success, andsize at hatch for larvae • Larval performance experiment (LF) • Measure larval traits through size and yolk size at hatch, and growth over 13-14 days

  14. Egg performance • Eggs were collected daily from collectors in each tank. Eggs were subsequently grouped by week # of the F1 experiment • Eggs incubated for 14 days in standard culture media, exposed to air for 2 hours and then placed into highly aerated seawater for 30 minutes • This hatching process occurred for 3 days, eggs unhatched on the 3rd day of the hatching process were termed “unhatched” or “dead” www.miljolare.no/virtue/img/Species/ pages/Fish%20eggs.php

  15. Egg performance Fundulus mean egg area by week (+/- SD) Sediment p < 0.0011 Egg area = sediment, food, week B B AB AB AB AB A A Food B A B A B A B A

  16. Egg performance • Hatching success • No sediment, food, or time treatment effect • Dry weight at hatch: • No sediment or food treatment effect • Week effect (heavier dry weight for week 6 and 16) • (p<0.0001) • Yolk area: • No sediment or food treatment effect • Week effect (larger yolk area for week 6 and 16) • (p<0.0001) • However, Weeks 5, 6, and 16 only had one tank represented • for these measurements. This response may not be real.

  17. ObjectivesI.F1 experiment: Adult mummichogs were exposed to 4 dilutions of Elizabeth River sediment and 2 levels of clean food for 120 days: • Measure growth in length and weight • Quantify reproduction from egg production II. Egg performance experiment (EP) • Measure egg size, yolk size, hatching success, andsize at hatch for larvae • Larval performance experiment (LF) • Measure larval traits through size and yolk size at hatch, and growth over 13-14 days

  18. Larval performance • Larvae were hatched from eggs collected during 2 weeks of the F1 experiment: • LP2 – week 2 • LP4 – week 4 • 9-20 larvae per treatment were placed into a 10 gal. tank • Fundulus larvae were fed ad libitum rations of Artemia larvae for 14 days • Total length was measured at the end of the incubation

  19. B A B A B A B A B B A A A A A A Larval performance LP2: Mean initial length (+/- SD) of Fundulus larvae p < 0.0001 TL = sediment, food, sediment*food Food Sediment N=9 N=15

  20. Larval performance Percent increase in growth in length for Fundulus larvae http://jonahsaquarium.com/picfundhetero.htm

  21. Conclusions www.elizabethriver.org/ monitoring/monpg1.htm • Adult Fundulus growth showed a dose-dependent response to contamination • In the egg performance experiments: • There was no significant effect of maternal exposure to • contamination with respect to hatching rates, larval size at • hatch, and yolk area • Maternal exposure and food treatment interacted to affect • egg size • In the larval performance experiments: • Maternal exposure and food treatment interacted to affect larval • size, but not growth

  22. Conclusions, cont. • Individual lifestages may differ in how they are affected by contaminants so it is important to look at the whole lifecycle of an organism • It appears that somatic growth is a more sensitive • indicator of sub-lethal effects in fish than • reproduction www.whoi.edu/fishtox/ bonyfish.html

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