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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13267

Title: Planktonic primary production in the western Dutch Wadden Sea

P. Jacobs*, J. C. Kromkamp, S. M. van Leeuwen, C. J. M. Philippart

*Corresponding author:

ABSTRACT: Pelagic primary production measurements provide fundamental information about the trophic status of a marine ecosystem. Measured carbon-fixation rates generally have a limited temporal and spatial resolution, but can be combined with Earth Observation data to extrapolate the measurements. Here, production-irradiance curves were fitted for three years of 14C incubation data from the western Wadden Sea, using four different models, two with and two without photo-inhibition. The curve-fit model by Jassby & Platt (1976) best fitted the data. Applying this model showed that the photosynthetic parameters, normalised for chlorophyll-a concentration, PBmax and αB, were correlated. Seasonality in photosynthetic parameters of this model and the relationship with environmental variables was explored, with a focus on variables that can be inferred from satellite algorithms. There was no significant correlations between αB and any of the environmental variables measured. While PBmax correlated with SST, the vertical light attenuation coefficient, silicate and nitrate + nitrite concentration, the multivariate model that best explained the variation in estimates of PBmax was a model that included SST and year. In the period from 2012 to 2014, daily and annual production ranged between 3.4 - 3800 mg C d-1 and between 131-239 g C m-2 y-1 respectively. Comparison of the results with historical data (1990-2003), indicated that the decline in planktonic primary production since the 1990s has halted. Although not tested, we believe that our approach is generally applicable to coastal waters.