THE OCEANOGRAPHY SOCIETY PACIFIC BASIN MEETING, July 1994, p.62

Do GF/F Filters underestimate particulate chlorophyll a and primary production in the oligotrophic ocean?

D.V. Hebel, F.P. Chavez, K.R. Buck, R.R. Bidigare, D. M. Karl, M. Latasa, M. E. Ondrusek, L. Campbell and J. Newton

Dickson and Wheeler (1993) recently reported that GF/F filters significantly underestimate in situ chlorophyll a (up to four-fold), relative to 0.2 µm membrane filters. These findings would have enormous oceanographic implications since most investigators use GF/F filters to quantify chlorophyll a and associated carbon parameters. A group of investigators at Monterey Bay Aquarium Research Institute (MBARI), the University of Washington and the University of Hawaii - Hawaii Ocean Time-series (HOT) program compiled field data comparing GF/F and 0.2 µm membrane filter chlorophyll retention characteristics. Field experiments were also conducted to assess aspects of the Dickson and Wheeler protocols relative io established MBARI, UW and HOT protocols. Our findings document no significant difference between the chlorophyll retaining characteristics of GF/F and 0.2 µm membrane filters in eutrophic and oligotrophic oceanic habitats. In addition, no significant difference was found in primary production estimates using either filter type in the oligotrophic environment.