Diatom sources of 13C-rich carbon in marine food webs

Abstract

Rapidly growing diatoms had 13C-rich isotopic compositions in the Georges Bank ecosystem. Diatoms in spring blooms and in well-mixed summer waters were relatively rich in 13C, with δ13C values in the -15 to -19‰ range, while other phytoplankton and most particulate organic matter collected over a 13 mo period had 13C-depleted values of -21 to -25‰. Zooplankton from central Georges Bank where diatoms are abundant had relatively high δ13C values, consistent with an important nutritional role for 13C-rich diatoms. At least 40% of the carbon present in zooplankton consumers of C Georges Bank is derived from diatoms. Bloom diatoms from the North Atlantic, NE Pacific, and the nearshore Gulf of Mexico also had 13C-rich compositions, indicating that diatoms can be a source of 13C-rich carbon in many marine food webs. -from Authors