Variabilidad del coeficiente de absorción por fitoplancton con influencia de marea roja en las bahías de Manzanillo y Santiago, México

Abstract

Five surveys (March, May, July, September and December 2004) in 6 stations at 3 depths (100, 10 and 1% E0(PAR)) were carried out in the bays of Manzanillo and Santiago, Mexico, to detect the temporal variation of water temperature, chlorophyll a concentration and specific absorption coefficient of phytoplankton at 440 nm and 676 nm (a*φ(440), a*φ (676)). The surface temperature was lower in spring and higher in summer. Meanwhile, the average surface chlorophyll a concentration changed from 1.1 mg m-3 in December to 20.8 mg m-3 in May, while integrated chlorophyll a in the euphotic zone was 36.2 to 146.6 mg m-2 in July and May, respectively. High chlorophyll a recorded in May was different from the other months as a result of harmful algal bloom event dominated by the dinoflagellate Ceratium balechii (Balech 1988) with an average abundance of 1.19 x 106 cells L-1, which represent 95.31% of total phytoplankton. The average values of a*φ (440), a*φ (676) were 0.051 and 0.029 m2 (mg Chl a)-1, respectively, which showed significant temporal variation between months, but had no differences through the euphotic zone. The spectra of the specific absorption coefficient of phytoplankton (a*φ (λ)) for May presented a clear packaging effect into the depths of 100 and 10% E0(PAR). The ratio between the maximum blue/red spectral absorption (440 nm/676 nm) showed lower values than 2.5, indicating a phytoplankton community dominated primarily by microphytoplankton cells.