Funcionalidad física de los arrecifes de coral en el Pacífico mexicano (Bahía de Los Ángeles, Bahía de La Paz, Bahía de Banderas y Bahías de Huatulco

Physical functionality of coral reefs in the mexican Pacific (Bahía de Los Ángeles, Bahía de La Paz, Bahía de Banderas y Bahías de Huatulco)

CLAUDIA REBECA NAVARRETE TORICES (2023, [Tesis de maestría])

Los corales son la base en la estructura y funcionamiento de los arrecifes. Sin embargo, en las últimas décadas, estos ecosistemas han sufrido un deterioro debido a presiones naturales, antrópicas y factores de gran escala como el cambio climático. En general, la cobertura de corales ha disminuido y aunque en algunos casos se ha observado su recuperación, la caracterización de la funcionalidad de la estructura física de los sistemas ha sido escasamente explorada. El presente trabajo evalúa la funcionalidad física de los arrecifes de coral en cuatro áreas a lo largo del Pacífico mexicano, empleando el Índice Funcional Arrecifal (IFA). El IFA considera la tasa de calcificación, la complejidad estructural y la abundancia de las especies de coral de en cada sitio; los valores que el índice puede adquirir varían de cero a uno, son valores cercanos a cero refieren a un arrecife con baja funcionalidad, mientras que los valores cercanos a uno indican un arrecife con alta funcionalidad. La cobertura coralina promedio de las cuatro áreas fue 35.62 ± 15.01%, siendo Bahías de Huatulco (BH) quien presentó la mayor cobertura coralina con 55.61 ± 21.94 %, mientras que Bahía de Los Ángeles (BLA) tuvo la menor cobertura coralina (17.16 ± 0.08 %). El IFA promedio de las áreas fue de 0.54 ± 0.12, y con base en el indicador, BH tuvo una mayor funcionalidad con un IFA de 0.68 ± 0.09, mientras que BLA tuvo una menor funcionalidad (0.34 ± 0.08). Los corales del género Pocillopora fueron los que mayor IFA aportaron en la mayoría de los sitios excepto en BLA que es representada por Porites panamensis. El coral con mayor coeficiente funcional (CF) fue Pocillopora grandis con 0.81, perteneciente a Bahía de Banderas (BB) y por ende fue el coral que mayor contribuyó al IFA en el área. El valor del IFA de 0.68 a lo largo del Pacífico mexicano, nos indica que tiene una alta complejidad estructural, debido a la forma de los corales Pocillopora que son clave para la permanencia de los arrecifes del área.

Corals are the basis for the structure and functioning of reefs. However, in recent decades, these ecosystems have suffered deterioration due to natural and anthropogenic pressures and large-scale factors such as climate change. In general, coral cover has decreased and although in some cases their recovery has been observed, the characterization of the functionality of the physical structure of the systems has been barely explored. This study evaluates the physical functionality of coral reefs in four areas along the Mexican Pacific, using the Reef Functional Index (IFA). The IFA considers the calcification rate, structural complexity, and abundance of coral species at each site; The values that the index can acquire vary from zero to one, values close to zero refer to a reef with low functionality, while values close to one indicate a reef with high functionality. The average coral cover of the four areas was 35.62 ± 15.01%, with Bahías de Huatulco (BH) having the highest coral cover with 55.61 ± 21.94%, while Bahía de Los Ángeles (BLA) had the lowest coral cover (17.16 ± 0.08%). The average IFA of the areas was 0.54 ± 0.12, and based on the indicator, BH had higher functionality with an IFA of 0.68 ± 0.09, while BLA had lower functionality (0.34 ± 0.08). Corals of the genus Pocillopora were the ones that contributed the highest IFA in most of the sites except in BLA, which is represented by Porites panamensis. The coral with the highest functional coefficient (CF) was Pocillopora grandis with 0.81, belonging to Bahía de Banderas (BB) and therefore was the coral that contributed the greatest to the IFA in the area. The IFA value of 0.68 along the Mexican Pacific indicates that it has a high structural complexity, due to the shape of the Pocillopora corals that are key to the permanence of the reefs in the area.

