fish stocks by about 3,000 tonnes (Marti and Musatov, 
1973; Bronfman, 1977). 
These flow modifications have also led to a 40-60 
percent reduction in nutrient supply, decreases of 
60-70 percent of sediment load and 80 percent reduction 
in spawning and nursery areas, with salt intrusion 
compressing the null zone into the pre-Delta and Delta 
areas and salinity increasing from 0.5 to 10 ppt 
(Baydin, 1980; Makarov, et al., 1982; Remisova, 
1984a,b; Volovic, 1986). Numerous attempts to stop the 
destruction of the Sea of Azov have failed. The 
institution of extensive fishery regulations and the 
release of more than 5.5 billion hatchery-reared fry in 
1976 and hundreds of millions of fry of anadromous and 
semi-anadromous fish between 1956-76 did not mitigate 
the detrimental effect of excessive water diversions on 
living resources of the ecosystem. 
Further, when the mean salinity of the Azov seawater 
stabilized at 14-16 ppt in the late 1970s (compared to 
9.5 ppt in the 1930s), there was an invasion of marine 
species. The billions of medusae (Figure 6B) that 
moved into the Sea of Azov (Makarov, et al., 1982) and 
into its formerly less brackish Taganrog Harbor and Don 
River Delta (Figure 1) from the Black Sea presented a 
serious threat to the survival of many indigenous 
species. These jellyfish have created severe problems 
in the Sea of Azov such as food competition between 
them and fish, and public health problems along 
hundreds of kilometers of beaches created by accumu¬ 
lation of dead medusae. 
6. Although the San Francisco Bay estuarine system has not 
yet deteriorated to the level of the Sea of Azov, the 
impact of freshwater diversion on the survival of 
living estuarine resources in both systems has many 
alarming similarities: accumulation of organic and 
inorganic compounds from agricultural drainage; 
saltwater intrusion along the deep channels into the 
Bay and Delta (Orlob, 1977); gradual salt buildup 
throughout the estuary; and spontaneous algal blooms 
(Cloern and Nichols, 1985a; Nichols et al., 1986). In 
addition, the alteration of the Delta into a sophisti¬ 
cated plumbing system has led to disruption of fish 
migration routes and their spawning and nursery areas 
(Moyle, 1976; California Department of Fish and Game, 
1976, 1983; Striped Bass Working Group, 1982; 
Herrgesell, et al., 1983) and a significant reduction 
of flushing intensity and circulation in all parts of 
the Bay (Rozengurt, 1983a; Cloern and Nichols, 1985a). 
All of these factors have contributed to diminishing 
48 
