The changes in temperature and dissolved oxygen concentration in the Pacific Ocean in the northern region of the shallow oxygen minimum zone (OMZ) off Mexico were analyzed on the basis of the Word Ocean Database and a series of oceanographic cruises (LEGOZ-Mex). In order to test the changes in both parameters between two similar oceanographic scenarios according to the Pacific Decadal Oscillation (PDO), a comparison was made between the last two cool PDO phases of 1962–1974 and 2002–2012 when conditions might be expected to be relatively similar. Results show that the surface layer (upper layer of 50 m depth) has been warming significantly in two of the three areas included in this study: 1) the southern end of the California Current (0.8 °C; p < 0.001), 2) the southern Gulf of California (0.49 °C; p < 0.001), and 3) the Tropical Transitional Pacific (0.4 °C). Simultaneously, the water column has been deoxygenating significantly (p < 0.001), not only in the subsurface shallow OMZ layer (~ 100 to 300 m depth) in the Tropical Transitional area (− 45%), as has been recorded previously, but from 300 to 1000 m depth (by between −38% and - 57%). The exception was the California Current area at the northern limit of the shallow OMZ, where the deoxygenation was only significant (p < 0.001) from 300 to 1000 m depth (~ − 20%). We conclude that the significant warming of the surface layer in the Pacific OMZ off Mexico has increased the stratification of the water column and contributed to the deoxygenation of the interior ocean, at least between the last two cool phases of the PDO. These changes may be significantly affecting the marine biota that inhabit the shallow OMZs.

在Word Ocean Database和一系列海洋航行（LEGOZ-Mex）的基础上，分析了墨西哥近海浅层最低氧区（OMZ）北部地区太平洋温度和溶解氧浓度的变化。为了根据太平洋年代际振荡 (PDO) 测试两个类似海洋情景之间两个参数的变化，在 1962-1974 年和 2002-2012 年的最后两个凉爽的 PDO 阶段之间进行了比较比较相似。结果表明，在本研究包括的三个区域中的两个区域，表层（50 m 深的上层）已显着变暖：1) 加利福尼亚洋流的南端 (0.8 °C；p  < 0.001)，2)加利福尼亚湾南部（0.49 °C；p  < 0.001)，和 3) 热带过渡太平洋 (0.4 °C)。同时，水柱已显着脱氧（p  < 0.001），不仅在热带过渡区（- 45%）的地下浅层 OMZ 层（约 100 至 300 m 深）中，如先前记录的那样，但从300 到 1000 m 深度（在 -38% 到 - 57% 之间）。唯一的例外是浅层 OMZ 北端的加利福尼亚洋流区域，那里的脱氧仅显着（p < 0.001) 从 300 到 1000 m 深度 (~ − 20%)。我们得出的结论是，墨西哥附近太平洋 OMZ 表层的显着变暖增加了水柱的分层，并导致内部海洋的脱氧，至少在 PDO 的最后两个凉爽阶段之间。这些变化可能会显着影响栖息在浅层 OMZ 的海洋生物群。