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Abstract In this paper, the ecological integrity hierarchy framework (EIHF) and the natural capital index framework (NCI) are integrated as decision-making tools for evaluating the natural capital of Mexico. Two hierarchy-levels of ecological integrity indicators are used to estimate the quality and quantity of the natural capital, the amount of ecological degradation and ecological sustainability. After human transformation, the extent still considered as "natural" in the country is ∼67%; while the amount of human transformed areas is ∼33%, which gives a total estimate of NCI = 0.334; i.e., only ∼33.4% of the national capital remains available, while ∼33% is ecologically degraded. Furthermore, the critical natural capital; i.e., the legacy for future generations that remains in the country is only ∼12%. The total estimated value of the current natural capital in Mexico is ∼$457.1 billion/yr, which is ∼435 times greater than the national GDP ($1.051 billion in 2010). The cost of maintaining the degradation of the natural capital is ∼$144.6 billion/yr (∼138 times greater than national GDP in 2010). The potential value of the natural capital after restoration would be ∼$602 billion/yr. Valuing the natural capital can be helpful for strategic environmental evaluations and useful for spatial decision support systems that evaluate natural capital as a decision-making tool. [ABSTRACT FROM AUTHOR]

Ants have historically been classified into "functional groups" (FGs) to facilitate their interpretation as bioindicators. A particularly popular classification scheme is the one proposed by Andersen, based on the Australian myrmecofauna. These classification criteria suggest that ant abundance is linked to stress and disturbance, such that their affinity to and tolerance of particular conditions enables them to inhabit specific ecological contexts. Herein, we aimed to validate whether the climatic affinity postulated by the FG approximation can suggest FG composition and abundances in Mexican ant communities, such as has been previously evaluated by studies in other regions worldwide. In a protected natural area with a history of anthropogenic pressure, we evaluated the variation in temperature and humidity of two habitat types during consecutive years: a native oak forest and an induced grassland. The ant communities of the two sites were monitored using three collected methods (baits, pitfalls, and direct observations) and classified into FGs under Andersen's criteria. We found 34 ant species. The induced grassland site (28 species) was more species rich, more diverse, and had higher ant abundance than the oak site (21 species). There was a similarity in species composition between the sites (44.78%). In the oak forest, FGs related to cold temperatures were the most abundant, while in the induced grassland, heat-tolerant FGs were most abundant. Our findings support that Andersen's functional group classification is useful in suggesting habitat use in Mexican ant species. Likewise, our data are in accordance with previous findings that both the presence and abundance of FGs must be considered for an adequate application of this classification scheme. [ABSTRACT FROM AUTHOR]

One of the most important water bodies in Mexico is the Purisima Reservoir. It has been declared a protected natural area and provides ecosystem services. The aim of the present study was to assess the water quality and the degree of contamination in the reservoir using an integrated methodological approach to obtain a comprehensive knowledge of the environmental status of the reservoir. Physicochemical analyses, metal/metalloid determination and biomonitoring techniques were carried out. Algae were identified as the most feasible bioindicator. Data were processed using WAWQI, PAST 4.03, JMP15.2 and QGIs 3.26.3. The main elements identified in the reservoir were Cd, Cr, Hg, Pb and As (0.002–0.1 mg L−1). The element pairs with high correlation (p < 0.05) were Cd and Pb; Cr with Hg and Pb; Hg with Pb and Zn; and Pb and As. The taxonomic divisions of the algae observed were Bacillariophyta, Cyanobacteria, Charophyta and Chlorophyta. The results obtained classify the water quality of the Purisima Reservoir as "poor", while the biomonitoring analyses classify it as "moderately polluted". As a future perspective, a DNA meta-coding study of algal genera is recommended as it would increase the effectiveness of future biomonitoring programmes as well as the development of mapping techniques that correlate the degree of eutrophication with the population of bioindicators in order to design and implement effective protection and restoration policies. Finally, it should be noted that this is the first reported work on the study of the algae present in the Purisima Reservoir. [ABSTRACT FROM AUTHOR]

