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M.A. Mora

Publications and source records attributed to M.A. Mora.

14 recordsLinked to original sources
USGS2008

Potential effects of environmental contaminants on P450 aromatase activity and DNA damage in swallows from the Rio Grande and Somerville, Texas

Cliff swallows (Petrochelidon pyrrhonota) and cave swallows (P. fulva) were sampled during the breeding season at several locations in the Rio Grande, Texas, to evaluate the potential effects of environmental contaminants on P450 aromatase activity in brain and gonads and DNA damage in blood cells. The tritiated water-release aromatase assay was used to measure aromatase activity and flow cytometry was used to measure DNA damage in nucleated blood cells. There were no significant differences in brain and gonadal aromatase activities or in estimates of DNA damage (HPCV values) among cave swallow colonies from the Lower Rio Grande Valley (LRGV) and Somerville. However, both brain and gonadal aromatase activities were significantly higher (P < 0.05) in male cliff swallows from Laredo than in those from Somerville. Also, DNA damage estimates were significantly higher (P < 0.05) in cliff swallows (males and females combined) from Laredo than in those from Somerville. Contaminants of current high use in the LRGV, such as atrazine, and some of the highly persistent organochlorines, such as toxaphene and DDE, could be potentially associated with modulation of aromatase activity in avian tissues. Previous studies have indicated possible DNA damage in cliff swallows. We did not observe any differences in aromatase activity or DNA damage in cave swallows that could be associated with contaminant exposure. Also, the differences in aromatase activity and DNA damage between male cliff swallows from Laredo and Somerville could not be explained by contaminants measured at each site in previous studies. Our study provides baseline information on brain and gonadal aromatase activity in swallows that could be useful in future studies. ?? 2008 Springer Science+Business Media, LLC.

Ecotoxicology↗
USGS2008

Simulating the impact of cholinesterase-inhibiting pesticides on non-target wildlife in irrigated crops

We present a simulation model for risk assessment of the impact of insecticide inhibitors of cholinesterase (ChE) applied in irrigated agricultural fields on non-target wildlife. The model, which we developed as a compartment model based on difference equations (??t = 1 h), consists of six submodels describing the dynamics of (1) insecticide application, (2) insecticide movement into floodable soil, (3) irrigation and rain, (4) insecticide dissolution in water, (5) foraging and insecticide intake from water, and (6) ChE inhibition and recovery. To demonstrate application of the model, we simulated historical and "worst-case" scenarios of the impact of ChE-inhibiting insecticides on white-winged doves (Zenaida asiatica) inhabiting natural brushland adjacent to cotton and sugarcane fields in the Lower Rio Grande Valley of Texas, USA. Only when a rain event occurred just after insecticide application did predicted levels of ChE inhibition surpass the diagnostic level of 20% exposure. The present model should aid in assessing the effect of ChE-inhibiting insecticides on ChE activity of different species that drink contaminated water from irrigated agricultural fields, and in identifying specific situations in which the juxtaposition of environmental conditions and management schemes could result in a high risk to non-target wildlife. ?? 2007 Elsevier B.V. All rights reserved.

Ecological Modelling↗
USGS2008

Persistent environmental pollutants in eggs of aplomado falcons from Northern Chihuahua, Mexico, and South Texas, USA

