BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-10-7235-2013 Downward fluxes of sinking particulate matter in the deep Ionian Sea (NESTOR site), eastern Mediterranean: seasonal and interannual variability Stavrakakis S. 1 Gogou A. https://orcid.org/0000-0001-7327-9223 1 Krasakopoulou E. 1 Karageorgis A. P. 1 Kontoyiannis H. 1 Rousakis G. 1 Velaoras D. https://orcid.org/0000-0001-6919-3734 1 Perivoliotis L. 1 Kambouri G. 1 Stavrakaki I. 1 Lykousis V. 1 Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, 46.7 km Athens-Sounio Av., 19013 Anavyssos, Greece 12 11 2013 10 11 7235 7254 Copyright: © 2013 S. Stavrakakis et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/10/7235/2013/bg-10-7235-2013.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/10/7235/2013/bg-10-7235-2013.pdf

In order to assess seasonal and interannual variability in the export of particulate matter and its main constituents, sediment traps were deployed at five successive depths from February 2006 to March 2010 in the deepest basin of the Mediterranean (SE Ionian Sea, NESTOR site). The average total mass fluxes were 66, 58, 54, 34, and 52 mg m<sup>−2</sup> d<sup>−1</sup>, at 700, 1200, 2000, 3200, and 4300 m, respectively. The temporal variations of the mass flux showed similar seasonal signal at all sampling depths with higher values in spring–summer and lower in autumn–winter. Changes in the main constituents of the mass flux (organic carbon, carbonates, opal, and lithogenic matter) largely followed the same temporal variability with total mass flux, revealing mechanisms of rapid vertical (top-down) transport from 700 m down to 4300 m depth. Lateral inputs at the deepest trap are probably of importance, attributed to the influence of the deep Adriatic water, characterized by relatively higher turbidity than overlying water masses. Two major processes seem to control the seasonal mass flux variability: (a) primary productivity at the euphotic zone; and (b) episodic dust input events. Primary productivity shows two maxima during late winter/early spring and late spring/summer, as witnessed by the organic carbon, carbonate, and opal fluxes in the mesopelagic and bathypelagic layers, whereas the influence of dust inputs is evidenced by enhanced lithogenic fluxes occurring during spring and summer. The interannual variability generally shows a gradual increase of fluxes during the time frame of the experiment. Both seasonal and interannual variability of mass flux are associated with variations in the intensity and position of the neighboring Pelops anticyclonic gyre, which appears to affect the upwelling of intermediate, nutrient-rich waters and subsequently the surface productivity. Combination of estimated satellite and algorithm-generated primary production data for the Ionian Sea, calculated POC fluxes out of the euphotic layer and POC fluxes measured by sediment traps at the mesopelagic and bathypelagic layers of NESTOR site during our 4 yr experiment, reveal that only a small portion of primary production (0.46%) reaches at 3200 m, corresponding to a mean annual carbon export of 1.12 g C m<sup>−2</sup> yr<sup>−1</sup>.

 References Aït-Ameur, N. and Goyet, C.: Distribution and transport of natural and anthropogenic CO<sub>2</sub> in the Gulf of Cádiz, Deep-Sea Res. Pt. II, 53, 1329–1343, 2006. Álvarez, M., Pérez, F., Shoosmith, D. R., and Bryden, H. L.: Unaccounted role of Mediterranean Water in the drawdown of anthropogenic carbon, J. Geophys. Res., 110, C09S03, <a href="http://dx.doi.org/10.1029/2004jc002633">https://doi.org/10.1029/2004jc002633</a>, 2005. Antoine, D., Morel, A., and Andre, J. M.: Algal pigment distribution and primary production in the eastern Mediterranean as derived from coastal zone color scanner observations, J. Geophys. Res., 100, 16193–116209, 1995. Armstrong, R. A., Lee, C., Hedges, J. I., Honjo, S., and Wakeham, S. G.: A new, mechanistic model for organic carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals, Deep-Sea Res. Pt. II, 49, 219–236, 2002. Betzer, P. R., Showers, W. J., Laws, E. A., Winn, C. D., DiTullio, G. R., and