The utilization of chemical communication by three species of ghost shrimp, Callichirus islagrande, Callichirus major, and Lepidophthalmus louisianensis, and the transport of chemical cues within and between burrows

Abstract

A multidisciplinary study of the factors affecting the potential use of chemical cues by three species of infaunal shrimp was performed in three parts. A set of modified y-maze choice experiments were performed to establish the ability of three species of ghost shrimp, Callichirus islangrande, Callichirus major, and Leptidophthalmus louisianensis, to detect conspecifics via chemical cue. The time budgets for the detection of conspecifics chemical cues differed significantly from controls (no cue) for both animal cues and odor only cues indicating that all three species were able to detect the difference in sex of conspecific chemical cues regardless of cue source. The differences between the trials in which the cue animal was present and odor cue alone was present may indicate the possible use of mechanical or ancillary cues in addition to odor. Odor plume behavior within the burrow environment was characterized using fluorescein dye visualization of an odor mimic in a model burrow for the second series of experiments. Combinations of slow and fast carrier and plume release rates were crossed with the following conditions: no shrimp mimic, 1 shrimp mimic (dye release source), and 2 shrimp mimics (one source and one 6 cm downstream). Release rate was more influential in determining plume structure and direction than carrier flow. Plumes retained their characteristics and did not become turbulent even in the presence of obstructions (shrimp mimcs). Communication between burrows was modeled using two porous burrow mimics built in natural sediment, 3.5 ml min-1 burrow effluent pumping rate, and 5 cm s-1 flow condition in a race track flume. Rhodamine-FWT effluent was tracked using fluorometery. The effect of burrow water density (natural and neutral) and pumping activity of the downstream burrow were crossed. A non-uniform zone of burrow water was established in the sediment surrounding the source burrow. Dilution of 1-2 orders of magnitude occurred between the effluent in the burrow and porewater, but 3-4 orders of magnitude in the surface sediments and downstream burrow. Density affected the concentration of effluent in the porewater around the source and downstream burrow. Pumping activity of the downstream burrow also affected dye distribution