(4) Species Diversity and Equitabllity . Species diversity (Shannon- 

 Weaver H') and equitability values CPielou's J') are presented in Table 20 

 (November-December 1979) and Table 21 CMay 1980) . Diversity values ranged 

 from 0.47 to 3.22 (stations 1-1 and CA) for November-December and 0.15 to 

 2.85 (^tations 1-1 and 2-3) for May. For transect stations 1, 2, and 3 and 

 stations CA and CB, diversity values generally decreased from November- 

 December to May. Transect stations 4 and 5 showed the least amount of 

 seasonal change. Borrow sites Bl and B2 were unusual in exhibiting a pro- 

 nounced increase in diversity from November-December to May. Diversity 

 values for transect stations 1 and 2 were generally much lower than all 

 other stations, for both sampling periods. Station 4 exhibited lower 

 diversity values than stations 3 or 5. 



Equitability values were generally quite high (>0.60) with the exception 

 of transect station 1, indicating a relatively low level of oligomixity 

 within the study area. 



Table 22 lists values for Simpson's diversity index (A) for transect 

 stations 1 to 5 for all nine transects, as well as stations CA and CB and 

 borrow sites Bl and B2. In this case a low X value indicates a high 

 diversity. This measure shows the trends illustrated in Tables 20 and 21, 

 i.e., stations 1 and 4 have the lowest diversities, with diversity increas- 

 ing slightly at the offshore stations. 



b. Comparison of Faunal Parameters to Saloman's (1976) Study . Compari- 

 sons of the species and number of individuals collected for all 47 stations 

 between the present study (1979-80) and Saloman's study (1974-75) are given 

 in Appendix C. The major differences are given below. 



(1) Species Richness . For November -December comparisons the number 

 of species collected at each station was greater in 1979 than in 1974, with 

 the exception of station 1-5, with 16 species collected during both studies 

 (Table 16). For May comparisons, 29 stations exhibited more species during 

 1980, 17 exhibited less, and 1 remained the same (Table 17). The number of 

 species at a station (averaged over 9 transects for stations 1 to 5) is de- 

 picted in Figure 9 (Nov/ember-December) and Figure 10 (May) . 



(2) Faunal Density . For November-December comparisons faunal densi- 

 ties were mostly greater in 1979 than 1974 (35 stations with faunal densities 

 in 1979 greater than 1974, 12 less than 1974; see Table 18). For May the 

 faunal densities were always higher in 1975 than 1980 (Table 19) . This was 

 primarily caused by the extreme abundance of some species in 1975: the bivalve 

 Donax texasianus (stations 1 to 4) and the amphipods Acanthohaustorius sp. 

 (stations 3, 4, and 5) and Protohaustorius n. (stations 3, 4, and 5). Faunal 

 density comparisons for each station (averaged over 9 transects for stations 



1 to 5) are exhibited in Figure 9 (November-December) and Figure 10 (May) . 



42 



