Figure 1.

Sampled stations across the five sub‐basins of the Baltic Sea during two cruises on board of R/V Elisabeth Mann Borgese on July 24–25 in 2014 and on board of R/V Meteor on July 30–31 in 2015. The core study site was the Eastern Gotland Basin (EGB, yellow diamond). In the Western Baltic (WB) and the Arkona, Bornholm, and Southern Gotland Basins (AB, BB, SGB), samples were taken only for basin‐specific “isoscapes” based on the δ¹³C values of essential AAs in mesozooplankton (black dots)