Campeche Sound Research Articles

Understanding the motivations of young people from marginalized rural communities to participate in small-scale fisheries in oil territories of the Gulf of Mexico

Small-scale fisheries (SSF) mainly operate in rural communities and face the challenge of a lack of generational renewal worldwide. Maslow's theory of human motivation was used to analyze the participation in SSF of 39 young men and women from households that depend on this activity in two highly marginalized rural locations in the Campeche Sound with high rates of youth migration. In this marine area, SSF and hydrocarbon extraction activities coexist. Using Fisher's exact test to detect statistical differences between motivations, we found that the most influential variables that inform the decisions of young people to engage in SSF are education, fishing skill level, self-identification as a fisher, income from fishing, and the opinions of a young person on fishing. Like their parents, young people participated in the entire fisheries supply chain, although they were less involved in sales, distribution, and management activities. Of the five needs identified by Maslow's theory, we found that fishing was most able to satisfactorily meet the needs of esteem and love and belonging in young people. In contrast, physiological needs were the least met by fishing. Moreover, the degree to which these needs were met depended on the income a young person received from fishing, reinforcing the idea that fishing in SSF is a subsistence activity. This was particularly notable with women due to the low pay or lack of remuneration they received for their work. Almost all interviewees would be willing to leave SSF for better jobs or to start businesses. Our results provide a better understanding of rural and coastal young people in SSF and may be used to develop inclusive fisheries management practices and incentives.

EVALUATION OF POTENTIALLY TOXIC METAL CONCENTRATIONS IN THE TERMINOS LAGOON, CAMPECHE, GULF OF MEXICO

The Terminos Lagoon is a region of great environmental and economic importance, due to its biodiversity, abundance of natural resources and proximity to the Campeche Sound. These characteristics encourage the development of numerous human activities in its surroundings, including oil, agricultural, industrial, urban and sanitary activities. We evaluated the concentration of Cr, Ni, Pb and V in surface sediment samples from Laguna de Terminos, Campeche, Mexico. The results obtained show that the concentrations of Cr and Pb remained below the ecological criteria of the minimum and maximum adverse ERL and ERM conditions for the biota, as well as within the ranges reported for other coastal lagoons in the Gulf of Mexico, with the exception of Pb, which decreased by almost 100%. Ni recorded values above the ERL and ERM, which have shown fluctuations in concentrations depending on the rainy and dry seasons. V maintained its concentrations below 27.73 mg/kg. High correlations were found between metals Cr – V, Cr – Ni and Ni – V, suggesting that these elements share the same source of origin. The statistics show that there are significant differences between the sampling sites PLZ and C, and PLZ and CDL. The reduction may be due to a decrease in urban, tourist, fishing and agricultural activities.

Environmental variables influencing the abundance of frog crabs (Brachyura: Raninoidea) of the southwest Gulf of Mexico

Due to anthropogenic pressures, the global loss of biodiversity has increased the interest in understanding the relationship between species and their environment. However, there is still a gap in knowing this relationship for most species, more evident in small non-commercial species. The present study is the first specific effort to document the environmental variables influencing the abundance of rare frog crab species (Superfamily Raninoidea) in the continental shelf of the southwest Gulf of Mexico. The relative abundance of frog crabs, depth, bottom water (water salinity, water temperature, and dissolved oxygen), and sediment (calcium carbonate, organic matter, total organic carbon, and texture) were determined in 143 sampling sites during four research cruises conducted from 2012 to 2015. Five hundred and fourteen frog crabs were collected (90% in the Campeche Sound), belonging to Lysirude nitidus (A. Milne-edwards, 1880), Raninoides laevis (Latreille, 1825), R. lamarcki A. Milne-edwards and bouvier, 1923, and R. louisianensis Rathbun, 1933. R. louisianensis was the most abundant (441 individuals) and frequent species (collected in 37 sites). A Multivariate Generalized Linear Model (GLM) – using a negative binomial regression model - was performed to assess which environmental variables best explain the abundance of frog crab species. The GLM results showed that depth, salinity, temperature, and sand content in sediment were the most explanatory variables influencing the abundance of the frog crab species. R. louisianensis was significantly related with salinity and depth-salinity-sand interactions, R. lamarcki with depth-temperature and depth-salinity interactions, L. nitidus with depth, and R. laevis with temperature. These results suggest that spatial environmental variability in the southwest Gulf of Mexico (mainly related to the depth) influenced distinctly the abundance of each studied raninoid species promoting interspecific spatial segregation. Environmental optimal range, tolerance range, and tolerance limits are provided for each species, representing important baseline references for ecosystem and resources management. Regional termsAtlantic Ocean, Gulf of Mexico, Mexico.

