Mexico has more than 750,000 ha of mangroves and more than 400,000 ha of seagrasses. However, approximately 200,000 ha of mangroves and an unknown area of seagrass have been lost due to coastal development associated with urban, industrial and tourist purposes. In 2018, the approved reforms to the General Law on Climate Change (LGCC) aligned the Mexican law with the international objectives established in the 2nd Article of the Paris Agreement. This action proves Mexico’s commitment to contributing to the global target of stabilizing the greenhouse gas emissions concentration in the planet. Thus, restoring and conserving mangrove and seagrass habitats could contribute to fulfilling this commitment. Therefore, as a first step in establishing a mitigation and adaptation plan against climate change with respect to conservation and restoration actions of these ecosystems, we evaluated Mexican blue carbon ecosystems through a systematic review of the carbon stock using the standardized method of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We used the data from 126 eligible studies for both ecosystems (n = 1220). The results indicated that information is missing at the regional level. However, the average above and below ground organic carbon stocks from mangroves in Mexico is 113.6 ± 5.5 (95% CI [99.3–118.4]) Mg C_org ha⁻¹ and 385.1 ± 22 (95% CI [344.5–431.9]) Mg C_org ha⁻¹, respectively. The variability in the C_org stocks for both blue carbon ecosystems in Mexico is related to variations in climate, hydrology and geomorphology observed along the country’s coasts in addition to the size and number of plots evaluated with respect to the spatial cover. The highest values for mangroves were related to humid climate conditions, although in the case of seagrasses, they were related to low levels of hydrodynamic stress. Based on the official extent of mangrove and seagrass area in Mexico, we estimate a total carbon stock of 237.7 Tg C_org from mangroves and 48.1 Tg C_org from seagrasses. However, mangroves and seagrasses are still being lost due to land use change despite Mexican laws meant to incorporate environmental compensation. Such losses are largely due to loopholes in the legal framework that dilute the laws’ effectiveness and thus ability to protect the ecosystem. The estimated emissions from land use change under a conservative approach in mangroves of Mexico were approximately 24 Tg CO₂e in the last 20 years. Therefore, the incorporation of blue carbon into the carbon market as a viable source of supplemental finance for mangrove and seagrass protection is an attractive win-win opportunity.

We assessed metrics of the metazoan parasite infracommunities of the dusky flounder (Syacium papillosum) as indicators of aquatic environmental health of the Yucatan Shelf (YS) prior to oil extraction. We sampled the dusky flounder and its parasites along the YS, mostly during the 2015 north wind season (November–April). Our aims were: (i) to determine whether the parasite infracommunity metrics of S. papillosum exhibit significant differences among YS subregions; (ii) to determine whether the probability of the occurrence of its parasite species and individuals were affected by environmental variables, nutrients, heavy metals and hydrocarbons at the seascape level; and (iii) to determine whether there were statistical differences between the parasite infracommunity metrics of S. papillosum from YS and those of Syacium gunteri from the Campeche Sound. Multivariate statistical analyses and generalised additive models (GAMs) were used to examine the potential statistical associations between the contaminants, environmental variables and parasite community metrics, and the maximum entropy algorithm (MaxEnt) was used to characterise the habitat’s suitability for the parasite’s probability of occurrence. We recovered 48 metazoan parasite species from 127 S. papillosum, with larval cestodes and digeneans being the most numerically-dominant. Multivariate analyses showed significant differences in parasite infracommunity metrics among Western YS, Mid YS and Caribbean subregions, with the latter being the richest in species but not in individuals. The GAM and MaxEnt results indicated a negative effect of top predators (e.g. sharks and rays) removal on parasite metrics. The parasite infracommunities of S. papillosum were twice as rich in the number of species and individuals as those reported for S. gunteri from the Campeche Sound. The significant differences among subregions in parasite metrics were apparently due to the interruption of the Yucatan current during the north wind season. The fishing of top predators in combination with an influx of nutrients and hydrocarbons in low concentrations coincides with an increase in larval cestodes and digeneans in S. papillosum. The dusky flounder inhabits a region (YS) with a larger number of metazoan parasite species compared with those available for S. gunteri in the Campeche Sound, suggesting better environmental conditions for transmission in the YS.

The southern Gulf of Mexico (sGoM) is highly susceptible to receiving environmental impacts due to the recent increase in oil-related activities. In this study, we assessed the changes in the bacterioplankton community structure caused by a simulated oil spill at mesocosms scale. The 16S rRNA gene sequencing analysis indicated that the initial bacterial community was mainly represented by Gamma-proteobacteria, Alpha-proteobacteria, Flavobacteriia, and Cyanobacteria. The hydrocarbon degradation activity, measured as the number of culturable hydrocarbonoclastic bacteria (CHB) and by the copy number of the alkB gene, was relatively low at the beginning of the experiment. However, after four days, the hydrocarbonoclastic activity reached its maximum values and was accompanied by increases in the relative abundance of the well-known hydrocarbonoclastic Alteromonas. At the end of the experiment, the diversity was restored to similar values as those observed in the initial time, although the community structure and composition were clearly different, where Marivita, Pseudohongiella, and Oleibacter were detected to have differential abundances on days eight–14. These changes were related with total nitrogen (p value = 0.030 and r² = 0.22) and polycyclic aromatic hydrocarbons (p value = 0.048 and r² = 0.25), according to PERMANOVA. The results of this study contribute to the understanding of the potential response of the bacterioplankton from sGoM to crude oil spills.

Nature-based solutions (NbSs) have long recognized the value of coastal and marine ecosystem management and associated ecosystem services as useful tools for climate change mitigation (e.g., blue carbon) and adaptation (e.g., coastal protection against flooding and storm surges). However, NbSs remain poorly acknowledged and mostly absent from coastal planning for disaster risk reduction policies in the Caribbean, as well as from ex-post disaster reconstruction funds. With the increasing frequency and intensity of hurricanes in the region, NbSs are now more needed than ever. Taking Mexico as a representative case study for the wider Caribbean, we here seek to identify and analyze the barriers and opportunities perceived by relevant stakeholders for mainstreaming coastal-marine NbSs into coastal management and disaster risk reduction policies (e.g., mangroves as green infrastructure) to protect coastal societies and national economies against hurricanes. We conduct semi-structured, in-depth interviews with twenty stakeholders covering academic, governmental, tourism, NGO, coastal planning, and financial domains. Among the twenty-three identified barriers, governance, institutional, financial, and human-capacity aspects are the most dominant perceptions behind the current lack of NbS implementation. Future action for the policy integration of NbSs requires widespread political will and better quantification of both the provision of ecosystem services and their economic benefits under conventional markets.