Corales, Pocillopora, Índice de función arrecifal, Pacífico mexicano Corals, Pocillopora, mexican Pacific, Reef Functional Index BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA OTRAS ESPECIALIDADES DE LA BIOLOGÍA OTRAS OTRAS

Análisis isotópico en plumas del Charrán mínimo (Sternula antillarum) para inferir su ecología trófica

Isotope analysis in feathers of the Least Tern (Sternula antillarum) to infer its trophic ecology

Andehui Danay Morales Flores (2024, [Tesis de maestría])

El análisis isotópico de plumas primarias utilizando las razones isotópicas δ13C y δ15N permitió estimar la amplitud y superposición del nicho trófico de los conjuntos de las colonias reproductivas de adultos y volantones del charrán mínimo. Se infirió la amplitud del nicho por medio del área de la elipse estándar estimada por métodos Bayesianos (SEAB), se encontró que existen diferencias entre el nicho trófico de adultos y volantones, pues los adultos tienen valores de la media SEAB de 16.3‰2 hasta 28.4‰2 y los volantones de 44.8‰2 hasta 75.5‰2, esto podría ser debido a diferencias en cuanto a las presas seleccionadas y la ubicación geográfica de los adultos durante la muda de las primarias. Por otro lado, la superposición del nicho indicó la similitud entre los adultos de diferentes colonias, por lo cual, se consideró que los adultos de algunas colonias podrían compartir un sitio de invernada o bien la temporalidad en la muda de las primarias. Además, se cumplió con el objetivo de caracterizar la variabilidad de las firmas isotópicas de carbono y nitrógeno durante el crecimiento secuencial de las plumas primarias por medio de los modelos aditivos generalizados y se observó la variabilidad entre las primarias utilizando las anomalías respecto a la media local de cada colonia, lo cual permitió diferenciar estrategias de alimentación específicas para ciertos conjuntos y la variabilidad en la dieta. La búsqueda bibliográfica de los sitios potenciales de migración en invierno más los mapas de gradientes isotópicos de δ13C permitió determinar que el Océano Pacífico Oriental Tropical es la región geográfica relacionada con la distribución δ13C en plumas primarias del charrán mínimo y es el sitio más probable de invernada.

The isotopic analysis of primary feathers using the isotopic ratios of δ13C and δ15N allowed the estimation of the breadth and overlap of the trophic niche of adult and fledgling least terns. Niche breadth was inferred through the standard ellipse area (SEAB) estimated by Bayesian methods. We found differences between the trophic niche of adults and fledglings, as adults presented mean SEAB values from 16.3‰2 to 28.4‰2 and fledglings from 44.8‰2 to 75.5‰2. This could be due to differences in the prey selected and the geographical location of the adults during the molt of the primaries. The overlap of these values among adults indicates similarity in prey selection and location between the adults of different colonies. Therefore, it was considered that the adults of some colonies could share a wintering site during the period of molt of the primary feathers. We characterized the variability of carbon and nitrogen isotopic signatures during the sequential growth of primary feathers through generalized additive models and the variability between primaries using the anomalies of these signatures and the local mean for each colony. This allowed us to differentiate specific feeding strategies of individual least terns and the variability in their diet. The bibliographic search for potential migration and wintering sites found published maps of δ13C isotopic gradients in the Tropical Eastern Pacific Ocean that correspond to the δ13C distribution in primary feathers of the least tern, indicating a potential wintering area for this species.

isótopos, carbono, nitrógeno, ave marina, ecología trófica isotopes, seabird, nitrogen, carbon, trophic ecology BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ECOLOGÍA VEGETAL ECOLOGÍA VEGETAL

Adsorption and Photocatalytic Degradation of Methylene Blue in Carbon Nanotubes: A Review with Bibliometric Analysis

