Search Results (6)

This study evaluated the ingestion of microplastics (MP) by copepods in Terminos Lagoon (TL), a RAMSAR-listed site in the southern Gulf of Mexico. The evaluation was carried out in two contrasting seasons of 2022, as follows: the dry (April) and the rainy (October). Copepods were collected using a conical plankton net (mesh size of 200 μm). In the laboratory, a pool of all pelagic adult copepod taxa was picked, and the MP inside the organisms were extracted, classified, and photographed using traditional optical and scanning electron microscopy. A total of 268 MP particles were extracted from the interior of copepods; among them, 149 and 119 corresponded to the dry and rainy seasons, respectively. The ingestion rate in the dry season was 0.14, while in the rainy season, it was 0.11. In addition, fibers, plastic fragments, and microspheres with different colors (blue, red, black, green, transparent, and multicolored), sizes, forms (angular, round, triangular, and twisted), and textures were also detected. Fibers were the most abundant MP found in a proportion of more than 85%. In addition, in some sampling sites, microspheres were observed with high relative abundance values (80%). In some sites, fragments reach 20% of the total abundance. Significant differences were observed between the two seasons. The sites closest to the urban area adjacent to TL observed high diversity and abundance of MP. The higher abundance of MP in the dry season is due to lower river discharge, on the other hand. Thus, MP particles accumulate and become available for consumption by copepods. This is the first study that has revealed that the MP was ingested by the copepods in TL. Furthermore, this study provides a baseline information for future research on the abundance of MP in the Gulf of Mexico region. Full article

The implementation of renewable energies represents a crucial step in meeting the sustainable development goal of the United Nations for affordable and clean energy. The Terminos Lagoon region in Campeche, the largest coastal lagoon in Mexico, offers potential for renewable energy sources such as wind, photovoltaic, and current energy. This study presents a renewable energy potential assessment for the main city at Terminos Lagoon, Ciudad del Carmen, which has the largest oil activity in Mexico and high electricity consumption. The outputs of high-resolution numerical models were analyzed to evaluate wind and photovoltaic resources and currents. A hybrid system consisting of 24 wind turbines, 5516 photovoltaic panels, and 32 hydrokinetic turbines could generate 521.33 GWh, which is 39.63% of the state’s energy demand and exceeds the energy consumption of Ciudad del Carmen by 10.24%. Wind and photovoltaic energy are the most significant contributors (517.15 GWh and 3.77 GWh, respectively), while hydrokinetic energy contribution is marginal (0.407 GWh) and requires further research and development. The results suggest that the region has the potential for clean and renewable energy technologies to reduce greenhouse gas emissions and contribute to the energy transition. Full article

Sediment cores maintain a historical record of the various sources of polycyclic aromatic hydrocarbons (PAHs). In 2020, one sediment core was collected within the oyster farming area of the Pom–Atasta lagoon system and the Terminos lagoon. A total of 16 PAH compounds were analyzed to identify the historical patterns of PAH inputs and the relationship with sediment materials. The core was classified into three strata at depths of 0.0–0.2 m, 0.2–0.6 m, and 0.6–1.1 m, in which the high content of silt–sand, organic matter, and carbonates indicates a system of high energy and productivity. The hydrology and characteristics of the sediment suggest a free access of adsorbed PAHs to the study area, mainly of pyrolytic origin. The concentration of ∑PAHs decreases from the surface (527.0 ng g⁻¹ dw) to a greater depth (75.7 ng g⁻¹ dw), which corresponds to 60% of the HMW (high molecular weight) of the total PAHs as combustion products at low temperatures, while LWM-PAH (low molecular weight) inputs are from discharges of petroleum products. The core sediments showed a low probability of toxicity quotient of 9%. The analysis of the carcinogenic toxic equivalent (TEQ^carc) in each section of the core was variable, decreasing with the depth from 107.91 ng TEQ g⁻¹ dw to 57.65 ng TEQ g⁻¹ dw, with the compounds benzo(a)pyrene (53.55 ng TEQ g⁻¹ dw) and dibenzo(a,h) anthracene (29.2 ng TEQ^carc g⁻¹ dw) having the highest TEQ^carc. The anthropogenic activities around the study area may increase the carcinogenic and mutagenic risk to human health. However, in the present study, the low toxic carcinogenic equivalents (TEQ_BaP) and mutagenic equivalents (MEQ_BaP) indicate a low probability of sediment toxicity. The ecosystem could be under constant threat from increasing anthropogenic activity; therefore, monitoring programs for the conservation of these ecosystems and oyster farms should be considered. Full article