Kroopnick, P. M.: Primary productivity and particle fluxes on a transect of the equator at 153° W in the Pacific Ocean, Deep-Sea Res. Pt. I, 31, 1–11, 1984. Bianchi, F., Boldrin, A., Civitarese, G., Del Negro, P., Giordani, P., Malaguti, A., Socal, G., Rabitti, S., and Turchetto, M. M.: Biogenic particulate matter and primary productivity in the Southern Adriatic and Northern Ionian seas. 4th MTP-Workshop MATER, Perpignan (France), Abstracts Volume, Les Presses Littéraires, Saint-Esteve, 120–121, 1999. Bishop, J. K. B.: Regional extremes in particulate matter composition and flux: effects on the chemistry of the ocean interior, in: Productivity of the Ocean: Present and Past, edited by: Berger, W. H., Smetacek, V. S., Wefer, G., John Wiley & Sons Limited, 117–137, 1989. Bishop, J. K. B., Stepien, J. C., and Wiebe, P. H.: Particulate matter distributions, chemistry and flux in the panama basin: response to environment forcing, Progr. Oceanogr., 17, 1–59, 1986. Boldrin, A., Miserocchi, S., Rabitti, S., Turchetto, M. M., Balboni, V., and Socal, G.: Particulate matter in the southern Adriatic and Ionian Sea: Characterisation and downward fluxes, J. Mar. Syst., 33–34, 389–410, 2002. Borzelli, G. L. E., Gačič, M., Cardin, V., and Civitarese, G.: Eastern Mediterranean transient and reversal of the Ionian Sea circulation, Geophys. Res. Lett., 36, L15108, <a href="http://dx.doi.org/10.1029/2009gl039261">https://doi.org/10.1029/2009gl039261</a>, 2009. Bosc, E., Bricaud, A., and Antoine, D.: Seasonal and interannual variability in algal biomass and primary production in the Mediterranean Sea, as derived from 4 years of SeaWiFS observations, Global Biogeochem. Cy., 18, GB1005, <a href="http://dx.doi.org/10.1029/2003GB002034">https://doi.org/10.1029/2003GB002034</a>, 2004. Boyd, P. and Newton, P.: Evidence of the potential influence of planktonic community structure on the interannual variability of particulate organic carbon flux, Deep-Sea Res. Pt. I, 42, 619–639, 1995. Bricaud, A., Bosc, E., and Antoine, D.: Algal biomass and sea surface temperature in the Mediterranean Basin Intercomparison of data from various satellite sensors, and implications for primary production estimates, Remote Sens. Environ., 81, 163–178, 2002. Broecker W. S. and Peng T. H.:. Tracers in the Sea. Lamont-Doherty Geological Observatory, Palisades, NY, 1982. Buesseler, K. O.: The decoupling of production and particulate export in the surface ocean, Global Biogeochem. Cy., 12, 297–310, 1998. Buesseler, K. O. and Boyd, P. W.: Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean, Limnol. Oceanogr., 54, 1210–1232, 2009. Buesseler, K. O., Lamborg, C. H., Boyd, P. W., Lam, P. J., Trull, T. W., Bidigare, R. R., Bishop, J. K. B., Casciotti, K. L., Dehairs, F., Elskens, M., Honda, M., Karl, D. M., Siegel, D. A., Silver, M. W., Steinberg, D. K., Valdes, J., Van Mooy, B., and Wilson, S.: Revisiting carbon flux through the ocean's twilight zone, Science, 316, 567–570, 2007. Canals, M., Puig, P., De Madron, X. D., Heussner, S., Palanques, A., and Fabres, J.: Flushing submarine canyons, Nature, 444, 354–357, 2006. Casotti, R., Landolfi, A., Brunet, C., D'Ortenzio, F., Mangoni, O., Ribera d'Alcala, M., and Denis, M.: Composition and dynamics of the phytoplankton of the Ionian Sea (eastern Mediterranean), J. Geophys. Res., 108, 8116, <a href="http://dx.doi.org/10.1029/2002JC001541">https://doi.org/10.1029/2002JC001541</a>, 2003. Civitarese, G., Gačić, M., Lipizer, M., and Eusebi Borzelli, G. L.: On the impact of the Bimodal Oscillating System (BiOS) on the biogeochemistry and biology of the Adriatic and Ionian Seas (Eastern Mediterranean), Biogeosciences, 7, 3987–3997, <a href="http://dx.doi.org/10.5194/bg-7-3987-2010">https://doi.org/10.5194/bg-7-3987-2010</a>, 2010. Colella, S., D'Ortenzio, F., Marullo, S., Santoleri, R., Ragni, M., and Ribera d'Alcala, M.: Primary production variability in the Mediterranean Sea from SeaWiFS data, Proc. SPIE 5233, P. Soc. Photo.