Hugo Albeiro Saldarriaga Noreña MARIO ALFONSO MURILLO TOVAR JOSEFINA VERGARA SANCHEZ JEANNETE RAMIREZ APARICIO Lorena Magallón Cacho MARIA LUISA GARCIA BETANCOURT (2023, [Artículo])

Wastewater-containing dyes are an environmental problem. The prime source of dye pollutants is the textile industry, such as paper manufacturing, food processing, leather, pigments, etc. Dye removal from wastewater using nanotechnology has received attention in recent decades thanks to efficient nanomaterials improving traditional technologies. In recent years, multiple research reports on carbon nanotubes for dye removal and photocatalytic dye degradation provided substantial insight into the comprehension of nanotechnology and remediation. This work presents a review and bibliometric analysis of carbon nanotubes for dye removal and photocatalytic dye degradation, which have an environmental impact today. The bibliometric study showed that the current research tendency on carbon nanotubes applied in dye removal and photocatalysis is still growing. According to research, this work observed that carbon nanotubes for dye removal exhibit high removal and efficient photocatalysis activity, indicating the functionality of nanotechnology for environmental remediation. The analysis of the parameters involved in the removal studies, such as temperature and pH, showed adsorption behavior. The photodegradation of methylene blue demonstrated the photocatalytic activity of carbon nanotubes attributed to the sp2 lattice of graphitic configuration.

BIOLOGÍA Y QUÍMICA QUÍMICA adsorption; carbon nanotubes; methylene blue; photocatalysis; photodegradation of methylene blue

La Funcionalidad Física Arrecifal, indicador de la diversidad funcional en ensamblajes de peces de arrecifes en el Parque Nacional Islas Marietas, Nayarit, México

Reef Physical Functionality, indicator of functional diversity on reef fishes assemblages from Islas Marietas National Park, Nayarit, Mexico

Luis Mario Montalvo Jaramillo (2023, [Tesis de maestría])

La ecología funcional se basa en el uso de rasgos funcionales; características de las especies (morfológicas, fisiológicas, comportamiento) medidas a nivel individual que influencian el rendimiento de una especie, siendo de gran utilidad para determinar cambios dentro del ecosistema. El presente trabajo busca evaluar la funcionalidad física como indicador de disponibilidad de hábitat de peces y su relación con la diversidad funcional. La funcionalidad física del arrecife se evaluó mediante el IFA integrando datos de cobertura coralina, complejidad estructural y tasa de calcificación. La estructura de los ensamblajes de peces se analizó mediante el cálculo de índices de diversidad funcional (riqueza, equitatividad y divergencia) con base en cuatro rasgos funcionales (tamaño corporal, movilidad, tipo de agregación y dieta). La relación entre la diversidad funcional del ensamblaje y el IFA se evaluó mediante un análisis de regresión lineal. El IFA fue influenciado de manera positiva por la presencia Pocilloporidos al generar un mayor aporte a la funcionalidad física (FF) y consecuentemente, una mayor provisión de hábitat. Por el contrario, el IFA disminuyó con la presencia de Porites panamensis debido a su baja tasa de calcificación.La diversidad funcional de los ensamblajes no presentó variaciones temporales, atribuible a una baja variabilidad entre los sitios debido a una alta cercanía, baja variacion batimétrica y alta conectividad. La relación entre el IFA y la riqueza funcional de los ensamblajes se atribuye a que sitios con mayor funcionalidad física otorgan disponibilidad de hábitat y refugio contra la depredación a especies crípticas, de talla pequeña y juveniles; ya que, especies de este tipo se asocian a hoyos similares a su tamaño corporal y la supervivencia de las mismas aumenta en sustratos más complejos.

