juvenile populations. The following explanations are possible: 

 (1) The studies did not adequately represent the fauna studies, which 

 may vary greatly, by season, by day, and from creek to creek; (2) the 

 low salinity regime of the estuaries studied prevented the influx of 

 marine species; and (3) the relatively simple and spatially restricted 

 nature of Pacific coast marshes has not encouraged extensive exploita- 

 tion of the tidal creek habitats by juveniles of marine species such 

 as has occurred on the Atlantic coast. 



Dunford's (1975) study of fish communities in slough and tidal 

 creek habitats of the Fraser River estuary provides comparative infor- 

 mation to the Oregon study. Juvenile chum, chinook, and sockeye 

 {Onaorhynahus nerka) salmon, which he collected in these habitats, 

 consumed mostly aquatic foods. However, there appeared to be more 

 terrestrial animals consumed in the tidal creeks than in sloughs, 

 and more of these animals were consumed in late May than in April. 

 The principal prey organisms were Homoptera and Collembola, although 

 other terrestrial animals were eaten. In some incidences, terrestrial 

 animals accounted for more than 40 percent of the prey biomass. The 

 implication is that the young salmon fed opportunistically on 

 available prey, which included increasing amounts of terrestrial 

 insects as populations increased during early spring. More insects 

 presumably wash into the marsh- lined tidal creeks than into sloughs. 

 In other studies of northwest estuaries, juvenile salmon consumed 

 predominantly benthic amphipods (Cliff and Stockner, 1973), harpacti- 

 coids (Healey, 1979), and a mixture of amphipods, isopods, dipterous 

 larvae, and copepods (Mason, 1974). The diurnal variation in 

 juvenile chum and coho (0. kisutah) salmon foods observed by Mason in 

 a small coastal creek is an excellent illustration of the dietary 

 flexibility exhibited by young salmonids. 



Other fish species in the slough habitat in Dunford's (1975) 

 study consumed mostly aquatic foods: (1) longfin smelt {Spirinchus 

 thaleiahthys)- -my sids; (2) peamouth--cladocera and ostracods; 

 (3) starry flounder--benthic amphipods and isopods, oligochaetes, 

 polychaetes, and chironomid larvae; (4) prickly sculpin- -benthic 

 isopods, chironomid and tabanid larvae, and benthic amphipods; 

 (5) staghorn sculpin--benthic amphipods and isopods, and juvenile 

 salmon; and (6) threespine stickleback--chironomid larvae, 

 oligochaetes, benthic amphipods tabanid larvae, copepods, cladocerans^ 

 and terrestrial insects. In the tidal creek, threespine stickleback 

 ate copepods and amphipods, and prickly sculpin ate mostly benthic 

 isopods and amphipods. 



In Siletz and Netarts Bays, small amounts of terrestrial inverte- 

 brates were consumed by fish collected in marsh habitats, and an 

 adjoining slough, and in bay channels. Amphipods, isopods, tanaids, 

 polychaetes, cumaceans, copepods, dipterous larvae and pupae, and 

 fish were the dominant food items. Thus, it appears that energy 

 flows into the aquatic communities primarily through the detrital 



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