-Opt. Ins., 371-393, <a href="http://dx.doi.org/10.1117/12.516791">https://doi.org/10.1117/12.516791</a>, 2004. Conte, M. H., Ralph, N., and Ross, E. H.: Seasonal and interannual variability in deep ocean particle fluxes at the Oceanic Flux Program (OFP)/Bermuda Atlantic Time Series (BATS) site in the western Sargasso Sea near Bermuda, Deep-Sea Res. Pt. II, 48, 1471–1505, 2001. Crombet, Y., Leblanc, K., Quéguiner, B., Moutin, T., Rimmelin, P., Ras, J., Claustre, H., Leblond, N., Oriol, L., and Pujo-Pay, M.: Deep silicon maxima in the stratified oligotrophic Mediterranean Sea, Biogeosciences, 8, 459–475, <a href="http://dx.doi.org/10.5194/bg-8-459-2011">https://doi.org/10.5194/bg-8-459-2011</a>, 2011. Cutter, G. A. and Radford-Knoery, J. Determination of carbon, nitrogen, sulfur and inorganic sulfur species in marine particles, in: Marine particles: analysis and characterization, edited by: Hurd, D. C. and Spencer, D. W., American Geophysical Union, Geophys. Monogr. Ser., 63, 57–63, 1991. De Lazzari, A., Boldrin, A., Rabitti, S., and Turchetto, M. M.: Variability and downward fluxes of particulate matter in the Otranto Strait area, J. Mar. Syst., 20, 399–413, 1999. De La Rocha, C. L., Nowald, N., and Passow, U.: Interactions between diatom aggregates, minerals, particulate organic carbon, and dissolved organic matter: Further implications for the ballast hypothesis, Global Biogeochem. Cy., 22, GB4005, <a href="http://dx.doi.org/10.1029/2007GB003156">https://doi.org/10.1029/2007GB003156</a>, 2008. D'Ortenzio, F. and Ribera d'Alcalà, M.: On the trophic regimes of the Mediterranean Sea: a satellite analysis, Biogeosciences, 6, 139–148, <a href="http://dx.doi.org/10.5194/bg-6-139-2009">https://doi.org/10.5194/bg-6-139-2009</a>, 2009. D'Ortenzio, F., Ragni, M., Marullo, S., and Ribera d'Alcala, M.: Did biological activity in the Ionian Sea change after the Eastern Mediterranean Transient? Results from the analysis of remote sensing observations, J. Geophys. Res., 108, 8113, <a href="http://dx.doi.org/10.1029/2002JC001556">https://doi.org/10.1029/2002JC001556</a>, 2003. Engel, A., Thoms, S., Riebesell, U., Rochelle-Newall, E., Zondervan, I.: Polysaccharide aggregation as a potential sink of marine dissolved organic carbon, Nature, 428, 929–932, 2004. Eppley, R. W. and Peterson, B. J.: Particulate organic matter flux and planktonic new production in the deep ocean, Nature, 282, 677–680, <a href="http://dx.doi.org/10.1038/282677a0">https://doi.org/10.1038/282677a0</a>, 1979. Fabres, J., Tesi, T., Velez, J., Batista, F., Lee, C., Calafat, A., Heussner, S., Palanques, A., and Miserocchi, S.: Seasonal and event-controlled export of organic matter from the shelf towards the Gulf of Lions continental slope, Cont. Shelf Res., 28, 1971–1983, 2008. Fischer, G., Donner, B., Ratmeyer, V., Davenport, R., and Wefer, G.: Distinct year-to-year particle flux variations off Cape Blanc during 1988–1991: Relation to δ<sup>18</sup>O-deduced sea-surface temperatures and trade winds, J. Mar. Res., 54, 73–98, 1996. Francois, R., Honjo, S., Krishfield, R., and Manganini, S.: Factors controlling the flux of organic carbon to the bathypelagic zone of the ocean, Global Biogeochem. Cy., 16, 34–31, 2002. Gačić, M., Civitarese, G., Eusebi Borzelli, G. L., Kovačević, V., Poulain, P.-M., Theocharis, A., Menna, M., Catucci, A., and Zarokanellos, N. On the relationship between the decadal oscillations of the northern Ionian Sea and the salinity distributions in the eastern Mediterranean, J. Geophys. Res., 116, C12002,<a href="http://dx.doi.org/10.1029/2011JC007280">https://doi.org/10.1029/2011JC007280</a>, 2011. Gkikas, A., Hatzianastassiou, N., Mihalopoulos, N., Katsoulis, V., Kazadzis, S., Pey, J., Querol, X., and Torres, O.: The regime of desert dust episodes in the Mediterranean based on contemporary satellite observations and ground measurements, Atmos. Chem. Phys. Discuss., 13, 16247–16299, <a href="http://dx.doi.org/10.5194/acpd-13-16247-2013">https://doi.org/10.5194/acpd-13-16247-2013</a>, 2013. Gogou, A. and Repeta, D. J.: Particulate-dissolved transformations as a sink for semi-labile