Marine protected areas have been established as essential components for managing and protecting coral reefs to mitigate natural and anthropogenic stressors. One noteworthy example within the Mexican Caribbean is the Arrecife de Puerto Morelos National Park (APMNP), where several studies on the coral communities have been carried out since 2006. In June 2019, we conducted a study in eight sites of the APMNP applying a coral reef assessment method based on biological indicators of both the benthos and the fish communities. In this paper, we present the quantitative results of our study and provide a qualitative criterion assessing seven condition indexes through a scoring system. We also present a statistical comparison with a previous study carried out in 2016. The general status of coral reefs was classified as regular due to the low values of coral recruitment rate and biomass of key commercial fish species. However, living coral cover average was above 20%, with a slight dominance of framework building coral species and the presence of low values of fleshy algae cover, these being positive indicators. Our study found a higher proportion of reef promoter elements and a lower proportion of detractors, compared to a previous study carried out in 2016. [ABSTRACT FROM AUTHOR]

We investigated microcrustaceans inhabiting arsenic contaminated and non-contaminated freshwater to identify potential bioindicators of arsenic contamination in the tropical freshwater of Matehuala in northern Mexico. We collected water, sediment, and zooplankton, at five sampling points during three sampling campaigns. We determined water temperature, pH, electrical conductivity, dissolved oxygen, alkalinity, salinity, and total arsenic concentration in water. Additionally, we determined total arsenic and arsenic speciation in sediment samples. We identified microcrustaceans and determined abundance, richness, and Shannon Index. We also investigated relationships and correlations between physiochemical and ecological variables. Results showed that arsenic concentrations in freshwater ranged from 0.001 to 53.23 mg/L, while total arsenic in sediments ranged from 10.37 to 2472.84 mg/kg as As + 5. Six microcrustacean species were found in highly and moderately contaminated water (Latonopsis australis, Eucyclops chihuahuensis, Acanthocyclops americanus, Pleuroxus (Picripleuroxus) quasidenticulatus, Macrocyclops albidus, and Paracyclops chiltoni), while five species were found in arsenic-free water (Simocephalus punctatus, Alona glabra, Eucyclops leptacanthus, M. albidus, and P. quasidenticulatus). An inverse relationship was observed between microcrustacean richness and arsenic. However, the scope of the data did not allow for a strong and significant correlation. Nevertheless, among the species inhabiting As-free water, S. punctatus showed potential to be further tested as a bioindicator of As contamination in Matehuala. Identification of potential bioindicators could help monitor water quality and increase understanding of the incorporation and toxicity of As in freshwater-sensitive and freshwater-metallotolerant microcrustaceans, which, in turn, might help us to understand As incorporation in the food web. [ABSTRACT FROM AUTHOR]

The presence of colonial and solitary ciliated peritrichous protozoa was determined in a Sequencing Batch Reactor system filled with tezontle, a volcanic rock, economic, and abundant material that can be found in some parts of the world, like Mexico. The presence of these protozoa was related to the removal efficiencies of organic matter. Also, two novel staining techniques are proposed for staining both colonial and solitary peritrichous protozoa. The results show that tezontle promotes the growth of solitary and colonial ciliated peritrichous protozoa, which, once identified, could be used as indicators of the efficiency of the wastewater treatment process. Additionally, the staining techniques established in the current study allowed the precise observation of protozoan nuclei. They can represent a useful complementary methodology for identifying protozoan species present in water treatment processes, along with the already existing identification techniques. The number and variety of protozoa found in the system may be considered potential bioindicators of water quality during biological treatments. [ABSTRACT FROM AUTHOR]

