physical and chemical parameters (including temperature, oxygen, 

 salinity, turbidity, and inorganic phosphate) were measured concurrently. 



In the study area, where salinity ranged from 0.53 ppt to 25.43 ppt, 

 one species of copepod, Acartia tonsa , dominated the zooplankton with 

 145,000 per five-minute haul and was abundant throughout the year. 



There were few other populations. Numerically important copepod 

 species were Eurytemora hirundoides , Pseudodiaptomus coronatus , 

 Paracalanus crassirostris , and Oithona spp. Meroplanktonic elements 

 such as nauplii and zoeae of Cirripedia also attained numerical 

 importance. 



Freshwater and marine fauna were localized and in minor numbers. 

 A major zooplankton outburst occurred in April 1960. No comparable 

 increase was recorded at any other time. Populations were more numerous 

 in open water than in bayou samples. Smallest numbers were found in 

 October. (A. A.) 



Keywords: zooplankton, salt marshes, copepods. Southeastern Louisiana 



V-E-8 



Williams, R.B., M.B. Murdoch, and L.K. Thomas. 1968. Standing crop and 



importance of zooplankton in a system of shallow estuaries. Chesapeake 



Science 9:42-51. 



The sequence, phytoplankton--zooplankton--carnivores, forms the 

 classical food chain for the aquatic environment. Although the 

 validity of this sequence for the open sea is unquestioned, studies 

 on Long Island Sound and the English Channel indicated that even 

 in these areas, 20 and 70 m deep, respectively, benthic animals are 

 important consumers of phytoplankton. The significance of zooplankton 

 as an intermediate step between phytoplankton production and carnivore 

 production in shallower marine areas had been examined before. A year- 

 long study of plankton in a system of shallow estuaries near Beaufort, 

 North Carolina, provided an opportunity to make observations of phyto- 

 plankton production and the standing crop and taxonomic composition 

 of zooplankton. These observations were used to estimate the importance 

 of zooplankton in the energy flow of the area. 



Previous work on the standing crop and taxonomic composition in 

 estuarine zooplankton in the area consisted of detailed observations 

 at a single location. Studies on other inshore areas along the eastern 

 seaboard have yielded diverse estimates of zooplankton biomass. The 

 range was from approximately 0.14 ml/m-^ in a 1-m deep Cape Cod salt 

 pond to 0.95 ml/m^ and 19 ml/m^ in Long Island Sound. 



Ten stations were sampled with a No. 10 net at 5-week intervals. 

 Copepods predominated; meroplanktonic larvae were second in importance. 



268 