The hydroperiod determines the biogeochemical conditions and processes developing in the mangrove soil. Floods control the input of nutrients and the presence of regulators such as salinity and sulfides that, in high concentrations, degrade mangrove vegetation. This work aimed to determine biogeochemical and hydroperiod characteristics in natural and degraded mangrove conditions. Three sampling sites were placed along a spatial gradient, including fringe and basin mangroves with different conditions. Tree characteristics and biogeochemical variables (temperature, salinity, pH, redox potential, sulfides) were measured. The structural analysis indicated two conditions: undisturbed (Rhizophora mangle fringe and Avicennia germinans basin under natural conditions) and disturbed (degraded basin, with standing A. germinans tree trunks). The soil porewater salinity, concentration of sulfides, and temperature were significantly higher, and redox potential lower in the disturbed site. The fringe mangrove was permanently waterlogged with higher tides than the basin mangrove. There were more extended flooding periods on the degraded mangrove due to the loss of hydrological connection with the adjacent water body. Waterlogging in basin mangroves increased soil porewater salinity to 87.8 and sulfides to 153 mg L⁻¹, causing stress and death in A. germinans mangroves. Our results show that the loss of hydraulic connectivity causes the chronic accumulation of salinity and sulfides, with consequences on tree metabolism, ultimately causing its death. It probably also involves the succession in microbial communities. Full article

The fluvial–lagoon–deltaic system of the Palizada River in Campeche is an ecosystem of socioeconomic and ecological importance. It is justifiable to carry out studies in this system due to its connection with another larger ecosystem called the Términos Lagoon. The objective of this investigation was to analyze the concentration of Pb and Cd in sediments of the fluvial–lagoon–deltaic system of the Palizada River and to determine, with this, the contamination index of these metals. Cd showed the highest concentration in sampling sites and climatic seasons with respect to Pb, with a maximum value of 53.9 ± 5.0, while the Pb concentration was 10.4 ± 0.2 μg∙g⁻¹. The same tendency was present with pollution and geoaccumulation indexes; here, the Cd index stands out. The enrichment of heavy metals was identified through the accumulation of Cd and Pb; such a process was evaluated through the geoacumulation index (Igeo). The results of this indicated that the contamination of these elements is mainly of anthropogenic origin. This element represents an ecological toxic risk due to the chronic presence of heavy metals in a priority area for the conservation of aquatic and terrestrial biota such as the Palizada system, owing to its high toxicity even at low concentrations. Thus, it is important to evaluate its sublethal effects in the organisms that inhabit this system, which requires the implementation of integral monitoring. Full article

Deltas and estuaries built by the Mississippi/Atchafalaya River (MAR) in the United States and the Usumacinta/Grijalva River (UGR) in Mexico account for 80 percent of all Gulf of Mexico (GoM) coastal wetlands outside of Cuba. They rank first and second in freshwater discharge to the GoM and owe their natural resilience to a modular geomorphology that spreads risk across the coast-scape while providing ecosystem connectivity through shelf plumes that connect estuaries. Both river systems generate large plumes that strongly influence fisheries production over large areas of the northern and southern GoM continental shelves. Recent watershed process simulations (DLEM, MAPSS) driven by CMIP3 General Circulation Model (GCM) output indicate that the two systems face diverging futures, with the mean annual discharge of the MAR predicted to increase 11 to 63 percent, and that of the UGR to decline as much as 80 percent in the 21st century. MAR delta subsidence rates are the highest in North America, making it particularly susceptible to channel training interventions that have curtailed a natural propensity to shift course and deliver sediment to new areas, or to refurbish zones of high wetland loss. Undoing these restrictions in a controlled way has become the focus of a multi-billion-dollar effort to restore the MAR delta internally, while releasing fine-grained sediments trapped behind dams in the Great Plains has become an external goal. The UGR is, from an internal vulnerability standpoint, most threatened by land use changes that interfere with a deltaic architecture that is naturally resilient to sea level rise. This recognition has led to successful efforts in Mexico to protect still intact coastal systems against further anthropogenic impacts, as evidenced by establishment of the Centla Wetland Biosphere Preserve and the Terminos Lagoon Protected Area. The greatest threat to the UGR system, however, is an external one that will be imposed by the severe drying predicted for the entire Mesoamerican “climate change hot-spot”, a change that will necessitate much greater international involvement to protect threatened communities and lifeways as well as rare habitats and species. Full article