SMITH ET AL.: ORGANIZATION OF NEKTON 



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FIGURE 6. — Seasonality of selected taxa at tidal 

 creek and shoal stations, York River estuary, Va. 

 Numbers on x axis are sample sizes too small to plot. 



Paralichthys dentatus 



 GOALDERS CK 

 G BLEVINS CK 



  



50 

 25 







84 



Ictalurus catus 



A 



_*o |o I 



107 



Morone americana 



1 ■O 



1500 



1000 



500 



« a & 



MAR APR MAY JUN JUL AUG SEP OCT 



MONTH 



individuals incorporated more Neomysis ameri- 

 cana, calanoid copepods, and gammaridean am- 

 phipods into their diet. In hogchokers, however, 

 gammarids predominated in smaller individuals, 

 <61 mm SL, but with increasing size became 

 somewhat less important and were replaced by 

 nereid polychaetes and clam siphons. Hogchokers 

 had the highest proportion of unidentified re- 

 mains (UID) of any predator examined due to the 

 high level of maceration characteristic of this 

 species. 



Neomysis americana was clearly the dominant 

 prey item of small (<60 mm SL) white perch, but 

 became less important in the diets of larger indi- 

 viduals which fed increasingly on gammarid am- 

 phipods and clam siphons. White catfish <120 mm 

 SL also fed conspicuously on amphipods but, 

 uniquely among the predators examined, also fed 

 upon xanthid crabs, and at larger sizes incorpo- 

 rated a substantial proportion of fishes into their 

 diet. 



Relative fullness indices displayed varying 

 trends on a species-specific basis (Table 5). Values 

 declined in the later part of the study for white 

 perch and white catfish, whereas no apparent 

 trends were observed for other species. 



TABLE 5. — Monthly relative fullness index (RFI) for six domi- 

 nant fishes in the York River estuary, Va. Values are means 

 for all individuals examined. 



DISCUSSION 



Species Composition and Abundance 



Along with other recent studies of shallow- 

 water nekton (Orth and Heck 1980; Weinstein and 

 Brooks 1983; Heck and Thoman 1984), the present 

 effort provides additional information on the use 

 of inshore habitats of the lower Chesapeake Bay A 

 striking characteristic of the marsh nekton com- 

 munity in the lower Chesapeake Bay is the gener- 

 ally low diversity of the constituent fauna and the 

 high level of dominance of only a few species. On 

 both the eastern shore of Virginia (Delmarva 

 Peninsula) (Weinstein and Brooks 1983) and in the 



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