dissolved organic matter: Chemical characterization of high molecular weight dissolved and surface-active organic matter in seawater and in diatom cultures, Mar. Chem., 121, 215–223, 2010. Gogou, A., Sanchez-Vidal, A., Durrieu de Madron, X., Stavrakakis, S., Calafat, A., Stabholz, M., Psarra, S., Canals, M., Heussner, S., Stavrakaki, I., and Papathanassiou, V.: Carbon Flux to the Deep in three open sites of the Southern European Seas (SES), J. Mar. Syst., in press, <a href="http://dx.doi.org/10.1016/j.jmarsys.2013.05.013">https://doi.org/10.1016/j.jmarsys.2013.05.013</a>, 2013. Guerzoni, S., Chester, R., Dulac, F., Herut, B., Loÿe-Pilot, M. D., Measures, C., Migon, C., Molinaroli, E., Moulin, C., Rossini, P., Saydam, C., Soudine, A., and Ziveri, P.: The role of atmospheric deposition in the biogeochemistry of the Mediterranean Sea, Progr. Oceanogr., 44, 147–190, 1999. Haake, B., Ittekkot, V., Rixen, T., Ramaswamy, V., Nair, R. R., and Curry, W. B.: Seasonality and interannual variability of particle fluxes to the deep Arabian sea, Deep-Sea Res. Pt. I, 40, 1323–1344, 1993. Herut, B., Collier, R., and Krom, M. D.: The role of dust in supplying nitrogen and phosphorus to the Southeast Mediterranean, Limnol. Oceanogr., 47, 870–878, 2002. Heussner, S., Ratti, C., and Carbonne, J.: The PPS 3 time-series sediment trap and the trap sample processing techniques used during the ECOMARGE experiment, Cont. Shelf Res., 10, 943–958, 1990. Heussner, S., Durrieu de Madron, X., Calafat, A., Canals, M., Carbonne, J., Delsaut, N., and Saragoni, G.: Spatial and temporal variability of downward particle fluxes on a continental slope: Lessons from an 8-yr experiment in the Gulf of Lions (NW Mediterranean), Mar. Geol., 234, 63–92, 2006. Honda, M. C.: Biological Pump in Northwestern North Pacific, J. Oceanogr., 59, 671–684, 2003 Honda, M. C., Kusakabe, M., Nakabayashi, S., Manoanini, S. J., and Honjo, S.: Change in pCO<sub>2</sub> through biological activity in the marginal seas of the western North Pacific: The efficiency of the biological pump estimated by a sediment Trap experiment, J. Oceanogr., 53, 645–662, 1997. Honjo, S., Manganini, S. J., Krishfield, R. A., and Francois, R.: Particulate organic carbon fluxes to the ocean interior and factors controlling the biological pump: A synthesis of global sediment trap programs since 1983, Progr. Oceanogr., 76, 217–285, 2008. Ignatiades, L., Gotsis-Skretas, O., Pagou, K., and Krasakopoulou, E.: Diversification of phytoplankton community structure and related parameters along a large-scale longitudinal east-west transect of the Mediterranean Sea, J. Plankton Res., 31, 411–428, 2009. Ittekkot, V., Haake, B., Bartsch, M., Nair, R. R., and Ramaswamy, V.: Organic carbon removal in the sea: The continental connection, in: Upwelling Systems: Evolution Since the Early Miocene, edited by: Prell, C. P. and Emeis, K. C., Geological Society Special Publication No. 64, 167–176, 1992. Kalivitis, N., A. Bougiatioti, A., Kouvarakis, G., and Mihalopoulos, N.: Long term measurements of atmospheric aerosol optical properties in the Eastern Mediterranean, Atmos. Res., 102, 351–357, 2011. Karageorgis, A. P.: Suspended particulate matter distribution at the NESTOR site, using optical methods and bottle data, Km3NeT Collaboration Meeting 16–18 April 2007, Pylos, Greece, 2007. Karageorgis, A. P., Gardner, W. D., Georgopoulos, D., Mishonov, A.V., Krasakopoulou, E., and Anagnostou, C.: Particle dynamics in the Eastern Mediterranean Sea: a synthesis based on light transmission, PMC, and POC archives (1991–2001), Deep-Sea Res. Pt. I, 55, 177–202, 2008. Karageorgis, A. P., Georgopoulos, D., Kanellopoulos, T. D., Mikkelsen, O. A., Pagou, K., Kontoyiannis, H., Pavlidou, A., and Anagnostou, C.: Spatial and seasonal variability of particulate matter optical and size properties in the Eastern Mediterranean Sea, J. Mar. Syst., 105–108, 123–134, 2012. Karl, D. M., Christian, J. R., Dore, J. E., Hebel, D. V., Letelier, R. M., Tupas, L. M., and Winn, C. D.: Seasonal and interannual variability in primary production and