Adaptation to salinity in Atlantic cod from different regions of the Baltic Sea

• Published in: Journal of Experimental Marine Biology and Ecology
• Main Authors: Kijewska, Agnieszka, Kalamarz-Kubiak, Hanna, Arciszewski, Bartłomiej, Guellard, Tatiana, Petereit, Christoph, Wenne, Roman
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: atlantic cod; Gadus morhua
• Online Access: https://oceanrep.geomar.de/id/eprint/31650/; https://oceanrep.geomar.de/id/eprint/31650/1/Kijewska%20et%20al%202016_Adaptation%20to%20salinity%20in%20Atlantic%20cod%20from%20different%20regions%20of%20the%20Baltic%20Sea.pdf; https://doi.org/10.1016/j.jembe.2016.02.003

Highlights: • The stress response to salinity in subpopulations of the Baltic cod was examined. • Two different profiles of response to salinity were observed. • Changes in response profiles may be a functional adaptation to variable salinity. • Adaptation protects cod against stress during vertical and long-distance migrations. • Salinity is a barrier maintaining the genetic and physiological separations of cod. Abstract: Atlantic cod (Gadus morhua) occur in marine water of different salinities: from oceanic waters at salinity of 35 to Baltic Sea waters where the lowest level of salinity reaches 5–6. The stress response to different salinities in the eastern and western Baltic cod populations was examined. Two genes of Na +, K + -ATPase 1a (atp1a) and heat shock protein 70 (hsp70) expression, plasma cortisol and osmolality were used as markers of osmotic stress to characterize the reaction profiles of two populations of G. morhua from the western and eastern parts of the Baltic Sea. Atlantic cod were sampled in November 2012 from western Kiel Bight (KIEL, salinity of 18) and eastern Gdańsk Bay (GDA, salinity of 8). Live fish were transported to the Marine Station of the University of Gdańsk in Hel and were settled in tanks (3500 L). Cod were kept at 10 °C in recirculated water, which simulated the natural salinities of the geographic source region of the fish. Results showed that in the reduced and elevated salinity water of the KIEL group, we observed no change in expression of atp1a and slightly increased expression of hsp70. In the GDA group, there were no significant changes of hsp70 expression but the level of atp1a was significantly increased in both salinities. In both groups, concentration of cortisol increased after exposure to elevated salinity, while in fish exposed to reduced salinity, a significantly higher concentration of cortisol was observed after 72 h. The high expression of atp1a that observed in the eastern group (GDA) supports the thesis of a genetic background to the adaptation to variable ...