WEINSTEIN: SHALLOW MARSH HABiTATS AS PRIMARY NURSERIES 



CONCLUSIONS 



Shallow marsh habitats are demonstrably criti- 

 cal areas for the earliest developmental stages of 

 fishes and shellfish. Postlarvae of most species im- 

 portant to man were found to reside in immense 

 numbers at the headwaters of shallow tributary 

 creeks and along the marsh fringe at the rivers 

 edge. With few exceptions these species were the 

 community dominants at all study sites. 



Salinity seemed to play an important role in 

 governing spatial distributions of many species 

 and to a lesser extent substratum characteristics 

 interacted with salinity to restrict certain species 

 to a narrow range of habitats. Based partly on 

 these observations, a hjrpothesis has been estab- 

 lished whereby sea.sonal programming and spatial 

 distributions mediated by salinity and sub- 

 stratum preferences (and probably other factors) 

 may serve to reduce competition among species 

 recruited to the estuary throughout the year. 



Similarly, these and other physicochemical 

 parameters, which affect individual tolerances, 

 create unique conditions in each marsh complex 

 that affects the composition of the nekton com- 

 munity. Species richness was highest in the 

 marshes closest to the ocean entrance where 

 higher salinities allowed seasonal invasion by 

 marine forms otherwise unable to reside in the 

 estuary. An apparently similar phenomenon, 

 more limited in extent, occurred at the head of the 

 estuary for freshwater species. Despite the sea- 

 sonal progression of species, it is apparent that 

 marsh communities in the Cape Fear are highly 

 structured and are able to maintain a specific 

 identity throughout the year. 



ACKNOWLEDGMENTS 



I am grateful to J. P. Lawler of the Lawler, 

 Matusky & Skelly iLMS) Engineers and W. T. 

 Hogarth of the Carolina Power and Light Co. for 

 the opportunity to conduct these studies. I am also 

 grateful to the biotechnicians of LMS, in particu- 

 lar, R. Beatty, R. Davis, L. Gerry, J. Hecht, W. 

 Pollard, and P. Woodard for their conscientious 

 efforts in the field and laboratory; the quality of 

 their work added measurably to the success of this 

 study. Several individuals have provided con- 

 structive criticism of the manuscript including K. 

 L. Heck, J. P. Lawler, G. W. Thayer, R. L. Wyman, 

 and two anonymous reviewers. S. Weiss contrib- 



uted significantly with his expertise in statistics, 

 and J. Berkun, B. McKenna, and S. Kaufman pro- 

 vided editorial and typing assistance. This pro- 

 gram was funded by the Carolina Power and Light 

 Co. 



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355 



