The green sea turtle (Chelonia mydas) is listed as an endangered species in Mexico and presents significant conservation challenges due to its changing migratory patterns throughout its life stages and the thousands of kilometers it travels between its birthplace and foraging grounds. To understand the natal origins of green sea turtle populations of the Baja California peninsula, samples were collected over two years from two populations at opposite sides in the Baja California peninsula, with one located in the middle of the Gulf of California (Bahía de Los Ángeles [BLA]) and the other on the Pacific Western coast (Complejo Lagunar Ojo de Liebre [CLOL]), both located in Mexico. The mitochondrial DNA control region was sequenced and compared with potential source populations in the Pacific Ocean. The mixed-stock analysis indicated that both Baja California populations originate from nesting sites in the Eastern Pacific, primarily from the Revillagigedo Islands and the coast of Michoacán. Statistical analysis was used to evaluate the contribution of turtles originating from the Revillagigedo Islands and the coast of Michoacán to both sites, which found that statistically both Revillagigedo and Michoacán contribute the same number of individuals to the BLA and CLOL zones (Bayes Factor <1.9 for both populations [1.59 and 1.14, respectively]).

The Cape Striped Racer (Masticophis aurigulus) is an elusive snake endemic to Baja California Sur, Mexico. Earlier reports of its diet are unverified, and both its geographic distribution and elevational range are inconsistently documented. Here, we announce ingestion by M. aurigulus of an Erinnyis moth pupa and the lizard Petrosaurus thalassinus, representing the only confirmed prey for this species. We also document new records that extend the distribution of M. aurigulus to the Sierra Las Cacachilas, Sierra La Gata, Sierra El Novillo, and western Sierra La Laguna. These records clarify that the species is not restricted to the higher elevations of the Sierra La Laguna as often indicated, yet the known upper and lower limits remain imprecise (sea level to 1750 m, approximately). We underscore the evergreen need for ecological and distributional information to be based on independently verifiable evidence.

Inter-individual variability is the range of phenotypes within a population and can shape adaptive responses to environmental change. However, how temperature influences this variability remains unclear despite its importance for predicting population resilience to warming. We tested how rearing temperature (15°C and 22°C) affects both trait means and variability in time to stage, size, oxygen consumption rate (V˙O2) and swim speed in Baja California chorus frog (Pseudacris hypochondriaca) tadpoles. Mean time to stage and morphological traits decreased at 22°C, while mass-specific V˙O2 and swim speed increased. Variance (s2, absolute variation) was lower at 22°C for time to stage and mass, higher for mass-specific V˙O2, and similar for length and swim speed. Coefficient of variation (CV, relative variation) was higher at 22°C for mass, tail length and depth, and mass-specific V̇O2, indicating trait-specific changes in canalization. Log-transformed Q10 response ratios for trait means (lnRRQ10), variance (lnVRQ10) and CV (lnCVRQ10) revealed strong thermal sensitivity for means but more limited and trait-specific responses in variability. Thus, temperature effects on variability are trait-specific and variability does not always change with, or in the same direction as, trait means. These phenotypic changes may have ecological consequences that influence physiological performance during subsequent life stages. This article is part of the theme issue 'Embracing variability in comparative physiology: why it matters and what to do with it'.

Obligately intracellular rickettsiae cause a broad spectrum of disease in humans and animals, ranging from mild illness to life-threatening infections. Multiple species co-circulate along the southern United States of America-northern Mexico border, yet their seroprevalence in susceptible hosts remains incompletely understood. Dogs serve as key amplifying hosts for several of these pathogens, including Rickettsia rickettsii and Rickettsia massiliae, and have been shown to be infected by flea-borne Rickettsia typhi and Rickettsia felis. To better characterize exposure and potential co-infection patterns, we conducted a large binational seroepidemiologic study of 779 dogs from urban households and shelter settings across seven subregions along both sides of the border. Using a custom multiplex micro-immunofluorescence assay, we simultaneously screened for antibodies to R. rickettsii, R. massiliae, R. typhi, and R. felis. Overall, 41.2% of dogs were seroreactive to at least one pathogen, with the highest seroprevalence for R. felis (19.3%), followed by R. massiliae (15.7%), R. typhi (14.5%), and R. rickettsii (9.8%). Co-seroreactivity was common, particularly between R. typhi and R. felis, with 34.2% of R. typhi-seroreactive samples also seroreactive to R. felis, and 16.7% exhibiting high titers to both. In contrast, R. rickettsii and R. massiliae showed limited overlap (15.2% co-seroreactive; 6.4% with high titers), suggesting possible cross-protection or competitive exclusion. Spatial analyses revealed distinct geographic patterns: R. massiliae predominated in western Baja California, R. rickettsii was concentrated in Mexicali and the Rio Grande Valley, and R. felis was widely distributed. Seroreactivity patterns were generally consistent across age and sex but varied modestly between shelter and neighborhood dogs, particularly for R. typhi. These findings highlight the complex ecology of rickettsial pathogens in a binational context, underscore the importance of dogs as sentinels for human risk, and provide a foundation for future studies on vector-host-pathogen interactions, cross-protective immunity, and spatial epidemiological risk.

