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Journal of Experimental Marine Biology and Ecology 249 2000 77–88
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Pigment signatures associated with an anoxic coastal zone: Bahia Concepcion, Gulf of California
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´ J. Bustillos-Guzman , D. Lopez-Cortes, F. Hernandez, I. Murillo
Northwest Center for Biological Research , POB 128, La Paz, B.C.S. Mexico
Received 14 April 1999; received in revised form 29 February 2000; accepted 2 March 2000
Abstract
Bahia Concepcion is a coastal lagoon that has bottom anoxic conditions and high pigment concentrations during the summer. The phytoplankton responsible for this pigment increase is
enigmatic, therefore we sampled the lagoon to analyze the pigment with a C8-HPLC system to look for signatures of phytoplankton groups. Analysis reveals a low pigment concentration in the
mixed layer with a higher concentration of zeaxanthin and increasing values of chlorophyll a, peridinin, and fucoxanthin below, which peaked at the depth where oxygen dramatically decreases
and H S increases. Below this depth, a high pigmentation was recorded and the most important
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signatures were six chlorophyll-like pigments that eluted between the fucoxanthin and the chlorophyll a, and one carotenoid that eluted just after the chlorophyll a. Spectral characteristics of
these last pigments are very similar to pigments present in the Chlorobiales group. These results suggest that cyanobacteria, diatoms, and dinoflagellates are responsible for the chlorophyll a
increases, though in highly pigmented samples, anoxygenic phototrophic bacteria are probably the main contributors to the increase in pigments.
2000 Elsevier Science B.V. All rights reserved.
Keywords : Bacteriochlorophylls; Coastal lagoons; Gulf of California; HPLC; Pigments
1. Introduction
Bahia Concepcion is one of the largest bays in the Gulf of California with about 400
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km of surface and a maximum depth of 30 m Lechuga-Deveze, 1994. Human
influence is small because it is in a zone of low precipitation between 150 and 250 mm per year, with practically no important towns only small tourist settlements, and little
maritime navigation. These characteristics allow the study of events i.e. red tides,
Corresponding author. Tel.: 1 33-112-536-33; fax: 1 33-112-536-25. ´
E-mail address : josecibnor.mx J. Bustillos-Guzman
0022-0981 00 – see front matter
2000 Elsevier Science B.V. All rights reserved. P I I : S 0 0 2 2 - 0 9 8 1 0 0 0 0 1 8 8 - X
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J . Bustillos-Guzman et al. J. Exp. Mar. Biol. Ecol. 249 2000 77 –88
biogeochemical cycles, etc. in an unperturbed environment. Phytoplankton in the area is dominated by diatoms, but red tide species are occasionally present Martinez-Lopez and
Garate-Lizarraga, 1994. For summer, Lechuga-Deveze 1994 reported bottom pigment
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concentrations of chlorophyll a Chl a between 7.1 and 45.5 mg l and chlorophyll b
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Chl b values between 10.4 and 99.1 mg l in more than a half of the area bay. These
values are high when compared with normal stations where Chl a and Chl b
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concentration maximum values, in general, are lower than 2 mg l . Although there are
several reports on the phytoplankton composition and abundance Kiefer and Laker, 1975; Gilmartin and Revelante, 1978; Martinez-Lopez and Garate-Lizarraga, 1994;
Lopez-Cortez, 1999; Lechuga-Deveze and Morquecho-Escamilla, 1999; Lechuga-De- veze et al., 2000, these high pigment concentrations are enigmatic because no one has
reported species or groups of species that can be related to such an increase of biomass. Recently, Lechuga-Deveze 1994 analyzed the spectra of acetone extracts and sug-
gested a population of prochlorophytes may be responsible for the high biomass. His reason is that highly pigmented samples have red-shift spectra when compared with
normally pigmented ones, similar to that existing between the Chl a and divinyl chlorophyll a DvChl a. Because of the difficulties of identifying and quantifying this
picoplanktonic group with traditional methods of microscopy, this hypothesis has not been tested.
We have used high-performance liquid chromatography HPLC to analyze the phytoplankton pigment and look for markers of phytoplankton groups in these samples.
Specifically, we tested for the existence of DvChl a, a marker of prochlorophytes Goericke and Repeta, 1993, or other phytoplankton group fingerprints that may be
responsible for this increase of biomass.
2. Material and methods
