Meeting Abstract
Gulf Flounder, a species of migratory flatfish commonly found in coastal waters spanning from North Carolina to the Gulf of Mexico, travel significant distances (10s-100skm) from shallow coastal nursery areas to reach deepwater spawning sites. However, the sensory basis guiding this movement remains a mystery. Previous research suggests that some aquatic animals can sense the earth’s magnetic and use that ability both to determine direction (a magnetic compass sense) and as a “magnetic map” for determining position on the earth’s surface, similar to a GPS used by humans. We aimed to determine if Gulf Flounder possess a “magnetic map sense,” which would allow them to use the Earth’s magnetic field to guide their migration from spawning grounds to feeding areas and back. To search for the presence of a magnetic map sense, we exposed flounder to one of two artificially-generated magnetic fields that replicate magnetic fields located north (near New Jersey) and south (near Jamaica) of the experimental site of Morehead City, NC. Juvenile flounder were placed in a small orientation arena and allowed to swim freely in either the New Jersey or the Jamaica field for 1.5 hrs. Video analysis indicated that flounder tested in the northern magnetic field of New Jersey significantly oriented towards magnetic SE, and flounder tested in the southern magnetic field of Jamaica showed weak orientation towards magnetic NE. Results from these two treatments were significantly different. These results provide evidence for a magnetic map sense in Gulf Flounder, adding flounder to the growing list of marine migrants that utilize this cue.
