Phytoplankton community dynamic detection from the chlorophyll-specific absorption coefficient in productive inland waters

Abstract

Cite as: Watanabe, F.S.Y. et al. Phytoplankton community dynamic detection from the chlorophyll-specific absorption coefficient in productive inland waters. Acta Limnologica Brasiliensia, 2017, vol. 29, e13. Abstract: Aim:In this research, we investigated the spectral variability of the specific phytoplankton absorption coefficient, a * φ , measured in a tropical meso-to-hypertrophic reservoir, aiming to find spectral features associated with the chlorophyll-a (chla) and other accessory pigments present in different phytoplankton species. Methods: To accomplish this research, two fieldworks were carried out in different seasons in order to report a high bio-optical variation. Phytoplankton absorption coefficient, a φ , and chla concentration were measured in laboratory to estimate a * φ . Results: The outcomes have indicated that there is a remarkable phytoplankton community dynamic as spatially as seasonally. Chla absorption features were well-defined at 440 nm and 675 nm. Conclusions: All the a * φ spectra exhibited the absorption peak around 630 nm associated with phycocyanin pigment present in cyanobacteria. Some spectra have shown a peak at about 460 nm, which is related to chlorophyll b and chlorophyll c (chlb and chlc, respectively) found in different phytoplankton species. In turn, absorption features of carotenoids around 490 nm also were identified, however, well defined just in curves measured in austral autumn. Such spectral features are found in phytoplankton groups already identified in the study area such as Chlorophyceae, Bacillariophyceae, Cyanophyceae, Conjugatophyceae, Chrysophyceae, among others. We expect that the results are useful in researches about remote sensing of phytoplankton and eutrophication in reservoirs.

Light Absorption Budget in a Reservoir Cascade System with Widely Differing Optical Properties

“…The variability of features observed in samples from different reservoirs indicate the species richness of the phytoplankton community along the cascade. Due to the different absorption peaks in a φ (λ) from upstream to downstream caused by the high variability in Chl-a concentrations and package effects [62], it is not possible to categorize the reservoirs according to the dominance of certain types of phytoplankton assemblages per reservoir. Conversely, it is possible to identify a longitudinal gradient of a φ (λ) magnitudes in TCSR (Figure 5a), as observed for Chl-a concentrations (Figure 2).…”

Assessment of Scattering Error Correction Techniques for AC-S Meter in a Tropical Eutrophic Reservoir

“…The BB reservoir receives a high nutrient load from the São Paulo metropolitan area, leading to harmful algal blooms. Taking into account the concentration of chlorophyll a (chla), the BB reservoir was classified as hypertrophic and dominated by algal particles [38]. In addition, there is a richness of phytoplankton species [36,37,39], with a predominance of cyanobacteria in the austral summer and diatoms in the austral winter [39].…”