Comment on essd-2021-466

Abstract

From 2017 to 2019, an extensive sampling campaign was conducted in Belgian inland and coastal waters, aimed at providing paired data of optical and biogeochemical properties to support research into optical monitoring of aquatic systems. The campaign was focused on inland waters, with sampling of four lakes and a coastal lagoon along the growth season, in addition to samples of opportunity of other four lakes. Campaigns also included the Scheldt estuary over a tidal cycle and two sam- pling campaigns in the Belgian coastal zone. Measured parameters include inherent optical properties (absorption, scattering and attenuation coefficients, near-forward volume scattering function, turbidity), apparent optical properties (Secchi disk depth, substrate and water-leaving Lambert-equivalent bi-hemispherical reflectance), and biogeochemical properties (suspended particulate matter, mineral fraction of particle mass, particle size distribution, pigment concentration, DNA metabarcoding, flow microscopy counts, and bottom type classification). The diversity of water bodies and environmental conditions covered a wide range of system states. The chlorophyll a concentration varied from 0.63 mgm−3 to 382.72 mgm−3, while the suspended particulate matter concentration varied from 1.02 gm−3 to 791.19 gm−3, with mineral fraction varying from 0 to 0.95. Depending on system and season, phytoplankton assemblages were dominated by cyanobacteria, green algae (Mamiellophyceae, Pyramimonadophyceae) or diatoms. The dataset is available from Castagna et al. (2022), https://www.pangaea.de/tok/c67200d99ea9bbbeadd9edec9690f937b5bacbff.