In this study, 3 quantitative trophic models were constructed using Ecopath with Ecosim (EwE) to estimate and compare the degree of development and functional indicators in the northwestern region of the Gulf of Mexico along 3 vertical strata (continental shelf, upper slope, bathyal), from 200 to 3608 m. Input parameters were sampled from different trophic components of the food web (phytoplankton, zooplankton, infauna, invertebrates, and fish) during 4 oceanographic surveys carried out between 2016 and 2017. To construct the models, 40 functional groups were considered, ranging from bacteria to marine mammals. Fish were grouped primarily by taxonomic order, while the remaining groups represented other major trophic components of the food web. These included 21 actinoperygian orders, Rajiformes, and 17 other trophic groups. The average biomass, production/biomass ratio, consumption/biomass relationship, ecotrophic efficiency, and diet of each trophic group were estimated. The continental shelf was characterized by 31 trophic groups with a biomass of 171.75 t km -2 and a total system throughput of 6967.17 t km -2 yr -1 . Mammals were the top predators on the continental shelf (TL 5.4) and upper slope (TL 4.6), while scombriform fish predominated in the bathyal zone (TL 4.7). The model schematically represents mixed trophic impacts, showing predator-prey interactions and potential trophic cascades, defined by strong interactions between trophic groups not directly related to the continental shelf (Aulopiformes-Brachyura) and the bathyal zone (Gadiformes, Cephalopoda-Echinoidea). The resulting model showed a high pedigree index (0.42-0.65). Our results provide new insights into the trophic structure of vertical strata between 200 and 3608 m depth, and highlight differences in energy and biomass between trophic groups.

This study focusses on the assessment of the vulnerability of Lerma, Campeche, a small coastal fishing community in the southern Gulf of Mexico to climate change-related threats using local knowledge gathered in semi structured interviews and closed ended surveys. Results show hurricanes and extreme rainfall as the two main climate change threats causing differential damage to households, infrastructure losses, health impacts, household income, breakdown in communication networks and damage and road closures in the coastline, flooded wetlands, historic center or the elevated zones of Lerma. The vulnerability analysis revealed a very high vulnerability for hurricanes for the coastline, a high vulnerability in the rest of the zones and a low vulnerability for extreme rainfalls at all Lerma zones. The socioeconomic family condition seems to be a key attribute that may shape the ability to recover from the hazard impacts. The main results suggest that Lerma vulnerability to hurricanes and extreme rainfall is a multidimensional phenomenon mainly associated with exposure, sensibility and the direct impact of threats and the complex interaction of pre-existing socioeconomic and physical environmental conditions within the family and community organizations. Our findings highlight the importance of understanding the local context when developing adaptation strategies to reduce the vulnerability of coastal communities such as Lerma, Campeche and the need to design tailored, small-scale adaptation strategies to strengthen the resilience of coastal communities.

Coastal ecosystems with karstic geology have a unique characteristic where the dissolution of carbonate rocks can increase total alkalinity (TA) and dissolved inorganic carbon (DIC). This results in higher inorganic carbon budgets in coastal areas. One such ecosystem is the Terminos Lagoon, the most extensive tropical estuarine lagoon system in Mexico, located in the karstic aquifer of the Yucatan Peninsula and connected to the southern Gulf of Mexico (sGoM). We measured TA and DIC to evaluate the variability in Terminos Lagoon’s of the carbonate system. We also estimated pH, partial CO2 pressure (pCO2), and aragonite saturation (ΩAr) along two transects from the main lagoon tributaries (Palizada and Candelaria rivers) to the coastal zone during the dry and rainy seasons. During the dry season, TA and DIC concentrations were significantly higher (3092 ± 452 µmol kg-1 TA, 2943 ± 522 µmol kg-1 DIC) than during the rainy season (2533 ± 228 µmol kg−1 TA, 2492 ± 259 DIC µmol kg−1). Our calculations indicate that the rainy season pCO2 (2532 ± 2371 µatm) seems higher than in the dry season (1534 ± 1192 µatm). This leads to a reduction in pH (7.9 ± 0.3 to 7.8 ± 0.3). These significant changes indicate that rain increases the flow of unsaturated river water into the lagoon. The results of this work contribute toward a dissolved inorganic carbon variability baseline in the sGoM and can be helpful to Terminos Lagoon decision-makers.

