Phenological characteristics of global coccolithophore blooms

Abstract

Coccolithophores are recognized as having a significant influence on the global carbon cycle through the production and export of calcium carbonate (often referred to as particulate inorganic carbon or PIC). Using remotely sensed PIC and chlorophyll data, we investigate the seasonal dynamics of coccolithophores relative to a mixed phytoplankton community. Seasonal variability in PIC, here considered to indicate changes in coccolithophore biomass, is identified across much of the global ocean. Blooms, which typically start in February-March in the low-latitude (~30°) Northern Hemisphere and last for~6-7 months, get progressively later (April-May) and shorter (3-4 months) moving poleward. A similar pattern is observed in the Southern Hemisphere, where blooms that generally begin around August-September in the lower latitudes and which last for~8 months get later and shorter with increasing latitude. It has previously been considered that phytoplankton blooms consist of a sequential succession of blooms of individual phytoplankton types. Comparison of PIC and chlorophyll peak dates suggests instead that in many open ocean regions, blooms of coccolithophores and other phytoplankton can co-occur, conflicting with the traditional view of species succession that is thought to take place in temperate regions such as the North Atlantic.

Phytoplankton dynamics in contrasting early stage North Atlantic spring blooms: composition, succession, and potential drivers

“…However, here we observed a typical North Atlantic community of coccolithophores (Savidge et al, 1995;Dale et al, 1999;Poulton et al, 2010), growing alongside the ICB diatom bloom, rather than just succeeding the diatoms. This is consistent with the rising tide hypothesis of Barber and Hiscock (2006), as well as observations from both in situ (Leblanc et al, 2009) and satellite measurements (Hopkins et al, 2015) suggesting that coccolithophores are present in North Atlantic spring blooms. Despite the contrasting environment and overall community structure of the NWB, the coccolithophore dynamics were similar, appearing independent of the overall community dynamics.…”

Diatom Phenology in the Southern Ocean: Mean Patterns, Trends and the Role of Climate Oscillations

“…However, by looking at the total Chla provided by satellite no information about the phytoplankton community composition (and changes in) is provided [72]. In this study we were able to look specifically at the diatom biomass by using a satellite-derived diatom concentration.…”

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

“…Margalef, 1978;Holligan et al, 1983;Lochte et al, 1993;Sieracki et al, 1993;Thunell et al, 1996;Balch, 2004). Indeed, a recent study of the phenological characteristics of coccolithophore blooms by Hopkins et al (2015) concluded that they often follow those of diatoms in many regions, with the sequencing driven by increasing stabilisation and/or nutrient depletion (mainly silicate and/or iron and possibly also favoured by an associated increase in carbonate saturation; Merico et al, 2004) of the surface layer. The slightly different seasonal pattern observed at both sampling depths (Fig.…”