ALLEN: LITTORAL FISH ASSEMBLAGE 



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FMAMJJASONDJ 

 MONTHS (1978  1979) 



Figure 10.— Monthly variation in mean production ( x± 2 SE, 

 g DW/m 2 ) of the littoral fishes from three stations in upper 

 Newport Bay (February 1978-January 1979). 



low from February to May 1978, increased rap- 

 idly from June to a peak in August (5.2 g DW/ 

 m 2 ). Monthly production then declined drastic- 

 ally in September, a period of heavy rainfall dur- 

 ing which many of the larger young-of-the-year 

 Atherinops affinis emigrated from the study 

 area. Production increased in October but then 

 showed a steady decline to zero in December, a 

 time of a sharp decrease in mean water tempera- 

 ture in the upper bay. 



Relationship of Abiotic Factors to 

 Fish Abundance and Distribution 



Temperature was found to have a significant, 

 positive correlation (P<0.01, df = 37) with num- 

 ber of species (r = 0.42), number of individuals 

 (r = 0.48), and biomass (r = 0.54) when station 

 totals were considered. Similarly, salinity was 

 significantly correlated with number of individ- 

 uals (r = 0.36) and biomass (r = 0.64) (Table 4). 



Temperature was the factor which yielded the 

 highest number of significant correlations (6) 

 with individual species, followed by salinity, dis- 

 solved oxygen, distance into the upper bay, and 

 depth of capture, each with four (Table 4). 



An analysis of intercorrelations among abiotic 

 factors yielded three significant (P<0.05, df = 

 37) positive relationships: 1) Temperature and 

 salinity (r = 0.48); 2) temperature and dissolved 

 oxygen (r = 0.53); and 3) dissolved oxygen and 

 distance into the upper bay (r = 0.32). 



According to canonical correlation analysis, 

 the six abiotic variables accounted for 93% of the 

 variation in individual species abundances along 

 the first canonical axis (Table 5). A second run 

 indicated that 83% of the variation in species 

 abundances could be accounted for by tempera- 

 ture and salinity alone. This finding strongly 

 implies that interactive effects of temperature 



Table 4. — Correlation coefficients (r)of individual species numbers and of total number of 

 species, number of individuals, and biomass with six environmental factors. TEMP = 

 temperature, SAL = salinity, DO = dissolved oxygen, DSTUPB = distance into upper 

 Newport Bay from Highway 1 bridge, APRTSZ = average particle size of sediments. 

 DPTHCAP = depth of capture. 



significant at 0.05 level, 

 significant at 0.01 level. 



783 



