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Partitioning of the diffuse attenuation coefficient for photosynthetically available irradiance in a deep dendritic tropical lake.

Authors :
Brandão LPM
Brighenti LS
Staehr PA
Barbosa FAR
Bezerra-Neto JF
Source :
Anais da Academia Brasileira de Ciencias [An Acad Bras Cienc] 2017 May; Vol. 89 (1 Suppl 0), pp. 469-489.
Publication Year :
2017

Abstract

We studied the effects of particulate and dissolved optically active components on the attenuation of photosynthetic active radiation (PAR) in a tropical lake. The temporal and spatial distribution of tripton, Chl-a and aCDOM(440) and their relative contribution to the diffuse PAR attenuation coefficient (Kd) was investigated at 21 sites (dry and wet seasons and two intermediate periods) and at monthly interval at 1 pelagic site. Higher values of ​​ Kd were observed during the mixing period, characterized by a higher concentration of tripton and Chl-a compared to the stratified rainy season. In the spatial sampling PAR attenuation was dominated by tripton absorption/scattering (average relative contribution of 79%), followed by Chl-a (average 11.6%). In the monthly sampling tripton and Chl-a accounted for most of the Kd with relative contributions of 47.8% and 35.6%, respectively. Multiple linear regression analysis showed that Chl-a and tripton in combination explained 97% of the monthly variation in Kd (p<0.001), but Chl-a had more influence (higher regression coefficient). Thus, although most of light attenuation was due to tripton, seasonal variations in phytoplankton abundance were responsible for most of the temporal fluctuations in Kd.

Details

Language :
English
ISSN :
1678-2690
Volume :
89
Issue :
1 Suppl 0
Database :
MEDLINE
Journal :
Anais da Academia Brasileira de Ciencias
Publication Type :
Academic Journal
Accession number :
28562827
Full Text :
https://doi.org/10.1590/0001-3765201720160016