Unique 16S rRNA sequences of Eurythenes gryllus (Crustacea: Amphipoda: Lysianassidae) from the Gulf of Mexico abyssal plain

Abstract

Amphipods of the species Eurythenes gryllus were collected at 2 locations on the abyssal plain (~3 400 m) of the Gulf of Mexico in order to test whether or not these scavenger amphipods are isolated in this peripheral sea or show connectivity by their predominant swimming behavior, moving horizontally along the abyssal water masses in the region. Partial sequences of the mitochondrial 16S rRNA gene from 2 individuals of E. gryllus were determined and showed small differences when compared to sequences of other amphipods of the same species from the Atlantic Ocean (3.6 to 3.9%) and Pacific Ocean (4.0 to 4.1%) and increasing (4.2 to 9.5%) when compared to sequences of specimens from sites of less than 500 m. The largest differences (18%) were observed when the sequences were compared to that of Eurythenes from the Tongue of the Ocean in spite of its closer geographical distance in the region. Isolation in the deep Gulf of Mexico could be attributed to limited genetic exchange with the western tropical Atlantic through the Caribbean over the 2 040 m deep sill and inexistent at abyssal depth through the Florida Straits.