Temporal variability of chlorophyll distribution in the Gulf of Mexico: bio-optical data from profiling floats

被引:44
作者
Pasqueron de Fommervault, Orens [1 ]
Perez-Brunius, Paula [1 ]
Damien, Pierre [1 ]
Camacho-Ibar, Victor F. [2 ]
Sheinbaum, Julio [1 ]
机构
[1] Ctr Invest Cient & Educ Super Ensenada, Dept Oceanog Fis, Ensenada 22860, Baja California, Mexico
[2] Univ Autonoma Baja Calif, Inst Invest Oceanol, Carretera Ensenada Tijuana 3917, Ensenada 22860, Baja California, Mexico
关键词
LOOP CURRENT; NORTH-ATLANTIC; BEAM ATTENUATION; WESTERN GULF; PHYTOPLANKTON PHYSIOLOGY; NUTRIENT CONCENTRATIONS; BIOLOGICAL PROCESSES; CONTINENTAL-MARGIN; MESOSCALE EDDIES; LIGHT-SCATTERING;
D O I
10.5194/bg-14-5647-2017
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
Chlorophyll concentration is a key oceanic biogeochemical variable. In the Gulf of Mexico (GOM), its distribution, which is mainly obtained from satellite surface observations and scarce in situ experiments, is still poorly understood. In 2011-2012, eight profiling floats equipped with biogeochemical sensors were deployed for the first time in the GOM and generated an unprecedented dataset that significantly increased the number of chlorophyll vertical distribution measurements in the region. The analysis of these data, once calibrated, permits us to reconsider the spatial and temporal variability of the chlorophyll concentration in the water column. At a seasonal scale, results confirm the surface signal seen by satellites, presenting maximum concentrations in winter and low values in summer. It is shown that the deepening of the mixed layer is the primary factor triggering the chlorophyll surface increase in winter. In the GOM, a possible interpretation is that this surface increase corresponds to a biomass increase. However, the present dataset suggests that the basin-scale climatological surface increase in chlorophyll content results from a vertical redistribution of subsurface chlorophyll and/or photoacclimation processes, rather than a net increase of biomass. One plausible explanation for this is the decoupling between the mixed-layer depth and the deep nutrient reservoir since mixed-layer depth only reaches the nitracline in sporadic events in the observations. Float measurements also provide evidence that the depth and the magnitude of the deep chlorophyll maximum is strongly controlled by the mesoscale variability, with higher chlorophyll biomass generally observed in cyclones rather than anticyclones.
引用
收藏
页码:5647 / 5662
页数:16
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