Childhood predictors of late-life diabetes: the case of Mexico

We investigated the interplay between characteristics of early childhood circumstances and current socioeconomic conditions and health, focusing specifically on diabetes in mid and late life in Mexico. The analysis used data from the 2001 Mexican Health and Aging Study (MHAS), a large nationally representative study of Mexicans born before 1950. We analyzed the extent to which childhood conditions, such as exposure to infectious diseases, a poor socioeconomic environment, and parental education, affect the risk of diabetes in later life. Our results indicate that individuals age 50 and older who experienced serious health problems before age 10 have a higher risk of having late-life diabetes. There is a significant inverse relationship between maternal education and diabetes in late life of adult offspring. Individuals with better educated mothers have a lower risk of being diabetic after age 50. This relationship remains after controlling for other childhood and adult risk factors.     

Influence of hurricanes on coastal ecosystems along the northern Gulf of Mexico

Available literature indicates that hurricanes do not generally produce long-term detrimental impacts to unmodified coastal systems and that they often provide net benefits along the U.S. Gulf Coast. While there is normally initial erosion from hurricanes, they also often result in a large influx of inorganic sediments, creating new wetlands and contributing to the maintenance of existing wetlands. The formation of washover deposits is disastrous where cultural development has occurred, but in natural areas these deposits are part of the natural cycle of shoreline development and contribute to habitat diversity and productivity. Abundant rainfall typically associated with hurricanes often results in large increases of sediment and nutrient inputs into coastal estuaries, leading to both short-term and long-term increases in productivity. Rainfall during tropical disturbances accounts for a significant part of total precipitation along the northern gulf. The immediate impact of hurricanes may be to reduce populations of some species but these populations generally recover rapidly. Overall, productivity in natural systems seems to be increased by periodic hurricanes. Hurricane impacts are often severe and long lasting in wetlands that have been modified by human impacts such as semi- or complete impoundments.     

Livestock grazing limits beaver restoration in northern New Mexico

The North American beaver (Castor canadensis) builds dams that pond water on streams, which provide crucial ecological services to aquatic and riparian ecosystems and enhance biodiversity. Consequently, there is increasing interest in restoring beavers to locations where they historically occurred, particularly in the arid western United States. However, despite often intensive efforts to reintroduce beavers into areas where they were severely reduced in numbers or eliminated due to overharvesting in the eighteenth and nineteenth centuries, beavers remain sparse or missing from many stream reaches. Reasons for this failure have not been well studied. Our goal was to evaluate certain biotic factors that may limit the occurrence of dam‐building beavers in northern New Mexico, including competitors and availability of summer and winter forage. We compared these factors at primary active dams and at control sites located in stream reaches that were physically suitable for dam‐building beavers but where none occurred. Beaver dams mostly occurred at sites that were not grazed or where there was some alternative grazing management, but were mostly absent at sites within Forest Service cattle allotments. Results indicated that cattle grazing influenced the relation between vegetation variables and beaver presence. The availability of willows (Salix spp.) was the most important plant variable for the presence of beaver dams. We conclude that grazing by cattle as currently practiced on Forest Service allotments disrupts the beaver‐willow mutualism, rendering stream reaches unsuitable for dam‐building beavers. We recommend that beaver restoration will require changes to current livestock management practices.     

The fishes of northern and central Veracruz,Mexico

The hydrographic structure of Abra Harbour, a tidal embayment located at the seaward end of the highly polluted estuary of Bilbao, is influenced by the inflow of a polluted estuarine plume, the asymmetry of the harbour basin, and the tidal circulation pattern. Multivariate analysis of the spatial variability of the zooplankton between May 1981 and May 1982 showed that significant differences in zooplankton abundance and species composition occurred from the inner-eastern to the outer-western side, related to the horizontal structure of the system. The annual temperature cycle, however, was the major source of temporal variability, and the seasonal stratification in the water column was responsible for the predominance of vertical differences in zooplankton composition during the spring-summer period. Wind-induced turbulence and tides were other sources of variation. With increasing turbulence (rough sea), the spatial gradients in zooplankton composition were not as clear, and with decreasing tidal height the compositional differences in the horizontal dimension tended to be more evident. Spionid larvae accounted for strong local differences within the Harbour. They were usually segregated from other taxa, and mainly associated to the deeper waters characterized by a greater hydrological instability.     