Background: This paper presents several spatial indicators developed to evaluate anthropogenic impacts on predator-prey interactions and their relationship with ecological integrity loss in Mexico. Ecological integrity loss is defined as the inability to sustain viable populations, habitat functions, and species interactions of Nearctic and Neotropical apex predators as a result of anthropogenic effects. As direct impacts, the indicators evaluate habitat loss and the number of inhospitable habitats. As indirect impacts, the indicators evaluate the avoidance of human features such as highways, roads, and human locations. The total impact level is described at 1 km2 resolution, and registered within the domain defined by the spatial habitat requirements of apex predators. The impact level is associated with ecological integrity loss, or the ecosystem capacity to reorganize habitat functions and sustain predator-prey interactions as the most visible elements of ecological integrity. Ecological integrity loss is evaluated for different groups of apex predators that are classified with different levels of anthropogenic threat.Results: The framework presented here identifies the spatial information needed for the assessment of cumulative anthropogenic impacts. By characterizing their distribution range, Nearctic predators have significantly larger intact habitats than neotropical predators but with higher ecological degradation, less landscape transformation, and overall less ecological integrity. As observed within their distribution areas, indirect impacts have a generalized effect in the broad range of landscapes in Mexico. Ecological integrity loss is the result of road, highway, and human settlement avoidance; but landscape transformation and human activity control the threshold for which ecological integrity loss becomes critical. On the other hand, there are no significant differences in impact levels among threat conservation categories for apex predators, which indicate that all predator species have the same threat level and should be all included in protection efforts.Conclusions: With the application of this spatial framework, the significance, scale, and baseline conditions can be established for evaluating anthropogenic impacts on ecological integrity. The analysis of the current condition shows the status for apex predator in the country, and identifies the ecological integrity threshold when human activities have severe to highly severe impacts in the landscape, threatening the viability of populations and their habitat. [ABSTRACT FROM AUTHOR]

Sustainable water management is important to ensure its availability for future generations. The study of water quality is fundamental for this purpose. Assessing the health of aquatic ecosystems through bioindicators has been shown to be reliable and inexpensive. The objective of this work was to evaluate water quality through a biomathematical model that involves environmental stress indicator organisms and their close relationship with dissolved oxygen. In this direction, a system of differential equations describing the population dynamics of aquatic macroinvertebrates under the influence of dissolved oxygen is proposed. The model is validated by its application in the Coyuca Lagoon, Mexico. Likewise, population changes over time were represented, which allowed us to deduce that the increase or decrease in the aeration/oxygenation rate significantly affects the population dynamics of the bioindicator organisms. In addition, to classify water quality, a one-to-one correspondence was established between water quality and the equilibrium points of the system of differential equations. The results obtained allow inferring that the proposed techniques are useful for the study of water quality since they can predict significant changes in the ecosystem and provide researchers and water managers with tools for decision making. [ABSTRACT FROM AUTHOR]

• Forest biocomplexity is a measure of forest integrity condition when is associated with human impacts. • Forest biocomplexity can be described with spatial indicators of stand biodiversity, structure and development. • Human impact indicators are inversely associated with biocomplexity. • Biocomplexity of temperate forests is in better condition than tropical forests in Mexico. This paper presents a conceptual framework for analyzing forest complexity as the combination of the variety of species and key structures that are associated with the composition, structure, and function of forest stands. Several spatial indicators have been developed to characterize the biodiversity, the structural complexity, and anthropogenic effects that can be observed in Mexican forests. By integrating several stand complexity attributes, the forest condition can be characterized as a function of species composition, stand structural attributes, and forest development. In addition, indicators of anthropogenic effects were also analyzed to identify their influence on forest eco-complexity, and therefore, on the current condition of forests. The results of applying this conceptual framework showed that Mexican forest are ecologically complex, with varying levels of anthropogenic impacts that modify the structural forest characteristics, particularly in tropical forests. The main factor explaining the current eco-complexity condition in tropical forests was associated with early stages of forest development, due to ecological degradation, and showed a generalized loss of attributes, particularly for stand complexity and stand development. In contrast, temperate forests exhibited better eco-complexity conditions, especially for those attributes that define forest stand occupancy and development. Mining activities, forest extraction as selective harvesting, forest fires, land use change, and road openings are critical human activities that directly affect forest structure and, ultimately, modify forest eco-complexity and integrity. This eco-complexity index derived for Mexican forests can be used to integrate measures of forest structure and functioning, and thereby better inform decision making and policy development. [ABSTRACT FROM AUTHOR]

