Southern flounder, continued 



Table 5.44. Relative abundance of southern floun- 

 der in 31 Gulf of Mexico estuaries (from Volume /). 



Relative abundance: 



# Highly abundant 



® Abundant 



O Common 



V Rare 



blank Not present 



Life stage: 



A - Adults 

 S - Spawning 

 J - Juveniles 

 L - Larvae 

 E - Eggs 



(Hoese and Moore 1977, Lee et al. 1980, Manooch 

 1984). It is not common in the southwest Florida 

 estuaries, and its range is apparently not continuous 

 around the southern tip of Florida. 



Within Study Area : The southern flounder is distributed 

 throughout the coastal and estuarine habitats of the 

 U.S. Gulf of Mexico from Florida to Texas, and is 

 particularly abundant along the Texas coast (Ginsburg 

 1 952, Hoese and Moore 1 977, Manooch 1 984, Reagan 

 and Wingo 1985, Gilbert 1986) (Table 5.44). 



Life Mode 



Eggs are planktonic, buoyant, and float at or near the 

 surface (Arnold et al. 1 977). Larvae are planktonic and 

 can be found throughout the water column (King 1 971 ). 

 King (1971) has shown no difference between night 

 and day larval distributions. Juveniles and adults are 

 demersal, and they are more active at night (Powell 

 and Schwartz 1977). 



Habitat 



Type : Eggs are marine, occurring in neritic waters. 

 Early larval stages are marine, while postlarvae be- 

 come estuarine. Juveniles and adults are estuarine, 

 riverine and marine in coastal areas usually depending 

 on size of the flounder and hydrography (Fischer 1 978, 

 Lee et al. 1 980, Shipp 1 986). Southern flounder can be 

 found at depths up to about 40 m (Fischer 1978). 



Substrate : Southern flounder frequent fine unconsoli- 

 dated substrates of clayey silts and organic-rich muddy 

 sands (Fischer 1978, Lee et al. 1980, Gilbert 1986, 

 Powell and Schwartz 1977). Juvenile fish have been 

 reported in association with seagrass beds (Stokes 

 1 977). In marshes they appear to be equally abundant 

 in vegetated and non-vegetated habitats (Minello et al. 

 1989). Juveniles and adults are associated with fine 

 sediments in flooded Spartina marshes, seagrasses 

 and muddy substrates while in estuaries (Stokes 1 977, 

 Wardetal. 1980). 



Physical/Chemical Characteristics 

 Temperature: This is a eurythermal species. The 

 reported temperature range for eggs is 9.1 to 22.9°C 

 with 14°C preferred; and for larvae 2 to 30°C with a 

 preferred range of 20 to 25°C (Ward et al. 1980). 

 Juveniles are apparently widespread over water tem- 

 peratures ranging from 2 to 31 .2° C. Adults are found 

 in temperatures ranging from 7 to 32°C and show a 

 preference for temperature between 14 and 22° C 

 (Pineda 1 975, Ward et al. 1 980, Prentice 1 989). Young 

 southern flounder appear to be more tolerant of cold 

 than adults, and both groups show increasing toler- 

 ance to cold as salinity is increased (Prentice 1989). 

 Temperature appears to have a greater effect on 

 growth than salinity (Peters 1 971 ). Adults in salt water 



335 