The northern aplomado falcon (Falco femoralis septentrionalis) disappeared from south Texas in the 1940s. Due to great success in the release of captive-reared aplomado falcons in south Texas, there are currently more than 40 established nesting pairs in the region. Addled eggs from aplomado falcons nesting in northern Chihuahua and south Texas were analyzed to determine organochlorine (OC) and inorganic element contaminant burdens and their potential association with egg failures and effects on reproduction. Among the OCs, DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] was present at the highest concentrations (range 262-21487??ng/g wet weight) followed by polychlorinated biphenyls (PCBs, range 88-3274??ng/g ww). DDE was greater (P = 0.03) in eggs from El Sueco (Chihuahua, Mexico) than in those from Matagorda Island (Texas, USA). DDE concentrations in eggs of aplomado falcons from El Sueco were elevated; however, reproductive success in the two Chihuahuan populations did not seem to be affected by DDE. DDE and metals in potential avian prey of the aplomado falcon from Matagorda Island were very low and below levels in the diet at which some negative effects might be expected. Except for mercury (Hg), metal concentrations in eggs were fairly low and were not different among locations in Chihuahua and south Texas. Hg was somewhat elevated and was greater (P < 0.001) in Texas than in the Chihuahua locations. Periodic monitoring of Hg concentrations in addled eggs of aplomado falcons in south Texas is recommended to continue evaluating potential negative effects on their recovery. ?? 2007 Elsevier Ltd. All rights reserved.

Environment International↗
USGS2007

Further assessment of environmental contaminants in avian prey of the peregrine falcon in big bend National Park, Texas

A small resident population of peregrine falcons (Falco peregrinus anatum) in the Big Bend region of Texas has suffered reproductive failures since 1990. To continue our assessment of the effects of environmental contaminants on the peregrine falcon, we collected representative avian prey species during 2001 at Mariscal Canyon, Big Bend National Park. The avian carcasses were analyzed for inorganic and organochlorine contaminants. Concentrations of Se and Hg were present at high levels (up to 11 and 2.2 ??g/g dry weight, respectively) in some avian prey and could be implicated in reproductive failures of the peregrine falcon in Big Bend National Park. All other inorganic elements were below concentrations known to affect reproduction or to be associated with other deleterious effects in birds. Of all the organochlorines analyzed, only DDE and total PCBs were present above detection limits in all species, although at low concentrations. Our study provides further support to the hypothesis that contaminants in potential avian prey of the peregrine falcon in the Big Bend region are implicated in the productivity failures observed in this species since 1990.

Southwestern Naturalist↗
USGS2006

Biomarkers of exposure and effects of environmental contaminants on swallows nesting along the Rio Grande, Texas, USA

We collected adult cave swallows (Petrochelidon fulva) and cliff swallows (P. pyrrhonota) during the breeding seasons in 1999 and 2000 from eight locations along the Rio Grande from Brownsville to El Paso (unless otherwise specified, all locations are Texas, USA) and an out-of-basin reference location. Body mass, spleen mass, hepatosomatic index (HSI), gonadosomatic index (GSI), thyroxine (T4) in plasma, DNA damage measured as the half-peak coefficient of variation of DNA content (HPCV) in blood cells, as well as acetylcholinesterase and butyrylcholinesterase in brain were compared with concentrations of organochlorines, metals, and metalloids in carcasses to determine potential effects of contaminants on swallows during the breeding season. Concentrations of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p???-DDE) were significantly greater in swallows from El Paso than in those from most locations, except for Pharr and Llano Grande. All swallows from these three locations had p,p???-DDE concentrations of 3 ??g/g wet weight or greater. Swallows from El Paso either had or shared the highest concentrations of p,p???-DDE, polychlorinated biphenyls, and 13 inorganic elements. Swallows from El Paso exhibited greater spleen mass and HPCV values as well as lower T4 values compared with those from other locations. Thyroxine was a potential biomarker of contaminant exposure in swallows of the Rio Grande, because it was negatively correlated with p,p???-DDE and Se. Spleen mass was positively correlated with selenium and HSI and negatively correlated with body mass, GSI, Mn, and Ni. Overall, the present study suggests that insectivorous birds living in areas of high agricultural and industrial activity along the Rio Grande bioaccumulate environmental contaminants. These contaminants, particularly p,p???-DDE, may be among multiple factors that impact endocrine and hematopoietic function in Rio Grande swallows. ?? 2006 SETAC.

