Aquatic ecotoxicology studies

Aquatic ecotoxicology evaluates the probability of an adverse impact of a substance on the aquatic environment at the present as well as in the future, considering the total flow into the system (Klein, 1999). It encompasses laboratory ecotoxicity tests on appropriate test organisms to explore relationships between exposure and effect under controlled conditions as well as studies of the effects of substances or effluents under a variety of ecological conditions in complex field ecosystems (Chapman, 1995). 

Good Laboratory Practice and Quality Assurance procedures required for acute and chronic health effect studies can be used for acute and chronic mammalian, aquatic and avian ecotoxicology studies. 

Manusadzianas, L., Balkelyte, L., Sadauskas, K., Blinova, I., Pollumaa, L. and Kahru, A. (2003) Ecotoxicological study of Lithuanian and Estonian wastewaters selection of the biotests, and correspondence between toxicity and chemical-based indices, Aquatic Toxicology 63 (1), 27-41. 

An ecotoxicological study of the effects of PG in aquatic systems has shown that PG should be classified as toxic to aquatic organisms [23]. The study was carried out using several ecological systems, but the IC50 values obtained ranged from 10 to 1090 xM, which might be related to a variety of factors. 

Numerous studies confirmed ubiquity of several antibiotics (i.e., ofloxacin, trimethoprim, roxythromycin, and sulfamethoxazole) in sewage influent, though at low ng level [8, 13, 14]. However, even at very low concentrations they can have significant ecotoxicological effects in the aquatic and terrestrial compartment [15, 16]. Indiscriminate or excessive use of antibiotics has been widely blamed for the appearance of so-called super-bugs that are antibiotic-resistant. It is of crucial importance to control their emissions into the environment through more cautious utilization and monitoring outbreaks of dmg-resistant infections. 

Environmental monitoring and toxicological studies dealing with water [266, 296-298], sediment [299-301], mussels [300], and fish [296,297,302] imply that these compounds continue to pose a major ecotoxicological threat in the aquatic environment. 

Laboratory toxicity tests have been developed and conducted over the past decades to demonstrate adverse effects that chemicals can have on biological systems. Along with other complementary tools of ecotoxicology available to measure (potential or real) effects on aquatic biota (e.g., microcosm, mesocosm and field study approaches with assessment of a variety of structural and/or functional parameters), they have been, and continue to be, useful to indicate exposure-effect relationships of toxicants under defined, controlled and reproducible conditions (Adams, 2003). 

Svenson, A. and Zhang, L. (1995) Acute aquatic toxicity of protolyzing substances studied as the Microtox effect, Ecotoxicology and Environmental Safety 30 (3), 283-288. 

ECETOC] European Center for Ecotoxicology and Toxicology of Chemicals. 1997. The value of aquatic model ecosystem studies in ecotoxicology. ECETOC technical report no. TR 073. 

Dawn Maycock is a director of wca environment. She has a first degree in biology and environmental studies and a PhD in ecotoxicology. Recent work on EQSs has included using survival time analyses and species sensitivity distributions to derive time-specific EQSs for monitoring specific discharges, and development of aquatic EQSs for a range of substances under the Water Framework Directive (Annex VIII). 

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