The number of finfish species in the nearshore 

 Gulf habitat is less than the number found in the 

 inland open water habitat, probably because of the 

 greater physical diversity of the latter habitat. Studies 

 of shallow waters, less than 5 m (16 ft), along the 

 beach indicate that bay anchovy and sea catfish domi- 

 nate these areas (Loesch 1976). Sea catfish, Atlantic 

 croaker, cutlass fish, and bay anchovy were the domi- 

 nant species at depths from 5 to 30 m (16 to 98 ft) 

 (Ragan and Harris 1976). 



4.11 BEACH AND RIDGE HABITATS 



Two related habitats in the Chenier Plain, easily 

 distinguished from all others, are the beach and ridge 

 habitats. Beaches represent the geological precursors 

 of cheniers; both formations are basicaUy linear 

 bodies of sand. Included as ridge habitat are natural 

 cheniers and stream levees. Pleistocene outcroppings, 

 artificial levees, and spoil banks. 



4.11.1 A FUNCTIONAL OVERVIEW OF BEACH 

 AND RIDGE HABITATS 



The total combined area of beach and ridge habi- 

 tats in the Chenier Plain is small compared to that for 

 surrounding habitat types (fig. 4-40). However, the 

 ecological influence of these habitats extends far 

 beyond their boundaries (fig. 4-41). One major 

 function of the beach habitat is to serve as a storm 

 barrier. As elevated features, beaches control the flow 

 of water between the Gulf and the inland open water 

 habitat. Cheniers and other inland ridges also serve 

 this function and control patterns of water circulation 

 inland as well. Beach and ridge habitats provide major 

 routes of travel for terrestrial animals, and they are 

 important refuges for all kinds of animals during 

 floods and seasonal migrations. Since cheniers provide 

 limited areas of high land in the midst of wetlands, 

 they are heavily exploited by man for residential, 

 agricultural, and industrial purposes. 



4.12 BEACH HABITAT 



The beach habitat has a structure and function 

 that is quite unlike that of other coastal habitats. The 

 area of this habitat type is small (table 4.23) in com- 

 parison to other types, but it is relatively constant. 

 The functional importance of beach habitat is related 

 to the controlling influence this habitat has on sur- 

 rounding areas, rather than on its own biological pro- 

 ductivity and species diversity. 



Plant production in this sandy environment is 

 limited by availability of nutrients and freshwater. 

 Organic material carried onto the beach by wave 

 action is the major source of food for small beach 

 consumers. Migrating organisms (especially birds), 

 which often use the beach habitat as resting or nesting 

 areas, feed predominantly in the Gulf and in adjacent 

 wetlands. 



Table 4.23. Area of beach habitat in the Chenier 

 Plain by basin. 



4.12.1 PHYSICAL PROCESSES 



The major physical function of beaches is to 

 buffer the inland area against marine processes. Along 

 the Chenier Plain coastline, the amount of coarse- 

 grained materials is highly variable. Such material, 

 largely shell, is virtually absent along the eastern sec- 

 tions of the coast, but accumulates to a thickness of 

 several feet along the western sections. Where beach 

 accretion is insignificant, marshes are exposed to 

 direct wave attack. 



During stormy periods sediments are moved 

 shoreward by waves and currents, and the suspended 

 materials create highly turbid conditions in the near- 

 shore waters. Upwash and backwash action of waves 

 along the coast move these sediments onto the beach. 

 When sufficient energy is available, onshore winds 

 blow sediments to the upper back-berm, forming 

 dunes. In this process, sorting and redistribution of 

 the original beach sediments occurs. The smaller frac- 

 tion is removed either offshore or inland, the larger 

 fraction remains on the beach, and medium-sized 

 materials are transported to form dunes. 



The accretion of beach ridges at river mouths is 

 evidence of sediment supplied from estuaries. 

 Although dams and other water control structures 

 have diminished riverine sediment supplies in the 

 Chenier Plain, quantities of sediments are flushed out 

 of the estuaries during storms and floods. Occasional 

 severe storms spread beach sands widely, permitting 

 wave action to cut back the coast. 



4.12.2 PRODUCERS 



Vegetation of the beach habitat is a mixture of 

 typical halophytic marsh plants and beach plants 

 characteristic of subtropical areas. On beaches along 

 the Rockefeller Wildlife Refuge in the Chenier Basin, 

 Chamberlain (1959) found saltmeadow cordgrass, and 

 camphorweed growing from the highest elevation of 

 the beach, about 1.5 m (5 ft), back into the adjacent 

 salt marshes. The salt marsh species, saltgrass and 

 smooth cordgrass, grew out from the marsh to within 

 about 8 m (26.4 ft) of the beach crest, in a zone also 



213 



