TITLE:
Changes in the Composition and Abundance of Phytoplankton in a Coastal Lagoon of Baja California, México, during 2011
AUTHORS:
María Fernanda Gracia-Escobar, Roberto Millán-Núñez, Enrique Valenzuela-Espinoza, Adriana González-Silvera, Eduardo Santamaría-del-Ángel
KEYWORDS:
Phytoplankton, Bloom, Pigments, CHEMTAX, Coastal Lagoon
JOURNAL NAME:
Open Journal of Marine Science,
Vol.5 No.2,
March
24,
2015
ABSTRACT: A time series with weekly
sampling was conducted from February 20, to December 16, 2011 at a station in
the interior of the San Quintín Bay to estimate seasonal changes in the
composition and abundance of phytoplankton. Water temperature was recorded and
the upwelling index was calculated for the period. Phytoplankton abundance was
estimated and phytoplankton were identified by using an inverted microscope and
the CHEMTAX program. There were 16 positive phytoplankton anomalies during the
year, but only three were considered to be blooms. The blooms were dominated by
diatoms and were recorded in the winter, spring and summer. Different genera
composed 80% of the total phytoplankton abundance of each of the blooms. The
first bloom consisted of diatoms of the genera Pseudo-nitzschia sp. (15.7%), Skeletonema sp. (14.6%), Eucampia sp. (7%), and Navicula sp. (7%); a haptophyte of the genus Imantonia sp. (13.1%); and dinoflagellates of
the genus Prorocentrum sp. (4.6%). The second bloom consisted
mainly of diatoms of the genera Guinardia sp. (30.6%), Pseudo-nitzschia sp. (21.5%), Skeletonema sp. (14.5%), Chaetoceros sp. (8.4%) and Eucampia sp. (5.3%). The third bloom consisted
of Chaetoceros sp. (46.3%), Pseudo-nitzschia sp. (22.6%), Skeletonema sp. (7.29%), and Imantonia sp. (6%). Dinoflagellates were
observed in the winter, summer and autumn, but they contributed less biomass
than diatoms. Prorocentrum sp., Gymnodinium sp., and Ceratium sp. were among the dinoflagellates
that were observed. The differences in abundance and composition of
phytoplankton groups in the blooms in San Quintín Bay during 2011 were due
primarily to seasonal changes in the physical and chemical factors of the
seawater and to upwelling events.