Environmental Toxicology and Chemistry↗
USGS2005

Residues of toxaphene in insectivorous birds ( Petrochelidon spp.) from the Rio Grande, Texas

Although it has been documented that wildlife in the Rio Grande Valley (RGV) contain increased concentrations of organochlorine (OC) contaminants, particularly DDE, little has been published on residues of toxaphene throughout this major North American watershed. In this study, 28 liver composites from adult swallows ( Petrochelidon spp.) collected along the Rio Grande from 1999 through 2000 were analyzed for toxaphene residues using congener-specific gas chromatography–electron-capture negative ionization–mass spectrometry. Estimated total toxaphene concentrations ranged from 12 to 260 ng/g wet wt and were highest in samples from the lower RGV near Llano Grande Lake in Hidalgo and Cameron counties (Texas). Toxaphene congener profiles were relatively invariant throughout the watershed and were dominated by 2,2,5-endo,6-exo,8,8,9,10-octachlorobornane (P-42a or B8-806) with lesser amounts of several other Cl 7 -Cl 9 compounds, many of which remain unidentified. Petrochelidon spp. liver profiles appear to be intermediate in complexity between those in invertebrates and fish (more complex) and mammals (less complex) and differs somewhat from those reported for other avian species. In addition to other legacy OC contaminants, toxaphene residues were most concentrated in the lower RGV and accumulated at up to hundreds of parts per billion in these insect-eating birds, underscoring their utility as avian bioindicators of persistent organic pollutants.

Archives of Environmental Contamination and Toxico↗
USGS2001

Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA

Eggs of neotropic cormorants ( Phalacrocorax brasilianus ), black-crowned night herons ( Nycticorax nycticorax ), and great egrets ( Ardea alba ) nesting on several locations in Galveston Bay (TX, USA) and at two control sites outside the bay were collected during April–May 1996 and analyzed for chlorinated pesticides, PCBs, polychlorinated dibenzo- p -dioxins, and polychlor-inated dibenzofurans. Additionally, concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs) were determined by use of relative potency factors (TEQs) or the H4IIE-luc bioassay TCDD-EQs. Concentrations of 1,1,-dichloro-2,2-bis( p -chlo-rophenyl)ethylene (DDE) were greater in eggs of neotropic cormorants from Alexander Island (mean = 1,040 ng/g wet wt) in the Houston Ship Channel (Houston, TX, USA) and in those from Telfair Island (mean = 1,460 ng/g wet wt), a reference location outside the bay, than in most locations inside the bay (mean range = 119–453 ng/g wet wt). Mean PCB concentrations were greater in eggs of neotropic cormorants from Alexander Island (mean = 5,720 ng/g wet wt) than in eggs of cormorants from areas farther away from the ship channel, including two reference sites outside the bay (mean range = 404–3,140 ng/g wet wt). The TCDD was the main dioxin congener detected in eggs from all locations within Galveston Bay. Instrumental TEQs in eggs ranged from 67 pg/g wet weight at control sites to 452 pg/g wet weight at Alexander Island. Concentrations of TCDD-EQs determined in the H4IIE assay were correlated with instrumental TEQs and were greater in eggs of cormorants from islands within the bay, although these were farther away from the ship channel. Overall, concentrations of DDE, PCBs, TCDD, and TCDD-EQs were less than the threshold levels known to affect reproduction. However, some eggs contained concentrations of total PCBs or DDE greater than what would elicit adverse effects on birds. No identifiable deformities or abnormalities were detected in embryos collected from all sites.

Environmental Toxicology and Chemistry↗
USGS2001

Selenium, selected inorganic elements, and organochlorine pesticides in bottom material and biota from the Colorado River delta

Concentrations of selenium (Se) in bottom material ranged from 0.6 to 5.0 μg g −1 , and from 0.5 to 18.3 μg g −1 in biota; 23% of samples exceeded the toxic threshold. Concentrations of DDE in biota exceeded the toxic threshold in 30% of the samples. Greater concentrations of selenium in biota were found at sites with strongly reducing conditions, no output, alternating periods of drying and flooding or dredging activities, and at sites that received water directly from the Colorado River. The smallest Se concentrations in biota were found at sites where an outflow and exposure or physical disturbance of the bottom material were uncommon.

