Thresholds of gross primary production for the metabolic balance of marine planktonic communities

Abstract

The notion that less productive marine planktonic communities tend to be heterotrophic was tested by synthesizing reported estimates of the relationships between the net community production or community respiration and gross primary production (GPP), allowing calculation of the threshold GPP separating less productive, heterotrophic communities from more productive, autotrophic ones. A total of 35 estimates of the threshold GPP were assembled, derived from reports of comparative analyses of individual regions (Mediterranean Sea, Atlantic Ocean, Southern Ocean, Pacific Ocean, and Indian Ocean) and global comparative analyses for open-ocean and coastal environments, time-series analyses of changes in planktonic metabolism at individual locations, experimental manipulations in mesocosms, and a semi-empirical modeling exercise. , with a general consistency across approaches for a given ecosystem. Plankton community respiration in the absence of or under low primary production is not negligible and is supported by semi-labile dissolved organic carbon. The analysis of GPP thresholds suggests that allochthonous organic inputs to the less productive regions of the ocean must be in the order of 5-6 mmol C m 22 d 21 , consistent with recent estimates of allochthonous inputs of organic carbon to the ocean.

Autotrophic and heterotrophic microbial plankton biomass in the NW Iberian upwelling: seasonal assessment of metabolic balance

“…Similar threshold values of GPP have been reported for other coastal upwelling systems (Duarte et al 2001) and other coastal areas around the world (Duarte et al 2004, Duarte & Regaudie-deGioux 2009) in general, but it is considerably higher than the values reported for the oligotrophic ocean (Arístegui & Harrison 2002, McAndrew et al 2008, Duarte & Regaudie-de-Gioux 2009.…”

Pelagic metabolism in the waters of the Great Barrier Reef

“…The relationship between volume-based measurements of NCP and GPP on the GBR is highly significant (p , 0.01, R 2 5 0.98) and indicates that a threshold GPP of 2.15 mmol O 2 m 23 d 21 is required to achieve metabolic balance. There are few studies of tropical shelf areas with which to compare the GBR data (see Duarte and Regaudie-de-Gioux 2009;McKinnon et al 2011 Area-specific measurements of both CR and NCP broadly accord with those from tropical environments elsewhere (Table 5), bearing in mind that the integration depth differs between studies. Ningaloo Reef, between 21u479S and 23u479S on the western coast of Australia, appears to be more productive with higher estimates of both area-specific CR and NCP and a higher P : R ratio.…”

Experimentally determined temperature thresholds for Arctic plankton community metabolism

“…This as well as previous short-term experiments (VaquerSuyner et al, 2010) indicate that warming leads to a steep increase in respiration rates of polar plankton communities, thus increasing the threshold GPP or the primary production needed to balance out respiration at higher temperatures (i.e., GPP / R > 1). It has already been hypothesized that polar communities may be more vulnerable to warming than temperate communities (Pomeroy and Wiebe, 2001 Agustí and Duarte, 2005), which is suggested to be due in part to access to large pools of dissolved organic carbon that lead to high bacterial respiration rates (Duarte and Regaudie-de-Gioux, 2009;Regaudie-de-Gioux and Duarte, 2010). Arctic glaciers are melting at an increasing pace and are expected to be a large source of ancient labile organic matter to the Arctic Ocean (Hood et al, 2009) thus increasing the pool of organic carbon available for bacterial metabolism in the future.…”