Notes on Dore et al. (2008)

• Is there more than one summer bloom than has been observed for a single year?
• Are the summer blooms and the plankton filaments the same thing? Which one is likely to be associated to more carbon export over a year?
• Read Wilson (2003) and Wilson et al. (2007) about observations and dynamics of summer blooms. In Wilson et al. (2007), they convincingly argue that the blooms may occur because of the import of buoyant organisms due to the converging surface flow northeast of the Hawaiian Islands (see their Fig. 10). Dore et al. (2008) argues the following: “Wilson et al. (2007) have suggested that the area of highest bloom frequency may be unusually calm in summer, due to the convergence of weak surface currents there, allowing for accumulation of buoyant organisms. However, we can see from the Station ALOHA record that the summer bloom represents both rapid growth of phytoplankton and accumulation of their biomass near the surface. Furthermore, exceedingly calm conditions can occur for long periods of time in summer over most of the gyre. It is difficult, therefore, to accept excessive calmness as a mechanism for bloom initiation unique to this area.” Instead, they “hypothesize that summer blooms in the NPSG occur where they do because the supply of phosphate in that region is sufficient to support them, while in the western NPSG, chronic P limitation is seldom if ever relieved. [...] The main point here is that the conditions in the northeastern section of the NPSG, where blooms are observed, are much more favorable for phosphate delivery to the upper water column than are conditions in the rest of the gyre, especially the region west of the Hawaiian Islands, where summer blooms are not observed.”
• “In this paper we define a bloom as a rapid (days-weeks) increase in observed phytoplankton biomass in the surface ocean (660 m) relative to the background condition, regardless of the mode of observation.”
• high vertical resolution Chl profile?
• Summer blooms are mostly a Chl anomaly of the upper (50-m) layer, so that satellite-observed surface Chl could be a good index of it, although not perfect (the maximum Chl of these blooms are found at times around 50 m depth).