Weinstein et al. (1977) found that artifi- 

 cial canals had lower species diversity of 

 benthic infauna and trawl -captured fishes 

 and generally finer sediments than the 

 natural communities. Courtney (1975) 

 reported a number of mangrove-associated 

 invertebrates which did not occur in the 

 artificial channels. 



Mosquito production is a serious 

 problem in black mangrove-dominated swamps 

 in Florida (Provost 1969). The salt marsh 

 mosquitos, Aedes taeniorhynchus and A. 

 sol 1 icitans , do not reproduce below the 

 mean high tide mark and for this reason 

 are not a serious problem in the inter- 

 tidal red mangrove swamps. Mosquitos lay 

 their eggs on the damp soil of the irregu- 

 larly flooded black mangrove zone; these 

 eggs hatch and develop when flooded by 

 spring tides, storm tides or heavy rains. 

 As with the "high marsh" of temperate 

 latitudes, there have been some attempts 

 to ditch the black mangrove zone so that 

 it drains rapidly after flooding. 

 Although properly designed ditching does 

 not appear to be particularly harmful to 

 mangrove swamps (other than the area 

 destroyed to dig the ditch and receive the 

 spoil), it is an expensive practice and 

 for this reason is not widely practiced. 

 Properly managed diking can be an effec- 

 tive mosquito control approach with mini- 

 mal side effects to black mangroves 

 (Provost 1969). Generally, ditching or 

 diking of the intertidal red mangrove zone 

 is a waste of money. 



Mangrove swamps have been proposed as 

 possible tertiary treatment areas for 

 sewage (see discussion by Odum and 

 Johannes 1975). To our knowledge, this 

 alternate use is not currently practiced 

 in south Florida. Until more experimental 

 results are available on the assimilative 

 capacities and long-term changes to be 

 expected in mangrove forests receiving 

 heavy loads of secondary treated sewage, 

 it would be an environmental risk to use 

 mangrove forests for this purpose. 



In many areas of the world mangrove 

 swamps have been converted to other uses 

 such as aquaculture and agriculture (see 

 de la Cruz, in press, a). Although some 



of the most productive aquaculture ponds 

 in Indonesia and the Philippines are 

 located in former mangrove swamps, there 

 is some question whether the original 

 natural system was not equally productive 

 in terms of fisheries products at no cost 

 to man (Odum 1974). Conversion to 

 aquaculture and agriculture is cursed with 

 a variety of problems including subsequent 

 land subsidence and the "cat clay" 

 problem. The latter refers to the 

 drastically lowered soil pH which often 

 occurs after drainage and has been traced 

 to oxidation of reduced sulfur compounds 

 (Dent 1947; Tomlinson 1957; Hesse 1961; 

 Hart 1962, 1963; Moorman and Pons 1975). 

 Experience in Africa, Puerto Rico, and 

 Southeast Asia confirms that mangrove 

 forests in their natural state are more 

 valuable than the "reclaimed" land. 



12.5 PROTECTIVE MEASURES INCLUDING 

 TRANSPLANTING 



Protection of mangroves includes (1) 

 prevention of outright destruction from 

 dredging and filling; (2) prevention of 

 drainage, diking and flooding (except for 

 carefully managed mosquito control); (3) 

 prevention of any alteration of hydrologi- 

 cal circulation patterns, particularly 

 i nvol ving tidal exchange; (4) prevention 

 of introduction of fine-grained materials 

 which might clog the aerial roots, such as 

 clay, and sugar cane wastes; (5) preven- 

 tion of oil spills and herbicide spray 

 driftage; and (6) prevention of increased 

 wave action or current velocities from 

 boat wakes, and sea walls. 



Where mangroves have been destroyed, 

 they can be replanted or suitable alter- 

 nate areas can be planted, acre for acre, 

 through mitigation procedures (see Lewis 

 et al. 1979). An extensive body of 

 literature exists concerning mangrove 

 planting techniques in Florida (Savage 

 1972; Carlton 1974; Pulver 1976; Teas 

 1977; Goforth and Thomas 1979; Lewis 

 1979b). Mangroves were initially planted 

 in Florida at least as early as 1917 to 

 protect the overseas railway in the 

 Florida Keys (Teas 1977). 



Both red and black mangroves have 



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