offers an ideal opportunity to test differences in the primary pro- 

 ductivity of different species of marsh plants. The irregularly 

 flooded marsh dominated by Juncus roemerianus , waterlogged salt flats 

 of Distichlis spicata , and salt meadows of Spartina patens are found 

 in Mississippi coastal estuaries. Mixed stands for several marsh 

 plant species are common. As many as 34 species may be found in one 

 locality although only a few of these are of major importance. 



Primary production studies in the northern Gulf of Mexico marshes p 

 are few. Kirby (1971) reported an annual net production of 1006-1410 g m" 

 for an S. alterniflora marsh in Louisiana. Eleuterius (1972) estimated 

 production value of about 2000 g m"^ yr"' for a J. roemerianus marsh 

 in Mississippi. More recently an initial study on a mixed vegetation 

 marsh at St. Louis Bay estuary in Mississippi showed production 

 value of 1100 g m"2 yr"' (Gabriel and De la Cruz 1974). In all these 

 studies, only the annual net primary productivity of aboveground 

 materials was measured. 



The annual net primary production of nine types of marsh communities 

 common in Mississippi Gulf coast estuaries was studied by means of 

 the Harvest Method. Production values ranged from 600 g m"^ yr"' for a 

 Sagittaria lancifolia marsh to 2,330 g m-2 yr"' for a Phragmites communis 

 marsh. Primary productivity values for the other marsh types are: 



Marsh Type Productivity 



Juncus roemerianus 1 ,697 g m"2 yr~] 



Scirpus robustus 1 ,056 g m'i yr~\ 



Spartina cynosuroides 2,190 g m'p. yr"-^ 



Spartina patens 1,922 g m" yr~ 

 Spartina alterniflora ^ , 



tall form 1,964 g m" yr' 

 S_. alterniflora ^ , 



short form 1 ,089 g m"2 yr~\ 



Distichlis spicata 1,484 g m~ yr" 



Annual net productivity in Mississippi marshes is generally slightly 

 higher than that reported for the Atlantic marshes. (A. A. and introduction) 



Keywords: primary productivity, marsh plants, coastal marshes, 

 Mississippi 



II-B-11 



Gabriel, B.C., and A. A. de la Cruz. 1974. Species composition, standing 



stock, and net primary production of a salt marsh community in Mississippi 



Chesapeake Science 15:72-77. 



Along the Gulf Coast and on barrier islands of Mississippi are some 

 27,000 hectares of verdant marshlands. These marshes generally consist 



40 



