Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Deep-Sea Research Part II : Topical Studies in Oceanography art. 104686 [8p.] Chlorophyll maxima Suboxia Persistence Euphotic zone Mexican Pacific MEXIQUE PACIFIQUE 2019 fdi:010077727 ENG Deep-Sea Research Part II : Topical Studies in Oceanography 0967-0645 ISI:000504782200008 No Spécial 10.1016/j.dsr2.2019.104686 https://www.documentation.ird.fr/hor/fdi:010077727 https://www.documentation.ird.fr/intranet/publi/2020/01/010077727.pdf 169 Horizon (IRD) The tropical Oxygen Minimum Zones (OMZ) are known to shelter a chlorophyll-a maximum (CM) within suboxic waters (<20 mu mol kg(-1)), below other chlorophyll-a maxima and with an unknown temporal variability in the Pacific OMZ off Mexico. Here, 1161 chlorophyll-a fluorescence and oxygen profiles collected between 2003 and 2016 were used to describe statistically the physical situation in which the suboxic-CM was found. Results indicate that the suboxic-CM was a persistent feature at seasonal scale at depths between 40 and 190 m at an average density potential anomaly of 26 +/- 0.2 kg m(-3), related to the Subtropical Subsurface Water, which is nearly unaffected by mixing with other water masses. The suboxic-CM south of 21 degrees N was generally associated with the upper limit of the suboxic waters of the OMZ. In this region, the distance between the suboxic waters and the euphotic zone (1% of surface irradiance) was > - 25 m year-round, which suggests that persistent low-light levels allow development of the suboxic-CM. The persistence of the suboxic-CM is consistent with its association with a stable microbial community. The effects on the ecosystem and biogeochemical cycles remain to be investigated. 032 ; 036 UR065 Mexique