particle flux at station ALOHA, Deep-Sea Res. Pt. II, 43, 539–568, 1996. Karl, D. M., Dore, J. E., Lukas, R., Michaels, A. F., Bates, N. R., and Knap, A.: Building the long-term picture: The U.S. JGOFS time-series programs, Oceanography, 14, 6–17, 2001. Kerhervé, P., Heussner, S., Charrière, B., Stavrakakis, S., Ferrand, J. L., Monaco, A., and Delsaut, N.: Biogeochemistry and dynamics of settling particle fluxes at the Antikythira Strait (Eastern Mediterranean), Progr. Oceanogr., 44, 651–675, 1999. Klaas, C. and Archer, D. E.: Association of sinking organic matter with various types of mineral ballast in the deep sea: Implications for the rain ratio, Global Biogeochem. Cy., 16, 63–61, 2002. Klein, B., Roether, W., Manca, B. B., Bregant, D., Beitzel, V., Kovacevic, V., and Luchetta, A.: The large deep water transient in the eastern Mediterranean, Deep-Sea Res. Pt. II, 46, 371–414, 1999. Km3NeT Collaboration: Report on evaluation of existing water, oceanographic, biological and geological data from candidate sites, Km3NeT Report, WP5, Deliverable 5.1, 2007. Knauer, G. A., Karl, D. M., Martin, J. H., and Hunter, C. N.: In situ effects of selected preservatives on total carbon, nitrogen and metals collected in sediment traps, J. Mar. Res., 42, 445–462, 1984. Kontoyiannis, H.: The status of the deep hydrography and eddy field during 2006–2009 at the southeast Ionian tentative neutrino-telescope site, 39th CIESM Congress, Venice, Italy, 2010. Kontoyiannis, H., and Lykousis, V.: Was the East Mediterranean deep thermohaline cell weakening during 2006–2009?, Nucl. Instrum. Meth. A, 626–627, S91–S93, 2011. Kouvarakis, G., Mihalopoulos, N., Tselepides, A., and Stavrakakis, S.: On the importance of atmospheric inputs of inorganic nitrogen species on the productivity of the Eastern Mediterranean sea, Global Biogeochem. Cy., 15, 805–817, 2001. Krasakopoulou, E., Souvermezoglou, E., and Goyet, C.: Anthropogenic CO<sub>2</sub> fluxes in the Otranto Strait (E. Mediterranean) in February 1995, Deep-Sea Res. Pt. I, 58, 1103–1114, 2011. Krom, M. D., Kress, N., Brenner, S., and Gordon, L. I.: Phosphorus limitation of primary productivity in the eastern Mediterranean Sea, Limnol. Oceanogr., 36, 424–432, 1991. Lampitt, R. S. and Antia, A. N.: Particle flux in deep seas: Regional characteristics and temporal variability, Deep-Sea Res. Pt. I, 44, 1377–1403, 1997. Larnicol, G., Ayoub, N., and Le Traon, P. Y.: Major changes in Mediterranean Sea level variability from 7 years of TOPEX/Poseidon and ERS-1/2 data, J. Mar. Syst., 33–34, 63–89, 2002. Laws, E. A., Falkowski, P. G., Smith Jr, W. O., Ducklow, H., and McCarthy, J. J.: Temperature effects on export production in the open ocean, Global Biogeochem. Cy., 14, 1231–1246, 2000. Lee, C., Peterson, M. L., Wakeham, S. G., Armstrong, R. A., Cochran, J. K., Miquel, J. C., Fowler, S. W., Hirschberg, D., Beck, A., and Xue, J.: Particulate organic matter and ballast fluxes measured using time-series and settling velocity sediment traps in the northwestern Mediterranean Sea, Deep-Sea Res. Pt. II, 56, 1420–1436, 2009. Lepore, K., Moran, S. B., Burd, A. B., Jackson, G. A., Smith, J. N., Kelly, R. P., Kaberi, H., Stavrakakis, S., and Assimakopoulou, G.: Sediment trap and in-situ pump size-fractionated POC/<sup>234</sup>Th ratios in the Mediterranean Sea and Northwest Atlantic: Implications for POC export, Deep-Sea Res. Pt. I, 56, 599–613, 2009. Loÿe-Pilot, M. D., Martin, J. M., and Morelli, J.: Atmospheric input of inorganic nitrogen to the Western Mediterranean, Biogeochemistry, 9, 117–134, 1990. Lutz, M., Dunbar, R., and Caldeira, K.: Regional variability in the vertical flux of particulate organic carbon in the ocean interior, Global Biogeochem. Cy., 16, 1037, <a href="http://dx.doi.org/10.1029/2000GB001383">https://doi.org/10.1029/2000GB001383</a>, 2002. Malanotte-Rizzoli, P., Manca, B., Ribera D'Alcala, M., Theocharis, A., Bergamasco, A., Bregant, D., Budillon, G., Civitarese, G., Georgopoulos, D., Michelato, A., Sansone, E., Scarazzato, P., and Souvermezoglou, E.: A synthesis of the Ionian