Objective: To determine water quality in the central zone of the Texcoco aquifer, Mexico, for human use and consumption and agricultural use. Methodology: The physical, chemical, and biological indicators of the water from 16 wells in urban areas of the central zone of the aquifer were determined. The sampling was carried out, based on the parameters and definition of water quality per use established in the current official Mexican standards. Results: According to the physical indicators and concentrations of CO3 2-, HCO3 -, Ca2+, Mg2+, Cl-, SO4 2-, PO4 3-, Na+, K+, Fe, Cu, and Zn, the water in the sample was suitable for human use and consumption and agricultural use. Based on the cadmium (Cd) concentration, the water was unsuitable for human use and consumption and agricultural use, in 12 and 6 wells, respectively. According to the lead (Pb) concentration, water was suitable for agricultural use in the 16 wells studied; however, it was unsuitable for human use and consumption in any of the wells. In eight wells analyzed, the presence of fecal coliforms was lower than the permissible limit for agricultural use. Implications: This study complements researches done in other areas of the aquifer. The causes of water pollution are unknown and researches about the vulnerability of the aquifer and the possible polluting sources should be carried out. Conclusions: The water from the aquifer in the central zone has limitations for human use and consumption and agricultural use, as a consequence of the high Cd and Pb concentrations and its microbiological quality. [ABSTRACT FROM AUTHOR]

We analyzed the spatial-seasonal patterns on the abundance, composition, structure (i.e. abundance distribution among species), and diversity of the ground-dwelling spiders belonging to the retrolateral tibial apophysis (RTA) clade in two pine-oak forest remnants from Mexico. Additionally, a short review to compare the RTA ground-dwelling communities from Mexican habitats was carried out. Spiders were collected monthly, from July 2010 to June 2011, using pitfall-traps at each site. Species composition was seasonally, but not spatially, different. Estimated diversity for the Hill number 1 was influenced by the sites, and a site–season interaction effect was yielded for the Hill number 2. Abundance and community structure were strongly influenced by both sites and seasons. Six species exhibited strong associations with spatial and seasonal-specific conditions (possible bioindicators). Bibliographic analysis showed the highest richness and the lowest number of undescribed species in desert habitats of northern Mexico, pointing those as possible species repositories for the RTA clade. Our results showed a heterogenous spatial-seasonal response in the RTA ground-dwelling spiders, together with a weak influence of the regional variation in temperature and precipitation on the abundance and species richness, suggesting a stronger influence of ecological drivers at the microhabitat scale. [ABSTRACT FROM AUTHOR]

Evaluate the effect of heavy metals (HM) on sentinel organisms such as vascular plants represent a model to estimate toxic hazard due to environmental pollution. In the present study, the plant Robinsonecio gerberifolius was used to evaluate the toxic effects of the HM contained in the leaves of plants that were exposed to 4 different sites in Mexico city and its metropolitan area, during the rainy and dry seasons in the period 2017–2019. The comet assay to evaluate genotoxicity revealed an increase with respect to control (p < 0.05), in 2nd and 8th week of exposure, in all 4 study sites and in both seasons, more significant in the rainy period. An increase in the induction of oxidative stress was also observed in the exposed leaves from the 4 study sites when compared with the control; in some cases, the increases were significant (p < 0.05). In general, α- and ß-carotenoids were increased at 8th week of exposure, in all plants exposed in both seasons, while miR398 increased in plants exposed in 2 study sites (p < 0.05). Finally, toxic HM like aluminum, vanadium, and cadmium, increased significantly in the rainy season, while lead increased in the dry season. We conclude that R. gerberifolius can be considered a sentinel plant for evaluating the presence and general toxic effects caused by the presence of toxic HM that have been documented in the atmosphere of Mexico City and its metropolitan area. [ABSTRACT FROM AUTHOR]

This study compares the variation of richness, abundance and diversity of butterfly species along an atmospheric pollution gradient and during different seasons in the Monterrey Metropolitan Area, Mexico. Likewise, we analyse the influence of environmental variables on the abundance and richness of butterfly species and quantify the indicator species for each atmospheric pollution category. Based on spatial analysis of the main atmospheric pollutants and the vegetation cover conditions, four permanent sampling sites were delimited. The sampling was carried out monthly in each of the sites using aerial entomological nets and ten Van Someren-Rydon traps during May 2018 to April 2019. A total of 8,570 specimens belonging to six families and 209 species were collected. Both species richness and abundance were significantly different between all sites, except for the comparison between the moderate contamination site and the high contamination site; diversity decreased significantly with increasing levels of contamination. The seasonality effect was absent on species richness; however, for species abundance the differences between dry season and rainy season were significant in each site excepting the moderate contamination site. Regarding diversity, the seasonal effect showed different distribution patterns according to each order. Relative humidity, vegetation cover and three pollution variables were highly correlated with both abundance and species richness. From the total number of species found, only 47 had a significant indicator value. This study constitutes the first faunistic contribution of butterflies as indicators of the environmental quality of urban areas in Mexico, which will help in the development of strategies for the management, planning and conservation of urban biodiversity. [ABSTRACT FROM AUTHOR]