Functional diversity it’s based on functional traits; characteristics of species (morphological, physiological, behavior) measured at individual level that impact their performance and have great utility to determine changes within the ecosystem. This work aims to evaluate physical functionality as indicator of fish habitat availability and its relationship with functional diversity. The physical functionality of the reef was evaluated using the RFI, integrating data on coral cover, structural complexity, and calcification rate. The structure of the fish assemblages was analyzed by calculating functional diversity index (richness, evenness, and divergence) based on four functional traits (body size, mobility, type of aggregation and diet). The relationship between functional diversity and RFI was evaluated using linear regression analysis. The RFI was influenced on positive way for the presence of Pocilloporids due to the great contribution to physical functionality (PF) creating more habitat availability. For the other hand, the RFI was influenced on negative way for the presence of Porites panamensis due their low calcification rate. The functional diversity of the assemblages did not present temporal variations, attributable to a low variability between the sites due high proximity, low bathymetric variation and high connectivity. The relationship between RFI and the functional richness of the assemblages is attributed to fact that sites with greater physical functionality provide more availability of habitat and refuge against predation to cryptic, small and juvenile species; species of this type are associate with holes similar to their body size and their survival increases in more complex substrates.

Pacífico Méxicano, Índice de Función Arrecifal, Diversidad Funcional, Arrecife Reef, Functional Diversity, Reef Functional Index, Mexican Pacific BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA OTRAS ESPECIALIDADES DE LA BIOLOGÍA OTRAS OTRAS

ANÁLISIS DE LA APTITUD RECREATIVA ORIENTADA A LA GESTIÓN AMBIENTAL DE LA PLAYA EL COCHÓRIT, SONORA, MÉXICO

GISELA GARCIA MORALES PEDRO ROSALES GRANO Gustavo Padilla Jose Alfredo Arreola Lizárraga Jaqueline García Hernández Alfredo Ortega Rubio Renato Arturo Mendoza Salgado (2017, [Artículo])

"La evaluación de la aptitud recreativa de playas es un asunto clave para diseñar estrategias de manejo. El objetivo de este estudio fue evaluar la aptitud recreativa y proponer una estrategia de manejo en la playa El Cochórit, municipio de Empalme, Sonora. La aptitud recreativa de la playa se evaluó con base en la percepción de los usuarios y en indicadores biofísicos. El valor estimado de la aptitud recreativa de la playa, según la percepción de los usuarios fue de 0.71 (medio) y con base en los indicadores biofísicos fue de 0.47 (medio). La aptitud recreativa de la playa requiere ser mejorada con atención prioritaria en: (1) inversión en infraestructura y servicios, (2) mantenimiento de limpieza, (3) implementación de programas de educación ambiental y (4) monitoreo anual de la calidad sanitaria del agua y de la arena. La estrategia de gestión ambiental debe considerar incluir a la playa El Cochórit en el Programa Playas Limpias de la Comisión Nacional del Agua con el propósito de orientar esfuerzos hacia su certificación como “playa limpia”."

"The assessment of recreational beaches fitness is a key issue to design management strategies. The aim of this work was to evaluate the recreational fitness and propose a management strategy for the Beach El Cochórit, municipality of Empalme, Sonora. The recreational beach fitness was evaluated based on the perception of users, as well as biophysical indicators. The estimated value of recreational suitability of the beach perceived by users was 0.71 (average) and based on the biophysical indicators was 0.47 (average). Fitness recreational beach needs to be improved focusing on: (1) investing in infrastructure and services, (2) maintaining cleanliness, (3) implementing environmental education programs and (4) monitoring annually the sanitary quality of water and sand. The environmental management strategy should consider including the beach El Cochorit in the Clean Beaches Program of the National Water Commission in order to address efforts towards the certification of “clean beach”."

playas recreativas, manejo de playas, indicadores ambientales, percepción pública recreational beaches, management of beaches, environmental indicators, public perception CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOLOGÍA GEOLOGÍA AMBIENTAL GEOLOGÍA AMBIENTAL

Evaluación de la intrusión salina utilizando el método electromagnético transitorio (TEM) y análisis de iones mayores e isótopos estables del agua en el acuífero La Misión, B.C., México