Sea hydrography, circulation and water mass pathways during POEM-Phase I, Progr. Oceanogr., 39, 153–204, 1997. Malanotte-Rizzoli, P., Manca, B. B., Ribera d'Alcala, M., Theocharis, A., Brenner, S., Budillon, G., and Özsoy, E.: The Eastern Mediterranean in the 80s and in the 90s: The big transition in the intermediate and deep circulations, Dynam. Atmos. Oceans, 29, 365–395, 1999. Malinverno, E., Triantaphyllou, M. V., Stavrakakis, S., Ziveri, P., and Lykousis, V.: Seasonal and spatial variability of coccolithophore export production at the South-Western margin of Crete (Eastern Mediterranean), Mar. Micropaleontol., 71, 131–147, 2009. Manca, B. B., Budillon, G., Scarazzato, P., and Ursella, L.: Evolution of dynamics in the eastern Mediterranean affecting water mass structures and properties in the Ionian and Adriatic Seas, J. Geophys. Res., 108, 8102, <a href="http://dx.doi.org/10.1029/2002JC001664">https://doi.org/10.1029/2002JC001664</a>, 2003. Markaki, Z., Oikonomou, K., Kocak, M., Kouvarakis, G., Chaniotaki, A., Kubilay, N., and Mihalopoulos, N.: Atmospheric deposition of inorganic phosphorus in the Levantine Basin, eastern Mediterranean: Spatial and temporal variability and its role in seawater productivity, Limnol. Oceanogr., 48, 1557–1568, 2003. Markaki, Z., Loÿe-Pilot, M. D., Violaki, K., Benyahya, L., and Mihalopoulos, N.: Variability of atmospheric deposition of dissolved nitrogen and phosphorus in the Mediterranean and possible link to the anomalous seawater N/P ratio, Mar. Chem., 120, 187–194, 2010. Ternon, E., Guieu, C., Loÿe-Pilot, M.-D., Leblond, N., Bosc, E., Gasser, B., Miquel, J.-C., and Martín, J.: The impact of Saharan dust on the particulate export in the water column of the North Western Mediterranean Sea, Biogeosciences, 7, 809–826, <a href="http://dx.doi.org/10.5194/bg-7-809-2010">https://doi.org/10.5194/bg-7-809-2010</a>, 2010. Martin, J. H., Knauer, G. A., Karl, D. M., and Broenkow, W. W.: VERTEX: carbon cycling in the northeast Pacific, Deep-Sea Res. Pt. I, 34, 267–285, 1987. Martin, J., Miquel, J. C., and Khripounoff, A.: Impact of open sea deep convection on sediment remobilization in the western Mediterranean, Geophys. Res. Lett., 37, L13604, <a href="http://dx.doi.org/10.1029/2010GL043704">https://doi.org/10.1029/2010GL043704</a>, 2010. Mazzocchi, M. G., Nervegna, D., D'Elia, G., Di Capua, I., Aguzzi, L., and Boldrin, A.: Spring mesozooplankton communities in the epipelagic Ionian Sea in relation to the Eastern Mediterranean Transient, J. Geophys. Res., 108, 8114, <a href="http://dx.doi.org/10.1029/2002JC001640">https://doi.org/10.1029/2002JC001640</a>, 2003. Meador, T. B., Gogou, A., Spyres, G., Herndl, G. J., Krasakopoulou, E., Psarra, S., Yokokawa, T., De Corte, D., Zervakis, V., Repeta, D. J.: Biogeochemical relationships between ultrafiltered dissolved organic matter and picoplankton activity in the Eastern Mediterranean Sea, Deep-Sea Res. Pt. II, 57, 1460–1477, 2010. Miquel, J. C., Martín, J., Gasser, B., Rodriguez-y-Baena, A., Toubal, T., and Fowler, S. W.: Dynamics of particle flux and carbon export in the northwestern Mediterranean Sea: A two decade time-series study at the DYFAMED site, Progr. Oceanogr., 91, 461–481, 2011. Monaco, A., Durrieu de Madron, X., Radakovitch, O., Heussner, S., and Carbonne, J.: Origin and variability of downward biogeochemical fluxes on the Rhone continental margin (NW Mediterranean), Deep-Sea Res. Pt. I, 46, 1483–1511, 1999. Mortlock, R. A. and Froelich, P. N.: A simple method for the rapid determination of biogenic opal in pelagic marine sediments, Deep-Sea Res., 36, 1415–1426, 1989. Moutin, T. and Raimbault, P.: Primary production, carbon export and nutrients availability in western and eastern Mediterranean Sea in early summer 1996 (MINOS cruise), J. Mar. Syst., 33–34, 273–288, 2002. Moulin, C., Lamber, C. E., Dayan, U., Masson, V., Ramone, M., Bousque, P., Legrand, M., Balkanski, Y., Guellel, W., Marticorena, B. Bergametti, G., and Dulac, F.: Satellite climatology of African dust transport in the Mediterranean atmosphere, J. Geophys. Res., 