WEINSTEIN SHALLOW MARSH HABITATS AS PRIMARY NURSERIES 



BALOHEAO I SEINE I 

 BALDHEAO L ROTENONE 1 

 SHELLBEO ( SEINE 1 

 BARNARDS ( ROTENONE < 

 DUTCHMAN 1 ROTENONE ) 

 WALDEN i ROTENONE 1 

 HECHTIC 1 SEINE ) 

 DUTCHMAN 1 SEINE 1 

 WALDEN 1 SEINE ) 



PERCENT SIMILARITY 



FIGL^RE 4. — Similarities among all stations collected from Feb- 

 ruary to December 1977 m the Cape Fear River estuary, N.C. 

 Associations m dendogram are based on pooled monthly collec- 

 tions. Sampling was not initiated at Bamards Creek. N.C. until 

 April. 



tions and by the Barnards Creek site which exhib- 

 ited the lowest overall degree of association. 

 Although the physicochemical factors at the Bar- 

 nards Creek site differed in some respects from 

 those of other stations ( particularly with respect to 

 percent organics, Table 1), it should be em- 

 phasized that this station was not collected until 

 April and, therefore, did not reflect a large portion 

 of winter recruitment. Since the rotenone stations 

 were not collected uniformly throughout the year, 

 they were omitted from further analysis. Data for 

 individual species, however, are used to support 

 conclusions drawn from seine studies. 



A two-way coincidence table (Table 8) was pre- 

 pared for seine data collected from February to 

 December 1977 by first clustering the matrix for 

 seine station associations and comparing these 

 with a dendrogram for species associations. In this 

 way, comparisons among stations was facilitated 

 by direct cross-referencing against the charac- 

 teristics species associations at each site. The five 

 seine stations fell into two clusters at the 659! 

 similarity level, designated A and B in the table. 

 Twelve species association clusters were recog- 

 nized at this same level. Clearly, several subcate- 

 gories of marsh communities may be distin- 

 guished for the Cape Fear region, although the 

 marshes also share many commonalities, as indi- 

 cated in Figure 4 by the generally high similarity 

 values among station clusters { >55'7(). 



Members of Group III (Table 8) were generally 

 ubiquitous, with most difference being reflected in 

 relative numbers. Leiostomus xanthurus, Mueil 



cephalua, and Brevoortia tyrannus, for example, 

 were more prevalent at Hechtic, Walden, and 

 Dutchman Creeks, while the bay anchovy, An- 

 choa mitchilli. and Mcnidia menidia dominated at 

 Baldhead Island stations. Species groups I, IV, and 

 X were characterized by the lower salinities at 

 Hechtic and Walden Creeks and included species 

 present in relatively higher densities, such as the 

 tidewater silverside, M. heryllina, and species 

 normally associated with lower salinities, such as 

 gizzard shad, Dorosoma cepedianum; mosquito- 

 fish, Gambi/sia affinis; AnguiUa rostrata; and 

 juvenile Micropogonias undulatus. Two freshwa- 

 ter fishes, the bluegill, Lepow/s macrochiriis, and 

 golden shiner, Notemigonus crysoleucas , also were 

 captured at these sites. In rotenone collections, by 

 comparison, tidewater silverside were absent from 

 Baldhead Creek collections and only six speci- 

 mens were captured at Dutchman Creek. In Wal- 

 den Creek, this species was a relativley abundant 

 member of the community, contributing 1.3% of 

 the total number of individuals (Table 5). At Bar- 

 nards Creek, however, only 15 individuals were 

 captured. Several other species were also more 

 abundant in low salinity rotenone collections, 

 postlarval and juvenile M. undulatus (9-83 mm), 

 for example, were the fifth most abundant species 

 captured in Barnards Creek samples, and A. ros- 

 trata and G. affinis contributed 2.6 and 1.6'7f of the 

 total number of individuals, respectively (Table 

 5). 



The Baldhead Creek and Shellbed Island sites 

 form a complex that is influenced by the nearby 

 marine environment. Groups VII, VIII, and IX 

 included many species associated with intermedi- 

 ate to higher salinities and probably also reflected 

 additional parameters such as the substratum 

 composition and proximity to the ocean entrance. 

 Several stenohaline marine species were collected 

 only at these locations. These included rough sil- 

 verside, Mcmbras martinica; several species of 

 searobins, Pnonotus spp.; windowpane flounder, 

 Scopthalmus aquosus; summer flounder, 

 Paralichthys dentatus; fringed flounder, Etropus 

 crossotus: gag, Mycteroperca microlepis: southern 

 blue crab, Callinectes similis: inshore lizardfish, 

 Synodus foetens; and pigfish, Orthopristis 

 chrysoptera. Except for Scopthalmus aquosus and 

 E. crossotus, these species were also recorded in 

 low to intermediate densities from Baldhead 

 Creek rotenone collections (e.g., pigfish ranked 

 17th in abundance out of a total of 61 taxa col- 

 lected). Members of the genus Prionotus were not 



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