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 USA ehpnet1.niehs.nih.gov/docs/ 1996/104-9/innov.html

 Usually exposed to only one contaminant  Mortality is used as the end point (LC 50 s)  Most are short-term studies (< I month) njwrri.rutgers.edu/graduate/ Many toxicology studies focus on individual- level responses of organisms:

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

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)CRC The aim is to quantify how low but chronic levels of pollutants affect ecologically important Bay species.

Elizabeth River Chesapeake Bay Norfolk,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

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

Objectives I. 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, and size at hatch for larvae under contaminated conditions III.Larval performance experiment (LF)  Measure larval traits through size and yolk size at hatch, and growth over 14 days

 Fully-factorial design involving gallon aquaria  4 sediment treatments 6.25% (ERL), 12.5 % (ERM) and 25 % (ERH) Elizabeth River Dilutions Control = Fishing Bay (FB) F1- Experimental design  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)

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

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

Fundulus mean egg production F1 experiment

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

Objectives I. 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, and size at hatch for larvae III.Larval performance experiment (LF)  Measure larval traits through size and yolk size at hatch, and growth over days

 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 3 rd day of the hatching process were termed “unhatched” or “dead” pages/Fish%20eggs.php Egg performance

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

Objectives I. 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, and size at hatch for larvae III.Larval performance experiment (LF)  Measure larval traits through size and yolk size at hatch, and growth over days

 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 Larval performance

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

Percent increase in growth in length for Fundulus larvae Larval performance

 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 monitoring/monpg1.htm Conclusions

 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 bonyfish.html Conclusions, cont.