Recent studies on the dispersal-relevant behavior of marine fish larvae suggest that they possess the behavioral capabilities necessary to directly affect dispersal outcomes. Current research has shifted to determining to what extent larvae and young juveniles can manage their dispersal, as well as what sensory cues they can use for orientation and settlement. There is little contemporary data to suggest that larvae can detect the speed and direction of current without an external reference, which suggests that they lack control over their trajectories and eventual settlement location. The mummichog (Fundulus heteroclitus) is a species of marine killifish that inhabits and breeds in shorelines and tidal creeks, where juveniles may be subject to both tidal and North Atlantic currents. It is important to determine if an external reference in the form of a fixed visual cue influences ability to hold position in a consistent flow, as this has implications for population demographics and connectivity. Individual juveniles from two different growth stages were each placed into round white trial tanks, one left blank and one with black markings for visual reference. Average middle current speeds for the reference and control tanks were 0.1 and 0.092 m/s respectively. Each tank had a slow current zone above and below the middle current. Time spent per zone was recorded to see if the juveniles chose to orient towards a visual reference. Further analysis using Noldus Ethovision is ongoing; however, preliminary observations suggest that the references are important to the maintenance of position in the chamber.

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Faculty Advisor

Jill Leonard

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