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Polycyclic aromatic hydrocarbons (PAHs) are organic chemicals that consist of carcinogenic and mutagenic properties, which are considered as high-priority persistent organic pollutants (POPs). Their source is due to an incomplete burning of fossil fuels and organic materials. In the present study, the distribution and concentrations of 16 priority PAHs in sediments of the Tampamachoco lagoon and Tuxpan River estuary at the Gulf of Mexico were analyzed. The surface sediment samples were collected during the dry (March–June) and rainy (August–November) seasons. PAHs were analyzed by means of a gas capillary chromatography-FID. In dry season, the average concentration of PAHs in sediments was 860 ± 390 ng/g, and in rainy season, it was 1140 ± 450 ng/g. During both seasons, the total concentration of chrysene was high and a domain of the compounds with 4 benzene rings was observed. The source of PAHs was investigated in 78.6% of the lagoon sites. 45.5% revealed indicators of a mixed origin between pyrolytic and petrogenic sources, and 36.4% was petrogenic, and the remaining 18.2% was pyrolytic PAHs. [ABSTRACT FROM AUTHOR]

Historically, the Antillean manatee (Trichechus manatus manatus) was distributed along the coastline comprised by the five Mexican states that border the Gulf of Mexico. However, the few healthy populations that currently exist in Mexico are now limited to relatively isolated regions with very specific habitat characteristics. In the state of Veracruz, a limited number of individuals are found in the Alvarado Lagoon System (ALS), located in the coastal zone of southern central Veracruz. The aim of this study was to characterize manatee habitat in the ALS. Transects were established in the ALS and 503 points selected and sampled along these transects, producing data pertaining to salinity, depth, dissolved oxygen, total dissolved solids, surface water temperature, pH, bottom type, and conductivity. A total of 45 outings were conducted, with a total sampling effort of 332.36 h. The average physicochemical parameters found were as follows: salinity 3.33 ppm, total dissolved solids 0.51 g/l, temperature 26.29 °C, dissolved oxygen 0.51%, pH 7.55, and oxidation–reduction potential 417.04 mV. Thirteen manatees were observed, mostly (84.6%) during the cold, where the parameters of electrical conductivity, salinity, total dissolved solids, dissolved oxygen, temperature, and oxidation–reduction potential showed differences between the sampled seasons, and in the lagoons with a presence of the floating and submersible vegetation species that form part of manatees' diet. This study shows that the ALS presents lagoons that favor the presence of the Antillean manatee, further narrowing the distribution of the species within the same ALS in the southern central zone of the state of Veracruz. [ABSTRACT FROM AUTHOR]

Petroleum industry in the southern Gulf of Mexico possesses relevant importance for the Mexican economy but it has also impacted the marine and coastal environments of this region. The objective of the current review is to provide a substantial panorama of the polycyclic aromatic hydrocarbons (PAHs) during the XXI century. The highest PAHs concentration in water was found in the Dos Bocas Maritime Terminal and the Mecoacán Lagoon; sediments and cores were found in Sontecomapan, Mandinga, and La Mancha Lagoons; maximum PAHs levels in biota were found in fish in Términos Lagoon. PAHs in water and oysters were comparable to others around the world; sediments concentrations were higher than in other regions. Mecoacán Lagoon, coastal shelf Tamaulipas, and Cayo Arcas Reef Complex showed a higher risk estimation based on sediment concentrations. It is necessary to establish monitoring programs in the study region due to the trends found in PAHs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The Laguna Madre Tamaulipas (LMT) is the largest hyperhaline coastal lagoon of Mexico, is diverse and provides a wide range of services, besides its economic importance for local and national fisheries. However, due to global and local pressures, the fish community is under stress. Here we study the LMT fish community to determine its biogeographical affinities with the Gulf of Mexico and Caribbean, understand its trophic relationships and habitat distribution, and to analyze the fisheries pressures in specific habitats and trophic groups (TGs). Our biogeographical analyses based on Parsimony Analysis of Endemism produce three provinces Center, South, and Northern, being this last the most related to the LMT, thus activities in this and the LMT directly affect each other. Through a nested cluster analysis using trophic values and size, 15 TGs were found, being the small‐species the most diverse and the largest the less diverse and most targeted by fishermen, which put on risk its ecological role and may provoke cascading effects on many species and processes. As well, mangroves and oyster banks habitats are supporting most of the fisheries. This is the first study of the whole fish community of the LMT, we pinpoint provinces, habitats, and TGs that need special attention and constant monitoring to generate integrative management plans that fit the actual needs of the community and prepare it to buffer future changes. [ABSTRACT FROM AUTHOR]

Coastal lagoons are ubiquitous along coastlines worldwide. Here, we compare the abundance of epifauna, seagrass-associated macroinvertebrates, and small fish across a gradient of seagrass cover in shallow coastal lagoons of the northern Gulf of Mexico. Two of the lagoons had little or no seagrass cover (0-18.8 %), and four had high cover (83.8-97.5 %). All of the lagoons were partially covered with fringing marsh. We hypothesized that, due to habitat redundancy between seagrass beds and fringing marshes, seagrass-associated fish and macroinvertebrates would not be largely reduced despite the large differences in seagrass cover among the lagoons. Our results support this hypothesis. For most sampling dates, we did not find significant differences in fish and macroinvertebrate abundance among the lagoons and, when we did, several highly vegetated lagoons did not have larger abundances than sparsely vegetated lagoons. The extreme shallowness of the lagoons studied (<1 m) may also provide further protection from large predatory fishes in the absence of seagrasses. Our results also suggest that marsh detritus, by providing habitat for epifauna and helping maintain prey availability, may further temper reductions in seagrass-associated fishes and macroinvertebrates following seagrass decline. The results highlight the importance of marsh-bordered, shallow lagoons as habitat for small fish and macroinvertebrates regardless of seagrass cover. This study contributes to the characterization of habitat redundancy in coastal ecosystems and pinpoints the importance of considering all habitats in concert for the proper understanding and management of coastal ecosystems. [ABSTRACT FROM AUTHOR]

