common freshwater amphipod

<em>Gammarus pulex</em> is a small crustacean in the family Gammaridae, order Amphipoda, commonly known as the common freshwater amphipod or freshwater shrimp. This species inhabits freshwater streams, rivers, and lakes across Europe, with documented occurrences in six European countries. <em>Gammarus pulex</em> is a key component of freshwater ecosystems, serving as an important detritivore and shredder that breaks down leaf litter and organic matter, contributing significantly to nutrient cycling in stream ecosystems. It also forms a critical prey item for freshwater fish, birds, and invertebrate predators, occupying a central position in freshwater food webs. The species is highly sensitive to water quality, particularly to organic pollution and chemical contaminants, and is frequently used as a bioindicator in freshwater ecological assessments. <em>Gammarus pulex</em> typically inhabits cool, well-oxygenated running waters with abundant leaf litter and debris. Biological traits of this species remain poorly documented in the scientific literature.