The distinction between shallow coral reefs and mesophotic coral ecosystems (MCEs) has not been fully clarified yet. The original definition of MCEs, by depths of 30–150 m, fixes their bathymetrical limits and fails to accommodate environmental and biological variation. Recent studies have indicated that water transparency and light availability may explain why MCEs do not occur at fixed depths but vary among localities. This study aimed to evaluate the presence and distribution of MCEs, along the central coast of Oaxaca, through optical depths and the associated benthic community. Using MODIS-Aqua satellite data (Kd490), we estimated the mesophotic optical depths monthly (z10%, z1%, z0.1%), over the last four years. In addition, to characterize benthic community structure, we conducted underwater photo quadrat surveys at two locations on the southern Mexican Pacific coast from 10 to 55 m depth. Significant differences between depths and locations were found in benthic communities. Furthermore, the lower distribution of photosynthetic taxa was different between the two locations but indicative to the z10% and z1% in both cases. Those differences were associated with the upwelling season, which reduces, drastically and differentially, the light availability for benthic communities between the two locations and limits the development of MCEs on the central coast of Oaxaca.

Current scientific knowledge about the threats jeopardizing the recovery of sea turtle populations in Mexico is essential for improving conservation strategies. This study presents the results of a systematic review of the scientific literature published between 1960 and 2024, with the aim of identifying the main threats contributing to the decline of sea turtle populations in Mexico, detecting trends in scientific production, identifying knowledge gaps, and offering a comprehensive view of the challenges and priority actions needed to improve conservation strategies by region in Mexico. The review revealed a significant increase in research since 1997, with a predominant focus on pollution, fishing, and disease, mainly in the Pacific region. While Chelonia mydas and Lepidochelys olivacea were the most studied species, Dermochelys coriacea and Lepidochelys kempii received less attention. A total of 22 stressors associated with 8 threats were identified, but knowledge gaps persist regarding emerging threats such as climate change, coastal and marine development, and marine noise pollution. The results underscore the need to expand research on less-studied species and regions, strengthen studies in marine ecosystems, and improve the alignment between research and conservation policies to ensure the long-term viability of sea turtles in Mexico.