Expression of Estrogenic Response Genes in Black Mollies (Poecilia Sphenops) Exposed to Pyrogenic Hydrocarbon and Petroleum from Campeche Sound

The estrogenic effects of endocrine disrupting compounds (EDC´s) in animals are not reversible and can reduce populations. Sensitive methods such Q-PCR have been used to determine changes in gene expression and thus predict the effects before they become irreversible. The present study was designed to detect the expression on the estrogen receptors and vitellogenin genes in the Black Mollies fish (Poecilia sphenops) exposed to pyrogenic hydrocarbon and petroleum from Campeche Sound. The results indicate that the expression of transcript of the estrogen receptor and vitellogenin indicates are potentially useful as molecular biomarker for detecting the presence of endocrine-disruption compounds in environment.

Geotechnical Characteristics of Natural and Reconstituted Lacustrine Mexico City Clays

The behaviour of natural and reconstituted clay samples from the Basin of Mexico under uniaxial stress and strain conditions is compared. Samples from two sites in the former lake zone were reconstituted following a procedure facilitating a comparison of the obtained experimental results with those of other researchers from tests on northern European sedimentary clays and on clays from the city of Bogota and the Campeche Sound in the Gulf of Mexico. The differences in the behaviour of natural and reconstituted materials with a wide range of plasticities is analysed, while referring to sedimentation compression lines (SCLs), oedometric compressibility curves, and intrinsic compression lines (ICLs). ICLs for the Mexico Basin clays plot above SCLs in the void ratio versus effective stress space, which reflects the influence of sedimentation conditions on the formation of more compact, less open structures in natural clays. New analytical expressions that relate intrinsic void ratios and intrinsic compressibility with index properties are presented and is demonstrated that the normalised ICL is unique for all of the clays considered herein. It is concluded that reconstituted materials are less sensitive and less fragile (more ductile) than natural soils.

Natural and anthropogenic oil impacts on benthic foraminifera in the southern Gulf of Mexico

The Campeche Sound is the major offshore oil producing area in the Southern Gulf of Mexico (SGoM). To evaluate the impact of oil related activities in the ocean floor sediments, we analyzed the geochemical (major and trace element, organic carbon and hydrocarbon concentrations) and biological (benthic foraminifera) composition of 62 superficial sediment samples, from 13 to 1336 m water depth. Cluster and Factor analysis of all the variables indicate that their distribution patterns are mainly controlled by differences between the terrigenous and carbonate platforms in the SGoM. Benthic foraminiferal assemblages were abundant and diverse, and their distribution patterns are mainly determined by water depth and sedimentary environment. However, most of the abundant species are opportunistic and/or low-oxygen tolerant, and many of their tests show oil stains and infillings, characteristic of oil polluted locations, suggesting the environment has been modified by natural seepage or oil-related activities. To determine if these conditions are natural or anthropogenic in origin, pre - industrial settings should be studied. Organic carbon (Corg) content (0.6–2.9%) and total hydrocarbon concentrations (PAHs 1.0–29.5 μg kg−1) were usually higher around the oil platforms area, the natural hydrocarbon seeps (“chapopoteras”) area and offshore rivers, but there is no accumulation of oil related trace elements in these areas. However, the comparison with international sediment quality benchmarks indicates that Cd, Cr and Ni concentrations are above the threshold effect level, and also As, Ba and Cu are above the probable effect level benchmarks, which indicate that these element concentrations might be of potential ecological concern. Comprehensive studies involving different proxies, and assessing pre-industrial conditions, must be undertaken before assessing environmental health of marine benthic ecosystems.

Metazoan parasite infracommunities of the dusky flounder (Syacium papillosum) as bioindicators of environmental conditions in the continental shelf of the Yucatan Peninsula, Mexico

BackgroundWe 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.ResultsWe 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.ConclusionsThe 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.

