Phytoplankton Size Structure in Association with Mesoscale Eddies off Central-Southern Chile: The Satellite Application of a Phytoplankton Size-Class Model

Abstract

Understanding the influence of mesoscale and submesoscale features on the structure of phytoplankton is a key aspect in the assessment of their influence on marine biogeochemical cycling and cross-shore exchanges of plankton in Eastern Boundary Current Systems (EBCS). In this study, the spatio-temporal evolution of phytoplankton size classes (PSC) in surface waters associated with mesoscale eddies in the EBCS off central-southern Chile was analyzed. Chlorophyll-a (Chl-a) size-fractionated filtration (SFF) data from in situ samplings in coastal and coastal transition waters were used to tune a three-component (micro-, nano-, and pico-phytoplankton) model, which was then applied to total Chl-a satellite data (ESA OC-CCI product) in order to retrieve the Chl-a concentration of each PSC. A sea surface, height-based eddy-tracking algorithm was used to identify and track one cyclonic (sC) and three anticyclonic (ssAC1, ssAC2, sAC) mesoscale eddies between January 2014 and October 2015. Satellite estimates of PSC and in situ SFF Chl-a data were highly correlated (0.64 < r < 0.87), although uncertainty values for the microplankton fraction were moderate to high (50 to 100% depending on the metric used). The largest changes in size structure took place during the early life of eddies (~2 months), and no major differences in PSC between eddy center and periphery were found. The contribution of the microplankton fraction was~50% (~30%) in sC and ssAC1 (ssAC2 and sAC) eddies when they were located close to the coast, while nanoplankton was dominant (~60-70%) and picoplankton almost constant (<20%) throughout the lifetime of eddies. These results suggest that the three-component model, which has been mostly applied in oceanic waters, is also applicable to highly productive coastal upwelling systems. Additionally, the PSC changes within mesoscale eddies obtained by this satellite approach are in agreement with results on phytoplankton size distribution

Twenty‐Year Variations in Satellite‐Derived Chlorophyll‐a and Phytoplankton Size in the Bohai Sea and Yellow Sea

“…In summer, prevalent southeasterly winds (Figures 11e and 11f) influenced horizontal advection of coastal and ocean currents, leading to a positive SLA in the central YS (Cai et al, 2015;Qiao, 2005). Previous studies showed that positive SLA was usually accompanied with a decrease in chlorophyll-a concentration and higher proportion of smaller-sized phytoplankton in the surface layer (Bricaud et al, 2012;Corredor-Acosta et al, 2018), which agreed with the observations in Figure 11c and confirmed the positive correlations between SLA and percentages of nanoplankton and picoplankton (Table 2). Moreover, due to the strong solar heating and weak wind forcing, shallow MLD took place in summer (Figure 11d), indicating the existence of a strong thermocline between the shallow mixed surface layer and deeper colder water (Fu et al, 2018).…”

Weak Response of Biological Productivity and Community Structure of Phytoplankton to Mesoscale Eddies in the Oligotrophic Philippine Sea

“…Indeed, Corredor‐Acosta et al. (2018) revealed that the phytoplankton size structure changes within mesoscale eddies could be affected by variations in nutrient concentrations and/or ratios.…”

“…Therefore, the observed picoplankton-dominated community structure under the mesoscale eddies may likely be a reflection of the combined effects of low nutrient supply and chemical composition (i.e., silicate limitation). Indeed, Corredor-Acosta et al (2018) revealed that the phytoplankton size structure changes within mesoscale eddies could be affected by variations in nutrient concentrations and/ or ratios.…”

Study on Cyclone Induced Phytoplankton Bloom in the Arabian Sea Through Gap-Free Reconstructed Chlorophyll-a Data

“…The unusual physical dynamics such as tropical cyclone (TC) triggers the biogeochemical properties present in the ocean, which disturbs the distribution and dynamics of phytoplankton (Lin, 2012;Wang & Zhao, 2008). Tropical cyclone passage on the sea causes two significant impacts that are generally encountered, first and foremost is intense wind and later is the sizeable freshwater discharge due to heavy rains near the shore (Corredor-Acosta et al, 2018). Most importantly during TC, the ocean faces fluctuation in the physical properties like cooling of sea surface temperature (SST) caused by vertical mixing of the water column (i.e.…”