lOOn 



c/) 

 ir 



LlI 

 DD 



75- 



< 



I- 

 o 



50- 



i Fish 



Invertebrates 



25- 





HEAVY 

 SEAGRASS 

 ( Halodule a 

 Thalossio ) 



THIN 



SEAGRASS 



(Halodule) 



SAND/ 

 SHELL 



MUD/ 

 SAND/ 

 SHELL 



Figure 18. Relative abundance of fishes and invertebrates over seagrass beds and adja- 

 cent habitats (after Yokel 1975a). 



by discriminating on the basis of form 

 (Barry 1974). Stoner (1980a) demonstrated 

 that common epifaunal amphipods were cap- 

 able of detecting small differences in the 

 density of seagrass and actively selected 

 areas of high blade density. VJhen equal 

 blade biomass of the three common sea- 

 grasses (turtle grass, manatee grass, and 

 shoal grass) were offered in preference 

 tests, shoal grass was chosen. When equal 

 surface areas were offered no preferences 

 were observed, indicating that surface 

 area was the grass habitat characteristic 

 chosen. 



5.3 FISHES 



Composition 



Seagrass meadows have traditionally 

 been known to be inhabited by diverse and 

 abundant fish faunas. Often the grass bed 

 serves as a nursery or feeding ground for 



fish species that will ultimately be of 

 commercial or sport fishery value. The 

 classification created by Kikuchi (1961, 

 1962, 1966) was largely inspired by the 

 fish community found in Japanese Zostera 

 beds and has effectively emphasized the 

 diverse character of seagrass fish and 

 major invertebrates, while also serving to 

 underscore the important ecological func- 

 tions of seagrass meadows within the estu- 

 ary as nursery and feeding grounds. 



Permanently resident fishes are typi- 

 cally small, less mobile, more cryptic 

 species that spend their entire life 

 within the grass bed. Few, if any, of 

 these species are of direct commercial 

 value but are often characteristic of the 

 seagrass habitat. The emerald clingfish 

 ( Acyrtops beryl! ina ) is a tiny epiphytic 

 species found only living on turtle grass 

 blades. In south Florida, members of 

 families Syngnathidae, Gobiidae, and 

 Clinidae may be included in this group. 



49 