103, 13137–13144, 1998. Nieuwenhuize, J., Maas, Y. E. M., and Middelburg, J. J.: Rapid analysis of organic carbon and nitrogen in particulate materials, Mar. Chem., 45, 217–224, 1994. Nittis, K., Pinardi, N., and Lascaratos, A.: Characteristics of the summer 1987 flow field in the Ionian Sea, J. Geophys. Res., 98, 10171–10184, 1993. Özsoy, E., Kubilay, N., Nickovic, S., and Moulin C.: A hemisphere dust storm affecting the Atlantic and Mediterranean in April 1994: Analyses, modeling, ground-based measurements and satellite observations, J. Geophys. Res., 106, 18439–18460, 2001 Pace, M. L., Knauer, G. A., Karl, D. M., and Martin, J. H.: Primary production, new production and vertical flux in the eastern Pacific Ocean, Nature, 325, 803–804, 1987. Pasqual, C., Sanchez-Vidal, A., Zúñiga, D., Calafat, A., Canals, M., Durrieu de Madron, X., Puig, P., Heussner, S., Palanques, A., and Delsaut, N.: Flux and composition of settling particles across the continental margin of the Gulf of Lion: the role of dense shelf water cascading, Biogeosciences, 7, 217–231, <a href="http://dx.doi.org/10.5194/bg-7-217-2010">https://doi.org/10.5194/bg-7-217-2010</a>, 2010. Passow, U.: Switching perspectives: Do mineral fluxes determine particulate organic carbon fluxes or vice versa?, Geochem. Geophys. Geosy., 5, 1-5, <a href="http://dx.doi.org/10.1029/2003gc000670">https://doi.org/10.1029/2003gc000670</a>, 2004. Passow, U., Shipe, R. F., Murray, A., Pak, D. K., Brzezinski, M. A., and Alldredge, A. L.: Origin of transparent exopolymer particles (TEP) and their role in the sedimentation of particulate matter, Cont. Shelf Res., 21, 327–346, 2001. Patara, L., Pinardi, N., Corselli, C., Malinverno, E., Tonani, M., Santoleri, R., and Masina, S.: Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities, Biogeosciences, 6, 333–348, <a href="http://dx.doi.org/10.5194/bg-6-333-2009">https://doi.org/10.5194/bg-6-333-2009</a>, 2009. Polymeris G. S., George Kitis, Liolios, A. K., Sakalis, A., Zioutas, K., Anassontzis, E. G., and Tsirliganis, N. C.: Luminescence dating of the top of a deep water core from the NESTOR site near the Hellenic Trench, east Mediterranean Sea, Quat. Geochronol., 4, 68–81, 2009. Rabitti, S., Bianchi, F., Boldrin, A., Da Ros, L., Socal, G. and Totti, C.: Particulate matter and phytoplankton in the Ionian Sea, Oceanol. Acta, 17, 297–307, 1994. Ridame, C. and Guieu, C.: Saharan input of phosphate to the oligotrophic water of the open western Mediterranean sea, Limnol. Oceanogr., 47, 856–869, 2002. Sabine, C. L. and Tanhua, T.: Estimation of anthropogenic CO<sub>2</sub> inventories in the ocean, Annu. Rev. Mar. Sci., 2, 175–198, 2010. Sanchez-Vidal, A., Calafat, A., Canals, M., and Fabres, J.: Particle fluxes in the Almeria-Oran Front: control by coastal upwelling and sea surface circulation, J. Mar. Syst., 52, 89–106, 2004. Sanchez-Vidal, A., Calafat, A., Canals, M., Frigola, J., and Fabres, J.: Particle fluxes and organic carbon balance across the Eastern Alboran Sea (SW Mediterranean Sea), Cont. Shelf Res., 25, 609–628, 2005. Schneider, A., Tanhua, T., Krtzinger, A., and Wallace, D. W. R.: High anthropogenic carbon content in the eastern Mediterranean, J. Geophys. Res., 115, C12050, <a href="http://dx.doi.org/10.1029/2010jc006171">https://doi.org/10.1029/2010jc006171</a>, 2010. Siegenthaler, U. and Sarmiento, J. L.: Atmospheric carbon dioxide and the ocean, Nature, 365, 119–125, 1993 Siokou-Frangou, I., Christaki, U., Mazzocchi, M. G., Montresor, M., Ribera d'Alcalá, M., Vaqué, D., and Zingone, A.: Plankton in the open Mediterranean Sea: a review, Biogeosciences, 7, 1543–1586, <a href="http://dx.doi.org/10.5194/bg-7-1543-2010">https://doi.org/10.5194/bg-7-1543-2010</a>, 2010. Stavrakakis, S. and Lykousis, V.: Interannual mass flux variations of settling particles in the NESTOR basins, SE. Ionian Sea (E. Mediterranean), Greece, Nucl. Instrum. Meth. A, 626–627, S99–S101, <a href="http://dx.doi.org/10.1016/j.nima.2010.04.076">https://doi.org/10.1016/j.nima.2010.04.076</a>, 2011. Stavrakakis, S., Chronis, G., Tselepides, A., Heussner, S., Monaco, A., and