Aquatic plants: Test species sensitivity and minimum data requirement evaluations for chemical risk assessments and aquatic life criteria development for the USA

Abstract

Phytotoxicity results from the publicly-available ECOTOX database were summarized for 20 chemicals and 188 aquatic plants to determine species sensitivities and the ability of a species-limited toxicity data set to serve as a surrogate for a larger data set. The lowest effect concentrations reducing the sublethal response parameter of interest by 50% relative to the controls (EC) usually varied several orders of magnitude for the 119 freshwater and 69 saltwater plants exposed to the same test chemicals. Generally, algae were more sensitive than floating and benthic species but inter-specific differences for EC values were sometimes considerable within and between phyla and no consistently sensitive species was identified for the morphologically-diverse taxa. Consistent equivalencies of the phytotoxicity databases for freshwater-saltwater plants and floating-benthic macrophyte species were not demonstrated. Two species-sensitivity distribution plots (SSDs) were constructed for each of the 20 chemicals, one based on all available phytotoxicity information (range = 10-76 test species) and another based on information for only five species recommended for pesticide hazard evaluations. HC values (hazardous concentration to 5% of test species) estimated from the two SSDs usually differed four-fold or less for the same chemical. HC values for the five species were often conservative estimates of HC values for the more species-populated data sets. Consequently, the collective response of the five test species shows promise as an interim aquatic plant minimum data requirement for aquatic life criteria development. In contrast, the lowest EC values for the five species usually were greater than HC values for the same test chemicals, a finding important to criteria-supporting Final Plant Values. The conclusions may differ for comparisons based on other test chemicals, test species, response parameters and calculations.

Effects of treated wastewater on the ecotoxicity of small streams – Unravelling the contribution of chemicals causing effects

“…Even at these low concentrations, some of them can elicit effects on aquatic organisms [1]. Herbicides, such as diuron or terbutryn, and other plant protection products, can inhibit the growth and photosynthesis of algae and aquatic plants [2, 3]. Neurotoxic chemicals such as organophosphate and carbamate insecticides or neonicotinoids may lead to enzyme inhibition with subsequent behavioural effects on aquatic invertebrates as well as vertebrates [4–8].…”

Data and Diversity in the Development of Acute Water Quality Criteria in the United States

“…A final option to consider is a modification of the minimum data requirements in the National Guidelines to include aquatic plant and algal species. Although aquatic plants and algae contribute considerable ecological and economic value, they have historically been excluded from WQC development in the United States because of uncertainty over how to include them in the process (Lewis & Thursby, 2018). There are now numerous studies available that use plant data in SSDs (Ding et al, 2016; Lewis & Thursby, 2018; Song et al, 2015), suggesting that this uncertainty should now be less of a factor in criteria development.…”

Acute Toxicity of Herbicides and Sensibility of Aquatic Plant Wolffia brasiliensis as a Bioindicator Organism

“…Thus, this plant presented an excellent sensitivity response to the three reference substances, indicating the potential for its use in biomonitoring programs of chemical substances such as herbicides (Hasenbein et al, 2017). In an analysis of databases on aquatic plant sensitivity, Lewis and Thursby (2018) found 76 species susceptible to copper compounds, 69 to atrazine, 48 to irgarol (antifouling algicide), and 46 to diuron. The species belonging to the family Lemnaceae were considered the most sensitive.…”