Using single‐species toxicity tests, community‐level responses, and toxicity identification evaluations to investigate effluent impacts

Abstract

Abstract-Whole effluent toxicity (WET) tests are increasingly used to monitor compliance of consented discharges, but few studies have related toxicity measured using WET tests to receiving water impacts. Here we adopt a four-stage procedure to investigate the toxicity and biological impact of a point source discharge and to identify the major toxicants. In stage 1, standard WET tests were employed to determine the toxicity of the effluent. This was then followed by an assessment of receiving water toxicity using in situ deployment of indigenous (Gammarus pulex) and standard (Daphnia magna) test species. The third stage involved the use of biological survey techniques to assess the impact of the discharge on the structure and functioning of the benthic macroinvertebrate community. In stage 4, toxicity identification evaluations (TIE) were used to identify toxic components in the effluent. Receiving-water toxicity and ecological impact detected downstream of the discharge were consistent with the results of WET tests performed on the effluent. Downstream of the discharge, there was a reduction in D. magna survival, in G. pulex survival and feeding rate, in detritus processing, and in biotic indices based on macroinvertebrate community structure. The TIE studies suggested that chlorine was the principal toxicant in the effluent.

Effects of municipal wastewater on aquatic ecosystem structure and function in the receiving stream

“…Amphipods, remaining leaf discs and any leaf tissue shredded off were removed after seven days of exposure, dried and weighed as described above. The feeding rate observed during the in situ bioassays as well as the laboratory feeding trial was calculated in milligram of consumed leaf mass per milligram dry weight of Gammarus per day (Maltby et al, 2000).…”

Effects of two sorbents applied to mercury-contaminated river sediments on bioaccumulation in and detrital processing by Hyalella azteca

“…The daily detrital processing rate measured during the first experiment was expressed as milligram of leaf mass loss per milligram dry mass of amphipod, while only replicates without mortality were assessed (Maltby et al 2000). To gage statistically significant differences between treatments, CI testing as described by Altman et al (2000) and suggested by Cumming (2012) was employed for detrital processing and bioaccumulation data for each contact time.…”

Ecotoxicological evaluation of three tertiary wastewater treatment techniques via meta-analysis and feeding bioassays using Gammarus fossarum

“…Amphipods, remaining leaf discs and any leaf tissue shredded off were removed after seven days of exposure, dried and weighed as described above. The feeding rate was calculated in milligram per milligram dry weight of Gammarus per day [28].…”