PROCEDURES 
Oysters used in the field experiment had to be obtained from 
a source that was free of phthalic esters, therefore, the natural 
oysters in the Chester River could not be used. Cultchless 
oysters with a height of approximately 3 cm were bought from 
Frank Wilde's Hatchery in Shadyside, Maryland. The oysters were 
distributed randomly over 15 trays with 96 oysters per tray. 
Trays were of stainless steel and measured 40 cm x 92 cm x 10 cm 
with a mesh of 2 cm x 2 cm. The lids were hinged by two rings 
through both lid and tray on one of the long sides and a stain¬ 
less steel clip hasp lock on the opposite side. Each tray was 
bridled by a 6.4 mm braided nylon line from each top corner that 
were joined about 1 m above the tray with a loop. Another 6.4 mm 
nylon line was fastened to the loop on one end and to the station 
on the other. Stations 8, 9 and 10 were suspended, but touching 
the bottom, from permanent structures; all other trays were set 
on the bottom with the line attached to either a buoy anchor 
chain, a ring on a day beacon, or to private docks. All trays 
had two bricks tied on edge to their bottom to hold the trays 
above the muck. 
Sampling Visits 
A total of nine visits were made to the study area. Eight 
visits were collecting and observation field trips after the sta¬ 
tions had been established on 15 May. These visits were made on 
23 May, 2 June, 14 June, 27 June, 12 July, 4 August, 23 August 
and 18 September. Not all stations were visited on each field 
trip due to mechanical breakdown of the outboard motor. Dates 
of visits and stations sampled are given below. 
Visit 1, 15 May--Was done from R.V. AQUARIUS and established the 
stations under the guidance of Dr. George Krantz. All sub¬ 
sequent visits were made by outboard runabout. 
Visit 2, 23 May--Twelve oysters were collected from every sta¬ 
tion except station 1 where the tray had been turned upside 
down with the lid open. Qualitative notes were kept on 
presence or absence of organisms associated with oyster com¬ 
munities. For hydrographic data see Table 1. 
Visit 3, 2 June--Visited stations 2, 3, 4, 8, 9 and 10 success¬ 
fully. Station 1 had been abandoned. Station 6 could not 
be found. Stations 5 and 7 had gotten so badly tangled up 
in the rusty metal of the day markers that the trays could 
not be brought to the surface for inspection and sample 
collection. 
Visit 4, 14 June--Successfully collected samples from stations 
3 - 10. 
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