Evaluation of the performance of HPLC–CHEMTAX analysis for determining phytoplankton biomass and composition in a turbid estuary (Schelde, Belgium)

Abstract

In the upper Schelde estuary in 2002, phytoplankton biomass and community composition were studied using microscopic and pigment analyses. Chlorophyll a concentration was a good predictor of phytoplankton biomass estimated from cell counts and biovolume measurements. The phytoplankton carbon to chlorophyll a ratio, however, was often unrealistically low (<10). CHEMTAX was used to estimate the contribution of the major algal groups to total chlorophyll a. The dominant algal groups were diatoms and chlorophytes. While diatom equivalents in chlorophyll a predicted diatom biomass relatively well, chlorophyte equivalents in chlorophyll a were only weakly related to chlorophyte biomass. The pigment-based approach to study phytoplankton overestimated phytoplankton biomass in general and chlorophyte biomass in particular in late autumn and winter, when phytoplankton biomass was low. A possible explanation for this overestimation may be the presence of large amounts of vascular plant detritus in the upper Schelde estuary. Residual chlorophyll a, chlorophyll b and lutein in this detritus may result in an overestimation of total phytoplankton and chlorophyte biomass when the contribution of phytoplankton to total particulate organic matter is low.

Bacteriochlorophyll and community structure of aerobic anoxygenic phototrophic bacteria in a particle-rich estuary

“…Cultivated AAP bacteria modulate the BChl a quota as much as 10-fold in response to light availability (Koblízek et al, 2003;Li et al, 2006), similar to photoadaptation by phytoplankton. As a result of photoadaptation, phytoplankton C-to-chlorophyll a ratios are low in turbid estuaries, such as the Schelde (Lionard et al, 2008), and high in clearer oceanic environments, such as the subtropical Atlantic Ocean (Veldhuis and Kraay, 2004). In contrast, the BChl a quota of AAP bacteria in Chesapeake Bay was not higher than that in the coastal North Atlantic Ocean and in the South Pacific Ocean.…”

Characterization of ultraphytoplankton pigments and functional community structure in Xiangxi Bay, China, using HPLC-CHEMTAX

“…In studies of different habitats, including an estuary (Lionard et al 2008), a bay (Madhu et al 2014), lagoons (Sarmento & Descy 2008), and freshwater (Guisande et al 2008), many adjustments were made to the choice of pigment matrix and the initial ratio. The intent was to isolate and incubate the phytoplankton in the laboratory to discover the pigment/Chl a ratio, but finding the ratio for every phylum was complex.…”

Modelling phytoplankton succession and nutrient transfer along the Scheldt estuary (Belgium, The Netherlands)

“…5a) in the freshwater estuary (between km 120 and 80) could be explained by the use of an inappropriate C:Chl a ratio for freshwater phytoplankton. Indeed, C:Chl a ratio measured in the Scheldt estuary highly varies with values between 1 and 70 (Lionard et al, 2008b). Sensitivity tests suggest that the model-data fit can be improved by modifying the C:Chl a ratio (not shown).…”

“…8b,d), with the Chlorophyceae contributing significantly (>50%) to phytoplankton in summer between km 140 and 160. On an annual mean basis, other algal groups represent less than 10% (Lionard et al, 2008b) and simulated cyanobacteria (not shown) represent a negligible biomass (b 2 mgC m −3 ). As observed (Lionard et al, 2008a,b), freshwater phytoplankton is present from spring to early autumn.…”