0
0
5
10
15
Fluorescence intensity
20
25
Drift starts
June 2004
July 2004
May 2004
Protected
instrument
Unprotected
instrument
30
(a)
(c)
(b)
10
20
30
Days
40
50
60
Plate 9. (a) Retrieval of an optical package after a deployment in the Penobscot River, Maine. (Photo
courtesy of C. Roesler and A. Barnard.) (b) Example of a copper biofouling shutter on a sensor.
(Photo courtesy of B. Downing.) (c) Drift of unprotected fluorometer due to biofouling. (Redrawn
from Delauney et al., 2010.)