Vertical migration in ichthyoplankton is relevant for its survive and it has been documented in estuaries with more than 10 m depth. In shallow estuaries this process is unknow or not supposed since no environmental stratification is assumed. The objective of this research is to investigate the vertical variability of fish larvae assemblages in shallow tropical estuarine zones. The model study site was the estuarine area of the San Pedro y San Pablo River located east of the Centla Wetland Biosphere Reserve in the Gulf of Mexico. The experimental design includes depth (bottom-surface), habitat type (coast-low complexity and mangrove-high complexity), circadian cycle (sunrise-midday- sunset-night), and season (dry-rainy). The ichthyoplankton were collected using a supporting net (150 cm in length, 50 cm mouth diameter, 400 mu m mesh size) device for simultaneous collection on the surface and bottom. Circular tows (2.7-4 km/h) were carried out for 5 min. A total of 40,968 fish larvae were collected, belonging to 13 orders, 26 families, and 38 species. The highest larval abundance expressed as mean density (693 +/- 916 ind/m3), richness (4.57 +/- 3.46), Shannon-Wiener diversity (1.05 +/- 48.48), and Pielou evenness (0.88 +/- 0.3) were recorded in the bottom. The variance component analysis indicated that the most important factors to explain the larval abundance was the depth (15.55%), the period of the day (11.20 %) and the interaction between all factors (10.51 %). Fish larvae species as Achirus lineatus, Trinectes maculatus, Etropus crossotus, and Symphurus civitatium occupied only the bottom. Despite the low depth, a vertical stratification was observed in the physicochemical parameters, especially in the salinity, being greater in the bottom than in the surface during the two seasons and habitat type and it was related with higher values of abundance, richness, and diversity of ichthyoplankton.(c) 2023 Elsevier B.V. All rights reserved.

We evaluated the diel variability of abundance and species diversity of the epibenthic community associated with seagrasses in Los Petenes Biosphere Reserve (LPBR) in the southwestern Gulf of Mexico. For this purpose, four collection campaigns were conducted (rainy season: October 2011 and June 2016, dry season: March 2012 and 2016) in a diel cycle with a periodicity of 3 h. Our results showed significant differences in diversity, richness, and abundance as a function of the diel cycle (p < 0.05), and in the community structure as a function of the diel cycle and the climatic sampling periods. Two different benthic assemblages, one for the day and the other for the night period were identified. Each assemblage varies on its species composition according to the climatic periods but maintains the general day-night pattern at all the sampled years. The abundance of diurnal species was significantly (p < 0.01) associated with the temperature, salinity, oxygen, and depth values. Our results suggest that the epibenthic community associated with seagrass habitats shows significant diurnal and nocturnal changes in community composition and abundance due to changes in light intensity that favors the appearance of characteristic species in each period. Understanding such community changes will allow us to establish the baseline parameters for assessing the environmental health of the benthic habitats of the LPBR with greater accuracy.

The dynamics and distribution of the carbonate system and the processes that regulate it over the Yucatan Shelf (YS), a region of karst geology and high productivity that is influenced by submarine groundwater discharges (SGDs) and upwelling, were explored with data from two oceanographic cruises. The first oceanographic cruise was conducted in November 2015 during the Nortes season, a period of intense northerly wind activity, and a second cruise was conducted during the rainy season in August/September 2016. Notable biogeochemical differences were present between them. At the surface, Caribbean Surface Water (CSW) predominated over the shelf in both periods. During the Nortes cruise, a surface nearshore-offshore gradient showed high dissolved inorganic carbon (DIC; similar to 2470 mu mol kg(-1)) and total alkalinity (TA; similar to 2460 mu mol kg(-1)) values near the coast and average pH(Total) and pCO(2) values of 7.42 +/- 0.10 and 2206 +/- 546 mu atm, respectively. These geochemical characteristics were attributed to the influence of SGDs, punctuated by relatively low delta C-13(DIC) values between -4.18 parts per thousand and -2.49 parts per thousand, which reflects an important oxidation of organic carbon and the dissolution of carbonate minerals. The presence of upwelled water on the eastern side of the YS showed average DIC and pH(Tota)(l) values of 2260 +/- 15 mu mol kg(-1) and 7.69 +/- 0.08, respectively, which were lower than coastal values. During the rainy cruise, the advection of CSW by the Yucatan Current was traced by its thermohaline properties. However, the surface water carbonate system was relatively homogeneous, with average DIC, TA, pH(Tota)(l) and pCO(2) values of 2047 +/- 16 mu mol kg(-1), 2388 +/- 11 mu mol kg(-1), 8.02 +/- 0.02, and 440 +/- 27 mu atm, respectively. Lastly, the delta C-13(DIC) values during this cruise ranged from -1.21 parts per thousand to 1.25 parts per thousand, which suggests that the carbonate system is mainly regulated by organic matter production and respiration.

