Abstract
Abstract. The relationship between the percent extracellular carbon release (PER) and the specific lysis rates of phytoplankton was examined across a range of communities spanning from highly oligotrophic ones in the subtropical Atlantic Ocean to productive ones in the N. African upwelling and the Southern Ocean. Communities in oligotrophic waters supported high phytoplankton cell lysis rates and low particulate primary production rates but high dissolved primary production and PER. The percent extracellular carbon released increased with increasing lysis rates to reach an asymptote at about 80% PER with specific lysis rates > 1.5 d−1, observed in the most oligotrophic conditions tested. These results confirm that high phytoplankton mortality in the oligotrophic ocean leads to high PER, accounting for the large fraction of the photosynthetic carbon channelled through bacteria characteristic of oligotrophic marine communities.
Highlights
Reconciling high bacteria carbon use with estimates of primary production and carbon flow from phytoplankton has remained a challenge for over two decades, for the oligotrophic ocean (Williams, 1984; del Giorgio et al, 1997; del Giorgio and Duarte, 2002)
Specific cell lysis rates were far more variable in the subtropical NE Atlantic than in the communities sampled off the Antarctic Peninsula, which showed relatively low lysis rates (Table 1)
Evidence that unproductive plankton communities release a high fraction of the primary production as dissolved organic carbon abounds (Karl et al, 1998; Teira et al, 2001; Moran et al, 2002)
Summary
Reconciling high bacteria carbon use with estimates of primary production and carbon flow from phytoplankton has remained a challenge for over two decades, for the oligotrophic ocean (Williams, 1984; del Giorgio et al, 1997; del Giorgio and Duarte, 2002). A high flux of phytoplankton carbon through bacteria in oligotrophic waters requires the release of much of phytoplankton production in dissolved form, as supported by reports of high release of dissolved organic carbon in the oligotrophic ocean (Karl et al, 1998; doulicgiovterotophhiicgwh aptheyrsto(pAlagnuksttoı neStcaeoll.l,lil1yd9s9isE8a,an2d0r0tmh1o; rAtagluitsytır,a2te0s0i4n; Hayakawa et al, 2008). The relationship between dissolved primary production and cell lysis rates has not yet been tested. We examine the relationship between the percent extracellular release of dissolved organic carbon and specific
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