Journal of Arid Environments↗
USGS2000

Environmental contaminants in blood, hair, and tissues of ocelots from the Lower Rio Grande Valley, Texas, 1986-1997

The ocelot (Felis pardalis) is an endangered neotropical cat distributed within a small range in the Lower Rio Grande Valley (LRGV), in Texas, U.S.A. Studies of the impacts of environmental contaminants in wild cats are few. Approximately one fourth of the estimated population (about 100) of ocelots in the LRGV was sampled to evaluate the impacts of chlorinated pesticides, polychlorinated biphenyls, and trace elements on the population. Hair was collected from 32 ocelots trapped between 1986-1992, and blood was collected from 20 ocelots trapped between 1993-1997. A few blood samples were obtained from individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were also analyzed. DDE, PCBs, and Hg were some of the most common contaminants detected in hair and blood. Mean Hg levels in hair ranged from 0.5 to 1.25 ??g g-1 dw, Se from 1.5 to 3.48 ??g g-1 dw, and Pb from 0.56 to 26.8 ??g g-1 dw. Mean DDE concentrations in plasma ranged from 0.005 ??g g-1 ww to 0.153 ??g g-1 ww, and PCBs ranged from 0.006 ??g g-1 ww to 0.092 ??g g-1 ww. Mean Hg levels in red blood cells ranged from 0.056 ??g g-1 dw to 0.25 ??g g-1 dw. Concentrations of DDE, PCBs, or Hg, did not increase significantly with age, although the highest concentrations of DDE and Hg were found in older animals. Overall, concentrations of DDE, PCBs, and Hg were low and at levels that currently do not pose any threat to health or survival of the ocelot. This is further supported by good reproduction of the ocelot in the LRGV, where adult females averaged about 1.5 kittens/litter. Thus, it seems that the current major threat to recovery of the ocelot in the LRGV may be habitat loss, although potential impacts of new generation pesticides, such as organophosphorus and carbamate insecticides need further study.The ocelot (Felis pardalis) is an endangered neotropical cat distributed within a small range in the Lower Rio Grande Valley (LRGV), in Texas, U.S.A. Studies of the impacts of environmental contaminants in wild cats are few. Approximately one fourth of the estimated population (about 100) of ocelots in the LRGV was sampled to evaluate the impacts of chlorinated pesticides, polychlorinated biphenyls, and trace elements on the population. Hair was collected from 32 ocelots trapped between 1986-1992, and blood was collected from 20 ocelots trapped between 1993-1997. A few blood samples were obtained from individuals recaptured two or three times. Tissue samples from 4 road-killed ocelots were also analyzed. DDE, PCBs, and Hg were some of the most common contaminants detected in hair and blood. Mean Hg levels in hair ranged from 0.5 to 1.25 ??g g-1 dw, Se from 1.5 to 3.48 ??g g-1 dw, and Pb from 0.56 to 26.8 ??g g-1 dw. Mean DDE concentrations in plasma ranged from 0.005 ??g g-1 ww to 0.153 ??g g-1 ww, and PCBs ranged from 0.006 ??g g-1 ww to 0.092 ??g g-1 ww. Mean Hg levels in red blood cells ranged from 0.056 ??g g-1 dw to 0.25 ??g g-1 dw. Concentrations of DDE, PCBs, or Hg, did not increase significantly with age, although the highest concentrations of DDE and Hg were found in older animals. Overall, concentrations of DDE, PCBs, and Hg were low and at levels that currently do not pose any threat to health or survival of the ocelot. This is further supported by good reproduction of the ocelot in the LRGV, where adult females averaged about 1.5 kittens/litter. Thus, it seems that the current major threat to recovery of the ocelot in the LRGV may be habitat loss, although potential impacts of new generation pesticides, such as organophosphorus and carbamate insecticides need further study.The impacts of PCBs, trace elements, and chlorinated pesticides on the endangered ocelot population in the Lower Rio Grande Valley, TX, was studied. Hair was sampled from 32 animals trapped during 1986-92 and blood was collected from 20 ocelots trapped during 1993-97. Mean mercury, selenium, and lead levels in hair were in the 0.5-1.25, 1.5-3.48, and 0.56-26.8 ??g/g