International agreements have been used to focus global attention on areas of both marine and terrestrial conservation concern. Currently, The Convention for the Protection and Development of the Marine Environment in the Wider Caribbean Region, known as the Cartagena Convention (Cartagena), is the only multilateral environmental agreement in force tht governs the marine environment of the Gulf of Mexico Large Marine Ecosystem (GoM-LME). The GoM-LME provides diverse habitats to maintain the high diversity of species, including endemic and endangered species, and provides natural resources for the United States, Cuba, and Mexico. This paper investigates the legal frameworks, currently recognized in the GoM-LME, to build a proposed tri-national framework. We investigated the selected multilateral agreements which currently govern conservation practices in the GoM-LME, and provide the legal context for decision-making at the national level. In addition, gaps in areas such as pollution, oil spill response, and species conservation were identified, providing the basis for the development of us to propose key elements of a tri-national agreement for the governance and biological conservation in the GoM-LME. The creation of a tri-national agreement which focuses conservation efforts in the Gulf of Mexico between the three GOM-LME countries, would allow their specific, regional conservation concerns to be comprehensively addressed.

Shelf and deep-water soft-bottom macrofauna were explored in the western Gulf of Mexico in terms of species and functional trait assemblages. Their variation was analysed as functions of depth and time, and the relationship with sea-bottom environmental conditions was examined to disentangle their association with potential environmental drivers. Four consecutive cruises (two per year, at the end of the dry and rainy seasons) were performed during 2016-2017 at 27 fixed stations distributed from 42 to 3565 m depth. Changes in macrofauna composition were tested considering species and functional trait assemblages. Environmental variables associated with sediment features (i.e., grain structure, organic matter, pH, redox), oceanographic conditions (i.e., temperature, dissolved oxygen, particulate organic carbon flux) and potential contaminants (i.e., hydrocarbons and metals) were analysed to identify potential drivers that would shape the structure of macrofauna assemblages. The results suggest that the structures of both species and functional trait assemblages change according to depth and show temporal variation in composition at seasonal and interannual scales. The effect of temporal variation represented about 12% of total variation in the assemblages (11.4 for species and 12.5% for functional-traits). Different patterns of spatial and temporal variation between shelf and deep benthic communities were observed. Variation in species assemblages on the shelf were related to the variation in lead, polycyclic aromatic hydrocarbons and the fine sand ratio. In the deep benthos, particulate carbon flux showed high correlation with the spatial and temporal variation in species assemblage. In the deep benthos the changes in the species assemblage between the dry and the rainy seasons and the interannual variation were highly correlated with particulate organic carbon input in the area.

AbstractTwo new genera and six new species of benthic amphipods from the soft sediments of the Perdido Fold Belt region, western Gulf of Mexico, are described. Morphological comparisons of the new species with description of their congeners resulted in the determination of one new genus and one new species of the family Melitidae as Dentimelita lecroyae gen. nov., sp. nov., one new genus and four new species of the family Pardaliscidae as Pardaliscella perdido sp. nov., Paraeperopeus longirostris gen. nov., sp. nov., Pardaliscoides ecosur sp. nov. and Tosilus cigomensis sp. nov., and one new species of the family Unciolidae as Neohela winfieldi sp. nov. The occurrence of the newly described amphipods in the Perdido Fold Belt region represented new geographic range extensions for the genera, including new records of Neohela in the Gulf of Mexico, Pardaliscella and Pardaliscoides in the western Atlantic and Tosilus in the Atlantic.

