Temperature, resources, and phytoplankton size structure in the ocean

Abstract

We conducted a meta-analysis of temperature, phytoplankton size structure, and productivity in cold, temperate, and warm waters of the world's oceans. Our data set covers all combinations of temperature and resource availability, thus allowing us to disentangle their effects. The partitioning of biomass between different size classes is independent of temperature, but depends strongly on the rate of resource use as reflected in the rate of primary production. Temperature and primary production explained 2% and 62%, respectively, of the variability in the contribution of microphytoplankton to total biomass. This contribution increases rapidly with total biomass and productivity, reaching values . 80% when chlorophyll a concentration is . 2 mg L 21 or primary production is . 100 mg C L 21 d 21 , irrespective of water temperature. Conversely, picophytoplankton contribution is substantial (. 40%), at all temperatures, only when chlorophyll a concentration is , 1 mg L 21 or primary production is , 50 mg C L 21 d 21 . The temperature-size rule cannot explain these changes, which instead reflect fundamental reorganizations in the species composition of the assemblage, arising from taxon-and sizedependent differences in resource acquisition and use. Given that resource availability, rather than temperature per se, is the key factor explaining the relative success of different algal size classes, there will be no single, universal effect of global warming on phytoplankton size structure.

Distribution of phytoplankton functional types in high-nitrate, low-chlorophyll waters in a new diagnostic ecological indicator model

“…Shifts in community size spectrum in response to rising temperatures are suggested by some studies (e.g., Hilligsøe et al, 2011), yet in others they are shown to depend primarily on total biomass and productivity (e.g., Maranón et al, 2012). Hence, ANNs could prove useful in examining these interactions in the context of variability among biogeochemical provinces rather than global average trends.…”

Temporal changes in total and size-fractioned chlorophyll-a in surface waters of three provinces in the Atlantic Ocean (September to November) between 2003 and 2010

“…Brewin et al, 2010;Devred et al, 2011;Hirata et al, 2011;Uitz et al, 2006;Vidussi et al, 2001), or through size-fractionated filtration (e.g. Brewin et al, 2014a, b;Marañón et al, 2012). These two techniques may be used to partition TCHLa into three phytoplankton size classes (PSC), micro-(N20 μm), nano-(2-20 μm) and pico-phytoplankton (b2 μm).…”

“…Global analysis of in-situ data illustrates coherent relationships between PSC and TCHLa, which have been quantified using various statistical methods and applied to remotely-sensed observations of TCHLa to map PSCs at regional to global scales (Brewin et al, 2010;Brotas et al, 2013;Hirata et al, 2011;IOCCG, 2014;Marañón et al, 2012;Uitz et al, 2006;Vidussi et al, 2001). Even standard empirical algorithms used for estimating TCHLa from satellite ocean-colour data implicitly assume a fixed relationship between TCHLa and PSC (Dierssen, 2010, IOCCG, 2014.…”

Intercomparison of Ocean Color Algorithms for Picophytoplankton Carbon in the Ocean

“…One of them is that it is only composed of picophytoplankton: though they are important contributors to the open-ocean phytoplankton biomass, picophytoplankton form a decreasing proportion of the phytoplankton biomass in more productive waters, where larger cells tend to become more important (Marañón et al, 2012;Marañón, 2015). One interesting avenue would be to expand the database with other phytoplankton groups (Buitenhuis et al, 2013;Sal et al, 2013).…”