WHOI-90-52

~
8
!E
:;
Electronic instrmentation is not currently capable of monitoring fec coliform bacteria (a
bacterial index use by regulatory agencies to trace human contamination). However, we were
able to employ the traditional culture tehniques along with tidal and current data to attack tlie
problem. Figure 4 shows the complex relationship between tidal displacement and tidal currents
for the mouth of Edgarown Harbor, as defined by ENECO/YSI instrments, a relationship that
would not be obvious from casual observations. This record reflects complex shallow water
harmonics of the principal tidal constituents affecting the Harbor. Havhig defined this
relationship, we were then able to interpret coliform bacterial data gathered over the 4th of July
holiday, 1989, at the entrance to Edgarown inner harbor. The results, when procsse
statisticaly, show an overal trend in bacterial count that follows the rise and fal in numbers of
transient boats. A more staing result, however, was that many of the highest counts were
associated with floo tide, for the first time suggesting an importt source of fec
contamination outside the Harbor.
a.a
a.4
a.2 a
6.Ø
6~Ð
s...
6.2
6
~
"'.8
...a
.....
...2
..
:3.6
:3.e
:3...
19 ..:S
l' ~
b!
i
ao
60
..0
:SO
20
10
0
-10
-20
-:30
-"'0
-50
-ao
19
Figure 4.
TIDAL HEIGHT
AUGUST 12-1ti
aT 91
TIMe: (HOURS. oorr.ot.d
CURRENT VELOCITY (EAST)
AUGUST 12-19. 1soa
115
TIIVU!: lHduRSI BEGINNING AUGUST 12. Uil-OO
1::9 ia::
Tidal elevation and currents at the mouth of Edgarown Harbor, Massachusetts,
August 12-19, 1989.
95