{"id":40858,"date":"2026-02-03T00:01:29","date_gmt":"2026-02-03T05:01:29","guid":{"rendered":"https:\/\/beyondpesticides.org\/dailynewsblog\/?p=40858"},"modified":"2026-03-10T18:27:24","modified_gmt":"2026-03-10T22:27:24","slug":"pesticide-contamination-in-small-water-bodies-threatens-biodiversity-and-ecosystem-functioning-study-finds","status":"publish","type":"post","link":"https:\/\/beyondpesticides.org\/dailynewsblog\/2026\/02\/pesticide-contamination-in-small-water-bodies-threatens-biodiversity-and-ecosystem-functioning-study-finds\/","title":{"rendered":"Pesticide Contamination in Small Water Bodies Threatens Biodiversity and Ecosystem Functioning, Study Finds"},"content":{"rendered":"

(Beyond Pesticides<\/em>, February 3, 2026) In analyzing the direct and indirect effects of pesticides that act simultaneously upon macrozoobenthos<\/a> communities (invertebrates living in or on sediment) in standing small water bodies (SWBs) in Germany, researchers find high risks to biodiversity<\/a> and ecosystem functioning<\/a>. Published in Hydrobiologia<\/em><\/a>, the experiment finds high risks to invertebrates and highlights how both direct and indirect effects are vital to comprehensive assessments of pesticides. While typically overlooked in regulatory reviews, SWBs are defined<\/a> as shallow standing or running freshwaters \u201cwith a surface area of less than 50 hectares (ha),\u201d such as lakes or ponds, including farm ponds, as well as headwater streams, springs and flushes, and ditches.<\/p>\n

SWBs are biodiversity hotspots that contribute to numerous ecosystem services<\/a> and are adversely affected by agricultural land use effects such as pesticide contamination. \u201cHolistic assessments of pesticide effects on invertebrate communities in standing small water bodies have, however, not yet been successful,\u201d the authors note. To address this, the researchers developed an indicator for evaluating pesticide impacts on macrozoobenthos communities, populated with aquatic invertebrates, such as snails, worms, crayfish, and clams, through indirect toxic effects on aquatic plants called INPOND: INdirect Pesticide impacts ON Diversity in standing small water bodies.<\/p>\n

As the researchers state: “The indicator development process included structural and functional biodiversity indices, tested for correlations with toxic units for invertebrates, algae, and aquatic plants. Our results indicate low direct pesticide toxicity risks for macrozoobenthos in most of the investigated water bodies. However, INPOND reveals a high risk to invertebrates through pesticide-induced changes in aquatic plant communities, an essential habitat component shaping invertebrate assemblages.\u201d<\/p>\n

Background<\/strong><\/p>\n

Standing small water bodies (SWBs) are \u201chighly abundant, with over 277 million SWBs worldwide, making up to 90% of the total water body count and about 16% of the water surface of all inland freshwater bodies,\u201d the authors note. They continue: \u201cIn Germany, there are around 292,000 SWBs, of which 58,000 are located in agriculturally dominated areas. The most common SWB type in northeastern Germany is kettle holes. Kettle holes are depressions in the landscape that were formed by melting of dead ice, i.e., old glacial boulders, at the end of the Last Ice Age. Overlying sediment settled in these depressions and formed sinkholes filled with water.\u201d<\/p>\n

SWBs, as compared to other water bodies such as rivers, have higher biodiversity of macrophyte (aquatic plant) and invertebrate communities, as well as higher numbers of rare and endangered species. These small bodies of water are also \u201cstepping stones for the dispersal of organisms and could support shifts in species distribution due to changes in climate and seasons,\u201d the researchers state. “Thus, kettle holes are essential for biodiversity on a landscape level, especially given the current global decline in insect diversity, abundance, and biomass.\u201d Kettle holes, and other SWBs, also contribute further ecosystem services such as water retention and carbon sequestration, both of which are increasingly important with climate change<\/a>.<\/p>\n

\u201cDespite their global abundance and importance in regard to species conservation and the climate crisis, there is only little research on SWBs and impacts on community compositions and their ecological functions under anthropogenic influence,\u201d the authors note. In analyzing macrozoobenthos in SWBs, this provides insight into these data gaps, as macrozoobenthos are bioindicators of ecosystem health. As these organisms have species-specific needs, habitat diversity is linked directly to the diversity of macrozoobenthos and overall community composition. Impacts on habitat diversity, and thus macrozoobethos, from pesticides are identified in previous research. (See here<\/a>, here<\/a>, here<\/a>, here<\/a>, and here<\/a>.)<\/p>\n

Pesticides and other environmental contaminants can enter surface water, and subsequently SWBs, during and after application via several input pathways, including drift, run-off, erosion, exchange with groundwater, and inflow from drainages, and adversely impact the diversity of macrozoobethos. \u201cIt has also been found that macrozoobenthos communities in SWBs are at greater risk from the input of pesticides than those in larger water bodies,\u201d the researchers explain. \u201cIn a similar way, nutrients from agricultural fertilization can enter surface water and can have an effect on macrozoobenthos communities, potentially decreasing their biodiversity<\/a>.\u201d (See studies here<\/a> and here<\/a>.)<\/p>\n

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

To assess the ecological status of standing SWBs in agricultural areas of northeastern Germany, the authors compare pesticide contamination in kettle holes to the diversity of macrozoobenthos within the water bodies. \u201cIn order to obtain pesticide and macrozoobenthos diversity data, 84 agriculturally influenced standing SWBs in the federal states of Brandenburg (n\u2009=\u200960) and Mecklenburg-Western Pomerania (n\u2009=\u200924) were sampled,\u201d the researchers say. They continue, \u201cEach water body was surrounded by at least 90% agricultural land within a radius of 500 m, in order to ensure a primary influence by agricultural methods via water quality and habitat structure.\u201d<\/p>\n

Water sampling at multiple locations for each of the water bodies were collected and analyzed for 91 pesticide substances commonly used in agriculture, including fungicides, herbicides, and insecticides. Biodiversity data was also collected at each site, as well as reference sites to offer a comparison. This includes data on habitat types within the SWBs and sampling of \u201call invertebrate organisms living on bottom substrates with grain sizes larger than 0.5 mm, for example, aquatic insects, snails, mussels, and crustaceans.\u201d<\/p>\n

Both direct and indirect pesticide effects were calculated, using calculations for acute pesticide load, toxicity, and biodiversity indexes, as well as the INPOND (INdirect Pesticide impacts ON Diversity) indicator. As a result, the authors find that:<\/p>\n