Medina-Gómez, I.; Villalobos-Zapata, G.J., and Herrera-Silveira, J.A., 2015. Spatial and temporal hydrological variations in the inner estuaries of a large coastal lagoon of the southern Gulf of Mexico. Coastal lagoons receive significant inputs from river basins, leading to inner estuaries or fluvial lagoon subsystems subject to the bidirectional flow of energy, organic matter, nutrients, and sometimes toxic materials between river mouths and lagoons. Such exchanges are highly dynamic and enhance lagoon productivity. Terminos Lagoon (TL) is a large coastal lagoon in the southern Gulf of Mexico that has two deep permanent inlets connecting the lagoon to the Gulf and strong riverine input. We evaluated the influence of river discharge on seasonal and spatial patterns of water quality in six fluvial lagoon subsystems in TL. Six bimonthly samplings were carried out from February to December 2001. Temperature, salinity, dissolved oxygen, dissolved inorganic nutrients (nitrate, nitrite, ammonium, soluble reactive phosphorus, and soluble reactive silica), and chlorophyll a were measured. There were large differences between the western and eastern river mouths due to differences in river discharge and the nature of their watersheds ( e.g., land use, size). Furthermore, the influence that the dominant depositional environment and local habitats ( i.e. submerged aquatic vegetation) developing adjacent to these estuarine lagoon subsystems may exert over the nutrient concentrations of the water column is discussed. These differences were more evident during the rainy season when river discharge was highest. It is suggested that the input of N rather than P could have the greatest impact on TL in the future. [ABSTRACT FROM AUTHOR]

Understanding the effects of regional processes on local community structure is a central issue of metacommunity studies. Here we examined the relative contribution of both regional and local processes to fish larvae community structure of seven brackish lagoons located along the Mexican Atlantic coast. The database analysed includes over 982 sampling stations. Partial Mantel tests were used to determine whether among lagoon differences in species composition were related to local, and/or regional-scale factors while controlling the effects of both geographical distances and lagoon environmental characteristics. Results indicate that regional processes had significant (P < 0.05) influence on the composition of the ichthyoplankton communities, with environmental characteristics either included (r2 = 19.5%) or removed (r2 = 23.7%), whereas local environmental characteristics were non-significantly associated (P = 0.917). Alongshore currents associated with larval duration appeared to be an important factor affecting connectivity among estuaries, whereas offshore currents seemed to represent an ecological boundary between the southern Gulf of Mexico and the Yucatán coasts. Also, regional terrestrial changes in freshwater sources between these regions appeared to be determinant for the presence of certain species. Metacommunity structure of the lagoons agrees with the “mass effects” model, in which patches are heterogeneous and regional phenomena represent the crucial spatial scales in community dynamics. There is an increasing need to model larval behaviour in relation to the physical scenario to evaluate the role of alongshore currents and oceanographic boundaries as they affect the extent of larval dispersal. [ABSTRACT FROM AUTHOR]

Summary: Salinity in estuaries is highly variable due to river discharge, tidal motion, and winds. Information on the spatial and temporal changes in salinity can provide important ecological indications, but accurate monitoring of the space–time variability for a large estuary is often costly and time-consuming. This study applied remote sensing techniques to develop a salinity prediction model for Lake Pontchartrain, a large estuarine lake located in the Northern Gulf of Mexico, USA. “Ground truth” salinity was measured along two transects across the lake and near the shoreline. Water-leaving reflectance from the measurement locations was extracted from Landsat Thematic Mapper (TM) images pre-processed through “banding” noise reduction and radiometrical correction approaches. Ordinary least square and ridge regression methods were performed to identify model parameters and to determine relationships between salinity and reflectance. Salinity in the lake on eight dates was predicted with the developed model. Difference in salinity level and patterns, and impacts of Hurricanes Katrina and Rita on salinity were assessed with ANOVA and Fuzzy Similarity methods. The results showed that the model achieved a high power in prediction of the lake salinity (R 2 =0.89 and RMSE of validation=0.27). Reflectance from TM bands 1, 2, and 4 was positively correlated to salinity levels and explained 1.9%, 20.3%, and 10.2% variance in salinity levels. Reflectance from bands 3 and 5 was negatively correlated to salinity and explained 34.1% and 31.2% variance. Under normal circumstances without the impacts of hurricanes, the lake salinity presented two patterns with average salinity level of 5.5ppt. After Katrina’s landfall, the average was significantly increased by 1.1ppt and the spatial patterns were altered. The pattern on 30 August 2005 was the most dissimilar one as compared to the two normal patterns, and then followed by the patterns on 9 and 25 October, and 7 September 2005. This study demonstrated that satellite remote sensing techniques can be applied to monitor salinity in coastal environments, and that freshwater discharge not only affects salinity levels and patterns under normal conditions but also is crucial for the return of salinity patterns to normal conditions after hurricane disturbance. [Copyright &y& Elsevier]