Estuarine caridean shrimp (Palaemon debilis Dana, 1852) (Decapoda: Caridea) can differentiate olfactory cues from different mangrove species for microhabitat selection

Environmental cues in mangroves such as chemicals released from senescent leaf litter could help guide juvenile nekton to their nursery habitats. A laboratory olfactory choice experiment was conducted using a three-channel choice flume to assess the ability of juveniles of the caridean shrimp Palaemon debilisDana (1852) to distinguish between water containing leachates from the leaf litter of the mangroves Avicennia marina (Forsk.) Vierh., Rhizophora stylosa Griff. and a mixture of the two species. Senescent leaves of these species of mangroves were soaked for 14 days in artificial seawater before being exposed to juvenile P. debilis in the flume. P. debilis spent significantly more time in R. stylosa water, followed by mixed R. stylosa and A. marina water, and least time in A. marina water. The consistent preference for R. stylosa water suggests that the chemical cues from senescent leaves of this mangrove species might influence choice selection by the shrimp. The olfactory choice experiment was further investigated to assess if the preference for senescent R. stylosa leachate (water) was due to the water-borne chemicals (either from the senescent R. stylosa leaf litter water or aged R. stylosa detritus) serving as an attractant to the shrimps, by comparing it to aged R. stylosa detritus and artificial seawater. Juvenile shrimp preferred senescent R. stylosa water, therefore suggesting a role of chemical attractants in the shrimp's choice of habitat.