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HPLC pigment analyses for evaluating algal
community
composition.
One
of the most useful tools
for identifying algal groups in natural waters is by the analysis of
photosynthetic and accessory pigments. These pigments are characterized
by
their chemistry (chlorophylls,
xanthophylls, carotenoids), and each
absorbs a
unique light wavelength. The
ability to separate and identify pigments
from
water samples via HPLC can result in a rapid assessment of algal
community
composition and abundance.
 Members
of algal groups
differ in the presence and ratios of photopigments, and pigment
“profiles” can
be a powerful taxonomic tool. For example, Karlodinium
micrum (see chromatogram at left),
is characterized by the marker pigments, chlorophyll c3,
19’-hex and 19’ but-fucoxanthins, and by gyroxanthin
diesters. Not all such profiles are species-specific, however, and in
general,
only major groups can be identified (other profiles from Kiawah ponds). Community composition can be estimated by
the relative abundance of marker pigments, relative to total
chlorophyll a. The
matrix-factoring program, CHEMTAX, uses pigment profile information to
estimate
the abundance of algal classes .
The
SCAEL maintains a library of pigment profiles from a large reference
culture
collection for
comparison with natural samples. We also isolate species from
our field samples to improve the resolution of our pigment database.
Our future
directions also include the detection and quantification of
water-soluble
pigments (phycobiliproteins) from cyanobacteria and cryptophytes.
All content © 2003 S.C.A.E.L. any
use of contents
requires permission from the Webmaster.
Algal Ecology Labs--331 Fort Johnson
Road--Charleston,
SC 29414.
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