_ 150 



X 



O 



a 

 6 



u 



z 



N 



100 



o 



=»^ 50 



Gl 



ycera 



J 



Arabella iricolor (7) 



dibranchiata (22) 



h 



Diopatra cuprea 



(39) 



Marphysa sp. (6) 



J. y.. 



Amphitrite I ornata 



(36) 



500 ipoO 1,500 



pG. IRON / G. DRY WEIGHT 



2000 



2^00 



Figure 18. — Relation between concentrations of zinc and iron in five species of polychaetous worms. Each value is rep- 

 resented by the mean and standard deviation of the number of samples indicated in parentheses. Each sample consists 

 of about 10 worms. 



RATES OF RESPIRATION OF 

 ESTUARINE FISH 



Donald E. Hoss 



The rates of respiration of fish and the 

 relation between these rates and the weight of 

 the fish have been used to calculate energy- 

 requirements of populations of fish. Respira- 

 tion is generally related to body weight by the 

 equation Q = aW"^ where Q is the respiration 

 rate or routine metabolism, a and k constants 

 for the species, and W the weight of the fish. 

 Some question exists, however, concerning this 

 relation. It is assumed in the equation that 

 respiration rate and weight are linearly re- 

 lated throughout life, but this assumption has 

 been questioned by many investigators. 



Extensive data on rates of respiration of 

 many different species of fish, predominately 

 fresh-water, have been reported in the litera- 

 ture. From these data (which were collected by 



many different methods), one investigator has 

 calculated a "basic" equation (Q = 0.3w'^-''*) to 

 be used as a first approximation of the relation 

 between weight and metabolism in fish. The 

 assumption is made that the relation between 

 weight and metabolism is linear and does not 

 change during ontogeny of the species. An 

 English scientist used a modification of this 

 equation to measure the energy requirements 

 of a population of fish in a river in England. 

 He found evidence that the value for k in the 

 "basic" equation (0.8) is correct but that the 

 value of a may vary over a considerable range 

 for different species. Calculated regression 

 lines for several species of fish, therefore, 

 would have the same slope (k) but not neces- 

 sarily the same intercept (a). Thus, he rec- 

 ommended modifying the "basic" equation by 

 using a fixed slope of 0.8 and calculating the 

 value of a from empirical data. 



The purpose of my experiments was to deter- 

 mine whether the "basic" equation or the 



35 



