BRYOZOAN SPECIES FROM LATERAL ECOZONES ACROSS LOOE KEY REEF (LOWER FLORIDA KEYS) -- MODERN ANALOGS FOR PLEISTOCENE INTERPRETATIONS

Looe Key, at 24° 32.8' N, 81° 24.4' W, 8 mi (13 km) SSW of Big Pine Key, is a large outer reef exhibiting well-developed ecozones: back reef (1-5 m depth), reef crest (0-5 m), and fore reef (5-30 m). Preliminary examination of reefal bryozoans here indicated striking similarity to those in the Pleistocene reef formerly exposed at the junction of U.S. 1 and Fla. 905, thereby stimulating more collecting (prior to establishment of marine sanctuaries) and identification of over 1500 colonies (representing 66 encrusting cheilostome species here, plus 10 other cyclostome and tuft-like species).

     Zonation among the Looe Key bryozoan species is subtle, expressed by varying proportions of common but through-ranging species, plus restricted-distribution but rare species.

     Fourteen species are most common in one ecozone but occur rarely in others: Microporella ciliata on the reef crest; Arthropoma cecilii, Codonellina montferrandi, Mastigophora pesanseris, Smittina smittiella in the back reef; Cellepora? coronata, Crepidacantha poissonii, Cribrilaria radiata, Exechonella antillea, Floridinella typica, Hippopodina feegeensis, Parasmittina signata, P. spathulata, Trematooecia turrita on the fore reef. Six additional are common throughout all three ecozones (and so tend to overshadow the variations in the others listed above): Cleidochasma porcellana, Crassimarginatella crassimarginata, Reptadeonella violacea, Smittipora americana, Steginoporella magnilabris, Stylopoma spongites.

     Each ecozone here contains several unique species but all so rare that their use as paleoecologic indicators is problematic (or, possibly, their restriction may be an artefact of their rarity): 3 on the reef crest, 30 in the back reef, 9 on the fore reef. Finally, 14 additional rare species occur in more than one ecozone.