creased biochemical oxygen demand, or even the presence of hydrogen 

 sulfide. However, as with inland pollution, tVie alteration of the plant- 

 animal associations of various types of waters constitutes the most 

 generally relj.able quick indicator both of deterioration and of recovery, 

 ■/Jith the harbors \vhich our group has investigated, it is the animals studied 

 rather than the more inconspicuous plants which have proved more useful 

 in this respect. 



Not all of the harbor animals are likely to be significant in formulating 

 a zoological index of harbor pollution. The floating population or plank- 

 ton will be perceptibly altered, particularly diminished in a somewhat 

 selective manner, but except where flushing is much reduced, the pollution 

 effects will be rather minimized. Horeover, the mortality of plankton 

 nets, v/hich are both relatively fragile and expensive, is a deterrent to 

 the use of a plankton index in those reaches seriously contaminated. The 

 strong swimmers or nekton, in the harbor mainly fish, also could be ranged 

 into a rough equivalent of the spectrum from trout to carp of inland vraters, 

 but a number of practical considerations gravitate against their use for 

 harbor studies, 



T'.vo important ecological groups remain which are immediately affected by 

 pollution: a) the forms fixed to or moving slug-'ishly about the bottom 

 and b) the fauna of -filings, floats and fenders, animals either attached 

 or of limited movements. Of these two biotas, it is the bottom fauna or 

 benthos which is the more profoundly modified by whatever toxicants occur. 

 At the bottom fresh supplies of oxygen are ordinarily farthest removed so 

 that lethal levels are reached most quickly. Here, in addition to the 

 killed animals belonging to this level, settle the victims of unfavorable 

 conditions above and here the sulfur bacte-oia accvmiulate in any sludges 

 which may result. Any hydrogen sulfide generated prolongs lethality be- 

 yond the primarj'' effects of contamination. Further, there is a strong 

 possibility that pollutants v/hich might othervirise be dissipated by tidal 

 flushing md:y be incorporated in the sludge preventing re-occupation of 

 the beds by animals from adjacent still productive areas. The findings 

 of the joint agencies' siu'vey are consistent with these generalities. 

 Eight separate areas of the harbors may be considered to be derelict 

 zones. From bottom samples of these areas no living animals were found 

 by use of a lovif povfer dissecting microscope. One of these areas lies at 

 the "keystone" of the arch of the Inner Harbor in Cerritos Channel, Here 

 the movements of successive high tides meet so that each half of the arch 

 in effect comes to a dead end. The remaining seven are dead end channels 

 only two of T^hich face on the Outer Harbor, Zone 1 in i.'atchorn Basin may 

 be affected by neighboring naval establishments and presumably is polluted 

 by domestic discharges from U. S. Coast Giaard Moorings and tliree private 

 establishments vfhich together haA/^e an estimated maximum population of 600 

 persons. The extent of the derelict bottom here is apparently very limited. 

 Zone 2, Fish Harbor, has a concentration of fish-procassing plants which 

 at the peak of canning season turn Fish Harbor itself and adjacent waters 

 into a virtually opaque, off-color, foul-smelling suspension. 



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