Abstract
8 pages, 1 figure, 1 table.-- Full-text available Open Access at the journal site.
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. Planktonic communities of the open ocean and continental shelf showed threshold GPP values ranging 30-fold, from 0.34 mmol O2 m-3 d-1 to 9.45 mmol O2 m-3 d-1, with those for estuarine and coastal locations reaching 50.60 mmol O2 m-3 d-1. Antarctic and ultra-oligotrophic ecosystems showed the lowest threshold GPP values (<2.2 mmol O2 m-3 d-1), 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 mmol O2 m-3 d-1, consistent with recent estimates of allochthonous inputs of organic carbon to the ocean.
This research was supported by project "COCA: Flujo de carbono en la región
Canaria: acoplamiento entre exportación costera y demanda oceánica", "RODA: Remolinos oceánicos y deposición atmosférica: efectos biológicos y biogeoquímicos en aguas del Atlántico
Este", "ATOS: Atmospheric inputs of organic carbon and pollutants to the polar ocean: Rates, significance and Outlook", and the "Malaspina 2010" CONSOLIDER project funded by the Spanish Ministry of Science and Innovation, and the integrated project Thresholds and the EUR-OCEANS network of excellence funded by the European Commission. A. R. d. G was supported by the METAOCEANS Marie Curie Network, of FP 6 of the European Commission.
Peer reviewed