Here we explored the potential association of the benthic macrofauna species composition with aliphatic hydrocarbons, polycyclic aromatic hydrocarbons and metals concentration detected in the sediments of the Yucatan continental Shelf (YCS), Mexico. The main objective was to provide insights on the temporal and spatial changes of such association in the function of the longitudinal and depth gradient. Benthic species composition, Al, Ni and Pb showed significant differences among YCS sub-regions (Western Caribbean, Mid-Yucatan and West Yucatan), and depth. Aliphatic and aromatic hydrocarbons had similar concentration in all sub-regions. The species composition was significantly associated with the levels of aliphatic hydrocarbons in the shallow sites (15–50 m) of the YCS sub-regions. Our results provide the first insights into the presence and spatial trends of different concentration of non-point source hydrocarbons and metals along the YCS, essential to establish the current ecological condition and to set a reference condition to identify further changes.

The biodiversity and biogeographic affinity of benthic amphipods from the Yucatan continental shelf with the warm Northwest Atlantic ecoregions were analysed using species occurrence data from benthic marine habitats of the continental shelf (< 200 m). A comprehensive collection of distributional data (presence-only) was obtained from different sources and newly-sampled material and sorted according to 12 ecoregions from the Northwest Atlantic. Distribution of species richness, taxonomic distinctness, endemism, and spatial replacement was analysed across ecoregions. The faunal relationships among ecoregions were explored using a clustering analysis based on the Sorensen dissimilarity index, and a cladistic analysis of distributions and endemism based on parsimony. Results from the Yucatan shelf showed a representative species pool from the highly diverse Northwest Atlantic amphipod fauna (202 spp.), with intermediate levels of endemism and taxonomic distinctness. Results from dissimilarity and parsimony showed two groups of amphipod assemblages consistent with two of the main biogeographic provinces in the Northwest Atlantic: Carolinian and Caribbean. The incorporation of the Yucatan shelf species assemblage, as an ecoregion into the used classification scheme, had implications on the amphipods biogeographic affinity identification. The Yucatan ecoregion led to a latitudinal spatial replacement of amphipod species across ecoregions and provinces, revealing that the Yucatan ecoregion has a higher biogeographic affinity with tropical ecoregions of the Caribbean province. The spatial replacement of amphipods suggests that the Southern Gulf of Mexico ecoregion has a higher affinity with warm-temperate ecoregions of the Carolinian province and is proposed as a transitional zone between the identified provinces.

Mollusk diversity in coastal areas of the Gulf of Mexico (GOM) has been studied extensively, but this is not the case for deep-water habitats. We present the first quantitative characterization of mollusks in shallow and deep waters of the Perdido Fold Belt. The data came from two research cruises completed in 2017. Sediment samples were collected from 56 sites using a 0.25-m2 box corer. We tested hypotheses about spatial patterns of α, β, and γ-diversity of bivalves in two water-depth zones, the continental shelf (43–200 m) and bathyal zone (375–3563 m). A total of 301 bivalves belonging to 39 species were identified. The two zones display similar levels of γ-diversity, but host different bivalve assemblages. In general, α-diversity was higher on the continental shelf, whereas β-diversity was higher in the bathyal zone. These patterns can be explained by the higher input of carbon (energy) to the near-coast shelf zone, as well as by the greater topographic complexity of habitats in the bathyal zone. These results enabled us to propose redirection of sampling efforts for environmental characterization from continental zones to the deep-water zone, especially in the context of environmental assessments during oil and gas exploration and production.