Abassi, A.: Downward fluxes of settling particles in the deep Cretan Sea (NE Mediterranean), Progr. Oceanogr., 46, 217–240, 2000. Suess, E.: Particulate organic carbon flux in the oceans – Surface productivity and oxygen utilization, Nature, 288, 260–263, 1980. Taillandier, V., D'Ortenzio, F., and Antoine, D.: Carbon fluxes in the mixed layer of the Mediterranean Sea in the 1980s and the 2000s, Deep-Sea Res. Pt. I, 65, 73-84, 2012. Takahashi, K., Fujitani, N., Yanada, M., and Maita, Y.: Long-term biogenic particle fluxes in the Bering Sea and the central subarctic Pacific Ocean, 1990–1995, Deep-Sea Res. Pt. I, 47, 1723–1759, 2000. Takahashi, K., Fujitani, N., and Yanada, M.: Long term monitoring of particle fluxes in the Bering Sea and the central subarctic Pacific Ocean, 1990–2000, Progr. Oceanogr., 55, 95–112, 2002. Theocharis, A., Nittis, K., Kontoyiannis, H., Papageorgiou, M., and Balopoulos, E.: Climatic changes in the Aegean Sea influence the Eastern Mediterranean thermohaline circulation (1986–1997), Geophys. Res. Lett., 26, 1617–1620, 1999. Theodosi, C., Parinos, C., Gogou, A., Kokotos, A., Stavrakakis, S., Lykousis, V., Hatzianestis, J., and Mihalopoulos, N.: Downward fluxes of elemental carbon, metals and polycyclic aromatic hydrocarbons in settling particles from the deep Ionian Sea (NESTOR site), Eastern Mediterranean, Biogeosciences, 10, 4449–4464, <a href="http://dx.doi.org/10.5194/bg-10-4449-2013">https://doi.org/10.5194/bg-10-4449-2013</a>, 2013. Thingstad, T. F. and Rassoulzadegan, F.: Nutrient limitations, microbial food webs, and biological C-pumps: Suggested interactions in a P-limited Mediterranean, Mar. Ecol.-Prog. Ser., 117, 299–306, 1995. Touratier, F. and Goyet, C.: Impact of the Eastern Mediterranean Transient on the distribution of anthropogenic CO<sub>2</sub> and first estimate of acidification for the Mediterranean Sea, Deep-Sea Res. Pt. I, 58, 1–15, 2011. Triantaphyllou, M. V., Ziveri, P., and Tselepides, A.: Coccolithophore export production and response to seasonal surface water variability in the oligotrophic Cretan Sea (NE Mediterranean), Micropaleontology, 50, 127–144, 2004. Trimonis, E. and Rudenko, M.: Geomorphology and bottom sediments of the Pylos area. In: Proceedings of the 2nd NESTOR International Workshop, edited by: Resvanis, L. K., p. 321, 1992. Verardo, D. J., Froelich, P. N., and McIntyre, A.: Determination of organic carbon and nitrogen in marine sediments using the Carlo Erba NA-1500 Analyzer, Deep-Sea Res., 37, 1, 157–165, 1990. Verdugo, P., Alldredge, A. L., Azam, F., Kirchman, D. L., Passow, U., and Santschi, P. H.: The oceanic gel phase: a bridge in the DOM-POM continuum, Mar. Chem., 92, 67–85, 2004. Volk, T. and Hoffert M.: Ocean carbon pumps: Analysis of relative strengths and efficiencies in ocean-driven atmospheric CO<sub>2</sub> changes, in: The Carbon Cycle and Atmospheric CO<sub>2</sub>: Natural Variations Archean to Present, Geophys. Monogr. Ser., vol. 32, edited by: Sundquist, E. T. and Broecker, W. S., AGU, Washington, DC, 99–110, <a href="http://dx.doi.org/10.1029/GM032p0099">https://doi.org/10.1029/GM032p0099</a>, 1985. Wong, C. S., Whitney, F. A., Crawford, D. W., Iseki, K., Matear, R. J., Johnson, W. K., Page, J. S., and Timothy, D.: Seasonal and interannual variability in particle fluxes of carbon, nitrogen and silicon from time series of sediment traps at Ocean Station P, 1982–1993: Relationship to changes in subarctic primary productivity, Deep-Sea Res. Pt. II, 46, 2735–2760, 1999. Yokokawa, T., De Corte, D., Sintes, E., and Gerndl, G. J.: Spatial patterns of bacterial abundance, activity and community composition in relation to water masses in the Eastern Mediterranean Sea, Aquat. Microb. Ecol., 59, 185–195, 2010. Zúñiga, D., Calafat, A., Sanchez-Vidal, A., Canals, M., Price, B., Heussner, S., and Miserocchi, S.: Particulate organic carbon budget in the open Algero-Balearic Basin (Western Mediterranean): Assessment from a one-year sediment trap experiment, Deep-Sea Res. Pt. I, 54, 1530–1548, 2007.