Table 13.— Summary statistics for forward selection of six 

 independent variables for Arenaeus cribrarius (Y, = response 

 variable; R = correlation coefficient). ("Highly significant, P^O.Ol; 

 ns not significant, P>0.05.) 



Table 16. — Summary statistics for forward selection of six 

 independent variables for Trachinotus carolinus (Y t = response 

 variable; R = correlation coefficient). ("Highly significant, P< 0.01; 

 ns not significant, P>0.05.) 



Step 



Variable 



Multiple 





Increase 



Partial 



Step 



Variable 



Multiple 





Increase 



Partial 



number 



entered 

 X 2 



R 



0.6830 



R 1 

 0.4665 



in R' 

 0.4665 



F-test 

 19.2372" 



number 



entered 



R 



R 2 



inR' 



F-test 



1 



1 



X 2 



0.6569 



0.4315 



0.4315 



16.7013" 



2 



*6 



0.7199 



0.5182 



0.0517 



2.2557 ns 



2 



x* 



0.7115 



0.5063 



0.0747 



3.1787 ns 



3 



x. 



0.7273 



0.5290 



0.0107 



0.4558 ns 



3 



x 6 



0.7348 



0.5399 



0.0337 



1.4634 ns 



4 



x 5 



0.7301 



0.5330 



0.0040 



0.1627 ns 



4 



x 3 



0.7392 



0.5464 



0.0064 



0.2698 ns 



5 



*3 



0.7309 



0.5343 



0.0013 



0.0494 ns 



5 



x 5 



0.7414 



0.5497 



0.0034 



0.1340 ns 



6 



x. 



0.7310 



0.5343 



0.0000 



0.0011ns 



6 



X, 



0.7415 



0.5498 



0.0001 



0.0029 ns 



Step 1 prediction equation: V,= -12.2821 + 1.1120 X 2 



Step 1 prediction equation: Y 4 = -7.6441 + 0.7025 X 2 



Table 14. — Summary statistics for forward selection of six 

 independent variables for Anchoa mitchilli (Y, = response variable; 

 R = correlation coefficient). ('Significant, P < 0.05; ns not sig- 

 nificant, P>0.05.) 



Table 17.— Summary statistics for forward selection of six 

 independent variables for Menticirrhus Hit oralis (Y 5 = response 

 variable; R = correlation coefficient). ('Significant, P< 0.05; ns not 

 significant, P> 0.05.) 



Step Variable Multiple 

 number entered R 



Increase 

 inff 



Partial 

 F-test 



x 7 



0.4046 



0.1637 



0.1637 



4.3065* 



x, 



0.5740 



0.3295 



0.1658 



5.1926* 



x 4 



0.6063 



0.3675 



0.0380 



1.2030 ns 



x, 



0.6249 



0.3905 



0.0230 



0.7159 ns 



x, 



0.6558 



0.4301 



0.0396 



1.2519 ns 



x fi 



0.6596 



0.4350 



0.0049 



0.1471 ns 



Step 2 prediction equation: Y = 7.3141 + 0.7816 X, - 34.4694 X 5 



Table 15. — Summary statistics for forward selection of six 

 independent variables for Menidia menidia (Y, = response variable; 

 R = correlation coefficient). ('Significant, P< 0.05; "highly sig- 

 nificant, P< 0.01; ns not significant, P> 0.05.) 



Step 



Variable 



Multiple 





Increase 



Partial 



number 



entered 



R 



R' 



inR' 



F-test 



1 



X 2 



0.7105 



0.5048 



0.5048 



22.4299" 



2 



x 6 



0.7694 



0.5920 



0.0872 



4.4892* 



3 



*3 



0.8409 



0.7070 



0.1150 



7.8503* 



4 



*5 



0.8553 



0.7316 



0.0246 



1.7395 ns 



5 



X, 



0.8619 



0.7430 



0.0113 



0.7943 ns 



6 



x, 



0.8624 



0.7437 



0.0007 



0.0494 ns 



Step 3 prediction equation: 









Y,= 566.8066 - 23.2452 X, - 



10.3017 X, 



+ 0.5368 X, 





The final regression equation for M. menidia contained 

 water temperature, the square of water temperature, and 

 salinity as predictor variables. Water temperature ac- 

 counted for 50% of the variation in Y due to regression 

 (R- = 0.50). The addition of salinity and the square of 

 water temperature as independent variables increased R 2 

 to 71%. Forcing the addition of the remaining variables 

 increased R 2 to only 74%. For all other species, except A. 

 mitchilli, water temperature was the only variable 

 selected. The final regression equation selected for A. 

 mitchilli contained water temperature and visibility of 

 Secchi disc as independent variables. The best fit (R 2 ) 

 was obtained for M. menidia (/J 2 = 0.71), followed by A. 

 cribrarius (R 2 = 0.47), T. carolinus (R 2 = 0.43), A. 

 mitchilli (R 2 = 0.33), and M. littoralis (R 2 = 0.25). 



Step 



Variable 



Multiple 





Increase 



Partial 



number 



entered 



R 



R' 



infl ! 



F-test 



1 



X, 



0.4969 



0.2469 



0.2469 



7.2144* 



2 



X, 



0.5909 



0.3492 



0.1022 



3.2991 ns 



3 



x, 



0.6372 



0.4060 



0.0568 



1.9124 ns 



4 



x,, 



0.6697 



0.4485 



0.0426 



1.4664 ns 



5 



x 6 



0.6835 



0.4672 



0.0187 



0.6313 ns 



6 



x 5 



0.6993 



0.4890 



0.0218 



0.7249 ns 



Step 1 prediction equation: Y 5 = -4.6371 + 0.5718 X 2 



Ordering the regression equations on the basis of R 2 for 

 the five selected species resulted in the same ranking as 

 the "importance" for surf and tidal pool combined 

 (Table 10) with the exception of a reversal of order 

 between A. mitchilli and M. littoralis. 



Livingston et al. (1976) performed similar regression 

 analyses for species collected in a study of Apalachicola 

 Bay, Fla. The only species analyzed in both their study 

 and ours was Anchoa mitchilli. Of the independent 

 variables examined for this species by Livingston et al. 

 only chlorophyll a and visibility of Secchi disc were 

 significant contributors to R 2 (with chlorophyll a being 

 more important). Their R 2 for A. mitchilli was 0.38. 

 Clarity of water (by visibility of Secchi disc), then, is an 

 important factor in determining the presence of A. 

 mitchilli. 



Annotated List of Selected Species 



The seven species included in the section on ranking 

 and several others are considered below in some detail. 

 Temperature and salinity ranges for these species are 

 presented in Table 3; and numbers and size ranges by 

 month are given in Table 4. 



Arenaeus cribrarius (Lamarck) (Crustacea, Decapoda, 

 Portunidae). This species was collected in spring, 

 summer, and fall of both years and in winter (one 

 specimen in March) of the second year. In 35 collections 

 (32 from the surf and 3 from the tidal pool), 422 

 specimens of 7 to 141 mm C W (417, 7-141 mm CW, from 

 the surf and 5, 17-59 mm CW, from the tidal pool) of A. 



14 