Diversidad y distribución de peces y su relación con variables ambientales, en el sur del Golfo de México

The Campeche Sound has a high heterogeneity of habitats, great fish species diversity, and a strong presence of oil and fishing industries. Even though some information of bento-demersal fish of the area is available, this has been focused on some economically important species. This way, our objective of this study was to obtain the ichthyofaunal spatial distribution and its relationship with this study were were to obtain updated information on a complete local fish species spatial distribution and their relationship with environmental elements, this will improve the baseline to evaluate the potential impact of future oil and fishing developments. For this, our approach used a database obtained in 2010, with a capture made in 54 sites with standard shrimp fishing trawls (60 feet long x 1¼ in. mesh size; towing time 30 min, 2 knots; 19 to 600 m depth) in the Campeche Sound. Our data analysis included: dominance, diversity, equity, assemblies, spatial management and a landscape representation of the area. We collected a total of 33 315 fish, of 80 families, 138 genera and 193 species, that corresponded to 2 502 438 kg. The fish classes Chondrichthyes and Actinopterygii predominated. A total of 17 were dominant, associated to sandy and muddy bottoms, although were species of estuarine environments, reef and pelagic habitats. Averaged diversity (H') was of 3.2 bits/individuals. In decreasing diversity order, the common fish belong to Perciformes (84 species), Pleuronectiformes (23), Scorpaeniformes (15) and Tetraodontiformes (14); in the same way, the higher richness families were Sciaenidae (15 species), Paralichthyidae (12), Carangidae (10), and Triglidae and Synodontidae (7). Most common genuses were Prionotus (6 species), Citharichthys and Sphoeroides (4 each). Per each station, richness varied between 3 and 56 species, with an average weight of 46 kg. Fish assemblage composition was different among habitats and areas, with divergent management strategies. Landscape analysis defines nodules of high density and diversity that corresponded to river mouths, lagoons and reef areas fish assemblages. Of the relation between variables and community descriptors, only the organic carbon was significant for both abundance and biomass, the REDOX for the species richness and the other variables were not important.

Density and depth distribution of the sympatric species <I>Squilla chydaea</I> and <I>Squilla empusa</I> (Stomatopoda: Squillidae) in the southern Gulf of Mexico

The present study analyzed the density and depth distribution of Squilla chydaea (Manning, 1962) and Squilla empusa (Say, 1818) along the continental shelf in Campeche Sound during the rainy season months (July, August, October) of 2012 and 2013. Samples were collected during both day and night at 26 stations in 2012 and 34 stations in 2013. In total, 234 stomatopods were collected: 45% were S. chydaea and 55% were S. empusa. The mean densities of each species varied significantly by year (2012 > 2013) and sampling time (night > day). The highest mean density (4.7 ind ha–1) was observed for S. empusa during night in 2012, which was 47 times higher than the lowest density of S. chydaea, found during the day in 2013. The highest densities for S. chydaea were observed offshore of Terminos Lagoon and for S. empusa in the vicinity of Terminos Lagoon and adjacent to Grijalva-Usumacinta and San Pedro–San Pablo rivers. Results indicated that for S. chydaea, the relationship between density and water depth was quadratic in form, with the highest densities occurring between 60 and 120 m. The density of S. empusa decreased linearly with depth; the highest densities were observed at <30 m. For both S. chydaea and S. empusa, differences in depth distribution varied little between years. These results provide new information about stomatopod species in the southern Gulf of Mexico and are of potential interest for fisheries management and environmental monitoring.

Distribución, abundancia y reproducción de &lt;i&gt;Opisthonema oglinum&lt;/i&gt; (Pisces: Clupeidae) en la plataforma continental del sur del Golfo de México

Se analizan diversos aspectos de la biología y ecología de Opisthonema oglinum con base en 813 individuos obtenidos en seis cruceros oceanográficos. Esta especie dependiente estuarina, se distribuye en la Sonda de Campeche entre los 12 y 36 m. Las hembras tienen una talla de primera madurez de 135 mm de LT. Se reproduce desde mayo a octubre, con dos máximos en mayo y agosto, a profundidades mayores de 18 m. Los juveniles se encuentran en la plataforma y dentro de la Laguna de Términos. El reclutamiento se presenta en junio y octubre. Las máximas abundancias se presentan alrededor de las iso batas de 12 y 36 m, y en nortes en el área carbonatada.

