Habitat-specific signal structure for olfaction: An example from artificial streams

Many animals use chemical signals to acquire information about their habita ts. The structure of this information is dependent upon specific features w ithin a habitat, and the information in signals can be habitat-specific. We quantified the spatial and temporal information in an aquatic odor plume i n three different artificial stream habitats with different substrate types by measuring turbulent odor plumes with an electrochemical detection syste m. Streams had one of three substrate types that correlated with typical aq uatic habitats: sand (approximate to 4.2 x 10(-2) cm diameter), gravel (app roximate to 2.5 cm), and cobble (approximate to 4.5 cm). As predicted from the hydrodynamics, the spatial and temporal structures of the signals were different on different substrates. Spectral analysis showed that the sand a nd cobble substrates had signals that were dominated by lower frequency flu ctuations, whereas gravel had the highest and broadest range of signal fluc tuations. Cross- and autocorrelations showed that signals on the gravel sub strate had the largest spatial and shortest temporal components. Our result s imply that the information obtained from chemical signals may be limited in some habitats. These constraints on information may affect how organisms perform chemically mediated behaviors.