Abstract

CANON PAEZ, Mary Luz  and  SANTAMARIA DEL ANGEL, Eduardo. Identification of phytoplankton blooms in the Gerlache Strait, West Antarctic Peninsula. Bol. Invest. Mar. Cost. [online]. 2021, vol.50, suppl.1, pp.13-30.  Epub Dec 13, 2021. ISSN 0122-9761.  https://doi.org/10.25268/bimc.invemar.2021.50.suplesp.922.

In order to identify phytoplankton blooms, the inherent optical properties index (IOPIndex) was used in surface water samples and the maximum chlorophyll-a (MPC) that were taken in the Third (January 2017) and in the Fourth Expedition (January 2018) from Colombia to Antarctica in the Gerlache Strait (EG). The IOPIndex is calculated from the standardized spatial anomalies of the phytoplankton, detritus and colored dissolved organic matter (CDOM) absorption coefficients using wavelength 443. In addition, the phytoplankton size index was calculated using the Blue / Red ratio and this related to the IOPIndex to determine the size structure of the phytoplankton responsible for the blooms. In 2017, four stations were identified under bloom conditions, where two were superficial blooms and two subsurface bloom; to three in conditions of decrease of the bloom and to twelve in conditions of non-bloom, with a structure of diverse size where populations of the micro, nano and the picophytoplankton predominated. In 2018, two stations were identified in bloom conditions, being one superficial bloom and the other subsurface bloom; to two in conditions of decrease in bloom and nine in conditions of non-bloom, the size structure that dominated the blooms was microphytoplankton. With the IOPIndex, subsurface bloom conditions were observed in both expeditions, also proving their effectiveness for blooms generated by natural or seasonal conditions at different depths of the water column.

Keywords : Absorption coefficients; Inherent optical properties index; Size index; Gerlache Strait; Phytoplankton.

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