Effects of oil spill related chemical pollution on helminth parasites in Mexican flounder Cyclopsetta chittendeni from the Campeche Sound, Gulf of Mexico

During an environmental impact study of an accidental oil spill in the Campeche Sound in October 2007, we examined the helminth parasites of the benthic flatfish Cyclopsetta chittendeni as well as the concentrations of hydrocarbons and heavy metals in the sediment. The aim of this study was to determine the potential effects of these contaminants on the helminth communities of the flatfish. A total of 427 hosts were examined, and 16,895 helminths, representing 17 species, were obtained from two surveys (March and July, 2008). Statistically significant negative associations were observed between the hydrocarbons and helminth parasite abundances using multivariate methods. The results suggest that in October 2007, the oil spill had a strong negative effect on these helminth communities. However, after five months, the impacted stations were re-populated by both the flatfish and helminths. The most likely explanation for this rapid recovery is the rescue effect from non-impacted habitats to impacted stations.

The environmental legacy of the Ixtoc-I oil spill in Campeche Sound, southwestern Gulf of Mexico

The southwestern Gulf of Mexico constitutes an important subsystem within a Large Marine Ecosystem. Due to its high biodiversity, living resources and energy resources, this region is strategic in the national plans for social and economic development of Mexico. The discovery of fossil fuel reserves in the seabed of Campeche Sound in the 1970s promoted the rapid expansion of the national oil industry in offshore waters. Unfortunately, the accidental blowout of the most productive well (Ixtoc-I) in June of 1979, caused the first–world massive oil spill in a tropical marine environment. More than 3.4 million of barrels of crude oil were liberated in an ecosystem formerly renowned for its pristine conditions. In the aftermath of this dreadful accident, an immediate concern emerged not only for the oil acute effects but also for the long-term environmental consequences derived from the residual hydrocarbon compounds accumulated in coastal environments of the southern Gulf of Mexico. The attempts to assess the magnitude of the environmental damage were strongly precluded by the lack of pre-spill information. Natural variability in the ecosystem and oil weathering-factors contributed to attenuate the acute pollution effects that lasted nine months. However, the post-spill environmental alterations caused by the Ixtoc-I blowout still remain unanswered. The sinking of the Deepwater Horizon oil platform in the deep-waters of the northern Gulf of Mexico, in 2010 rekindled our concern for the great risk involved for human lives and the health of shallow and deep sea habitats. The authors of this contribution offer their views on this environmental riddle from their own perspective as direct witnesses of the Ixtoc-I environmental tragedy.

Approaching a functional measure of vulnerability in marine ecosystems

Ecosystem vulnerability is a major concern for management purposes, especially when directed toward conservation and sustainable exploitation. We estimate the relative vulnerability of selected marine-ecosystems in the Gulf of Mexico through simulation experiments based on trophic models. The same perturbation pattern was applied to different functional groups at different trophic levels. Perturbation consisted of increasing biomass extraction for a single group up to 98% at a constant rate over 50 years. The ratio Ascendency to Capacity of Development, A/C, was estimated as a measure of ecosystem order. The maximum negative difference respect to the initial A/C represents the gain of entropy. The slope of the relationship between entropy gained and the trophic level provides an estimate of the relative vulnerability of the ecosystem. This was applied to five ecosystems in the Gulf of Mexico: Florida coral reef; Mexican coastal lagoon, Terminos Lagoon; and three continental shelves, the northern Gulf of Mexico, USA; Yucatan and the Campeche Sound, Mexico. The pattern of vulnerability among ecosystems is related to ecosystem complexity. The coral reef exhibited a lower slope, corresponding to higher vulnerability, which is related to higher connectivity, production efficiency, and net ecosystem production. Increasingly higher slopes, corresponding to lower vulnerability, followed a gradient from the coral reef to the continental shelves to the least vulnerable system, the coastal lagoon. Middle trophic levels contribute to higher vulnerability. This interpretation is supported by the concept of energy flows within trophic networks. The relevance of these findings for management is discussed.

