LIVINGSTON ET AL.: LONG-TERM FLUCTUATIONS OF POPULATIONS 



Tl ME-- MONTHS (3/72-3/75: 



Figure 6. — Relative importance (% of total) of four dominant species of invertebrates and fishes taken in 

 the Apalachicola Bay system from March 1972 through February 1975. Such species represent 82.4 and 

 86.0% of the respective 3-yr totals. 



determined by various natural and man-induced 

 phenomena such as overfishing and pollution. 

 The stability of the system depends on the 

 maintenance of various populations within cer- 

 tain limits of fluctuation. This has serious impli- 

 cations for any estuarine management program. 

 Holling (1973) pointed out that instability (in the 

 sense of large fluctuations) of individual popula- 

 tions may actually introduce a capacity for per- 

 sistence or resilience. Such resilience can be at- 

 tributed not only to component populations but to 



the system as a whole. Stability thus is seen as 

 the "ability of a system to return to an equilib- 

 rium state after a temporary distiu-bance," (Hol- 

 ling 1973). Resilience, however, is a measure of 

 the ability of a given system to absorb changes of 

 primary forcing functions and still persist. By 

 this measure, an estuarine system such as 

 Apalachicola Bay comprises various populations 

 which undergo considerable annual fluctuations 

 but nevertheless are maintained within a rela- 

 tively stable temporal succession. 



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