Saline intrusion assessment using transient electromagnetic method (TEM) and analysis of major ions and stable isotopes of water in La Mision aquifer, B.C., Mexico

Yesica Guadalupe Cabrera Sillas (2023, [Tesis de maestría])

El acuífero La Misión constituye una fuente importante de abastecimiento de agua en la zona semiárida de Ensenada, Baja California, México. La explotación intensiva del acuífero puede haber desarrollado el deterioro de la calidad del agua subterránea, y con ello el avance del agua de mar. El presente estudio se centra en la evaluación de la posible intrusión salina en el acuífero costero La Misión a partir de técnicas geofísicas e hidrogeoquímicas. De acuerdo con investigaciones anteriores, se plantea la hipótesis de que el acuífero está afectado por procesos de mezcla de agua de mar principalmente en la franja costera. El estudio geofísico comprende 11 sondeos Transitorios Electromagnéticos (TEM). Además, se recolectaron 18 muestras de agua subterránea en temporada de secas y lluvias, donde se analizaron isótopos estables (δ18O y δ2H) y los principales iones mayores (Na+, K+, Ca2+, Mg2+, Cl-, HCO3, CO32- y SO42-). La inversión de datos geofísicos en 1D revela dos acuíferos en la zona de estudio; 1) el acuífero de depósitos de arena aluvial saturado superficial con un rango de resistividad de 2.1-5.5 Ωm y un espesor <80 m (UH2); 2) el segundo pertenece a un acuífero semiconfinado compuesto por limolitas y areniscas con resistividades de 13.8 a 21.4 Ωm (UH4). Los resultados hidroquímicos muestran que los principales tipos de aguas subterráneas son Ca-Cl, mixtas y Na-Cl. Además, las diversas relaciones iónicas confirmaron el proceso de intercambio iónico inverso donde el Ca2+ y el Mg2+ en la matriz del acuífero se han reemplazado por Na+ en sitios favorables. El cálculo del índice de saturación de minerales indica que las muestras de agua subterránea están saturadas con respecto a los minerales de carbonato. Por lo tanto, estos resultados sugieren que el acuífero costero La Misión está sujeto a la influencia continua de la mezcla de agua de mar, disolución de minerales carbonatados ayudado por la interacción agua-roca, y los procesos de intercambio iónico. Considerando que éstos son los factores determinantes que están controlando la evolución del agua subterránea en esta zona.

The Misión aquifer is an important source of water supply in the semi-arid zone of Ensenada, Baja California, Mexico. Intensive exploitation of the aquifer may have developed groundwater quality deterioration, and the advance of seawater. The present study focuses on the evaluation of possible saline intrusion in the coastal aquifer of La Misión, using geophysical and hydrogeochemical techniques. Based on previous research, it is hypothesized that the aquifer is affected by seawater mixing processes mainly in the coastal strip. The geophysical survey comprises 11 Transient Electromagnetic soundings (TEM). In addition, a total of 18 groundwater samples were collected in dry and post rainy season, where stable isotopes (δ18O and δ2H) and the main major ions (Na+, K+, Ca2+, Mg2+, and Cl-, HCO3-, CO32- and SO42-) were analyzed. One-dimensional inversion geophysical data reveals two aquifers in the study area. 1) the shallow saturated alluvial sand deposit aquifer with a resistivity range of 2.1-5.5 Ωm and a thickness <80 m (UH2). 2) the second belongs to a semi-confined aquifer composed of siltstones and sandstones with resistivities of 13.8 to 21.4 Ωm (UH4). Hydrochemical results show that the main groundwater types are Ca-Cl, mixed and Na-Cl. In addition, the various ionic ratios confirmed the reverse ion exchange process where Ca2+ and Mg2+ in the aquifer matrix have been replaced by Na+ at favorable sites. Calculation of the mineral saturation index indicates that the groundwater samples are saturated with respect to carbonate minerals. Therefore, these results suggest that the coastal Mission aquifer is subject to the continuous influence of seawater mix, dissolution of carbonate minerals aided by water-rock interaction, and ion exchange processes. Considering these processes, the important determining factors that are controlling the evolution of groundwater in this zone.

