Occurrence of agricultural pesticides in Mississippi Delta Bayou Sediments and their effects on the Amphipod: Hyalella azteca

Authors: Lizotte, Richard; Steinriede, Robert; Locke, Martin

Submitted to: Chemistry and Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2021
Publication Date: 2/17/2021
Citation: Lizotte Jr, R.E., Steinriede Jr, R.W., Locke, M.A. 2021. Occurrence of agricultural pesticides in Mississippi Delta Bayou Sediments and their effects on the Amphipod: Hyalella azteca. Chemistry and Ecology. https://doi.org/10.1080/02757540.2021.1886281.
DOI: https://doi.org/10.1080/02757540.2021.1886281

Interpretive Summary: Invertebrates, such as crustaceans, are important in assessing the effects of agricultural pesticides in low-flow streams (bayous). Bottom sediment from three Mississippi streams was examined for 14 different pesticides seasonally from 2011-2014 and crustacean survival, growth, and biovailability was used to determine potential biological impacts. While all 14 pesticides were detected in at least one sample, only four of the pesticides measured varied across bayous: heptachlor, bifenthrin, p,p’-DDT, and p,p’-DDE. Seasonally, sediment-bound '-cyhalothrin and p,p’-DDT were greatest in winter while trifluralin, atrazine, and clomazone were greatest in the fall. Nine pesticides were detected in crustacean tissues with greatest concentrations for atrazine, p,p’-DDT, and ß-cyfluthrin. Crustacean survival and growth varied in conjunction primarily with tissue p,p’-DDT indicating that this banned insecticide continues to significantly impact sediment quality in agricultural stream watersheds. Study results are of interest to regulatory and other agencies and farming stakeholders by providing additional information on pesticide contamination to help improve and sustain water quality and overall environmental quality.

Technical Abstract: Sediment quality within three intensively cropped low-flow streams (bayous) of Mississippi, USA, was evaluated across bayous, habitats (upstream, midstream, downstream), and seasonally (winter, spring, summer, fall) from 2011-2014 for pesticide contamination, effects, and bioavailability to Hyalella azteca. Four-week (28-day) sediment bioassays using H. azteca were conducted to assess biological effects (survival and growth) and biovailability (tissue residues). Fourteen pesticides were detected in at least one sediment sample and nine pesticides were detected in H. azteca tissues. Spatially only four pesticides varied with p,p’-DDT and p,p’-DDE greatest in Cow Oak Bayou sediments and heptachlor and bifenthrin greatest in Howden Lake Bayou sediments. Seasonally, sediment-bound '-cyhalothrin and p,p’-DDT were greatest in winter while trifluralin, atrazine, and clomazone were greatest in the fall. Sediment H. azteca 28-day survival and growth (mg wet weight) ranged from 0-100% and 0.8-4.1 mg, respectively, with response patterns showing: Cow Oak > Roundaway, Howden (survival); Cow Oak > Roundaway > Howden (growth); downstream > upstream, midstream; and spring > winter. Greatest tissue pesticide residues during the study occurred for (1,003 µg/kg). However, patterns in tissue pesticide residues were influenced primarily by p,p’-DDT: Cow Oak < Roundaway < Howden; fall and spring < winter; fall < summer. Regression models indicated H. azteca tissue p,p’-DDT residues had the greatest contribution to biological impairment in bayou sediments. Despite the banned use of p,p’-DDT in the USA for 40 years, this insecticide continues to significantly impact sediment quality in agricultural stream watersheds.