Environmental Monitoring and Assessment↗
USGS1998

Simulating cholinesterase inhibition in birds caused by dietary insecticide exposure

We describe a stochastic simulation model that simulates avian foraging in an agricultural landscape to evaluate factors affecting dietary insecticide exposure and to predict post-exposure cholinesterase (ChE) inhibition. To evaluate the model, we simulated published field studies and found that model predictions of insecticide decay and ChE inhibition reasonably approximated most observed results. Sensitivity analysis suggested that foraging location usually influenced ChE inhibition more than diet preferences or daily intake rate. Although organophosphorus insecticides usually caused greater inhibition than carbamate insecticides, insecticide toxicity appeared only moderately important. When we simulated impact of heavy insecticide applications during breeding seasons of 15 wild bird species, mean maximum ChE inhibition in most species exceeded 20% at some point. At this level of inhibition, birds may experience nausea and/or may exhibit minor behavioral changes. Simulated risk peaked in April–May and August–September and was lowest in July. ChE inhibition increased with proportion of vegetation in the diet. This model, and ones like it, may help predict insecticide exposure of and sublethal ChE inhibition in grassland animals, thereby reducing dependence of ecological risk assessments on field studies alone.

Ecological Modelling↗
USGS1995

Contaminants in fishes from great lakes-influenced sections and above dams of three Michigan Rivers: III. Implications for health of bald eagles

Recently, there have been discussions of the relative merits of passage of fishes around hydroelectric dams on three rivers (Au Sable, Manistee, and Muskegon) in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on bald eagles that could consume such fishes from above and below dams on the three primary rivers. The hazard assessments were verified by comparing the reproductive productivities of eagles nesting in areas where they ate primarily fish from either above or below dams on the three primary rivers, as well as on two additional rivers in Michigan, the Menominee and Thunder Bay. Concentrations of organochlorine insecticides (OCI), polychlorinated biphenyls (total PCBs), 2,3,7,8-tetrachlorodibenzo- p -dioxin equivalents (TCDD-EQ), and total mercury (Hg) were measured in composite samples of fishes from above and below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Mean concentrations of OCI, total PCBs, and TCDD-EQ were all greater in fishes from below the dams than in those from above. The hazard assessment indicated that current concentrations of Hg and OCI other than DDT (DDT + DDE + DDD) in fish from neither above nor below dams would present a significant hazard to bald eagles ( Haliaeetus leucocephalus ). Both total PCBs and TCDD-EQ in fishes from below the dams currently present a significant hazard to bald eagles, since their mean hazard quotients (HQ) were all greater than one.

Michigan↗
USGS1994

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. I: Concentrations of organo chlorine insecticides, polychlorinated biphenyls, dioxin equivalents, and mercury

Fishes of the Great Lakes contain hazardous chemicals such as synthetic halogenated hydrocarbons and metals. These fish can move from the lakes into the Great Lakes tributaries of Michigan. In doing so, they transport concentrationsof contaminants which may represent a risk to wildlife. Concentrations of mercury (Hg), total polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachlorodibenzo- p -dioxin equivalents (TCDD-EQ), total DDT complex, aldrin, endrin, dieldrin, heptachlor, heptachlor epoxide, lindane, hexachlorobenzene, cis -chlordane, oxychlordane, endosulfan-I, methoxychlor, trans -chlordane, and trans -nonachlor were determined in composite samples of fishes from above and below Michigan hydroelectric dams, which separate the fishes which have access to the Great Lakes from fishes that do not. Mean concentrations of total PCBs, TCDD-EQ, DDT, and most of the other pesticides were greater in composite samples of six species of fishes from below than above the dams on the Au Sable, Manistee, and Muskegon Rivers. Concentrations of mercury, were the same or greater above the dams than below. However, this difference was statistically significant only on the Au Sable. Mercury concentrations ranged from less than 0.05 mg/kg to 0.73 mg Hg/kg, ww. Total concentrations of PCBs ranged from 0.02 to 1.7 mg/kg, ww. Concentrations of 2,3,7,8-tetrachlordibenzo- p -dioxin equivalents varied among fishes and locations. The concentrations of TCDD-EQ ranged from 2.4 to 71 μg/kg, ww, with concentrations in carp being the greatest. Concentrations of TCDD-EQ were greater than the concentrations which would be expected to occur, due solely to the presence of polychlorinated dibenzo- p -dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and technical mixtures of PCBs.