Kelp forests are experiencing extreme declines globally, yet local social-ecological factors may mediate their responses to climate perturbations. Using a combination of long-term field surveys (2016–2023) and satellite data (2004–2023), we examined the regional effects of the 2014–2016 marine heatwaves regime on kelp forest ecosystems along a 600 km latitudinal gradient in Baja California, Mexico. We documented three distinct geographical subregion trajectories: (1) a remarkable resilience of giant kelp Macrocystis pyrifera , at its thermal limits in the southern subregion, recovering 95% of the historical canopy area despite experiencing the highest temperatures; (2) understory-dominated state in the mid-subregion, with a 96% decrease in M. pyrifera canopy, where understory brown macroalgae filled the ecological niche left by declining giant kelp, maintained by moderate herbivore densities; and (3) a shift to an urchin barren alternative stable state in the northern subregion, characterized by a 2,485% increase in herbivore densities from 2016 to 2023 —dominated by purple sea urchin Strongylocentrotus purpuratus (44%)— and a 95% reduction in giant kelp canopy area compared to pre-warming baseline. The southern subregion’s resilience was associated with high predators’ (10.26 ± 5.63 per 60 m²) and low herbivores’ (25.20 ± 8.89 per 60 m²) densities, dominated by turban snails Megastraea spp. (83%) with S. purpuratus absent. In contrast, the northern subregion’s shift from kelp forests to urchin barrens coincided with low predator abundances (5.05 ± 2.32 per 60 m²), potentially linked to fragmented fisheries management. Our findings challenge the assumption that range-edge populations are inherently more vulnerable to warming and underscore how local biological factors and management approaches can either enhance or compromise ecosystem resilience to climate stress. These divergent trajectories suggest that while temperature acts as an initial driver of change, the persistence of alternative states is governed by ecological feedback involving predator-herbivore dynamics, herbivores’ assemblages, and management contexts, providing insights for developing climate-adaptive conservation strategies under intensifying global environmental change.

Purpose This paper aims to conceptualize diasporic medication tourism and examine the factors influencing the revisit intention of diasporic medication tourists to the border city of Tijuana, Baja California. Design/methodology/approach Based on the push–pull model, four constructs were examined: medication availability (MA) and cultural proximity (CP) (push) and medication quality (MQ) and medication price (MP) (pull). An online survey was conducted with 384 diasporic medication tourists in Tijuana, Mexico, who reported repeated medication purchases from local pharmacies. Findings The results indicate that MA, CP and MQ significantly influence diasporic medication tourists’ revisit intention, while MP shows no significant effect. Practical implications The findings suggest that pharmacies and destination stakeholders in border regions can strengthen diasporic visitors’ loyalty by prioritizing consistent MA, culturally familiar service environments and credible quality assurance. At the policy level, enhanced binational coordination and regulatory clarity may support safe, efficient and culturally responsive pharmaceutical access for diasporic communities. Originality/value This study advances research on medication tourism by reframing diasporic medication travel as a trust-based and culturally embedded form of cross-border pharmaceutical mobility. It proposes a context-sensitive model suited to border regions where developed and developing pharmaceutical systems intersect.

