HPLC Pigment methods

Method by Wright et al (Mar. Ecol. Prog. Ser. 1991, 77:183-196) CHLA1,
CHLA2, CHLB1 and CHLB2 estimated following the method of Latasa et al
(Mar. Chem. 1996, 51:315-324)


Pigment data for P2 & P5:

A comparison of the TURNER-determined chlorophyll a concentrations with the
HPLC-determined TOTCHLA concentrations (monovinyl chlorophyll a + divinyl
chlorophyll a + monovinyl chlorophyllide a;  units = ng Chl a
equivalents/L) was performed for Process Cruise #2 (TTN-045) and Process
Cruise #5 (TTN-050).  While good correlations were obtained for both
cruises, the slope obtained for Process Cruise #5 was significantly
different from 1 (i.e., TURNER > HPLC).  This difference was probably
caused by the presence of Chl a-related pigments during Process Cruise #5.
Thus, we recommend that whenever possible use the HPLC pigment data and not
the TURNER pigment data.  If HPLC data is not available for a given cast,
we further recommend that you use the following equations to transform the
TURNER data into HPLC-equivalent concentrations (cf., Babin, M., A. Morel,
H. Claustre, A. Bricaud, Z. Kolber and P.G. Falkowski.  1996.  Nitrogen-
and irradiance-dependent variations of the maximum quantum yield of carbon
fixation in eutrophic, mesotrophic and oligotrophic marine systems.
Deep-Sea Research, in press).

Results of geometric mean regression analyses (reduced major axis):

Y = HPLC TOTCHLA (monovinyl chlorophyll a + divinyl chlorophyll a +
monovinyl chlorophyllide a), units = ng Chl a equivalents/L

X = TURNER chlorophyll a (it is necessary to convert the Turner Chl a
concentrations in the Arabian Sea data base from mg/m3 to ng/L by
multiplying concentrations by 1000)

(1) Process Cruise #2 (TTN-045)

HPLC TOTCHLA = TURNER*(0.975) + 4.833 (r = 0.9822, n = 146)

(2) Process Cruise #5 (TTN-050)

HPLC TOTCHLA = TURNER*(0.708) + 12.881 (r = 0.9772, n = 575)


Robert R. Bidigare
Department of Oceanography
University of Hawaii
Honolulu, HI  96822
808-956-6567 (voice mail)
808-956-9516 (fax)