Direct and indirect fishery effects on small coastal elasmobranchs in the northern Gulf of Mexico

Globally, bycatch in tropical/subtropical shrimp trawl and longline fisheries is threatening many marine species. Here we examine the joint effects of increased mortality caused by shrimp trawling bycatch, and reduced predation caused by losses of large sharks because of longline fishing. Research surveys in the Gulf of Mexico (1972–2002) demonstrated precipitous declines in shallow water coastal elasmobranchs where shrimping effort was highest (bonnethead 96%, Bancroft's numbfish (lesser electric ray) 98%, smooth butterfly ray > 99%) and consistent increases in deeper water elasmobranchs (Atlantic angel shark, smooth dogfish). These increases are the first empirical support for predation release caused by the loss of large sharks, which have been theorized to structure tropical/subtropical marine ecosystems. Bycatch of elasmobranchs in shrimp trawls is a critical conservation concern which is not solved by present mitigation measures; similar loss of elasmobranchs is expected to be occurring in tropical/subtropical regions worldwide where ever intensive shrimp trawling occurs.     

Structural and chemical defenses of echinoderms from the northern Gulf of Mexico

The feeding deterrent effects of echinoderm body-wall tissues and ethanolic extracts containing mid-polarity compounds were evaluated utilizing generalist fish and crabs as model predators. The body-wall tissues of the echinoderms examined ranged 10-fold from 0.9–9.4 mm in thickness, and four and a half-fold in level of mineralization (17.8–82.7% ash content). Holothuroids had the thickest body-wall tissues and contained the lowest levels of mineralization in their body-walls. Crinoids and ophiuroids had high levels of mineralization in their arms. Asteroid body-wall tissues varied the most in thickness and ash content (0.9–3.9 mm in thickness and 29.2–55.5% in ash content). Body-wall tissues of 19 species of echinoderms were tested for their feeding deterrent properties against the marine fishes Lagodon rhomboides (Linnaeus) and Cyprinodon variegatus (Lacepede), as well as the decapod crustacean Libinia emarginata (Leach). Equivalent sized pieces of fresh body-wall tissue of 16 species of echinoderms caused observable feeding deterrence responses in at least two of the three model predators. There was no significant correlation between body-wall thickness or percent ash and its palatability to any of the three model predators. Agar pellets containing ethanolic body-wall extracts of 12 of 18 echinoderm species caused observable feeding deterrence responses in the fish L. rhomboides. In similar experiments with the arrow crab Stenorhyncus seticornis (Herbst), using carrageenan fish-meal blocks as food models, no differences in consumption of control fish-meal and experimental body-wall extract blocks were detected. Our findings indicate that invertebrate and vertebrate predators may respond quite differently to echinoderm body-wall extracts.     

An annual study of airborne pollen in northern Mexico City

An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00.     

An annual study of airborne pollen in northern Mexico City

An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00.     

Geochemical environments of continental shelf-upper slope sediments in the northern Gulf of Mexico

Geochemical environments were characterized for 14 sites along the northern Gulf of Mexico continental shelf and upper slope, in an effort to examine the relationship between sediment geochemistry and carbonate shell taphonomy in a long-term study—Shelf and Slope Experimental Taphonomy Initiative (SSETI). Three groups of environments of preservation (seep, near-seep, and shelf-and-slope) were identified based on their geochemical characteristics (i.e., oxygen uptake rate and penetration depth, pore-water saturation states, and carbonate dissolution fluxes). Diffusive oxygen uptake rate increased in the order of shelf-and-slope, near-seep, and seep, although carbonate dissolution flux did not show significant correlation with O₂ flux, presumably due to non-diffusive behavior at some sites. Using pore-water saturation indices with respect to aragonite and calcite and sedimentation rates, we defined a semi-quantitative parameter, carbonate dissolution index (CDI), to predict carbonate preservation potential during the taphonomic processes. Our limited database suggests that both the seep and the shelf-and-slope sediments may have higher carbonate preservation potential than the near-seep sediments.     

Connectivity of priority areas for the conservation of large carnivores in northern Mexico

The loss and fragmentation of habitat has negative effects on populations of large carnivores, but ecological corridors that allow dispersal of individuals among habitat remnants mitigate these effects. Our objectives were to identify 1) priority areas for the conservation of three species of large carnivores in northern Mexico, 2) the corridors that can maintain connectivity between them, and 3) pinch points signifying habitat loss that threatens connectivity. We generated species distribution models using MaxEnt and GLM to obtain a consensus model for each species. We applied an inverse function to the probability gradient of the consensus models to calculate the resistance and identify the corridors between priority areas. With Linkage Mapper software, we generated the corridors, calculated their centrality and that of the priority areas, and identified the areas where the corridors are narrower (i.e., pinch points). Finally, we identified the main anthropic fragmentation elements in the most important corridors. We identified 6 priority areas for jaguar, 20 for puma and 21 for black bear, with 5 corridors for jaguar, 22 for puma and 29 for black bear. The pinch points were produced by agricultural fields, human settlements, roads, or combinations of these factors. Depending on the element of fragmentation in each corridor, we propose specific strategies at the pinch points, e.g., applying restoration programs, including wildlife crossings to mitigate road killed cases, promoting payment programs for environmental services or compensation in cases of conflict, to increase the support of local inhabitants for conservation.