 C. maenas can live in all types of protected and semi @-@ protected marine and estuarine habitats , including habitats with mud , sand , or rock substrates , submerged aquatic vegetation , and emergent marsh , although soft bottoms are preferred . C. maenas is euryhaline , meaning that it can tolerate a wide range of salinities ( from 4 to 52 ‰ ) , and survive in temperatures of 0 to 30 ° C ( 32 to 86 ° F ) . The wide salinity range allows C. maenas to survive in the lower salinities found in estuaries , and the wide temperature range allows it to survive in extremely cold climates beneath the ice in Winter . A molecular biological study using the COI gene found genetic differentiation between the North Sea and the Bay of Biscay , and even more strongly between the populations in Iceland and the Faroe Islands and those elsewhere . This suggests that C. maenas is unable to cross deeper water . 
