MP3 Chronic and Sublethal Sediment Toxicity
254 Portland Ballroom
1:20 PM - 4:40 PM, Monday
() Sensitivity and performance of chronic sediment toxicity tests in dredged material management.
Kennedy, A1, Farrar, J2, Steevens, J2, 1 Analytical Services, Inc., Vicksburg, MS, USA2 US Army Engineer Research and Development Center, Vicksburg, MS, USA
ABSTRACT- Although U.S. EPA / U.S. ACE dredged material evaluation guidance recommends use of chronic sediment toxicity tests, management decisions commonly use only acute lethality. Acute lethality, however, may inherently underestimate benthic population level effects associated with contaminated sediments. Chronic tests (28-d) using Leptocheirus plumulosus and Neanthes arenaceodentata and acute toxicity tests (10-d) using Americamysis bahia, Ampelisca abdita and Leptocheirus were conducted with nine contaminated sediments (e.g., PAHs 4,000 − 19,000 ppb) collected from New York Harbor, U.S.A. Test results were statistically compared to a control sediment. Significant differences were not observed in any of the sediments tested for Americamysis 10-d survival (≥75%) or Neanthes 28-d survival (≥70%) and biomass. Significant reductions in 10-d survival were observed in 6 and 7 of the sediments for Ampelisca (36 − 72%) and Leptocheirus (11 − 79%), respectively. Survival and reproduction of Leptocheirus during the 28-d test were significantly reduced in 4 and 3 of the sediments, respectively, while no significant response in biomass was observed. Preliminary findings suggest that the 10-d Americamysis protocol was insensitive to these contaminated sediments while the 10-d Leptocheirus and Ampelisca tests, in some cases, have greater sensitivity than chronic tests. Performance of the 10-d Leptocheirus protocol was validated using dilutions of the two most toxic sediments (i.e., Hudson, Newark) by dose-dependence (LC50 = 32 (22−46), 48 (43−54)%) and replicability was confirmed by similar survival in the 100% Hudson (11 ± 4, 12 ± 12%) and Newark (27 ± 14, 20 ± 11%) sediments. Lesser response in chronic tests may have resulted from confounders such as sediment matrix alterations (e.g., water renewals), contaminant bioavailability changes (e.g., food additions, sediment avoidance) and statistical power (e.g., high variability). Future work should involve interlaboratory comparison evaluating sensitivity/consistency of standard test methods and additional experimentation using dilutions of sediments contaminated by different chemicals.
Key words: aquatic toxicity, sediment toxicity, chronic toxicity, dredged material