Asociaciones de megacrustáceos epibentónicos en la Sonda de Campeche, golfo de México

Megacrustacean epibenthic assemblages of the continental shelf of Campeche Sound were analyzed using multivariate analysis. Seven cruises were done during 1994 (May, August, November) and 1995 (February, May, August and November). Benthic samples were obtained with a semicommercial trawl net (18.3 meters of mouth aperture and 2.5cm mesh size) in a depth range of 14 to 215 m. A total of 11,113 megacrustaceans belonging to 55 species and 24 families was recorded. Total biomass weighted 173.28 kg. Leucosiidae, Penaeidae and Portunidae families were the most abundant in species number and represented 27% of total species. Diversity, dominance and equitability indexes did not show marked variations either in climatic periods or between years. Depth and sediment type were the first and second environmental factors that mainly explained megacrustacean biomass and density variations. Shallow megacrustaceans assemblages were more numerous and differed clearly from the deep one. This can be attributed to substrate heterogeneity of shallow areas that have a transition zone between lime-clay and carbonate sediments.

Climatological, annual, and seasonal variability in chlorophyll concentration in the Gulf of Mexico, western Caribbean, and Bahamas using NASA colour maps

This study investigates climatological, seasonal, and interannual variability in chlorophyll concentration (Chl) throughout the Gulf of Mexico (GM), the western Caribbean Sea (WC), and the Bahamas (BI). For this purpose, Coastal Zone Color Scanner (CZCS) (1979–1986), Ocean Color and Temperature Scanner (OCTS) (1996–1997), and Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) (1997–2008) NASA climatology, yearly, and seasonal Level-3 Standard Mapped Image series were used. Inspection of the original Chl and the obtained fuzzy unsupervised classified maps show the existence of a transition zone between the already known coastal and open waters. The extension (total number of pixels) and form of polygons representing these water masses vary both annually and seasonally, showing their greatest differences during spring and autumn in the northeastern and northwestern GM, Campeche Sound, and the Honduras coast in the Caribbean. In contrast, the BI present polygons having an almost invariant extension and form. The seasonal averaged Chl values up to 0.8 mg m−3 present a cyclic variation, showing the highest Chl during winter months and the lowest Chl during summer months, independent of the basin or the sensor under consideration. The CZCS and OCTS products must be considered with care; however, they provide results that are compatible with findings from the SeaWiFS time series. Annual and winter/autumn trends – a decrease in Chl – were identified in the GM and BI. The Caribbean reports constant Chl values during the two periods under study. Possible interpretations of these trends will come from detailed interpretation of local data.

Natural vs. anthropogenic sources of hydrocarbons as revealed through biomarker analysis: A case study in the southern Gulf of Mexico

Biological markers are organic compounds in geological samples with an unambiguous link to specific precursor molecules in living organisms. They provide information on the origin and depositional environment of fossil organic matter as well as about its thermal maturation caused by geothermal heat flow during burial. Petroleum and its refinery products carry this biomarker information into the environment when they are released during anthropogenically-induced pollution. Soils or aquatic surface sediments in contaminated areas usually contain binary mixtures of fossil hydrocarbons and recent biogenic hydrocarbons like higher-plant wax esters, together with (often olefinic) hydrocarbons from earliest diagenetic transformation of functionalized biomolecules. Surface sediments collected in the shelf area of the Campeche Sound, Gulf of Mexico, sampled in the course of environmental monitoring for possible petroleum pollution due to industrial activity, however, revealed a third group of hydrocarbons. GC-MS analysis of biomarkers in the nonaromatic hydrocarbon fractions of the sediment extracts yielded overlapping hydrocarbon assemblages indicating multiple sources. Samples taken close to known asphalt seeps exhibit biomarker patterns virtually identical to those of reference crude oils. Other sediments contain mature fossil hydrocarbons and biomarkers that are not typical of either fossil fuels or immature organic matter in marine surface sediments. Instead, they come from drill cuttings recovered during penetration of Tertiary to Cretaceous deposits that were littered on the shallow sea bottom.

Sources of hydrocarbon pollution in surface sediments of the Campeche Sound, Gulf of Mexico, revealed by biomarker analysis

Surface sediments from the shelf area of the Campeche Sound (Gulf of Mexico) and the adjacent abyssal plain were sampled in the course of environmental monitoring for petroleum pollution as a result of industrial activity in the largest oil field in Mexico. Offshore oil production, refinery activities and heavy ship traffic, as well as natural petroleum seeps, are potential sources of pollution of water and sediment in the area. Gas chromatography–mass spectrometry (GC–MS) analysis of the nonaromatic hydrocarbon fractions of the sediment extracts revealed overlapping hydrocarbon assemblages indicating multiple sources. Samples taken close to known asphalt seeps exhibit biomarker patterns virtually identical to those of reference crude oils, so the asphalts have apparently escaped from petroleum reservoirs with fractured cap rocks. Other sediments, with distributions superimposed on mature fossil hydrocarbons, contain biomarkers typical of neither fossil fuels nor immature organic matter (OM) in marine surface sediments. They obviously derive from drill cuttings recovered during penetration of Tertiary to Cretaceous deposits and disposed of into the shallow sea, as indicated by the comparative analysis of drill cuttings from several wells in the area.