Agua subterránea, resistividad, interacción agua-roca, índice de saturación, salinidad. Groundwater, resistivity, water-rock interaction, saturation index, salinity. CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO GEOFÍSICA GEOMAGNETISMO Y PROSPECCIÓN MAGNÉTICA GEOMAGNETISMO Y PROSPECCIÓN MAGNÉTICA

Vibrissa growth rate in California sea lions based on environmental and isotopic oscillations

MARTHA PATRICIA ROSAS HERNANDEZ (2018, [Artículo])

Pinniped vibrissae provide information on changes in diet at seasonal and annual scales; however, species-specific growth patterns must first be determined in order to interpret these data. In this study, a simple linear model was used to estimate the growth rate of vibrissae from adult female California sea lions (Zalophus californianus) from San Esteban Island in the Gulf of California, Mexico. The δ15N and δ13C values do not display a marked oscillatory pattern that would permit direct determination of the time period contained in each vibrissa; thus, time (age) was calculated in two ways: 1) based on the correlation between the observed number of peaks (Fourier series) in the δ15N profile and the length of each vibrissa, and 2) through direct comparison with the observed number of peaks in the δ15N profile. Cross-correlation confirmed that the two peaks in the δ15N profile reflected the two peaks in the chlorophyll-a concentration recorded annually around the island. The mean growth rate obtained from the correlation was 0.08 ± 0.01 mm d-1, while that calculated based on the observed number of peaks was 0.10 ± 0.05 mm d-1. Both are consistent with the rates reported for adult females of other otariid species (0.07 to 0.11 mm d-1). Vibrissa growth rates vary by individual, age, sex, and species; moreover, small differences in the growth rate can result in significant differences over the time periods represented by the isotopic signal. Thus, it is important to assess this parameter on a species-by-species basis. © 2018 Rosas-Hernández et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

carbon, nitrogen, animal, California, chemistry, diet, female, island (geological), Mexico, Otariidae, physiology, Animals, California, Carbon Isotopes, Diet, Female, Islands, Mexico, Nitrogen Isotopes, Sea Lions CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Cell carbon content and biomass assessments of dinoflagellates and diatoms in the oceanic ecosystem of the Southern Gulf of Mexico

LORENA PATRICIA LINACRE ROJAS (2021, [Objeto de congreso])

This study assessed the cell carbon content and biomass for genera of dinoflagellates and diatoms in the oceanic ecosystem of the Southern Gulf of Mexico. Carbon content estimates were based on biovolume calculations derived from linear dimension measurements of individual cells and the approximate geometric body shape of each genus. Then, biomass assessments were performed for both groups in two gulf regions (Perdido and Coatzacoalcos) using these carbon content factors and cell abundances. After four seasonal cruises, 11,817 cells of dinoflagellates and 3,412 cells of diatoms were analyzed. Diverse body shapes and cell sizes were observed among 46 dinoflagellate genera and 37 diatom genera. Nano-cells of dinoflagellates (68% &lt;20 μm) and micro-cells of diatoms (77% 20–200 μm, mostly 50–75 μm) were predominant. According to this cell-size structure, on average, diatoms contained 40% more carbon per cell than dinoflagellates. Contrasting carbon content estimates were observed within the genera of both microalgae. Large carbon averages (&gt;10,000 pg C cell-1) were attributed to Gonyaulacal and some occasional genera of dinoflagellates (e.g., Pyrocystis and Noctiluca) and centric diatoms. In contrast, values up to 3 orders of magnitude lower were found for Peridinial and Gymnodinial dinoflagellates and pennate diatoms. Based on these carbon content estimates, which can be considered representative for most of this oceanic ecosystem, seasonal and regional differences were found in the biomass assessments conducted for these functional groups. Overall, dinoflagellates (mostly low-carbon Gymnodinales) had larger depth-integrated biomass than diatoms (mainly rich-carbon centric forms) within the euphotic zone. An exception to it was the late-summer cruise at the Coatzacoalcos region when a surface bloom of centric diatoms was observed in stations influenced by river runoff. This work contributes useful reference information for future ecological studies and models for understanding the biogeochemical functioning of this open-ocean ecosystem. © 2021 Linacre et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Carbon, biomass, Oceanic ecosystem, Southern Gulf of Mexico, Mexico CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA

