Overcoming water quality effects in biological monitoring: a case study of amphipod in situ exposures in Ontario agricultural streams

• DOI: 10.1007/s10661-025-13665-8
• Publication Date: 2025-02-04T18:33:31Z
• Authors: Matthew Hammond; Lisa Brown; John Struger; Lee Grapentine; Vince Palace; Adrienne J. Bartlett
• Keywords: Environmental Monitoring; Carbamate

Abstract Bioindicators add valuable understanding of biological impacts to contaminant monitoring programs. However, attributing effects (e.g., mortality and growth impairment) exposures is challenging because potential confounding by environmental variables. We assessed the influence four water quality variables (temperature, dissolved oxygen, pH, conductivity) on assessments during in situ amphipod Hyalella azteca six agricultural urban watersheds southern Ontario, Canada (2005–06, 2008–10). further tested whether sampling specific months growing season would minimize effects. While high toxicity from organophosphate carbamate pesticides increased reduced caged amphipods, warmer stream temperatures also affected endpoints, increasing improving growth. Seasonal patterns indicated early summer (June) as optimal for detecting when: (1) pesticide concentrations were highest, (2) acetylcholinesterase (AChE) inhibition (a biomarker organophosphate/carbamate exposure) was (3) temperature below its seasonal peak. Specifically, higher correlations among concentrations, AChE inhibition, better attribution cause this month (r = 0.53—0.76, p < 0.05). Ability discriminate between pesticide-impacted sites reference greater than other (June 100% correct assignment high-impact or site). Considering times bioindicators that maximize responses limit may improve accuracy resource-efficiency