Which group of organisms is primarily affected by pesticide runoff into water bodies?

Pesticide runoff into water bodies primarily affects aquatic organisms because these chemicals often enter lakes, rivers, and streams directly, where they can be toxic to fish, amphibians, and invertebrates that inhabit these ecosystems. Aquatic organisms are particularly vulnerable due to their reliance on water for survival, reproduction, and feeding. The toxicity of various pesticides can disrupt physiological functions, impair development, and lead to mortality in these organisms, causing significant ecological imbalances.

Moreover, aquatic ecosystems are interconnected with terrestrial environments; pesticides that enter these water bodies can affect the entire food web, including organisms that rely on aquatic plants and animals for food. Therefore, understanding the impact of pesticide runoff is crucial for protecting aquatic life and maintaining biodiversity in these ecosystems.