The goal of this study was to evaluate the effect of organic waste from yellowtail kingfish (Seriola lalandi) mariculture on seafloor sediments in Magdalena Bay, Baja California Sur. For the spatial analysis of the benthic macroinvertebrate community, sediment samples were collected below the cage and control areas in 2017. Sandy sediments predominated in the study area; organic matter content ranged from 0.96% to 1.18%, except for the control zone III, where it reached 1.48%. Total nitrogen and total phosphorus concentration showed significant differences between cage and control areas. A total of 63 benthic families were identified, and the highest density corresponded to polychaete annelids. BOPA index values indicate a low disturbance level in the study area; however, the distribution of benthic abundance shows a clear separation between zones, related to differences in total phosphorus and total nitrogen contents. The results obtained indicate that the fish farm generated a spatial differentiation of the benthic macroinvertebrate community, although organic farm waste has had a low impact on the seafloor. Results also show that benthic macrofauna is a good ecological indicator and that benthic indices provide a useful tool to evaluate environmental quality. [ABSTRACT FROM AUTHOR]

Background. Mangrove forests provide many ecosystem services, including the provision of habitat that supports avian biodiversity. However, hurricanes can knock down trees, alter hydrologic connectivity, and affect avian habitat. In 1995, Hurricanes Opal and Roxanne destroyed approximately 1,700 ha of mangrove forest in Laguna de Términos, Mexico. Since then, hydrological restoration has been implemented to protect the mangrove forest and its biodiversity. Methods. Since avian communities are often considered biological indicators of ecosystem quality, avian diversity and species relative abundance were evaluated as indicators of mangrove restoration success by comparing undisturbed mangrove patches with those affected by the hurricanes. Using bird surveys, similarity analyses, and generalized linear models, we evaluated the effects of water quality variables and forest structure on the relative abundance and diversity of the avian community in disturbed, restored, and undisturbed mangrove patches. Results. Higher bird species richness and relative abundances were found in disturbed and restored sites compared to the undisturbed site. After restoration, values of frequency of flooding, water temperature, tree density, and the number of tree species were more similar to that of the undisturbed site than to the values of the disturbed one. Such variables influenced the relative abundance of bird guilds in the different habitat conditions. Furthermore, some insectivorous bird species, such as the Yellow Warbler and Tropical Kingbird, were found to be similarly abundant in both undisturbed and restored sites, but absent or very low in occurrence at the disturbed site. Conclusions. Collectively, our results strongly suggest that hydrologic restoration helps to enhance niche availability for different bird guilds, including water and canopy bird species. Our work can help inform management strategies that benefit avian communities in mangrove forests and wetland systems. [ABSTRACT FROM AUTHOR]