Michigan↗
USGS1994

Contaminants in fishes from Great Lakes-influenced sections and above dams of three Michigan rivers. II: Implications for health of mink

Populations of mink ( Mustela vison ) have declined in many areas of the world. Such declines have been linked to exposures to synthetic, halogenated hydrocarbons. In the Great Lakes region, mink are fewer in areas along the shore of the Great Lakes and their tributaries where mink have access to fish from the Great Lakes. Recently, there has been discussion of the relative merits of passage of fishes around hydroelectric dams on rivers in Michigan. A hazard assessment was conducted to determine the potential for adverse effects on mink, which could consume such fishes from above or below dams on the rivers. Concentrations of organochlorine insecticides, polychlorinated biphenyls (PCBs), 2,3,7,8-tetrachloridibenzo- p -dioxin equivalents (TCDD-EQ), and total mercury were measured in composite samples of fishes from above or below hydroelectric dams on the Manistee and Muskegon Rivers, which flow into Lake Michigan, and the Au Sable River, which flows into Lake Huron. Concentrations of organochlorine insecticides, PCBs, and TCDD-EQ were all greater in fishes from below the dams than those from above. Concentrations of neither organochlorine insecticides nor mercury in fishes are currently a risk to mink above or below the dams. All of the species of fishes collected from downstream of the dams contained concentrations of PCBs and TCDD-EQ, which represent a hazard to mink. The hazard index for PCBs was less than one for the average of all species from the upstream reaches of the Manistee and Au Sable Rivers, but not the Muskegon. The hazard index (concentration in fish/NOAEC) was greater than 1 for all of the species collected from below the dams, in all three rivers. The greatest hazard index was observed for carp ( Cyprinus carpio ) downstream on the Muskegon River. Because the concentrations of PCBs used in the hazard assessment were corrected for relative toxic potencies, the hazard ratios based on PCBs should be similar to those based on TCDD-EQ. This was found to be true. Thus, either total PCBs or TCDD-EQ could be used as the critical toxicant in the hazard assessment. However, if uncorrected concentrations of PCBs, expressed as Aroclors ® , were used in the hazard assessment, the toxicity of the weathered mixture would have been underestimated by approximately five-fold, and, in that instance, TCDD-EQ would be the critical contaminant for the hazard assessment. The average maximum allowable percentage of fish from above the dams, which would result in no observable adverse effects of TCDD-EQ, was 70%. Based on the average TCDD-EQ concentrations in the fishes, an average of 8.6% of the diet could be made up of fishes from below dams on the rivers. The most restrictive daily allowable intakes were for carp on the Muskegon and steelhead trout ( Onchorhyncus mykiss ) on the Manistee Rivers. Only 2.7% of the diet could be made up of these two species from influenced portion of the Au Sable River, they would be exposed to 390 μg PCBs and 8.55 ng of TCDD-EQ per day, respectively (Giesy et al. 1994b). Thus, it would take 15.1 or 77 days for mink to receive their total annual dose of PCBs or TCDD-EQ, respectively. At least for chinook salmon, the critical contaminant for the purposes of hazard assessment would be total concentrations of PCBs. Consuming chinook salmon for as little as 2 weeks would deliver the annual allowable dose of PCBs to mink.

Michigan↗