Papers by Elodie Martinez
Global change biology, Jan 19, 2015
Shifts in global climate resonate in plankton dynamics, biogeochemical cycles, and marine food we... more Shifts in global climate resonate in plankton dynamics, biogeochemical cycles, and marine food webs. We studied these linkages in the North Atlantic Subpolar Gyre (NASG), which hosts extensive phytoplankton blooms. We show that phytoplankton abundance increased since the 1960s in parallel to a deepening of the mixed layer and a strengthening of winds and heat losses from the ocean, as driven by the low frequency of the North Atlantic Oscillation (NAO). In parallel to these bottom-up processes, the top-down control of phytoplankton by copepods decreased over the same time period in the western NASG, following sea surface temperature changes typical of the Atlantic Multi-decadal Oscillation (AMO). While previous studies have hypothesized that climate-driven warming would facilitate seasonal stratification of surface waters and long-term phytoplankton increase in subpolar regions, here we show that deeper mixed layers in the NASG can be warmer and host a higher phytoplankton biomass. T...
Science, 2009
Phytoplankton---the microalgae that populate the upper lit layers of the ocean---fuel the oceanic... more Phytoplankton---the microalgae that populate the upper lit layers of the ocean---fuel the oceanic food web and affect oceanic and atmospheric carbon dioxide levels through photosynthetic carbon fixation. Here, we show that multidecadal changes in global phytoplankton abundances are related to basin-scale oscillations of the physical ocean, specifically the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. This relationship is revealed
SpringerBriefs in Earth System Sciences, 2013
Journal of Geophysical Research, 2009
Global Biogeochemical Cycles, 2012
1] We investigated the phenology of oceanic phytoplankton at large scales over two 5-year time pe... more 1] We investigated the phenology of oceanic phytoplankton at large scales over two 5-year time periods: 1979-1983 and 1998-2002. Two ocean-color satellite data archives (Coastal Zone Color Scanner (CZCS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS)) were used to investigate changes in seasonal patterns of concentrationnormalized chlorophyll. The geographic coverage was constrained by the CZCS data distribution. It was best for the Northern Hemisphere and also encompassed large areas of the Indian, South Pacific, and Equatorial Atlantic regions. For each 2 pixel, monthly climatologies were developed for satellite-derived chlorophyll, and the resulting seasonal cycles were statistically grouped using cluster analysis. Five distinct groups of mean seasonal cycles were identified for each half-decade period. Four types were common to both time periods and correspond to previously identified phytoplankton regimes: Bloom, Tropical, Subtropical North, and Subtropical South. Two other mean seasonal cycles, one in each of the two compared 5-year periods, were related to transitional or intermediate states (Transitional Tropical and Transitional Bloom). Five mean seasonal cycles (Bloom, Tropical, Subtropical North, and Subtropical South, Transitional Bloom) were further confirmed when the whole SeaWiFS data set (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) was analyzed. For 35% of the pixels analyzed, characteristic seasonal cycles of the 1979-1983 years differed little from those of the 1998-2002 period. For 65% of the pixels, however, phytoplankton seasonality patterns changed markedly, especially in the Northern Hemisphere. Subtropical regions of the North Pacific and Atlantic experienced a widespread expansion of the Transitional Bloom regime, which appeared further enhanced in the climatology based on the full SeaWiFS record (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010), and, as showed by a more detailed analysis, is associated to La Niña years. This spatial pattern of Transitional Bloom regime reflects a general smoothing of seasonality at macroscale, coming into an apparent greater temporal synchrony of the Northern Hemisphere. The Transitional Bloom regime is also the result of a higher variability, both in space and time. The observed change in phytoplankton dynamics may be related not only to biological interactions but also to large-scale changes in the coupled atmosphere-ocean system. Some connections are indeed found with climate indices. Changes were observed among years belonging to opposite phases of ENSO, though discernible from the change among the two periods and within the SeaWiFS era (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010). These linkages are considered preliminary at present and are worthy of further investigation. Citation: D'Ortenzio, F., D. Antoine, E. Martinez, and M. Ribera d'Alcalà (2012), Phenological changes of oceanic phytoplankton in the 1980s and 2000s as revealed by remotely sensed ocean-color observations, Global Biogeochem. Cycles, 26, GB4003,
Global Biogeochemical Cycles, 2013
1] In recent decades, it has been found useful to partition the pelagic environment using the con... more 1] In recent decades, it has been found useful to partition the pelagic environment using the concept of biogeochemical provinces, or BGCPs, within each of which it is assumed that environmental conditions are distinguishable and unique at global scale. The boundaries between provinces respond to features of physical oceanography and, ideally, should follow seasonal and interannual changes in ocean dynamics. But this ideal has not been fulfilled except for small regions of the oceans. Moreover, BGCPs have been used only as static entities having boundaries that were originally established to compute global primary production. In the present study, a new statistical methodology based on non-parametric procedures is implemented to capture the environmental characteristics within 56 BGCPs. Four main environmental parameters (bathymetry, chlorophyll a concentration, surface temperature, and salinity) are used to infer the spatial distribution of each BGCP over 1997-2007. The resulting dynamic partition allows us to integrate changes in the distribution of BGCPs at seasonal and interannual timescales, and so introduces the possibility of detecting spatial shifts in environmental conditions.
Geophysical Research Letters, 2004
Chlorophyll a in the Marquesas islands has been analyzed for the period 1997–2002 as well as simu... more Chlorophyll a in the Marquesas islands has been analyzed for the period 1997–2002 as well as simultaneous sea surface height anomaly, sea surface temperature, wind and rainfall. For the first time, the seasonality of phytoplankton blooms is shown around the Marquesas Islands. Clearly, the data show three types of blooms in this area: seasonal blooms, episodic ones, and La Niña
Coral Reefs, 2007
... Moruroa and Fangataufa atolls (Boulanger et al. 1993). ... For latitudes higher than 20°S,edd... more ... Moruroa and Fangataufa atolls (Boulanger et al. 1993). ... For latitudes higher than 20°S,eddy-like structures are observed between 24°S and 30°S, notice-ably in the transition zone between the SEC and the eastward SPC (Stramma et al. 1995). ...
Aquaculture International, 2012
The growth and reproductive cycle of cultured black-lipped pearl oysters, Pinctada margaritifera ... more The growth and reproductive cycle of cultured black-lipped pearl oysters, Pinctada margaritifera (L.), were studied in the Gambier Islands (134°52 0 W, 23°07 0 S) from September 2002 to August 2003. Temperatures were recorded throughout the year, revealing seasonal temperature variations between 22.3 and 27.8°C. The mean annual chlorophyll a value, as computed from satellite data, was 0.188 ± 0.075 lg L -1 . To study growth and reproduction, 720 two-year-old individuals were ear hung on long-lines suspended at a depth of 7 m. Samples were taken twice a month to obtain the following measurements: shell height; wet weight of flesh and total oyster; dry weight of adductor muscle, mantle and visceral mass; and glycogen content. Gonad development was also studied by histology on parallel samples. Growth was relatively fast during the first 6 months of the study: average shell height increased from 89.
Journal of Geophysical Research, 2011
Page 1. Phytoplankton spring and fall blooms in the North Atlantic in the 1980s and 2000s Elodie ... more Page 1. Phytoplankton spring and fall blooms in the North Atlantic in the 1980s and 2000s Elodie Martinez,1 David Antoine,1 Fabrizio D'Ortenzio,1 and C. de Boyer Montégut2 ... C11029 C11029 2 of 11 Page 3. light photosynthesis model [Morel, 1991; Antoine and Morel, 1996]. ...
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Papers by Elodie Martinez