Salinity selection by mummichogs
(animal behaviour by videography)
Mummichogs are essentially marine fish that live in estuaries. We found that mature males and immature males and females preferred to stay in seawater, when presented with a halocline with 10% seawater (SW) over and 100% SW under. However, mature, ovulating females showed a different behaviour, with no aversion to freshwater. Thus the mature ovulating females freely entered the upper layer of the halocline. The result, we believe, is that in the field, females who are ovulating lead the males into the shallows where the water is dilute and trher is vegetation on which to lay the eggs. To do this, we built a simple halocline chamber (see figure) with an antechamber for initial acclimation to the apparatus, and a main chamber with FW and SW. The halocline is easily visible because of the refraction of light. Publication: Marshall, W.S., Tait, J.C. Mercer, E.W. 2015 Salinity Preference in the Estuarine Teleost Fish Mummichog (Fundulus heteroclitus): Halocline Behavior Physiol. Biochem. Zool. 89(3):225-232. |