FISHERY BULLETIN: VOL. 80, NO. 4 



Table 5. — Summary of two canonical cor- 

 relation runs of individual species abun- 

 dances against environmental variables. 



Axis 



R 2 



df 



Run No. 1 (6 environmental; 18 species) 



1 0.93 0.96 212.9* 126 



2 0.84 0.92 144.1* 102 



3 0.73 0.85 96.3 80 

 Run No. 2 (temperature, salinity only, 18 species) 



1 0.83 0.91 77.8" 36 



2 0.61 0.78 26.5 17 



* = significant at 0.01 . 



and salinity were important in influencing spe- 

 cies abundance. 



The 18 most common species were ordinated 

 along temperature and salinity axes using sim- 

 ple correlation values (r) as an index of relative 

 influence of these two factors (Fig. 11). Thirteen 

 of the 18 species were positioned in the upper 

 right quadrant indicating that they were all 

 positively correlated with temperature and sa- 

 linity. Three species, Gambusia affinis, Gillich- 

 thys mirabilis, and Lepomis cyanellus, located in 

 the upper left quadrant correlated positively 



Sspp. 

 Ac* 



Aa 



._ I 



• Qy 



ig 



,Gm 



La» •Hgj 



•Em ] 



• Ca 



Fp. 

 . Lt 

 Ad 



I 

 j 

 i 

 i 

 i 

 --i-- 



— ; ! 1 ; 1 1 1 1 — 



.6 .5 .4 -.3 .2 .1 .1 .2 .3 .4 .5 .6 



Correlation Coefficient (r) with Salinity 



Figure 11.— Ordination of 18 common species of the littoral 

 zone of upper Newport Bay on correlation coefficients (r) for 

 temperature (y-axis) and salinity (x-axis). Dashed lines indi- 

 cate 0.05 significance levels. Aa-Atherinopsaffin is, Ac- A nchoa 

 compressa, Ad-Anchoa delicatissima, Ca-Cymatogaster aggre- 

 gate!, Ci-Clevelandia ios, Em-Engraulis mordax, Fp-Fundulus 

 parvipinnis, Ga-Gambusia affinis, Gm-GUlichthys mirabilis, 

 Hg-Hypsopsetta guttulata, Ig-Ilypmis gilberti, La-Leptocottus 

 armatus, hm-Lepomis macrochirus, Lt-Leuresthes tenuis, Mc- 

 Mugil cephalus, Qy-Quietula ycauda, Sspp- Syngnathus spp. 



with temperature, but negatively with salinity. 

 The lower left quadrant includes two species, 

 Lepomis macrochirus and Mugil cephalus, with 

 negative temperature and salinity influences. 

 No species were positioned in the negative tem- 

 perature, positive salinity quadrant probably be- 

 cause this situation rarely occurred in the littoral 

 zone in 1978. 



DISCUSSION 



Composition, Diversity, and 

 Seasonal Dynamics 



The ichthyofauna of the littoral zone in upper 

 Newport Bay was numerically dominated by a 

 few, low trophic-level species (five species ac- 

 counted for >98% of all specimens collected), a 

 situation similar to that found in many estuarine 

 fish populations (Allen and Horn 1975). Atherin- 

 ops affinis is an opportunistic feeder and has 

 been characterized as both a herbivore/detriti- 

 vore (Allen 1980) in upper Newport Bay and a 

 low-level carnivore (Fronk 1969; Quast 1968). 

 The second most abundant fish, Fundulus parvi- 

 pinnis, is a low-level carnivore that feeds on 

 small crustaceans and insects (Allen 1980; Fritz 

 1975). Gambusia affinis, Clevelandia ios, and 

 Anchoa compressa are, likewise, low-level carni- 

 vores, feeding mainly on insects, benthic micro- 

 invertebrates, and zooplankton (Allen 1980). 



Large individuals of Mugil cephalus were not 

 sampled effectively, but probably constituted a 

 significant proportion of biomass within these 

 fish assemblages. Adult M. cephalus fed mainly 

 on detritus and pennate diatoms (Allen 1980). 

 This essentially herbivorous diet closely matches 

 that described by Odum (1970) for M. cephalus. 



The overall H' diversity values (H'x range, 

 0.42-1.76; overall 0.89) for the littoral zone were 

 comparable to values derived from other studies 

 of bay-estuarine fish faunas and to other studies 

 in Newport Bay. Haedrich and Haedrich (1974) 

 derived values of 0.33-1.03 for Mystic River Es- 

 tuary, Mass.; Stephens et al. (1974) presented in- 

 dices of 0.65-2.08 for Los Angeles Harbor, Calif.; 

 Allen and Horn (1975) published values of 0.03- 

 1.11 for Colorado Lagoon, Alamitos Bay, Calif.; 

 and Quinn (1980) calculated values of 0.21-2.59 

 (overall 1.9) for Serpentine Creek in subtropical 

 Queensland. Using otter trawl data, I calculated 

 #; values of 0.20-1.96 (overall 0.98) for the upper 

 Newport Bay in 1974-75 (Allen 1976). The con- 

 current bimonthly portion of this study (Horn 



784 



