Some aspects of pigments and halocarbons distribution from the coastal eastern Arabian Sea and Southern Ocean with special reference to LOHAFEX experiment


Thursday, September 20, 2012
Redfield Auditorium - 12:00 Noon
Dr. Rajdeep Roy
Fulbright Fellow, Biology
Woods Hole Oceanographic Institution

Phytoplankton are an important source of biogenic halocarbons in the ocean which play a vital role in atmospheric photochemistry. Hence it is important to understand the annual variability of phytoplankton groups which may influence oceanic biogenic fluxes. Monitoring phytoplankton groups has been possible with phytoplankton pigment analysis which is fast, however has its own limitations. Our phytoplankton pigment measurements from seasonally anoxic waters of coastal eastern Arabian show annual variability in the dominant groups such as diatoms to cyanobacteria in response to nutrient dynamics. Biogenic halocarbons measured in conjunction with this suggest diatoms to be an important source of chloroform in the region. Similar measurements carried out during Lohafex iron fertilization experiment shows significant response of the prymesiophytes and prasinophytes to iron addition. Dissolved methyl iodide concentrations during Lohafex increased by a factor of two within the patch. This could be attributed to the dominance of the phaeocystis sp during this experiment. In this talk I will present some data and discuss our present understanding of pigments and halocarbons from the Arabian Sea and Lohafex iron fertilization experiment.