Oiling scenarios following spills vary in concentration and usually can affect large coastal areas. Consequently, this research evaluated different crude oil concentrations (10, 40, and 80 mg L−1) on the nearshore phytoplanktonic community in the southern Gulf of Mexico. This experiment was carried out for ten days using eight units of 2500 L each; factors monitored included shifts in phytoplankton composition, physicochemical parameters and the culturable bacterial abundance of heterotrophic and hydrocarbonoclastic groups. The temperature, salinity, and nutrient concentrations measured were within the ranges previously reported for Yucatan Peninsula waters. The total hydrocarbon concentration (TPH) in the control at T0 indicated the presence of hydrocarbons (PAHs 0.80 μg L−1, aliphatics 7.83 μg L−1 and UCM 184.09 μg L−1). At T0, the phytoplankton community showed a similar assemblage structure and composition in all treatments. At T10, the community composition remained heterogeneous in the control, in agreement with previous reports for the area. However, for oiled treatments, Bacillariophyceae dominated at T10. Hydrocarbonoclastic bacteria were associated with oiled treatments throughout the experiment, while heterotrophic bacteria were associated with control conditions. Our results agreed with previous works at the taxonomic level showing the presence of Bacillariophyceae and Dinophyceae in oil-related treatments, where these groups showed the major interactions in co-occurrence networks. In contrast, Chlorophyceae showed the key node in the co-occurrence network for the control. This study aims to contribute to knowledge on phytoplankton community shifts during a crude oil spill in subtropical oligotrophic regions.

Different hypotheses related to the regional-scale configuration of the Yucatan Continental Shelf (YCS) between the Gulf of Mexico (GoM) and the Caribbean Sea have been proposed. Hypotheses regarding its regional boundaries include: (i) an ecoregional boundary at Catoche Cape, dividing the Western Caribbean and the Southern GoM ecoregions; and (ii) a boundary within the Southern GoM ecoregion at 89°W, separating the West and Mid-Yucatan areas. We tested the hypothesis of no variation in benthic macrofaunal assemblages between regions delimited by the former boundaries using the species and functional traits of soft-bottom macrofauna. We considered that the depth and temporal environmental dynamics might interact with regional variations, generating complex benthic community patterns. The data were collected over five years (2010–2012, 2015–2016) at 86 stations (N = 1, 017 samples, 10–270 m depth), comprising 1,327 species with 45 combinations of functional traits. The variation in species composition and functional trait assemblages were both consistent with the occurrence of three separate regions in the Yucatan Peninsula (West Yucatan, Mid-Yucatan and Western Caribbean). This regional configuration was consistent with changes in assemblage structure and depth zonation as well as temporal variation. Along with spatial and temporal variation, diversity diminished with depth and different regions exhibited contrasting patterns in this regard. Our results suggest that the spatial and temporal variation of soft-bottom macrofauna at YCS demonstrate the complex organization of a carbonate shelf encompassing different regions, which may represent transitional regions between the Caribbean and the GoM.

A fundamental understanding of the impact of petrochemicals and other stressors on marine biodiversity is critical for effective management, restoration, recovery, and mitigation initiatives. As species-specific information on levels of petrochemical exposure and toxicological response are lacking for the majority of marine species, a trait-based assessment to rank species vulnerabilities to petrochemical activities in the Gulf of Mexico can provide a more comprehensive and effective means to prioritize species, habitats, and ecosystems for improved management, restoration and recovery. To initiate and standardize this process, we developed a trait-based framework, applicable to a wide range of vertebrate and invertebrate species, that can be used to rank relative population vulnerabilities of species to petrochemical activities in the Gulf of Mexico. Through expert consultation, 18 traits related to likelihood of exposure, individual sensitivity, and population resilience were identified and defined. The resulting multi-taxonomic petrochemical vulnerability framework can be adapted and applied to a wide variety of species groups and geographic regions. Additional recommendations and guidance on the application of the framework to rank species vulnerabilities under specific petrochemical exposure scenarios, management needs or data limitations are also discussed.

Amphipod species collected during three oceanographic campaigns (2010–2012) were analyzed to describe their spatiotemporal community distribution trends and their relationships with bottom water and sediment variables. The results show that the species richness (117 spp.) did not reach its maximum value according to the species accumulation curve (up to 187 spp.). Multivariate analyses and constrained ordinations techniques detected three main amphipod assemblages along the longitudinal gradient (i.e., Western Caribbean, Mid-Yucatan, and West-Yucatan) and during two temporal hydrographic scenarios (i.e., upwelling in 2010–2011 and non-upwelling in 2012). In 2010–2011, low values in species richness and abundance from the Western Caribbean and eastern Mid-Yucatan assemblages were associated with relatively low bottom-water temperatures from the upwelling systems. In 2012, the absence of upwelling and the occurrence of a warm-core anticyclonic eddy seemed to cause an increase in species richness and abundance in the three assemblages. The hydrographic variability and sediment characteristics are suggested as the major environmental drivers that shapes the soft-bottom amphipod community structure and diversity in the Yucatan continental shelf.

