Vertical Biogeography and Realized Niche Traits of Living Coccolithophore Community in the Eastern Indian Ocean

Abstract

AbstractCoccolithophores are crucial components of marine calcifying microalgae and found to be important indicators of ecological changes. The interannual scale and vertical biogeography of springtime living coccolithophore communities were determined in the chronically under‐sampled eastern Indian Ocean (EIO) during seven consecutive years (spring 2011–2018). In addition, we quantified the realized ecological niches of dominant coccolithophore species in the region based on the ecological modeling method (MaxEnt statistics). Results indicated the interannual mean coccolithophore abundance ranged 4,306–11,140 cells L−1. The ecologically important species such as Gephyrocapsa oceanica, Emiliania huxleyi, Algirosphaera robusta, Florisphaera profunda, Umbilicosphaera sibogae, and Umbellosphaera irregularis were identified as dominant species in the coccolithophore community. Based on the ratios of coccoliths and plated coccolithophores, we observed coccolith detachment rates showed a valley near deep chlorophyll maximum layer and peaked in the surface or bottom of euphotic layer which was potentially relevant to near‐surface circulations, nutrients and light availability. From applying the ecological modeling method, we quantified three types of realized niches in coccolithophore species based on mean niche (μ) and breadth of niche (σ) which were consistent with their conventionally vertical biogeography. Our data set could be further incorporated into climatic ecological models.