Pygmy Killifish and Mosquitofish 99 



148.3 mg/g/day. Doble and Eggers (1978) found that Onchorhynchus 

 nerka juveniles ate 15.3 and 44.1. mg/g/day in Lake Washington in 

 winter and summer, respectively. Garcia and Adelman (1985) reported 

 that Cyprinus carpio L. in the Mississippi River consumed 204 mg/g/day 

 in summer (assuming a fish dry to wet ratio of 20%). Cech et al. (1981) 

 stated that in the laboratory, newborn G. affinis ate from 70 to 820 

 mg/g/day at 10-35° C. Thorpe (1977, in Elliott and Persson 1978) 

 reported summer consumption by Perca fluviatilis L. in Loch Leven to 

 be 54 mg/g/day (dry weights, assuming fish dry to wet ratio of 20% and 

 prey wet to dry ratio of 6; Freeman and Freeman 1985), but this was an 

 underestimate according to Elliott and Persson (1978). Basimi and 

 Grove (1985) reported that summer consumption by small Pleuronectes 

 platessa L. off the coast of Wales was 43 mg/g/day (assuming the same 

 ratios). Sagar and Glova (1988) found that juvenile Oncorhynchus 

 tshawytscha Walbaum in the Rakaia River, New Zealand, ate 83 

 mg/g/day at a mean temperature of about 15°C. Consumption by O. 

 kisutch ranged from 21 to 44 mg/g/day at 5.8-7.5° C (Ruggerone 1989). 

 Food consumption rates of L. ommata and G. affinis from the 

 Okefenokee wetland clearly fall within the range offish in other types of 

 environments. 



As expected, area-based consumption by the two fishes was low in 

 winter and higher in summer. Leptolucania ommata in the Okefenokee 

 marsh consumed 0.71 and 22.99 mg/m /day in winter and summer, 

 respectively. Gambusia affinis ate less, presumably because of their 

 lower biomass; they consumed 0.33 and 3.32 mg/m /day in winter and 

 summer, respectively. In comparison, in a small New Zealand lake with 

 only one fish species, Staples (1975) reported that Philypnodon breviceps 

 Stokell in summer consumed 203 mg/m /day (assuming a wet to dry 

 ratio of 6); this value was an underestimate according to Elliott and 

 Persson (1978). In a New Zealand stream where trout and eels were also 

 present (Hopkins 1970, in Staples 1975), the maximum reported area- 

 based consumption by P. breviceps was equivalent to 74 mg/m 2 /day. 



Consumption data are consistent with a hypothesis that invertebrate 

 prey production in Okefenokee blackwater marshes is substantial. 

 Consumption values in spring and fall are usually between winter and 

 summer values, rising in a nonlinear manner as a function of temperature 

 (see Feeding Dynamics above; Staples 1975, Doble and Eggers 1978). 

 Thus, the geometric mean of winter and summer consumption values 

 may give a reasonable estimate of mean daily food consumption for the 

 whole year. Calculating the geometric mean of consumption values 

 (from Table 2) yields estimates of 47.5 and 69.0 mg/g/day for L. 

 ommata and G. affinis, respectively. When each of these values is 

 multiplied by average dry biomass per m 2 (from Oliver and Schoenberg 



