FISHERY BULLETIN: VOL. 78, NO. 2 



Table 4. — Pearson correlation coefficients (r) and coefficients of 

 determination (r^) for p)ercentages of total stomach contents (dry 

 weight) compMjsed of: amphipods and shrimp in Lagodon rhom- 

 boides from 16 to 35 mm SL, tested as functions of food abun- 

 dance. AM = amphipods/m^, CC = calanoid copepods/m^, PM = 

 grams dry weight benthic macrophytes/m^, and SH = shrimp 

 and shrimp postlarvae/m^. 



Fenholloway 12 



Econfina 10 



Econfina 1 2 



'P«0.05; "PsO.OI ; n.s. = not significant. 



100 



I- 



"O 



c 



(U 



c 

 o 

 (J 



sz 

 (J 



(T5 

 E 



o 



-♦-' 



2 3 4 5 



(51) (52) (761 (48: 



6 7 8 9 10 11 



(45) (44) (47) (49) (51) (54) 



Month 



Figure 7. — Seasonality in diet of Lagodon rhomboides between 

 36 and 80 mm SL from three stations (F 12-top, E 10-middle, E 

 12-bottom) in Apalachee Bay, Fla. (February to November 

 1977). Diet is given as the relative proportion of the dry weight of 

 stomach contents. Codes for the dietary components are given in 

 Table 1. Numbers in parentheses are the mean lengths offish. 



variation in the diet of this ontogenetic group, 

 however, showed that plant material made up 

 only a small portion of the diet in winter and early 

 spring (Figure 7). Amphipod consumption was 

 highest in March and decreased through the 

 spring and fall, during which time plant material 

 became the most important food item. Consump- 

 tion of shrimp and shrimp postlarvae was low in 

 the spring but increased to as much as 30% of the 

 diet in the summer and fall. Consumption of 

 calanoid copepods by this fish size class was gener- 

 ally limited to winter. Harpacticoid copepods con- 

 sistently contributed a small amount to the diet of 

 these fish but consumption of isopods, crab zoea, 

 and polychaetes was sporadic. 



For fish from 36 to 80 mm, temporal variations 

 in consumption of amphipods, plant matter, and 

 shrimp were analyzed with stepwise multiple re- 

 gression, using abundance of shrimp, amphipods, 

 polychaetes, and benthic macrophytes as inde- 

 pendent variables. Pearson correlation coef- 

 ficients show that consumption of amphipods 

 was negatively correlated with abundance of 

 shrimp and macrophytes in the field and positively 

 related to amphipod abundance (Table 5). The re- 

 lationships with polychaete abundance were 

 mixed. Multiple correlation coefficients explained 

 between 60.8 and 79.4% of the temporal variation 

 in amphipod consumption using from two to four 

 independent variables. Consumption of plant 

 matter by fish from 36 to 80 mm was positively 

 related to plant biomass and shrimp abundance. 



Table 5. — Pearson correlation coefficients (r) and coefficients of 

 determination (r^) for percentages of total stomach contents (dry 

 weight) composed of amphipods, plant matter, and shrimp in 

 Lagodon rhomboides from 36 to 80 mm SL, tested as functions of 

 food abundance. AM = amphipods/m^, PC = polychaetes/m^, 

 PM = grams dry weight benthic macrophytes/ m^, and SH = 

 shrimp and shrimp postlarvae/m^. 



Fenholloway 12 



Econfina 10 



Econfina 12 



*P«0.05;"P=s0.01;n.s. = not significant. 



344 



