The prop roots support an abundance 

 of sessile organisms. The vertical 

 zonation of both mobile and sessile inver- 

 tebrates has been studied extensively in 

 other parts of the world (Goodbody 1961; 

 Macnae 1968; Rutzler 1969; Coomans 1969; 

 Bacon 1970; Kolehmainen 1973; Sasekumar 

 1974; Yoshioka 1975). Vertical zonation 

 certainly exists on Florida red mangrove 

 roots. The generalized scheme shown in 

 Figure 9 essentially contains two zones: 

 an upper zone dominanted by barnacles and 

 a lower zone dominated by mussels, oysters 

 and ascidians. Between mean high tide and 

 mean tide, the wood boring isopod, 

 Sphaeroma terebrans (discussed at length 

 in section 2.7) is important, both numeri- 

 cally and through the provision of 

 numerous holes for use by other organisms 

 (Estevez 1978). 



The most complete study of the 

 Florida mangrove prop root community is 

 Courtney's (1975) comparison of seawall 

 and mangrove associations. He reported an 

 extensive list of invertebrates from man- 

 grove prop roots at Marco Island, Florida, 

 including: Crassost rea v i r g i n i c a , 

 Li ttori na angul i fera , Crepidula pi ana , 

 Diodora cayenensis , Urosalpinx perrugata , 

 Pisania tincta , Brachidontes exustus , 

 nine species of polychaetes, Sphaeroma 

 t erebrans , Pal ae m on floridanus , 

 Peri cl i menes longi caudatus , Synalpheus 

 fritz m uelleri , Thor floridanus , 

 Petrol isthes armatus , and at least eight 

 species of crabs. The following species 

 were found only on mangrove roots and not 

 on seawalls: T u r i t e 1 1 a sp., Mel ongena 

 corona , Anachi s semiplicata , Bulla 

 striata , Hypselodoris sp., Area imbricata , 

 Carditamera floridana , Pseudoi rus typica , 

 and Martesia striata. 



Tabb et al. (1962) and Odum and Heald 

 (1972) reported a variety of invertebrates 

 associated with prop roots in the White- 

 water Bay region. Although many species 

 coincide with Courtney's (1975) list, 

 there are also significant differences due 

 to the lower salinities in this region. 

 It is probably safe to conclude that prop 

 root communities vary somewhat from site 

 to site in response to a number of factors 



including latitude, salinity, and proxi- 

 mity to other communities such as sea 

 grass beds and coral reefs. 



Sutherland (1980), working on red 

 mangrove prop root communities in 

 Venezuela, found little change in the 

 invertebrate species composition on indi- 

 vidual prop roots during an 18-month 

 period. The species composition varied 

 greatly, however, between adjacent prop 

 roots, presumably in response to stochas- 

 tic (chance) processes. 



The mud flats adjacent to mangroves 

 provide feeding areas for a range of in- 

 vertebrates that scuttle, crawl, and swim 

 out from the cover of the mangrove roots. 

 Some emerge at low tide and feed on algae, 

 detritus, and small invertebrates on the 

 mud flats while they are high and dry. 

 Others emerge while the tide is in, parti- 

 cularly at night, and forage across the 

 flooded flats in search of the same foods 

 plus other invertebrates which have 

 emerged from the mud. In many ways the 

 mangrove-mud flat relationship is analo- 

 gous to the coral reef (refuge) sea grass 

 (feeding area) relationship reviewed by 

 Zieman (in prep.). The net effect is that 

 the impact of the mangrove community may 

 extend some distance beyond the boundaries 

 of the mangrove forest. 



In addition to the organisms which 

 move from the mangroves to the mud flats, 

 there is a small group which uses the 

 substrate adjacent to mangroves for both 

 habitat and feeding. In the Whitewater 

 Bay region, four crabs exploit the inter- 

 tidal muds from the safety of burrows: 

 Ilea pugi 1 ator , LL speciosa , U. thayeri , 

 and Euryti urn 1 i mosum (Tabb et al. 1962). 

 In low salinity mangrove forests of south 

 Florida, the crayfish, Procambarus alleni , 

 is a dominant member of the burrowing, 

 benthic community (Hobbs 1942) as is the 

 crab, Rhithropanopeus harrisii (Odum and 

 Heald 1972). Both organisms are found in 

 a remarkable number of fish stomachs. 



The benthic fauna and infauna of 

 creek and bay bottoms near mangrove 

 forests are highly variable from one 



48 



