Survival and precopulatory guarding behavior of Hyalella azteca (Amphipoda) exposed to nitrate in the presence of atrazine

Abstract

Nitrate is one of the most commonly detected contaminants found in aquatic systems with other pesticides such as atrazine. The current study examined potential combined effects of nitrate and atrazine on adults of the freshwater amphipod Hyalella azteca, using survival and precopulatory guarding behavior as toxic endpoints. Although significant differences in acute toxicity with nitrate alone and in binary combination with atrazine (200 µg/L) in water-only tests were not consistently observed for each time point, potential biologically relevant trends in the data were observed. Posttest growth and behavioral observations (10-day period) conducted after 96-hour exposure suggested that atrazine and nitrate at these concentrations did not result in delayed effects on H. azteca. However, when test conditions were modified from standard toxicity tests by feeding amphipods, nitrate was found to be more toxic, with a reduction in median lethal concentration (LC50) values of approximately 80%. We also demonstrated that nitrate exhibits a dose-response effect on precopulatory guarding behavior of H. azteca, suggesting that reproductive effects may occur at environmentally relevant concentrations.

Contrasting effects of chloride on growth, reproduction, and toxicant sensitivity in two genetically distinct strains ofHyalella azteca

“…Influence of chloride on ( A ) relative growth in 10‐d tests, ( B ) acute nitrate toxicity, and ( C ) acute sulfate toxicity to the US laboratory and Burlington strains of Hyalella azteca . Sulfate toxicity data for the US laboratory strain are from Pandey et al . LC50 = median lethal concentration.…”

“…A chloride dependence of acute nitrate toxicity to H. azteca is consistent with other reported acute values from the literature. Pandey et al obtained a 96‐h LC50 of 124 mg N‐NO 3 /L in a water with 1.9 mg Cl/L, whereas Soucek and Dickinson reported an LC50 of 667 mg N‐NO 3 /L in Borgmann water, which has a nominal chloride concentration of 72 mg/L.…”

“…Toxicity of sulfate to H. azteca was strongly influenced by chloride, with mean lethal concentration (LC50) values increasing from 512 mg/L to 1881 mg/L when chloride was increased from 5 mg/L to 25 mg/L, respectively [10]. Furthermore, a nitrate LC50 value reported by Pandey et al [11] for adult H. azteca tested in water with 1.9 mg Cl -/L was approximately 5-fold lower than that reported for juveniles by Soucek and Dickinson [12] in water containing 72.7 mg Cl -/L.…”

Burrowing in the Freshwater MusselElliptio complanatais Sexually Dimorphic and Feminized by Low Levels of Atrazine

“…At time = 0, either ATR, estradiol or vehicle was added to the tanks and carbon filters were removed, but water continued to circulate and all other conditions were maintained as above. Atrazine degradation in aquaria was shown to be minimal (Mazzanti et al, 2003), and other studies used a single ATR water contamination for exposures lasting 72 and 96 hr (Griggs and Belden, 2008; Pandey et al, 2011), suggesting that the desired concentrations were maintained for the 6-hr experimental period although ATR concentration in the tank water was not independently verified.…”

Acute toxicity of nitrate in Litopenaeus vannamei juveniles at low salinity levels

“…The material presented in this research adds to the current knowledge more data about the sensitivity of the penaeid shrimp Litopenaeus vannamei to the nitrate. Although, there are studies on acute toxicity to some aquatic organisms (CAMARGO et al, 2005;PANDEY et al, 2011;SOUCEK & DICKINSON, 2012) there is still a demand for more information of the effects on this species, especially at low salinity. In aquaculture it is important to know the limits of tolerance of the species that is aimed to be cultivated since the parameters of water quality are determinant factors for the maintenance of cultivation systems.…”