FISHERY BULLETIN: VOL. 82, NO. 3 



York River estuary, no more than two species com- 

 prised >90% of the total number of individuals 

 captured at polyhaline tidal creek stations. On the 

 average, spot comprised 71.8% of this total. Only 

 in the oligomesohaline Goulders Creek was 

 species dominance shared by more than two 

 species (Table 1), but once again, spot predomi- 

 nated with 65.4% of the total. By comparison, 

 Hackney et al. (1976) reported a mean of seven 

 species totaling >90.0% at four trawl stations in 

 their study of a mesopolyhaline tidal creek in 

 Georgia, while in several studies in South and 

 North Carolina (Cain and Dean 1976; Bozeman 

 and Dean 1980; Weinstein et al. 1980) three to nine 

 species (x = 7) comprised this total. Species rich- 

 ness was significantly greater in Goalders Creek 

 than in the polyhaline Blevins Creek system. This 

 is somewhat surprising since previous studies 

 have often shown that diversity decreases for both 

 fishes and invertebrates in the upstream direction 

 (Dahlberg 1972; Boesch 1977; Gainey and Green- 

 berg 1977; Weinstein et al. 1980). The absence or 

 scarcity of stenohaline marine species derived 

 largely from the seasonally abundant southern 

 Carolinian ichthyofauna may partially explain 

 this difference in the York River estuary In North 

 Carolina, for example, these taxa increased 

 species richness in polyhaline tidal creeks, espe- 

 cially near the estuary mouth (Weinstein 1979; 

 Weinstein et al. 1980). Also present in estuaries 

 below the Chesapeake Bay are species with 

 warm-temperate affinities which share domi- 

 nance with spot and bay anchovy, including Mugil 

 cephalus, M. curema, Lagodon rhomboides, 

 Paralichthys lethostigma, Bairdiella chrysura, and 

 the brown shrimp, Penaeus aztecus. These species 

 are much less common in the Chesapeake Bay 



Another noteworthy finding is that species re- 

 placement does not occur from regional and north- 

 erly taxa. For example, Ophidion marginata, 

 Stenotomus chrysops, Urophysis regia, and Cen- 

 tropristis striata were only rarely encountered in 

 our studies (Weinstein and Brooks 1983). In the 

 present investigation, these species were re- 

 stricted to shoal stations outside of the tidal creek 

 mouths (Table 1). Thus, there appears to be an 

 underutilization of shallow nursery habitats by 

 transient marine fishes in the Chesapeake Bay 

 compared with the lower latitude estuaries (for 

 more detailed discussion see Weinstein and 

 Brooks 1983 and Heck and Thoman 1984). This 

 difference is perhaps due partly to the unique loca- 

 tion of the Chesapeake Bay in the transition zone 

 between faunal provinces (Briggs 1974) with 



neither taxonomic group able to adapt fully to 

 conditions (primarily temperature regimes and 

 their variance?) associated with this transition 

 zone. The recent geological and evolutionary his- 

 tory of northern estuaries, including the Chesa- 

 peake Bay (Shubel and Hirschberg 1978), may also 

 play a role in determining the degree of estuarine 

 dependency of local faunas. 



A unique aspect of this study was the opportu- 

 nity to compare utilization of the tidal creeks with 

 adjacent shoal areas. Previously, these compari- 

 sons had to be made among collections with differ- 

 ent gears (and their associated selectivity and effi- 

 ciency) or in different years or by different inves- 

 tigators (Chao and Musick 1977; Markle 1976). 

 The results for spot are of interest because of the 

 general dominance of this species in many es- 

 tuaries along the Atlantic and Gulf coasts. 



Recently, Weinstein and Walters (1981), Wein- 

 stein and Brooks (1983), and Weinstein (1983) de- 

 scribed the importance of marshes, specifically 

 tidal creeks, to this species and the relationship 

 between productivity and energy export via sev- 

 eral fish vectors — from the marshes ultimately to 

 the marine environment (Weinstein 1981). Spot 

 were recruited into upstream marshes of the York 

 River estuary earlier than to downriver sites and 

 tended to remain there longer (Fig. 3). Once re- 

 cruited into the marshes (by June) spot reside here 

 until fall, when they emigrated into deeper water, 

 and finally (for most individuals) return to the 

 marine environment. As expected, however, there 

 is an upstream limit to utilization in oligohaline 

 tidal creeks where we found densities of spot de- 

 creased (Table 2) as salinities became more vari- 

 able (approaching 0%o) and where temperature re- 

 gimes became more unstable (Hackney et al. 

 1976). Whether the lower abundance of spot out- 

 side of the creeks is due to differential mortality 

 and/or habitat selection remains unknown. Other 

 taxa, e.g., young-of-year Atlantic croaker, weak- 

 fish, and hogchoker, apparently prefer the shoals 

 and generally deeper water. There is little ques- 

 tion that they are more abundant outside of the 

 marshes (Chao and Musick 1977; Orth and Heck 

 1980; Weinstein and Brooks 1983; Middleton, 

 unpubl. data). If, as many would argue, predation 

 is a major regulator of local abundance and ulti- 

 mately community structure, what protection 

 would the homogenous, relatively unstructured 

 shoals and flats afford these species? Considering 

 the apparent physical and behavioral similarities, 

 as well as recruitment dynamics between spot and 

 Atlantic croaker, there does not seem to be any 



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