The use of higher taxa to assess the benthic conditions in the southern Gulf of Mexico

Polychaetes are a key group in marine benthic communities worldwide because they are ubiquitous and generally abundant and diversified at all depths. Their anatomical complexity, however, makes it very difficult and time consuming to identify them correctly to species level, increasing the costs of any study involving them. Thus, the use of higher taxonomic levels in this group is a useful tool in monitoring or pollution-related studies. In this study, we compared the results obtained at both the species and family levels to assess the faunal changes associated to the different environmental conditions in the southern Gulf of Mexico, a large region known for its ecological and economic importance. We collected and identified 5686 polychaetes from 44 families, 95 genera and 206 species at 68 stations. Their relative density varied from 0% to 29.3% (ind. l−1) being higher in the Campeche Bank. The family richness (1–17) and specific richness (1–46) were both higher in the Campeche Bank. The same pattern was found for diversity and evenness at both taxonomic levels analyzed. The absolute diversity values were different using different taxonomic levels, but increased or decreased similarly at both levels. With the non-metric multidimensional scaling analysis, two main groups of stations emerged: Campeche Bank and Campeche Sound, with two less defined groups indicating a transitional sedimentary zone between them. All the groups were consistent both at family and species level, indicating little loss of information when the family level is used instead of the species level. We conclude that, if good previous basic knowledge of that fauna exists, the family level can be used to monitor environmental and pollution effects in these types of bottoms.

Mesozoic extensional tectonics: its impact on oil accumulations in Campeche Sound, Gulf of Mexico

Compressional tectonics of the Tertiary age created large structures in the easternmost part of the Akal horst, in the Campeche Sound, offshore Campeche, Mexico (Figure 1). Prolific fields such as Cantarell, Sihil, Ku, Abakatun, Taratunich, and Bacab are on those structures. The tremendous magnitude of these structural events left very little evidence (have masked the presence) of the Mesozoic extensional system. For these reasons, much effort has been dedicated to explaining the compressional tectonic events and associated structural styles while the importance of the Mesozoic extensional system has been underestimated or minimized. Our current work suggests that some of these large structures are more closely related to the Mesozoic extensional tectonics than previously thought.

The pink shrimp Farfantepenaeus duorarum, its symbionts and helminths as bioindicators of chemical pollution in Campeche Sound, Mexico

The pink shrimp Farfantepenaeus duorarum may acquire pollutants, helminths and symbionts from their environment. Statistical associations were studied between the symbionts and helminths of F. duorarum and pollutants in sediments, water and shrimps in Campeche Sound, Mexico. The study area spatially overlapped between offshore oil platforms and natural shrimp mating grounds. Spatial autocorrelation of data was controlled with spatial analysis using distance indices (SADIE) which identifies parasite or pollutant patches (high levels) and gaps (low levels), expressing them as clustering indices compared at each point to produce a measure of spatial association. Symbionts included the peritrich ciliates Epistylis sp. and Zoothamnium penaei and all symbionts were pooled. Helminths included Hysterothylacium sp., Opecoeloides fimbriatus, Prochristianella penaei and an unidentified cestode. Thirty-five pollutants were identified, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and heavy metals. The PAHs (2-3 ring) in water, unresolved complex mixture (UCM), Ni and V in sediments, and Zn, Cr and heptachlor in shrimps were significantly clustered. The remaining pollutants were randomly distributed in the study area. Juvenile shrimps acquired pesticides, PAHs (2-3 rings) and Zn, while adults acquired PAHs (4-5 rings), Cu and V. Results suggest natural PAH spillovers, and continental runoff of dichlorodiphenyltrichloroethane (DDT), PCBs and PAHs (2-3 ring). There were no significant associations between pollutants and helminths. However, there were significant negative associations of pesticides, UCM and PCBs with symbiont numbers after controlling shrimp size and spatial autocorrelation. Shrimps and their symbionts appear to be promising bioindicators of organic chemical pollution in Campeche Sound.