Tropical Cyclone Landfall Frequency and Large-Scale Environmental Impacts along Karstic Coastal Regions (Yucatan Peninsula, Mexico)

Drivers of mangrove vulnerability and resilience to tropical cyclones in the North Atlantic Basin

The North Atlantic Basin (NAB) has seen an increase in the frequency and intensity of tropical cyclones since the 1980s, with record-breaking seasons in 2017 and 2020. However, little is known about how coastal ecosystems, particularly mangroves in the Gulf of Mexico and the Caribbean, respond to these new "climate normals" at regional and subregional scales. Wind speed, rainfall, pre-cyclone forest height, and hydro-geomorphology are known to influence mangrove damage and recovery following cyclones in the NAB. However, previous studies have focused on local-scale responses and individual cyclonic events. Here, we analyze 25 years (1996-2020) of mangrove vulnerability (damage after a cyclone) and 24 years (1996-2019) of short-term resilience (recovery after damage) for the NAB and subregions, using multi-annual, remote sensing-derived databases. We used machine learning to characterize the influence of 22 potential variables on mangrove responses, including human development and long-term climate trends. Our results document variability in the rates and drivers of mangrove vulnerability and resilience, highlighting hotspots of cyclone impacts, mangrove damage, and loss of resilience. Cyclone characteristics mainly drove vulnerability at the regional level. In contrast, resilience was driven by site-specific conditions, including long-term climate trends, pre-cyclone forest structure, soil organic carbon stock, and coastal development (i.e., proximity to human infrastructure). Coastal development is associated with both vulnerability and resilience at the subregional level. Further, we highlight that loss of resilience occurs mostly in areas experiencing long-term drought across the NAB. The impacts of increasing cyclone activity on mangroves and their coastal protection service must be framed in the context of compound climate change effects and continued coastal development. Our work offers descriptive and spatial information to support the restoration and adaptive management of NAB mangroves, which need adequate health, structure, and density to protect coasts and serve as Nature-based Solutions against climate change and extreme weather events.

Microplastics in sediments from the southern Gulf of Mexico: Abundance, distribution, composition, and adhered pollutants

Approximately 23 Mt of plastics reaches the ocean each year, fragmented into microplastics (MP). MPs are widely dispersed in the sea, becoming deposited in sediments. MPs are considered carriers of pollutants such as heavy metals and polycyclic aromatic hydrocarbons and, when ingested by biota, pose a high health risk. This study determined metals and PAHs in sedimentary microplastics from the southern Gulf of Mexico (GOM). One hundred twenty-four sediment samples were collected, covering an area of 26,220 km². The mean (±SD) of MPs in sediments was 16.46 ± 17.76 MPs/kg. The most abundant polymers were cellophane (CE), polyvinylidene fluoride (PVDF), polyethylene (PE), polyamides (PA), and nylon (NYL). A strong correlation (r: 0.83) was found between MP density and sediment depth. PA and PE were found near shorelines and PVDF near oil platforms. Aluminum, arsenic, and tin had the highest concentration (89.6 ± 94.6, 23.1 ± 70.3, and 19 ± 29.2 μg g^-1, respectively), and acenaphthylene was the PAH with the highest concentration (3.4 ± 12.6 μg g^-1). This study shows that MP with a higher density is found at greater depths, and this research is one of the first to cover a large area of the Gulf of Mexico.

Development and Structural Organization of Mexico’s Mangrove Monitoring System (SMMM) as a Foundation for Conservation and Restoration Initiatives: A Hierarchical Approach

Mangroves provide ecosystem services worth billions of dollars worldwide. Although countries with extensive mangrove areas implemented management and conservation programs since the 1980s, the global area is still decreasing. To recuperate this lost area, both restoration and rehabilitation (R/R) projects have been implemented but with limited success, especially at spatial scales needed to restore functional properties. Monitoring mangroves at different spatial scales in the long term (decades) is critical to detect potential threats and select cost-effective management criteria and performance measures to improve R/R program success. Here, we analyze the origin, development, implementation, and outcomes of a country-level mangrove monitoring system in the Neotropics covering >9000 km2 over 15 years. The Mexico’s Mangrove Monitoring System (SMMM) considers a spatiotemporal hierarchical approach as a conceptual framework where remote sensing is a key component. We analyze the role of the SMMM’s remote sensing products as a “hub” of multi- and interdisciplinary ecological and social-ecological studies to develop national priorities and inform local and regional mangrove management decisions. We propose that the SMMM products, outcomes, and lessons learned can be used as a blueprint in other developing countries where cost-effective R/R projects are planned as part of mangrove protection, conservation, and management programs.

Tropical cyclones cumulatively control regional carbon fluxes in Everglades mangrove wetlands (Florida, USA)

Mangroves are the most blue-carbon rich coastal wetlands contributing to the reduction of atmospheric CO2 through photosynthesis (sequestration) and high soil organic carbon (C) storage. Globally, mangroves are increasingly impacted by human and natural disturbances under climate warming, including pervasive pulsing tropical cyclones. However, there is limited information assessing cyclone's functional role in regulating wetlands carbon cycling from annual to decadal scales. Here we show how cyclones with a wide range of integrated kinetic energy (IKE) impact C fluxes in the Everglades, a neotropical region with high cyclone landing frequency. Using long-term mangrove Net Primary Productivity (Litterfall, NPPL) data (2001-2018), we estimated cyclone-induced litterfall particulate organic C (litter-POC) export from mangroves to estuarine waters. Our analysis revealed that this lateral litter-POC flux (71-205 g C m-2 year-1)-currently unaccounted in global C budgets-is similar to C burial rates (69-157 g C m-2 year-1) and dissolved inorganic carbon (DIC, 61-229 g C m-2 year-1) export. We proposed a statistical model (PULITER) between IKE-based pulse index and NPPL to determine cyclone's impact on mangrove role as C sink or source. Including the cyclone's functional role in regulating mangrove C fluxes is critical to developing local and regional climate change mitigation plans.