16 



Fishery Bulletin 100(1) 



significant, whereas the (difference between inshore and 

 midshore was not. Overall, four species were caught, but 

 C. bocourti prevailed at all the stations with at least 73.2'^f 

 of the total quantity ( Table 3 ). Frequency of crabs by spe- 

 cies varied significantly with the distance of the station 

 to the shore (G=17.024. 0.05 >P>0.01. df=8). C. bocourti 

 maintained a constant presence through the three sta- 

 tions, ranging from 73.2 to 75. 09^ of total crabs at each 

 station, the abundance of C. maracaiboensis increased sea- 

 ward, and the abundance of C. cjrnatus decreased. Calli- 

 nectes danae did not show any trend. 



In this set of samples, taken at a distance from the 

 shoreline, the highest diversity (Shannon-Weaver index) 

 was registered at the midshore station, closely followed by 

 the inshore station and the offshore station. Hill's diver- 



sity number 1 (Nl), which indicates abundant species, was 

 also highest at the midshore station, followed by inshore 

 and offshore stations (Table 3). 



Temporal variability 



Because data for C. bocourti, C. sapidus, C. e.xasperatus, C. 

 maracaiboensis and C. larvatus were too scarce to allow 

 useful analysis, temporal variability of the abundance at 

 the surf and at the estuarine pond was examined only 

 for A. crihrxii-ius. C. danae, and for total crabs. Temporal 

 variability of the abundances of these species are shown 

 in Figure 4. Abundances fluctuated widely and randomly 

 throughout our study. The density of A. cribrarius peaked 

 in April, July, and October 1993, as well as in February 

 and October 1994 (Fig. 4). In the estuarine site, C. danae 

 abundance peaked in May and October 1993, as well as 

 in February, April, August, and November 1994 (Fig. 4). 

 In the marine sites, C. danae abundance was considerably 

 lower and maxima occurred in June, September, and Octo- 

 ber 1993, and in May and October 1994 (Fig. 4). No sig- 

 nificant correlations were found between abundances of 

 these two species and rainfall, water temperature, salin- 

 ity, and dissolved oxygen (Table 4). However, when total 

 crabs were regressed against rainfall at the estuarine site 

 and oxygen at the foreshore, correlations were significant 

 (Table 4). The negative correlation of this latter factor 

 reached almost significant levels for both species at the 

 marine ecotope. 



Diel variations 



Surf zone A total of 196 crabs were caught with hand 

 seines at the foreshore during September 1997-February 

 1998 samplings: 82 crabs at night and 114 during the 

 day (Table 5). Six species appeared in the diurnal samples 

 (A. cribrarius, C. danae, C. bocourti, C. larvatus, C. mara- 

 caiboensis and C. sapidus), one of which (C. sapidus) did 



