White shrimp, continued 



Table 5.08. Relative abundance of white shrimp 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/postlarvae 



E - Eggs 



Indicator of Environmental Stress Pesticides have 

 been found to have adverse effects on shrimp popula- 

 tions along the coast of the Gulf of Mexico (Christmas 

 and Etzold 1977, Couch 1978). White shrimp at 

 locations in Galveston treated by aerial sprays of 

 Malathion have experienced mortalities of up to 80%. 

 The use of this pesticide has increased to the point that 

 currently much of the Gulf coast uses some form of it in 

 mosquito control programs. Other pesticides, as well 

 as industrial and agricultural discharges, pose serious 

 threats when used or discharged in drainage areas 

 where they can enter water systems. The effects of 

 petroleum products on penaeid shrimp is not well 

 known. Mortality and pathological conditions have 

 been induced in species exposed to different concen- 

 trations of these chemicals. Penaeid shrimp are sen- 

 sitive to heavy metals (Couch 1978). Jackson (1975) 

 found mercury to be two orders of magnitude more 

 toxic than zinc for juvenile white shrimp, with higher 

 mortalities occurring at higher temperatures. Mortali- 

 ties were also higher during spring compared to winter. 



Ecological : Penaeid shrimp provide an important link in 

 the estuarine food web by converting detritus and 

 plankton into available biomass for fishes and other 

 predators. White shrimp are preyed on by many 

 species of estuarine and coastal finfish. Abundant 

 juvenile penaeid shrimp appear to be important in 

 supporting large populations of certain fish species 

 (Hettler 1 989). The postlarvae and juveniles are more 

 tolerant of lower salinities than other Penaeus species 

 (Williams 1984, Zein-Eldin and Renaud 1986), and 

 may venture further into brackish marshes. White 

 shrimp remain in estuaries longer and grow largerthan 

 brown shrimp (Christmas and Etzold 1 977). They may 

 be displaced by brown shrimp from Spartina marshes 

 to nearby mud substrates in areas where they are 

 sympatric (Giles and Zamora 1973, Zimmerman and 

 Minello1984). 



Range 



Overall : The white shrimp ranges from Fire Island, New 

 York, to the St. Lucie Inlet, Florida, on the Atlantic 

 coast. In the Gulf of Mexico, it is found from Ochlockonee 

 River, Florida, to Campeche, Mexico. It is rarely found 

 near the Dry Tortugas, Florida, and is absent around 

 the southernmost portion of the Florida peninsula. The 

 centers of abundance occur off Georgia and northeast- 

 ern Florida for the Atlantic coast; and Louisiana, Texas 

 and Tabasco for the Gulf of Mexico (Williams 1984, 

 Klima et al. 1987), but greatest densities occur off the 

 coast of Louisiana (Klima et al. 1982). NOAA (1985) 

 reports the range within the Gulf of Mexico from 

 Apalachee Bay, Florida, to northeast Campeche Bay, 

 Mexico. Perez-Farfante (1 969) distinguishes the area 

 of Ciudad, Mexico as the southern limit in the Gulf of 

 Mexico. 



74 