Waterhole detection using a vegetation index in desert bighorn sheep (Ovis canadensis cremnobates) habitat

Jonathan Gabriel Escobar Flores (2019, [Artículo])

In arid ecosystems, desert bighorn sheep are dependent on natural waterholes, particularly in summer when forage is scarce and environmental temperatures are high. To detect waterholes in Sierra Santa Isabel, which is the largest area of desert bighorn sheep habitat in the state of Baja California, Mexico, we used the normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) from Sentinel-2 satellite images. Waterhole detection was based on the premise that sites with greater water availability, where NDVI was higher, can be identified by their density of vegetation greenness. For the detected waterholes, we estimated the escape terrain (presence of cliffs or steep, rocky slopes) around each by the vector ruggedness measure to determine their potential use by desert bighorn sheep based on the animals’ presence as documented by camera traps. We detected 14 waterholes with the NDVI of which 11 were known by land owners and 3 were unrecorded. Desert bighorn were not detected in waterholes with high values of escape terrain, i.e., flat areas. Waterhole detection by NDVI is a simple method, and with the assistance and knowledge of the inhabitants of the Sierra, it was possible to confirm the presence each waterhole in the field. © 2019 Escobar-Flores et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Article, bighorn sheep, environmental aspects and related phenomena, environmental parameters, habitat, Mexico, nonhuman, normalized difference vegetation index, normalized difference water index, water availability, waterhole, animal, bighorn sheep, CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS CIENCIA FORESTAL CIENCIA FORESTAL

Trophic ecology of Mexican Pacific harbor seal colonies using carbon and nitrogen stable isotopes

MARICELA JUAREZ RODRIGUEZ (2020, [Artículo])

There is limited information that provides a comprehensive understanding of the trophic ecology of Mexican Pacific harbor seal (Phoca vitulina richardii) colonies. While scat analysis has been used to determine the diet of some colonies, the integrative characterization of its feeding habits on broader temporal and spatial scales remains limited. We examined potential feeding grounds, trophic niche width, and overlap, and inferred the degree of dietary specialization using stable carbon and nitrogen isotope ratios (δ13C and δ15N) in this subspecies. We analyzed δ13C and δ15N on fur samples from pups collected at five sites along the western coast of the Baja California Peninsula, Mexico. Fur of natal coat of Pacific harbor seal pups begins to grow during the seventh month in utero until the last stage of gestation. Therefore pup fur is a good proxy for the mother's feeding habits in winter (∼December to March), based on the timing of gestation for the subspecies in this region. Our results indicated that the δ13C and δ15N values differed significantly among sampling sites, with the highest mean δ15N value occurring at the southernmost site, reflecting a well-characterized north to south latitudinal 15N-enrichment in the food web. The tendency identified in δ13C values, in which the northern colonies showed the most enriched values, suggests nearshore and benthic-demersal feeding habits. A low variance in δ13C and δ15N values for each colony (&lt;1‰) and relatively small standard ellipse areas suggest a specialized foraging behavior in adult female Pacific harbor seals in Mexican waters. © 2020 Juárez-Rodríguez et al.

carbon, delta carbon 13, delta nitrogen 15, isotope, nitrogen, unclassified drug, carbon, nitrogen, Article, correlational study, feeding behavior, latitude, Mexico, nonhuman, organism colony, Pinnipedia, population abundance, species richness, troph BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA ANIMAL (ZOOLOGÍA) BIOLOGÍA ANIMAL (ZOOLOGÍA)