A Test Battery Approach for the Ecotoxicological Evaluation of Estuarine Sediments

Abstract

The purpose of this study was to evaluate the overall sensitivity and applicability of a number of bioassays representing multiple trophic levels, for the preliminary ecotoxicological screening (Tier I) of estuarine sediments. Chemical analyses were conducted on sediments from all sampling sites to assist in interpreting results. As sediment is an inherently complex, heterogeneous geological matrix, the toxicity associated with different exposure routes (solid, porewater and elutriate phases) was also assessed. A stimulatory response was detected following exposure of some sediment phases to both the Microtox and algal bioassays. Of the bioassays and endpoints employed in this study, the algal test was the most responsive to both elutriates and porewaters. Salinity controls, which corresponded to the salinity of the neat porewater samples, were found to have significant effects on the growth of the algae. To our knowledge, this is the first report of the inclusion of a salinity control in algal toxicity tests, the results of which emphasise the importance of incorporating appropriate controls in experimental design. While differential responses were observed, the site characterised as the most polluted on the basis of chemical analysis was consistently ranked the most toxic with all test species and all test phases. In terms of identifying appropriate Tier I screening tests for sediments, this study demonstrated both the Microtox and algal bioassays to be more sensitive than the bacterial enzyme assays and the invertebrate lethality assay employing Artemia salina. The findings of this study highlight that salinity effects and geophysical properties need to be taken into account when interpreting the results of the bioassays.

Sediment contact tests as a tool for the assessment of sediment quality in German waters

“…from different trophic and organizational levels [23,[35][36][37]. Tuikka et al [23], who investigated seven natural sediments using a test battery similar to that of the present study (SCTs with invertebrates, fish, and bacteria), demonstrated differences in the sensitivities of the species and highlighted the need for data on multiple species, when estimating the effect of sediment pollution on the benthic community.…”

Sensitivity of bacterial vs. acute Daphnia magna toxicity tests to metals

“…A bioluminescence (BL) inhibition assay using Vibrio fischeri is often chosen as the first screening method in a test battery, based on speed and cost considerations [1][2][3]. V. fischeri has been used for more than 30 years in whole effluent toxicity testing (WET) [4], waste water treatment efficiency evaluation [5,6], surface water and sediment quality monitoring [7][8][9], ground water studies [10], risk assessment [11], and also as a model organism for fundamental studies on mode of action and toxicological pathways of various substances and mixtures [12][13][14][15][16].…”

Evaluation of Multixenobiotic Resistance in Dreissenid Mussels as a Screening Tool for Toxicity in Freshwater Sediments

“…In assessing the quality status of aquatic habitats, it has long been shown that particular attention must be paid to the chemical and ecotoxicological characterization of sediments (Cleveland et al 1997;Pederson et al 1998;Ghirardini et al 1999;Davoren et al 2005) because the sediment compartment acts as a sink and source of internal contaminant load posing a permanent threat to resident biota. Contaminants accumulated in the sediment have the potential to remobilize, and thus become bioavailable, after chemical (e.g., pH, salinity fluctuations), physical (e.g., dredging), or biological (e.g., bioturbation) processes (Davoren et al 2005).…”

“…Contaminants accumulated in the sediment have the potential to remobilize, and thus become bioavailable, after chemical (e.g., pH, salinity fluctuations), physical (e.g., dredging), or biological (e.g., bioturbation) processes (Davoren et al 2005). For the ecotoxicological evaluation of sediments, various acute and chronic bioassays have been developed, standardized, and successfully applied: Toxicity tests with bacteria and unicellular algae, crustacean bioassays, tests based on sediment-dwelling organisms, fish toxicity tests, etc.…”