location to the next. Many of these 

 organisms, particularly the deposit and 

 filter feeders, benefit from particulate 

 organic matter originating from mangrove 

 litter fall (Odum and Heald 1972, 1975b). 

 Tabb and Manning (1961) and Tabb et al. 

 (1962) present lists and discussions of 

 many of the benthic invertebrates adjacent 

 to mangrove areas of Whitewater Bay. 

 Weinstein et al. (1977) compared the ben- 

 thic fauna of a mangrove-lined creek and a 

 nearby man-made canal on Marco Island. 

 They found (1) the mangrove fauna to be 

 more diverse than the canal fauna and (2) 

 a higher diversity of organisms at the 

 mouths of mangrove creeks than in the 

 "heads" or upstream ends. Courtney (1975) 

 found the same pattern of upstream 

 decreases in diversity, presumably in 

 response to decreasing oxygen concentra- 

 tions and increasingly finer sediments. 



Finally, the irregularly flooded sub- 

 strates in the center of mangrove forests 

 contain a small but interesting assemblage 

 of invertebrates. The litter layer, 

 composed largely of mangrove leaves, evi- 

 dently includes a variety of nematodes. 

 Due to the usual taxonomic difficulties in 

 identifying nematodes, complete species 

 lists do not exist for mangrove forests; 

 however, many species and individuals are 

 associated with the decaying leaves 

 (Hopper et al. 1973). In addition to 

 nematodes, the wetter sections of the 

 swamp floor can contain mosquito and other 

 insect larvae, polychaetes, harpacticoid 

 copepods, isopods, and amphipods. 

 Simberloff (1976) lists 16 species of 

 insects associated with the muddy floor of 

 mangrove forests. Roaming across the 

 forest floor during low tide are several 

 crustaceans including the mangrove tree 

 crab, Aratus pi soni i , crabs of the genus 

 Sesarma , and the pulmonate gastropods, 

 M e 1 a m pu s coeffeus and Cerithidea 

 scalariformis. Both snails clearly have 

 the ability to graze and consume recently 

 fallen leaves (personal observation). 

 With favorable conditions (relatively fre- 

 quent tidal inundation plus the presence 

 of red mangroves) Melampus populations can 



exceed 500/m and average 100 to 200/m 

 (Heald, unpublished data). Cerithidea i s 

 found largely in association with black 

 mangroves ayid can reach densities of at 

 least 400/n/. 



6.4 WATER COLUMN COMMUNITY 



This section is embarrassingly short; 

 the reasons for this brevity are (1) the 

 paucity of research on zooplankton in 

 Florida mangrove-dominated areas and (2) 

 our inability to discover some of the work 

 which undoubtedly has been done. Davis 

 and Williams (1950) are usually quoted as 

 the primary reference on Florida mangrove- 

 associated zooplankton, but their paper 

 only lists zooplankters collected in two 

 areas. Zooplankton near mangroves are 

 probably no different from those found in 

 other shallow, inshore areas in south 

 Florida. Based on Davis and Williams 

 (1950) and Reeve (1964), we can hypothe- 

 size that the community is dominated by 

 copepod species of genus Acartia , particu- 

 larly Acarti a tonsa . In addition, we 

 could expect a few other calanoid cope- 

 pods, arrow worms ( Sagi tta spp.), many 

 fish, polychaete and crustacean larvae and 

 eggs. Another component of the "plankton" 

 particularly at night, are benthic 

 amphipods, mysids, and isopods which leave 

 the bottom to feed (personal observation). 



Plankton are not the only inverte- 

 brates in the water column. Swimming 

 crabs, such as the blue crab, Callinectes 

 sapidus , are plentiful in most estuarine 

 mangrove regions of south Florida. Other 

 swimming crustaceans include the caridean 

 shrimp ( Pal aemonetes spp. and Peri - 

 climenes spp.), the snapping shrimp 

 ( Al pheus ~spp.), and the penaeid shrimp 

 ( Penaeus spp). All of these swimming 

 crustaceans spend considerable time on or 

 in the benthos and around mangrove prop 

 roots. From the economic point of view, 

 the pink shrimp, Penaeus duorarum , is 

 probably the most important species asso- 

 ciated with mangrove areas (see discussion 

 in section 11 ). 



49 



