Contribution by different marine bacterial communities to particulate beam attenuation

Abstract

Contribution of heterotrophic marine bacteria (HB) to the particulate beam attenuation coefficient (cp) was estimated as a function of latitude in diverse marine regions. Calculations were based on surface measurements (0 to 20 m depth) of bacterial abundance and biovolume, physiooptical empirical relationships, and light scattering models. Relative contribution of spherical HB to cp (cHB/cp) was commonly below 10%, and slightly increased (̃3%) when bacterial shape was assumed to be cylindrical. HB accounted for a larger fraction of cp magnitude at lower latitudes because of the greater abundance of bacteria. HB explained about a third of cp spatial variability in Antarctic (Antarctic Polar Front, Ross Sea) and non-polar (equatorial Pacific Ocean, Arabian Sea) oceanic regions. © Inter-Research ch 2009.