Information on the structure and ecology of the animal communities of 

 Pacific coast salt marshes is incomplete. MacDonald [1969) studied the 

 local, seasonal, and latitudinal variations in molluskan fauna in level 

 marsh and tidal creek habitats along the Pacific coast from Baja, Califor- 

 nia, to Washington. He found Assiminea trccnsluaens , a small prosobranch, 

 to be ubiquitous in level marshes of this region, with Littorina newoombiana 

 (Prosobranchia) and Phytia myosotis (Pulmonata) joining Assiminea to form 

 a characteristic Oregonian assemblage. Tidal creek mollusks were mostly 

 bivalves, a Maaoma-Mya assemblage characterizing the Oregonian Province. 

 The number of species recorded from edch habitat increased from north to 

 south. Level marsh mollusks fed predominantly on algae or plant detritus 

 by rasping; tidal creek forms included deposit and suspension feeders as 

 well as predators and scavengers. 



Whitlatch (1974) observed the growth, production, and seasonal 

 abundance patterns of Batiltaria zonalis , a small introduced prosobranch, 

 in pans, tidal creeks, mudflats, and Saliaomia level marshes of Tomales 

 Bay, California. Abundance was greatest in pans and creeks, but recruit- 

 ment was lacking in the creeks which apparently resulted in the relative 

 stability of the populations there. Influx was likely due to immigration 

 from the pans where recruitment was successful. 



Two studies have been made of insect populations of San Francisco Bay 

 marshes. Using a sweep net for collecting. Lane (1969) identified 124 

 species in Spartina-Salicomia marshes. The majority of species were in 

 the orders Diptera (flies) and Homoptera (planthoppers) ; Delphacidae 

 (Homoptera) , and Chloropidae, Ephydridae, and Chironomidae (all Diptera) 

 were the dominant families. Cameron (1972) used a clip-quadrat method in 

 a similar marsh to study insect trophic diversity and its relation to 

 resource availability (living and dead plant materials) . He found that 

 herbivore diversity increased with primary production, and that saprovore 

 diversity increased during periods of detrital input. In general, trophic 

 diversity showed seasonal patterns relating to physical factors and (more 

 clearly) to resource availability. Cameron hypothesized that seasonal 

 increases in diversity occurred as seasonal species joined persistent 

 species in exploiting expanding resources. 



The only major study of trophic relations in a Pacific coast salt 

 marsh ecosystem is the Coos Bay, Oregon, study sponsored by the National 

 Science Foundation (Hoffnagle, et al., 1976). Short-term field and 

 laboratory studies were used to measure net primary production, detrital 

 production, decomposition rate, nutrition of key species, and the composi- 

 tion of insect and fish populations of several marsh sites. 



In recent years, interest has increased in the role of estuarine food 

 chains in the growth and survival of seaward-migrating juvenile salmonids 

 along the Pacific Northwest coast. There is evidence that those juveniles 

 which benefit from favorable estuarine conditions have a better chance at 

 sea (e.g., Reimers, 1971). These fish seem to adjust their habitat and 

 feeding strategies to exploit freshwater and marine as well as estuarine 

 food chains while making the transition to marine life (Mason, 1974) . The 

 fish are found in some marsh habitats, especially tidal creeks. Dunford 

 (1975) found juvenile, chum salmon {Onoorhynohus keta) and chinook salmon 

 {0. tshawytschd) residing in sloughs and creeks of the Fraser River estuary 



