process was especially useful for samples collected with the large enclosure 

 in the fall when detached vegetation was present. 



a. Level Marsh . The principal method for collecting submerged 

 invertebrates in the level marshes was the large enclosure (Table 3) . It 

 was dropped over a preselected sample point and secured at the soil by 

 standing on the leadline, which closely conformed to the soil contours. 

 The 0.5-millimeter-mesh aquatic sweep net was then repeatedly swept 

 within the enclosure until capture rates were very low or zero. The 

 animals and debris were concentrated and preserved. This method provides 

 a semiquantitative measure of the aquatic and terrestrial animals found 

 near or in submerged vegetation, although in a few cases it was difficult 

 to remove all of the highly abundant isopods found in the low silt marsh 

 (Siletz Bay) study site. 



Large enclosure studies were designed primarily for the low marshes 

 although a single sample set was collected in the immature high marsh 

 during an extremely high winter tide. Samples from the low marshes were 

 collected on three to four occasions. 



Large enclosure sample sites were established where a stand of 

 selected type of vegetation occurred in a reasonably accessible location. 

 Each site was a 10- by 10-meter grid divided into 100 sampling areas. On 

 each sampling day, four randomly preselected areas were sampled. Each 

 area was sampled only once during the study. 



A similar sampling plan was established to study the infauna of level 

 marshes. A plug of soil and roots 10.2 centimeters in diameter and up to 

 25 centimeters deep was removed at selected sampling areas in a grid 

 (separate from but near the large enclosure grid) . The plug was disaggre- 

 gated by hand under water and then sieved on a 0.5 -millimeter screen. 

 Early results showed that the majority of the animals were near the surface, 

 so later samples were only 5 to 10 centimeters deep. It was also decided 

 that the few animals collected and the relative unlikelihood of their 

 directly entering aquatic food chains did not warrant the time and effort 

 required for extensive sampling. Therefore, only one set of four samples 

 per marsh was collected and completely processed. 



Sampling of terrestrial invertebrates of the level marsh was conducted 

 during low tides with the terrestrial sweep nets, clip-quadrat method, and 

 small enclosure (Table 3) . One set of samples was taken at each marsh. 

 Collections were planned during the warmest and driest period of the year, 

 but an unusually wet season forced the postponement of several collecting 

 trips. The collections were finally accomplished during favorable tides 

 and weather on 29 August 1978 (low sand and immature high marshes of 

 Netarts Bay) , of September 1978 (low silt and sedge marshes of Siletz 

 Bay) , and 25 September 1978 (mature high marsh of Netarts Bay) . On these 

 dates, the air temperature was 19° to 24° Celsius, the wind to 16 kilo- 

 meters per hour, and the sky sunny to overcast. 



All samples were taken at low tide. The wind was minimal, the air 

 temperatures were moderate, and the marsh vegetation was slightly damp. 

 Within each level marsh type, sample sites met the following criteria: 

 (1) selected vegetation community, (2) uniform vegetational cover, (3) 



