{"id":42101,"date":"2026-07-22T00:01:19","date_gmt":"2026-07-22T04:01:19","guid":{"rendered":"https:\/\/beyondpesticides.org\/dailynewsblog\/?p=42101"},"modified":"2026-07-20T10:19:07","modified_gmt":"2026-07-20T14:19:07","slug":"aquatic-ecosystems-at-risk-study-finds-declines-in-macroinvertebrate-diversity-with-pesticide-exposure","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2026\/07\/aquatic-ecosystems-at-risk-study-finds-declines-in-macroinvertebrate-diversity-with-pesticide-exposure\/","title":{"rendered":"Aquatic Ecosystems at Risk; Study Finds Declines in Macroinvertebrate Diversity with Pesticide Exposure"},"content":{"rendered":"

(Beyond Pesticides<\/em>, July 22, 2026) A study of aquatic macroinvertebrates, including insects in their nymph and larval stages, snails, worms, crayfish, and clams, finds that pesticide exposure leads to biodiversity declines. Published in Environment International<\/em><\/a>, this research also finds that multiple stressors and chemical mixtures increase ecosystem effects. \u201cThe individual and interactive impacts of pesticide contamination and other environmental stressors on freshwater macroinvertebrates remain insufficiently quantified under real-world, multi-stressor conditions,\u201d the authors note. This research addresses that gap, identifying pesticide pollution as a threat to aquatic organisms<\/a> and ecosystem functioning<\/a>.<\/p>\n

In studying the Wei River Basin, one of the most intensively managed agricultural and urban regions in China, the data reveals that \u201cpesticides contributed more than 40% to both [Alpha] \u03b1-diversity loss (species richness<\/a>) and [Beta] \u03b2-diversity nestedness<\/a> [hierarchical interconnectedness], exceeding the combined effect of the other factors that were considered.\u201d Additional results, such as interactive effects between pesticides and land use, show that during the dry season there is \u201ca 2.1-fold increase in functional sensitivity and a 56% rise in interaction contributions.\u201d Ecological harm thresholds are also highest for the neonicotinoid insecticide imidacloprid<\/a>, followed by the herbicides hexazinone<\/a>, atrazine<\/a>, and simazine<\/a>.<\/p>\n

Study Importance<\/strong><\/p>\n

Freshwater ecosystems<\/a>, such as lakes, rivers, streams, reservoirs, and wetlands, are crucial habitats for numerous species. These areas also provide nutrient cycling and supply additional essential ecosystem services for food, water, and energy resources. \u201cGlobal freshwater ecosystems are subject to multiple, often synergistic<\/a>, pressures from anthropogenic activities and climate change<\/a>, potentially causing biodiversity losses and impaired ecological functioning,\u201d the researchers state. They continue, \u201cAmong these pressures, chemical pollution\u2014particularly pesticide contamination\u2014in certain landscapes is likely to be one of the more important stressors.\u201d<\/p>\n

Research<\/a> shows that in agriculture-dominated landscapes, pesticides are a widely recognized anthropogenic stressor, disrupting aquatic ecosystem structure and functioning with cascading impacts<\/a>. Additional scientific literature (see here<\/a>, here<\/a>, and here<\/a>) finds adverse effects on macroinvertebrates from insecticide exposure. Natural ecosystems are exposed to multiple environmental drivers, including but not limited to climate change, human land use intensity, hydrology alterations, and chemical pollution. The combined effects of multiple stressors can be additive or synergistic, causing greater damage to organisms and the environment when encountered simultaneously.<\/p>\n

\u201cTraditional ecological risk assessments typically rely upon single-pollutant, single-species laboratory tests, which may underrepresent the ecological consequences of stressor interactions under field conditions,\u201d the authors state. Understanding the effects of pesticide mixtures, as well as pesticides and other stressors, is crucial to protecting all organisms. Macroinvertebrates, in particular, are valuable bioindicators as they are sensitive to habitat and water quality changes.<\/p>\n

Methodology and Results<\/strong><\/p>\n

The aim of the study is to:<\/p>\n

“(1) quantitatively assess the relative contributions of pesticide contamination and co-occurring environmental stressors (including water quality, hydrology, and land use) to patterns of macroinvertebrate taxonomic and functional diversity;<\/p>\n

(2) examine whether interactive or modulatory relationships exist between pesticide stress and other environmental stressors, with particular attention to how hydrological seasonality influences the strength and pathways of these effects;<\/p>\n

(3) identify community-level ecological thresholds along pesticide toxicity gradients, in order to improve the ecological relevance of pesticide risk assessment under realistic, multi-stressor conditions.\u201d<\/p>\n

The Wei River is the largest tributary of the Yellow River, where the basin \u201cprovides an ideal model system for examining the interactive effects of pesticide pollution and land use on stream macroinvertebrate communities across contrasting hydrological seasons\u201d due to intensive agricultural activities and strong anthropogenic pressures in the area. Thirty-nine sites were chosen across the Wei River Basin and were sampled in both September 2023 (normal season) and April 2024 (dry season). This includes 25 riverine sites (along the banks of rivers or streams) and 14 tributary confluence sites. Samples of both water and macroinvertebrates were collected.<\/p>\n

Water samples were then analyzed for 49 commonly used and representative pesticides, including carbamates (CAs), neonicotinoids (NEOs), triazines (TRIs), and organophosphates (OPPs), and macroinvertebrates were identified. The results show that all “49 pesticides were detected, including 11 CAs, 9 NEOs, 14 OPPs, and 15 TRIs.\u201d The authors continue, saying: \u201cAt least one pesticide was detected at each sampling site, while 10 pesticides showed detection frequencies exceeding 90% (92.5-100.0%) on average across both sampling periods, comprising 5 NEOs, 4 TRIs, and 1 CAs. Imidacloprid, thiamethoxam, and atrazine achieved 100% detection rates at all sampling sites during both sampling periods.\u201d<\/p>\n

Additional noteworthy results include:<\/p>\n