Aquatic pollen and non‐pollen palynomorphs (NPPs) from a 72‐m‐long sediment core from Lake Chalco in central Mexico document macrophyte vegetation and paleolimnological conditions during the last glacial (∼85–10.8 k cal a BP). We compared macrophyte vegetation and NPP records with data for authigenic carbonate deposition estimated from concentrations of total inorganic carbon. We estimated saline and variable trophic conditions during the last glacial. An association indicative of higher salinity conditions characterized by NPP and diatom assemblages characteristic of alkaline and saline environments is documented. Changes in hydrophyte taxa and microalgae assemblages were related to trophic level fluctuations. Higher salinity environments were contemporary with arid intervals reconstructed based on abundances of inorganic carbonate. Two main periods were evident in this record: (i) 85–29 k cal a BP [Marine Isotope Stage (MIS) 5b–MIS 3] characterized by saline conditions with high abundance of Type‐TXA, and variable high carbonate content, and (ii) 29–10.8 k cal a BP (MIS 2–MIS 1) when conditions changed to higher trophic levels and lower salinities, characterized by extremely low values of Type‐TXA and carbonate content. Spring and summer insolation and latitudinal position of the Intertropical Convergence Zone over the last glacial were considered as possible controllers of the recorded paleoenvironmental changes. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the amount and quality of water in the Magdalena-Eslava river system and to propose alternatives for sustainable water use. The system is the last urban river in the vicinity of Mexico City that supplies surface water to the urban area. Historical flow data were analyzed (1973–2010), along with the physicochemical and bacteriological attributes, documenting the evolution of these variables over the course of five years (2008–2012) in both dry and rainy seasons. The analyses show that the flow regime has been significantly altered. The physicochemical variables show significant differences between the natural area, where the river originates, and the urban area, where the river receives untreated wastewater. Nutrient and conductivity concentrations in the river were equivalent to domestic wastewater. Fecal pollution indicators and various pathogens were present in elevated densities, demonstrating a threat to the population living near the river. Estimates of the value of the water lost as a result of mixing clean and contaminated water are presented. This urban river should be rehabilitated as a sustainability practice, and if possible, these efforts should be replicated in other areas. Because of the public health issues and in view of the population exposure where the river flows through the city, the river should be improved aesthetically and should be treated to allow its ecosystem services to recover. This river represents an iconic case for Mexico City because it connects the natural and urban areas in a socio-ecological system that can potentially provide clean water for human consumption. Contaminated water could be treated and reused for irrigation in one of the green areas of the city. Wastewater treatment plants and the operation of the existing purification plants are urgent priorities that could lead to better, more sustainable water use practices in Mexico City. [ABSTRACT FROM AUTHOR]

Mexico has experienced changes in its demographic and epidemiologic profile accompanied by recent changes in nutrition and income. Thus, the old and the young have experienced very different environments. Using data from the Mexican National Health Nutrition Survey 2006, we examine age and sex differences in physiological status and dysregulation and assess how socioeconomic factors associate with variability in biological indicators of health. Results indicate that young people have experienced better physical development as evidenced by their being taller and having less stunting. There is currently little under-nutrition in Mexico, but there is evidence of over-nutrition as indicated by high prevalence of overweight across the age range. Physiological dysregulation across multiple systems is higher in Mexicans than Americans across all ages. Mexicans have: higher levels of blood pressure, plasma glucose, and especially for women, dysregulated cholesterol and higher body weight. Low education is associated with both being stunted and overweight, and with adverse levels of HDL cholesterol and more physiological risk factors. Rural dwelling males are less likely to be overweight as are females living in poor states. Living in a poor state among females and having rural residence among males is associated with a higher number of high-risk factors. Overweight is a strong predictor of hypertension. Age differences in indicators of physiological development suggest that the epidemiological and demographic transitions in Mexico were accompanied by improved physical development; however, increases in nutrition may have reached a point of diminishing returns as Mexico switched from a state of under-nutrition to over-nutrition. [ABSTRACT FROM AUTHOR]

Aims: Waterborne outbreaks of hepatitis A and Norovirus disease have been reported and associated with contaminated water supply in various countries. However, in Mexico, there are no studies that report HAV and NV presence in water. This study reports the application of ultrafiltration and RT-nested PCR methods to concentrate and identify these viruses. Methods and Results: Forty estuarine water samples were collected from the Huizache Caimanero Lagunary Complex. Samples were concentrated by ultrafiltration system (UFS) and RT-nested PCR was performed for HAV and NV identification. These viruses were found in 80% and 70% of the samples collected respectively and both were present in 57·5%. The DNA sequences analysis showed that 21 estuarine water samples were associated with HAV and 13 with NV. Faecal coliforms were isolated in 48·57% of the samples, while Escherichia coli were found in 34·28%. Conclusions: DNA sequencing showed that the genotype IB for HAV and GII for NV were predominant in México. No significant relationships were detected between indicators and viruses ( P < 0·05). Significance and Impact of the Study: This study shows that the UFS is adequate for viral concentration. This is the first study analysing the genetic sequence of HAV and NV isolated from Mexican estuarine water. [ABSTRACT FROM AUTHOR]

