STONER: SKAdKASS ICHTHYOKAUNA 



TABLE 1.— Abundance of the 20 most numerous fishes at four seagrass sites in Apalachee Bay, Fla. 

 Values are the total number offish collected and percentages (in parentheses) of the total catch for 

 each station. Macrophyte biomass (g dry wt/m 2 ) for each station is given in parentheses. 



TaBLK 2. — Summary of statistics from regression analyses for 

 Apalachee Bay, Fla., fishes. R values are Pearson correlation co- 

 efficients; N is the total number of fish collected; F values are for 

 tests of regression significance by analysis of variance. 



Regression 



F 

 value 



Signifi- 

 cance 



Tested as a function of mean macrophyte biomass 

 Total number of fishes 988 



Number of pintish 998 



Number of non-pinfish 882 



Tested as a function of macrophyte biomass, 



all dates examined separately 

 Total number of fishes 572 



Number of pinfish 565 



Number of non-pinfish 



380 



were combined, a similar positive relationship with 

 seagrass biomass was found (r = 0.882; P < 0.10). 

 The dominant fish at the unvegetated site (F- 1 1) was 

 spot, Leiostomus xanthurus, most of which were 

 juveniles (10-20 mm SL). Silver perch, Bairdiella 

 chrysoura, was most abundant at station F-12; the 

 same was true for pigfish, Orthopristis chrysoptera, 

 although numerical differences among the stations 

 were small (Table 1). Fishes that increased in abun- 

 dance with seagrass biomass or were most abundant 

 at the most heavily vegetated site (E-12) included 

 spot-tail pinfish, Diplodus holbrooki; dusky pipefish, 

 Syngnathus floridae; fringed filefish, Monacanthus 

 ciliatus; planehead filefish, M. hispidus; southern sea 

 bass, Centropristis melana; and white grunt, 

 Haemulon plumieri (Table 1); of these six species, on- 

 ly M. ciliatus was collected at the unvegetated site. 

 The total number of fishes collected per unit effort 



(seven trawls) was lowest in winter months (Decem- 

 ber, January, and February) and highest between 

 May and August, except at the unvegetated site 

 where peak fish abundance occurred in February 

 (Fig. 1). A brief abundance of juvenile spot and pin- 

 fish at station F-ll, as they moved from offshore 

 spawning sites to the marshes of the Fenholloway es- 

 tuary, was responsible for the winter peak in total fish 

 abundance at that station. After the brief transience 

 of early juveniles, a consistently low number of fishes 

 characterized the unvegetated site. At vegetated 

 stations, the abundance of pinfish and spot con- 

 tinued to increase after initial recruitment of 

 juveniles until midsummer. 



Because of major seasonal patterns in the abundance 

 of fishes and macrophytes in Apalachee Bay (Figs. 1, 

 2), two tests of the relationship between these biotic 

 components were made. In the first test, using the 48 

 points available for 1 2 collections at four stations, to- 

 tal numbers of fishes, numbers of pinfish, and num- 

 bers of non-pinfish all proved to be weak linear 

 functions of macrophyte biomass (Table 2). The sec- 

 ond test, using the four stations as separate points on 

 a month- by-month basis, found significant positive 

 correlations between fish abundance and seagrass 

 biomass during certain periods (Table 3). Pinfish 

 abundance was closely related to seagrass biomass 

 between May and October, the season during which 

 first-year pinfish use the benthic habitat for a nursery 

 ground. Total fish abundance showed a similar posi- 

 tive correlation with seagrass standing crop from 



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