This study investigates the community composition, structure, and abundance of sulfate-reducing microorganisms (SRM) in surficial sediments of the Northwestern Gulf of Mexico (NWGoM) along a bathymetric gradient. For these purposes, Illumina sequencing and quantitative PCR (qPCR) of the dissimilatory sulfite reductase gene beta subunit (dsrB gene) were performed. Bioinformatic analyses indicated that SRM community was predominantly composed by members of Proteobacteria and Firmicutes across all the samples. However, Actinobacteria, Thermodesulfobacteria, and Chlorobi were also detected. Phylogenetic analysis indicated that unassigned dsrB sequences were related to Deltaproteobacteria and Nitrospirota superclusters, Euryarchaeota, and to environmental clusters. PCoA ordination revealed that samples clustered in three different groups. PERMANOVA indicated that water depth, temperature, redox, and nickel and cadmium content were the main environmental drivers for the SRM communities in the studied sites. Alpha diversity and abundance of SRM were lower for deeper sites, suggesting decreasing sulfate reduction activity with respect to water depth. This study contributes with the understanding of distribution and composition of dsrAB-containing microorganisms involved in sulfur transformations that may contribute to the resilience and stability of the benthic microbial communities facing metal and hydrocarbon pollution in the NWGoM, a region of recent development for oil and gas drilling.

Here, we show a spatially explicit assessment of the vulnerability of benthic communities from the Yucatan Continental Shelf (YCS) to multiple pressures: fishing activities, shipping traffic, storms and hurricanes, and marine acidification. The vulnerability index was obtained by combining benthic biological traits with exposure and sensitivity and recovery capacity; this was then represented in a spatially explicit model. Moreover, we estimated a cumulative vulnerability index using three different scenarios that were based on 1) equal weight for each vulnerability layer to each stressor, 2) results of expert consultation and 3) a linear reduction in the weight of the pressures. By comparing scenarios, the synergistic and antagonistic effects of the multiple stressors were determined. The main results showed that, independent of the considered scenario, approximately 90% of the YCS presented moderate to high vulnerability to cumulative pressures, while areas with high recovery and high potential impact on a particular stressor showed low or moderate vulnerability to the pressures. Meanwhile, areas classified as having medium impact levels and low recovery capacities of benthic fauna showed moderate to high vulnerability to the same threats. Our findings also showed that ship traffic and marine acidification were the threats that contributed to the greatest vulnerability. The paired comparison of scenarios allows for the identification of areas with higher probabilities of synergistic effects. No antagonistic effects were detected. Overall, our results constitute the first effort to understand the ecological status of the benthic communities of the YCS and their potential vulnerability to the multiple pressures they face.

The diversity and distribution of benthic amphipods has been explored in the Alacranes Reef, which is the largest coral reef ecosystem in the Gulf of Mexico. New insights into species richness, spatial distribution and extension of geographical ranges are presented by using data from published records and field surveys. A total of 117 species have been recorded, 9 of which are potentially new to science, 39 of which have new geographical records, and 7 are non-indigenous and previously reported in the literature as potentially invasive. Based on the use of a species-richness indicator (Chao 2), the expected species number is 40% higher, up to 200 spp., when compared to the observed species richness. The spatial distribution of amphipods varied significantly as a function of habitat type, showing the highest richness values on coral patches and the major abundances on man-made structures, such as navigation buoys and fishing traps. Multivariate analyses suggested the distinction between three taxonomically diverse species assemblages that showed similar ecological affinities, i.e. those on: (1) soft-bottom environments, grouping bare substrata and seagrass beds habitats; (2) hard-bottom environments, grouping coral patch and reef wall habitats; and (3) artificial substrata. The results highlight the importance of this reef ecosystem for a high amphipod diversity, but it is susceptible to future modifications in the presence of non-indigenous species, potentially invasive, on artificial substrata.