Isotopic ratios in freshwater gammarids (caged) and wild fish from 15 continental sites (2018) and one reference site (2019)

This dataset reports δ13C and δ15N measurements in caged gammarids (Gammarus fossarum) and wild fish (chub Squalius cephalus; barbel Barbus barbus; roach Rutilus rutilus) from 15 sites in French rivers. Gammarids were collected at a pristine site, sorted in order to select male individuals of about 2 mm size, and exposed in the field for three weeks, without food added (AFNOR standard XP T 90-721 (2019) Encagement in situ de gammares pour la mesure de la bioaccumulation de substances chimiques). This was repeated three times (June, September and November) in 2018. Fish were caught by electrofishing between July and November, 2018. Each fish sample is composed of several individualsof the same size class. δ13C and δ15N were analyzed by isotopic mass spectrometry after separation of N and C by chromatography. The dataset comprises 55 gammarid records of each isotopic ratio, including 10 records from a reference site (T0), and 15 fish records for both δ13C and δ15N.