Plant-animal interaction within the red mangroves, Rhizophora mangle L., of Tampa Bay: Mangrove habitat classification and isopod, Sphaeroma terebrans Bate, colonization of a dynamic root substrate

A descriptive study was conducted to compare the above and below-water architecture of the red mangrove, Rhizophora mangle L., habitat of Tampa Bay, FL along with the Tampa Bay-wide distribution, abundance, and demography of the wood boring isopod, Sphaeroma terebrans Bate, that utilizes the prop roots of R. mangle prop roots as habitat. Additionally, physical setting and root quality features which influence the colonization of prop roots by the isopod and measures of tree response to isopod attack were evaluated.; Based upon habitat architecture, the results of this study do not indicate a sharp distinction between overwash and fringing mangrove habitat; the two appear architecturally undistinguishable. Similarly, no difference was found in the distribution or abundance of S. terebrans within the two habitat types. Although infestation by S. terebrans in Tampa Bay was consistent between habitat types and similar to that of more tropical regions, the distribution of S. terebrans was not continuous around the Bay. A substantially higher occurrence and density of S. terebrans was found in the northern versus more southern regions of Tampa Bay, most likely due to dispersal limitation and/or differential juvenile survivorship.; Experimental manipulation, using natural root substratum, uniquely identified the submergence depth of a prop root, a characteristic of a root's physical setting, as an important feature of habitat suitability for S. terebrans . Root diameter was the most important root quality feature found to influence colonization. Colonization of new root substratum was rapid and juveniles, the predominant colonizers, preferred to burrow into the root tip region (i.e. youngest part of the root). The absence of colonization on grounded roots in Tampa Bay appeared to be related to intrinsic plant features and not predation. After attack, abandoned burrows in mangrove prop roots are repaired. Moreover, the most common response of Rhizophora to isopod damage was the replacement of root tissue rather than the stimulation of new tissue production via lateral roots. These last results question the classification of this mangrove-isopod relationship as one of beneficial herbivory.