O'NEIL and WEINSTEIN: FEEDING HABITATS OF SPOT 



that spot feed on seasonally and spatially domi- 

 nant prey types from the available array and that 

 the observed differences between creeks and 

 shoals simply reflect availability of dominant 

 prey types. The diversity of food types in spot 

 stomachs may also reflect the general strategy of 

 the feeding opportunist, which is favored when 1) 

 food densities are periodically low and there is a 

 premium on the ability of the predator to take a 

 range of prey, 2) the predator has a relatively long 

 period to gain energy, and 3) prey densities fluc- 

 tuate widely (Schoener 1969). These are charac- 

 teristics of the marsh habitats that spot frequent 

 as well as the general life history strategy of spot 

 in terms of spawning season and residence period 

 in the primary nurseries (Weinstein 1981; Wein- 

 stein and O'Neil 1986). 



Finally, there is the question posed in the intro- 

 duction to this paper, i.e., the relative role of these 

 tidal creeks as feeding versus refuge zones. As 

 suggested in the introduction and discussed 

 above, there seeemed to be adequate food for 

 growth of spot in tidal creeks and shoal areas, at 

 least during the year of this study. This observa- 

 tion was confirmed in a separate effort using in- 

 crements of daily growth observed in the otoliths 

 of spot collected in Goalders and Blevins Creeks 

 in 1983, and in the same two creeks plus a meso- 

 haline creek (Kings Creek, also located in the 

 York River system) in the following year 1984 

 (Weinstein and O'Neil fn. 5). Unfortunately, com- 

 parative data on the mortality of spot in different 

 tidal creeks and other habitats are not readily 

 available. Weinstein and Walters (1981) reported 

 evidence of differences in spot mortality among 

 creeks in different marshes of the Cape Fear 

 River estuary. Mortality was significantly higher 

 in the polyhaline marshes of the Cape Fear sys- 

 tem in 1977, and although the mean value was 

 highest in the same marshes in 1978, the overall 

 variability of the data resulted in a nonsignifi- 

 cant diff'erence among marshes. Mortality rates 

 calculated for spot in the studies of Weinstein (in 

 press) and Weinstein et al. (1984) in Little Mon- 

 day Creek and Blevins Creek (located about 1 km 

 apart) differed from the values reported for poly- 

 haline creeks in the Cape Fear estuary 0.029 and 

 0.015/day versus 0.061 and 0.052/day, respec- 

 tively. The diff'erence in mortality rates calcu- 

 lated for the two studies lies partly in the age 

 distribution sampled from each population 

 (youngest age cohorts were not sampled in the 

 York River), but this factor alone is not believed 

 to account for all of the diff'erence in the rates. 



The role of diff'erential mortality in shaping the 

 population dynamics of this species is clearly in 

 need of further study. 



ACKNOWLEDGMENTS 



We thank K. Anderson, J. Hoff", and S. Smith 

 for help in the field and laboratory. P. Sheridan 

 and R. J. Livingston reviewed versions of this 

 paper, their comments improved this draft. C. 

 Frost typed several drafts of the manuscript and 

 M. Pinkham edited the final version. This study 

 was funded by a U.S. Environmental Protection 

 Agency Grant #R808707 to M. P. Weinstein and 

 by the Virginia Institute of Marine Science. 



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