Over 80% of tuberculosis cases in the United States are due to reactivation of untreated latent tuberculosis infection (LTBI), most of whom were foreign born. LTBI treatment can greatly lower the risk of progression to active TB disease, and shorter treatment regimens increase the potential of migrants and other persons in vulnerable conditions, to complete treatment. We conducted across-sectional study to assess willingness to complete a one-month course of LTBI treatment among internal and international migrants living in Tijuana, BC, Mexico, and to identify factors associated with treatment unwillingness between November 2020 and April 2021. Prior to administering TB skin tests (TST), participants were asked if they would accept LTBI treatment if indicated by test results and clinical examination. Recruitment occurred in migrant shelters throughout Tijuana and at a storefront office conducting research and harm reduction services for people who use drugs. Among 595 participants, 80.4% were living in shelters, 3.5% were recruited at shelters but living independently, and 16.1% were recruited through the storefront office. Overall, 71 (11.9%) indicated that they were unwilling to take LTBI treatment and 109 (18.3%) had positive TST results. Unwillingness to take LTBI treatment was more common among participants from the storefront office compared to the shelter (64.6% vs. 1.8%, p<0.001). Since only 1.8% of shelter participants were unwilling to receive treatment, multivariable Poisson regression with robust variance estimation via GEE for identifying factors independently associated with LTBI treatment unwillingness was restricted to storefront participants. Treatment unwillingness among storefront participants was positively associated with perceiving health status as "good" or "very good" (prevalence ratio [PR]=2.37, 95% confidence interval [CI]: 1.52, 3.99) and heroin use in the past six months (PR=1.70; 95% CI: 1.33, 2.19). Unstable housing was reported as a barrier to treatment. These findings suggest that most migrants in Tijuana were willing to receive short-course LTBI treatment if indicated, yet willingness was lower among those at greatest risk of TB. Efforts to increase testing and treatment, as well as further research on overcoming barriers to treatment willingness are needed.

This article presents research on the relationship between emotional intelligence and the effectiveness of business leaders in La Paz, Baja California Sur. This study does not evaluate objective work efficiency, but rather the perception that leaders have about their own performance and about the role that their emotional skills play in that performance. It is hypothesized that leaders with greater self-perception of emotional intelligence show higher levels of self-perception of effectiveness in the performance of their organizational functions. The research was carried out using a mixed approach, which combined the application of a structured questionnaire to 100 leaders of companies of different sizes: small, medium and large. In addition, six semi-structured interviews were conducted with selected leaders. The variables analyzed in the questionnaire include self-awareness, self-regulation, empathy, social skills and motivation, five competencies based on the model proposed by Daniel Goleman. The results show that leaders have predominantly positive self-perception in all the dimensions evaluated. Active listening (90%), emotion recognition (80%) and management of emotions and thoughts (80%) stand out, followed by motivation and a positive attitude (74%). Overall, the findings support the hypothesis, showing that greater emotional self-awareness is associated with a higher perception of effectiveness in business leadership. Likewise, the results suggest that emotional intelligence is a key resource to strengthen the perceived performance of leaders.

Increasing temperature and decreasing precipitation threaten the extent, persistence, and dynamics of snow across spatial scales, particularly ephemeral snow in Mediterranean mountain regions. This study estimates ephemeral snow cover and snow water equivalent (SWE) in the Sierra de San Pedro Mártir, Baja California, Mexico, using open-access datasets and remote sensing. Camera trap images and limited in situ data were used to calibrate the normalized difference snow index (NDSI) for snow detection and to estimate SWE and topographic effects on SWE from 2002 to 2023, encompassing wet, dry, and normal years. The optimal NDSI threshold for snow detection was 6.4 for MODIS Terra and 5.3 for MODIS Aqua, substantially lower than thresholds commonly reported for seasonal snowpacks in forested regions. In wet years, snowfall contributed up to 20% of annual precipitation, compared with ~13% in dry years. In normal years, the average SWE is 70 mm (24% of annual precipitation). SWE increased by 30% (91 mm) during wet years and decreased by 21% (55 mm) during dry years. Eastness (aspect) was the only statistically significant topographic predictor of SWE for MTerra, with higher SWE values observed on west-facing slopes. This study provides the first quantitative assessment of ephemeral SWE dynamics in a Mexican Mediterranean mountain system and establishes a framework for monitoring marginal snowpacks under increasing climatic variability.

Abstract Amagmatic geothermal systems in coastal locations are promising energy resources, yet the processes that localize and sustain their hot‐spring discharge remain unclear. We investigate La Jolla Beach (NW Baja California, Mexico)—one of the hottest known examples worldwide (∼100°C)—using large‐scale 3D coupled thermal–hydraulic simulations. The models are calibrated against observed temperature, salinity, surface area and location of the springs, and verified using meteoric‐water residence times. The results imply that a highly permeable coastal segment of the Agua Blanca Fault (ABF) transfers meteoric water from a hinterland recharge zone to the coast via deep (&gt;5 km) circulation. Within the coastal fault, dense seawater forms a hydraulic barrier to the meteoric water, while thermal buoyancy steepens the meteoric–seawater interface and creates a near‐vertical upflow plume that focuses hot, mixed fluids to the shoreline, resulting in high discharge temperatures. Tracer simulations indicate that deep fault flow is supplied approximately equally by infiltration through the exposed fault trace and by lateral inflow from the surrounding fractured country rocks. This underscores the system's inherently 3D nature and the capacity of regional faults to collect recharge from broad catchments, even where overall infiltration rates are low. Permeable sediments draped over a basement high and bounded by less‐permeable sediments focus the hot upwelling water at La Jolla Beach. Our findings explain the thermal‐hydraulic coupling that controls amagmatic coastal fault–controlled geothermal systems, providing a basis to assess the geothermal potential of analogous systems worldwide.

