Verdugo-Díaz, G., A., Martínez-López & F.J., Gómez-Ochoa (2021). Implicaciones de la profundidad de la zona eufotica e irradiancia de compensación sobre la productividad primaria en Cuenca Alfonso, BCS, Mexico. J., De La Cruz-Agüero (Eds.), CICIMAR Oceánides. 36(1-2): 49-58. DOI: 10.37543/oceanides.v36i1-2.258.
Gerardo Verdugo-Díaz 1, Aída Martínez-López 1 y Francisco Javier Gómez-Ochoa 1
The euphotic zone of marine ecosystems has been defined as the layer between the water surface andthe depth to which 1% of solar irradiance penetrates. However, it has been proposed that this should be extendedto 0.1% to include phytoplanktonic communities adapted to low irradiances that contribute significantly to primaryproductivity. Sampling was conducted during April, May, September, and November, 2016, in Cuenca Alfonso atdepths of 100, 33, 3, and 0.1% of active photosynthetic radiation, and at the standard depth of 150 m. CTD castswere performed and samples were collected to estimate chlorophyll-a concentrations and primary productivity. Amixed layer was observed at less than 16 m in April, May, and September that increased to 48 m in November. Thehighest chlorophyll-a concentrations were recorded at 33 and 3% and in one case at the 0.1% level. The microphytoplanktonic fraction concentration of chlorophyll had values that ranged from undetectable to 0.084 mg m-3, whilethe picophytoplanktonic fraction measured between 0.012 and 0.33 mg m-3. Microphytoplanktonic primary produc-tivity varied from 0.25 to 0.41 mg C m-3 h-1 (scored values) and 22.39-41.69 mg C m-2 h-1 (integrated values). Thepicophytoplanktonic fraction varied from 0.25-0.34 mg C m-3 h-1 to 19.92-34.44 mg C m-2 h-1. The concentration ofchlorophyll-a was significantly greater in the picophytoplanktonic fraction than in the microphytoplanktonic fraction (p<0.05); but was not significant in primary productivity (p=0.05). We conclude that the depth of the euphoticzone directly influences the productive capacity of the ecosystem, and propose deepening the zone’s profundity to atleast 0.1% of surface irradiance since this could mean an increase of as much as 30% in total productivity.
Palabras clave: compensation depth; Primary productivity; chlorophyll-a; photosynthetically active radiation
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