Except for some difficulties associated with the initial operations, the nine 
tanks were run identically during the first four months in order to assess the 
replicability of the systems. Some of the data obtained during this time are 
used in this paper to test the similarity of the tanks to each other and to 
Narragansett Bay. 
Biological measurements used in comparisons 
Table 24-2 gives a list of the data used in the analyses to be presented here. 
A brief description of the analytical procedures follows. 
Nutrient analyses were performed using Technicon AutoAnalyser 
procedures somewhat modified for our purposes. Chlorophyll a was 
determined by the fluorometric method of Holm-Hansen et al. (1965). 
Phytoplankton were counted on 1-ml aliquots from a pooled sample (3 
depths pooled) from each MERL tank or from single samples taken at the end 
of the dock or in the bay. Generally the samples were counted live using a 
Table 24-2. List of Measurements Yielding Data Used 
for Intercomparisons; Weekly Sampling During 
August-December 1976 Unless Noted 
MERL 
9 microcosms 
Narragansett Bay* 
a b c 
ammonia 
X 
X 
X 
— 
nitrate i nitrite 
X 
X 
X 
— 
silicate 
X 
X 
X 
— 
phosphate 
X 
X 
X 
— 
chlorophyll a 
X 
X 
X 
— 
phytoplankton species counts 
X 
X 
X 
X 
zooplankton biomass 
X 
X 
X 
X 
*Narragansett Bay 
a. Data from a year-long biweekly survey made in 1972-73 at stations 
(surface and bottom). 
b. Input water to MERL microcosms, sampled from end of dock near intake 
line, close in time to weekly sampling of the tanks. 
c. Three stations (S. Quonset, S. Patience Island, and Ohio Ledge area) 
sampled weekly from September to November 1976, from Durbin and 
Durbin (unpublished data). 
364 