Geochemical controls on silicification and biofilm stabilization in an intertidal hydrothermal spring: evidence from Puertecitos, Baja California

Predicting how species will respond to global change requires understanding how environmental drivers shape both neutral and adaptive genetic variation across space. The kelp Eisenia arborea is a thermally tolerant foundation species spanning more than 3000 km of coastline and a broad latitudinal temperature gradient in the Northeast Pacific, yet how environmental and demographic processes influence genomic and population structure remain unclear. We used genome-wide ddRAD sequencing to investigate patterns of genetic diversity, connectivity and local adaptation in E. arborea across two depths and ~2700 km of coastline. We detected strong genetic differentiation between northern (British Columbia, Canada) and southern (Baja California, Mexico) populations, indicating limited gene flow across the species' broad range. Southern populations also had the lowest genetic diversity and highest inbreeding, broadly consistent with expectations for populations occupying environmentally marginal portions of a species' range. However, the two southernmost populations (~200 km apart) were highly similar and well connected, whereas mid-range sites were more differentiated, indicating that the geographic range edge population was not genetically isolated as is often hypothesised. Environmental association analyses identified SNPs correlated with both sea surface temperature and depth, revealing signals of local adaptation to broad climatic gradients and fine-scale habitat variation. The combination of high inbreeding, restricted connectivity and local adaptation highlights both the vulnerability and potential conservation value of distinct genetic units, especially warm-adapted southern populations, for maintaining the resilience of these Eisenia forests under ocean warming.

The evolving burden of drug use disorders in Mexico: Secondary data analysis from the global burden of disease study 2021.

Developing replicable social-ecological indices for spatial planning: Evidence from Baja California Sur, Mexico

Small and medium-sized enterprises (SMEs) in Mexicali, Baja California, play a fundamental role in the economic and social progress of the area. These companies are an important source of employment and contribute significantly to the revival of the local economy. The purpose of this study is to contribute to SMEs in Mexicali, Baja California, by discovering how strategic management and innovation can positively impact the profitability of small and medium-sized enterprises. The research has a quantitative, non-experimental, correlational, and cross-sectional design. A structured questionnaire on a 5-point Likert scale was administered to a representative sample of 361 establishments determined by probabilistic sampling. The study includes a validation of the relationships between the variables Strategic Management, Innovation, and Profitability using the Structural Equation Modeling (SEM).

Since 2010, the Centro Interdisciplinario de Ciencias Marinas - Instituto Politécnico Nacional (CICIMAR-IPN; La Paz, Mexico) and the Monterey Bay Aquarium (MBA; California, USA) have collaborated on a dolphinfish research program in the Eastern Pacific Ocean to study movement patterns and habitat use of this ecologically, economically, and culturally significant pelagic species. Fish were tagged in waters offshore of both mainland Oaxaca and Baja California. As of December 2024, 244 dolphinfish have been tagged during 13 summer and fall trips off Baja California, and 69 more during 10 winter trips off Oaxaca. Of that total, 153 pop-up archival (PAT) tags have been deployed, with durations ranging from 0 to 141 days (average: 33 days). Conventional tag recapture rate was 3% (n = 5 of 160), while electronic tags showed high rates of early release (n = 33) and non-reporting (n = 43). This large, long-term, novel dataset from 109 successful PAT deployments along with metadata from all 313 individual dolphinfish tagged is now publicly available via the Animal Tracking Network (ATN) and the DataONE Research Workspace.

The upper Miocene Boleo Formation (Baja California Sur, México) provides a record of tectonic controls on mixed evaporite-siliciclastic sedimentation in a transtensional pull-apart basin during continental break-up and onset of seafloor spreading in the central Gulf of California. The thin basal limestone, recently dated at 6.35 ± 0.21 Ma, records abrupt onset of subsidence and rapid marine transgression over a formerly emergent landscape. The siliciclastic member contains coarsening-up mud-sand-gravel parasequences that record progradation of fan deltas into a saline shelf. The laterally equivalent gypsum member consists of shallowing-up parasequences formed by evaporative drawdown in the distal evaporite depocenter. Thin, laterally extensive mudstone and breccia units, which host Cu-Co-Zn stratiform ore deposits, record short-lived pulses of marine transgression, fault activity, hydrothermal activity, and mineralization. Growth strata, internal unconformities, and paleocurrent data record NE tilting on a network of NW-striking syn-depositional normal faults during sediment transport to the northeast. Our results support a model for syn-basinal growth of a large monocline above the tip of a propagating oblique-dextral normal fault at the southwest margin of the Santa Rosalía basin. Large-scale displacement across the monocline was the primary mechanism of subsidence, which likely was enhanced by loading related to mafic intrusions and seafloor spreading in the adjacent Guaymas basin. We propose that marine flooding was geologically instantaneous within existing age uncertainties (± 0.2 m.y.) for &amp;gt;1000 km along the Pacific−North America plate-boundary fault system, consistent with models for rapid acceleration of transtensional strain when the plate boundary became localized in the modern Gulf of California at ca. 7−6 Ma.

