was abundant, as in the high marsh low vegetation suggesting that the 

 debris line of the low sand marsh provides a rich, but unstable, habitat 

 comparable to the accumulated litter found in high marshes. Other debris 

 line taxa were the amphipod Orchestia traskianaj found in all the marshes ^ 

 Saldidae (Hemiptera) , found principally in the low marshes, and Lim- 

 nebiidae (Coleoptera) found mostly in the low sand marsh. Dipterous 

 adults were not abundant; most were spaerocerids, which occurred in both 

 high and low marshes. 



Several terrestrial taxa were collected from inundated vegetation 

 during high tide (Figs. 7 and 8). Adult Coleoptera, Homoptera, Hemip- 

 tera, and Collembola appeared in many of the submerged marsh samples, 

 where several beetle families were collected. Limnebiid beetles were 

 as abundant in the submerged low sand marsh as they were during tidal 

 exposure. Adult Diptera were rare except in the low sand marsh. The 

 data suggest that more active flying animals (Diptera) are less apt 

 to be inundated than animals less likely to fly (Coleoptera, Homoptera, 

 Collembola, Hemiptera). Opinions differ as to the ability of terres- 

 trial insects in salt marshes to escape submergence. Cameron (1972) 

 tested the response of adult insects to submergence in several strata 

 of salt marsh plants during different phases of exposure and submergence. 

 He detected no differences to the animal communities that would suggest 

 exodus or upward migration on the plants. He did not provide the 

 taxonomic composition for his samples. Since Cameron used the clip- 

 quadrat sampling technique, it is unlikely that adult dipterans were 

 adequately sampled. Thus, he probably studied the less active orders 

 of insects, such as those found in the submerged vegetation in the 

 Oregon marshes. 



The infauna of pans and tidal creeks include estuarine animals 

 (e.g., Polychaeta, Amphipoda, Tanaidacea, isopoda) and animals of 

 terrestrial origin (dipterous larvae) (Table 7) . Many of the taxa 

 found in the Oregon tidal creeks also occur in Atlantic coast tidal 

 creeks or embayments. These include Neanthes, Streblospio, Polydora, 

 Hobsoniaj Capitellidae, Eteone, Coroph'tum, Ovahestia, Dolichopodidae, 

 Ephydridae, and Muscidae (Nixon and Oviatt, 1973; Cammen, 1976). The 

 polychaete, Hobsonia ftorida, is common on the east coast and is 

 apparently widespread in the Pacific Northwest estuaries, where it has 

 only recently been identified (Banse, 1979). The Atlantic coast tidal 

 creeks apparently are inhabited by a greater variety of decapods, in- 

 cluding fiddler crabs {Uoa) , the green crab [Cavcinides maenas) , and 

 the blue crab [Callineotes sapidus) (Nixon and Oviatt, 1973). Only 

 one decapod, Hemigrapsus oregonensis, was found in the sedge and 

 mature high tidal creeks, although it is possible that estuarine 

 decapods, such as Crangon, Callianassa, and Canoev , occur in other 

 Oregon tidal creeks. Molluskan diversity was also low in the Oregon 

 tidal creeks. Only two taxa were abundant, Alderia and Maaoma balthica. 

 MacDonald (1969) found Maaoma inconspi-oua (considered here to be 

 synonomous with M. balthica) and Mya arenavia in a marsh tidal creek 

 of Coos Bay, a southern Oregon estuary. He found these species plus 

 Maaoma nasuta and Cryptomya aalifomiaa in Grays Harbour, Washington. 

 All four species are common in the Pacific Northwest estuaries. 

 Fewer species of tidal creek mollusks tended to occur in the Oregonian 

 Province than in the Californian Province. These tidal creek mollusks 



47 



