@article {5043, title = {Hydrothermal Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments}, journal = {EARTH AND PLANETARY SCIENCE LETTERS}, volume = {419}, year = {2015}, month = {JUN 1}, pages = {143-153}, abstract = {

Submarine hydrothermal venting has recently been identified to have the potential to impact ocean biogeochemistry at the global scale. This is the case because processes active in hydrothermal plumes are so vigorous that the residence time of the ocean, with respect to cycling through hydrothermal plumes, is comparable to that of deep ocean mixing caused by thermohaline circulation. Recently, it has been argued that seafloor venting may provide a significant source of bio-essential Fe to the oceans as the result of a close coupling between Fe and organic carbon in hydrothermal plumes. But a complementary question remains to be addressed: does this same intimate Fe-C-org association in hydrothermal plumes cause any related impact to the global C cycle? To address this, SCOR-InterRidge Working Group 135 developed a modeling approach to synthesize site-specific field data from the East Pacific Rise 9 degrees 50{\textquoteright} N hydrothermal field, where the range of requisite data sets is most complete, and combine those inputs with global estimates for dissolved Fe inputs from venting to the oceans to establish a coherent model with which to investigate hydrothermal C-org cycling. The results place new constraints on submarine Fe vent fluxes worldwide, including an indication that the majority of Fe supplied to hydrothermal plumes should come from entrainment of diffuse flow. While this same entrainment is not predicted to enhance the supply of dissolved organic carbon to hydrothermal plumes by more than similar to 10\% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich hydrothermal plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean sediments, worldwide. (C) 2015 Elsevier B.V. All rights reserved.

}, issn = {{0012-821X}}, doi = {{10.1016/j.epsl.2015.03.012}}, author = {German, C. R. and Legendre, L and Sander, S. G. and Nathalie Niquil and LutherIII, G. W. and Bharati, L. and Han, X. and Le Bris, Nadine} } @article {SakkaHlaili_etal2013, title = {Planktonic food webs revisited : reanalysis of results from the linear inverse approach}, journal = {Progress in Oceanography}, volume = {120}, year = {2014}, month = {01/2014}, pages = {216{\textendash}229}, abstract = {

Identification of the trophic pathway that dominates a given planktonic assemblage is generally based on the distribution of biomasses among food-web compartments, or better, the flows of materials or energy among compartments. These flows are obtained by field observations and a posteriori analyses, including the linear inverse approach. In the present study, we re-analysed carbon flows obtained by inverse analysis at 32 stations in the global ocean and one large lake. Our results do not support two {\textquotedblleft}classical{\textquotedblright} views of plankton ecology, i.e. that the herbivorous food web is dominated by mesozooplankton grazing on large phytoplankton, and the microbial food web is based on microzooplankton significantly consuming bacteria; our results suggest instead that phytoplankton are generally grazed by microzooplankton, of which they are the main food source. Furthermore, we identified the {\textquotedblleft}phyto-microbial food web{\textquotedblright}, where microzooplankton largely feed on phytoplankton, in addition to the already known {\textquotedblleft}poly-microbial food web{\textquotedblright}, where microzooplankton consume more or less equally various types of food. These unexpected results led to a (re)definition of the conceptual models corresponding to the four trophic pathways we found to exist in plankton, i.e. the herbivorous, multivorous, and two types of microbial food web. We illustrated the conceptual trophic pathways using carbon flows that were actually observed at representative stations. The latter can be calibrated to correspond to any field situation. Our study also provides researchers and managers with operational criteria for identifying the dominant trophic pathway in a planktonic assemblage, these criteria being based on the values of two carbon ratios that could be calculated from flow values that are relatively easy to estimate in the field.

}, doi = {10.1016/j.pocean.2013.09.003}, author = {Sakka-Hlaili, A and Nathalie Niquil and Legendre, L} }