A series of bioindicator organisms for aquatic ecosystems are being maintained under laboratory conditions in order to analyze effects of pollution on aquatic wildlife and potential effects on human health. Growth kinetics of algae Pseudokirchneriella subcapitata was used to evaluate effects of the surfactant nonilphenol (NP). Brachionus calyciflorus was used to set up a model of endocrine disruption using the fungicide vinclozolin (Vc). We exposed salamanders from the genus Ambystoma sp., to different concentrations of both the aneugen colchicine (COL) and the clastogen cyclophosphamide (CP) and we determined the frequency of micronucleated cells (MNC) in their shed skin. The presence of spontaneous micronuclei in peripheral blood erythrocytes from 10 fish species in Lake "La Alberca," Michoacan (Mexico), was evaluated as a possible biological indicator of genotoxic agents. Results confirm the sensivity of Pseudokirchneriella subcapitata to growth kinetics: the range of concentration of NP (20, 200 and 2000 μ g L-1) shows an inverted U shape in its maximum growth rate; Dimethyl sulfoxide (DMSO) used as a positive control and to solvate NP induced an inverse stimulatory effect on growth rate in the range of concentrations analyzed (0.0023, 0.023 and 0.23% v v-1). In the use of the rotifer Brachionus calyciflorus, the range of Vc from 0.185 mg L-1 to 3 mg L-1 clearly showed an inverted U shape characteristic of endocrine disruptions. We were able to use shed skin from Ambystoma sp., to measure MNC frequencies induced either by an aneugenic or a clastogenic compound. The MNC frequency was increased significantly by all doses of COL and CP, administered either as single or repeated exposures. The presence of MNC in the shed skin and the speed of sloughing lead us to propose that the sheds of Ambystoma sp., or other amphibians that slough their skin, as suitable alternative models for detecting genotoxic exposures relevant to aquatic environments. In the survey to determine potential biological fish indicators for genotoxic agents, the frequency of spontaneous micronucleated erythrocytes (MNE) found in the goodeid Xenotoca melanosoma (3.7 ± 1.6 MNC) and the cichlid Oreochromis aureus (2.0 ± 1.0 MNC) suggests that these species can be considered as potential biological indicators. [ABSTRACT FROM AUTHOR]

Field studies were conducted in Mexico to investigate the possibility of replacing sentinel animals as baits for female New World screwworm Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) with a synthetic odour-bait composed of compounds identified from wounds infested with the larvae of C. hominivorax. Studies using sheep held in stanchions surrounded by an incomplete ring of electrified nets showed that both male and female C. hominivorax were attracted to an unwounded animal (ratio of male : female flies caught 1.11 : 1.00), although they were not observed to land. By contrast, catches associated with unwounded sheep with larval wound fluid applied to shaven shoulders suggested that female C. hominivorax were attracted to (male : female ratio of electrified nets catch 0.14 : 1.00) and landed on the wound fluid but male flies did not respond (male : female ratio alighting on fluid 0.05 : 1.00). In related studies the attractiveness of synthetic blends of 25 electrophysiologically active compounds identified in fluids associated with wounds infested with the larvae of C. hominivorax were tested. The acidic components of the wound fluids were found to attract and elicit a landing response from both male and female flies, whereas the non-acidic components alone caught only low numbers of flies. However, the numbers of male and female flies that were attracted to and landed on a synthetic bait could be increased significantly by increasing the proportion of non-acid to acid components in the lure. In some replicates the most effective blend caught a number of C. hominivorax comparable to that caught by a standard synthetic attractant, Swormlure-4, although, unlike with Swormlure-4, the catch was predominately composed of female flies. It is uncertain whether Swormlure-4 contains compounds that elicit a landing response from male C. hominivorax or whether the synthetic and natural wound odours contain compounds that inhibit a landing response from male C. hominivorax. Further work is required to simplify the blend of compounds needed to attract female flies and to better understand the role of the compounds that elicit behavioural responses from both male and female C. hominivorax before a synthetic substitute can be fully developed to replace sentinel animals. [ABSTRACT FROM AUTHOR]