BackgroundUncorrected refractive errors (UREs) are the predominant cause of vision impairment and blindness worldwide, despite the availability of eyeglasses as a cost-effective intervention. Sociocultural factors, including restricted access to healthcare and inadequate self-care education, exacerbate the burden of UREs. There is a paucity of studies evaluating UREs in Mexico with comprehensive national coverage across various age groups. This clinic-based study aimed to assess the profile of UREs and associated visual impairment (VI) in Mexico using a substantial sample of individuals seeking care at a large nationwide outpatient network.MethodsWe evaluated UREs and URE-related VI by analyzing eye examination data from 3.6 million outpatients who attended Salud Digna clinics in 2024.ResultsThe national clinic-based prevalence of UREs was 26.5% (980,718 affected individuals, 95% CI:26.5%-26.59%), highest in Baja California Sur state (6,515 affected individuals, 43.8%, 95% CI:42.99%-44.59%), among males aged 40–49 years (71,002 affected individuals, 34.1%, 95% CI:33.91%-34.32%), and females under 10 years (17,132 affected individuals, 32.3%, 95% CI:31.88%-32.67%). Clinic-based prevalence of uncorrected astigmatism, uncorrected hyperopia, uncorrected hyperopia-astigmatism, uncorrected myopia, and uncorrected myopia-astigmatism were 1.3% (48,978 affected individuals, 95% CI:1.31%-1.34%), 10.2% (376,701 affected individuals, 95% CI:10.16%-10.23%), 1.7% (61,171 affected individuals, 95% CI:1.64%-1.67%), 6.4% (235,285 affected individuals, 95% CI:6.34%-6.39%), and 7% (258,583 affected individuals, 95% CI:6.97%-7.02%), with highest rates in Tlaxcala (444 affected individuals, 3.9%, 95% CI:3.54%-4.26%), Tabasco (10,235 affected individuals, 20%, 95% CI:19.66%-20.35%), Baja California Sur (673 affected individuals, 4.5%, 95% CI:4.2%-4.87%), Zacatecas (3,149 affected individuals, 10.2%, 95% CI:9.85%-10.52%), and Tlaxcala (1,504 affected individuals, 13.17%, 95% CI:12.55%-13.8%).The national URE-related VI clinic-based prevalence was 0.89% (32,962 affected individuals, 95% CI:0.88%-0.9%), highest in Hidalgo state (527 affected individuals, 1.8%, 95% CI:1.63%-1.93%) and among those over 80 years (1,457 affected males, 6%, 95% CI:5.97%-6.59%; 2,206 affected females, 5.8%, 5.83%-6.33%). The national clinic-based prevalence of mild, moderate, and severe visual impairment was 0.62% (22,858 affected individuals, 95% CI:0.61%-0.63%), 0.26% (9,683, 95% CI:0.26%-0.27%), and 0.01% (421 affected individuals, 95% CI:0.01%-0.01%).ConclusionsThis outpatient-based study highlights the clinic-based prevalence of UREs and related VI in Mexico, emphasizing the need for improved access to eye care services.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12889-026-26598-9.

ABSTRACT Continental margins are reservoirs of materials of terrestrial and marine origin, and they play a crucial role in understanding the spatial and temporal variability of biogeochemical cycles. This, in turn, provides insights into the development and intensity of oxygen minimum zones (OMZs). In the present investigation, a series of geochemical variables was evaluated, including grain size, organic carbon and nitrogen contents, calcium carbonate, biogenic opal, stable isotopes of carbon and nitrogen, and dissolved oxygen concentration. In order to facilitate comprehension of the interactions and relative importance of the source and the state of organic matter degradation, hydrodynamic processes and dissolved oxygen availability, we analysed samples from the northern border of the Mexican Pacific OMZ. Seven perpendicular transects were sampled from the shallow shelf to the continental slope, where surface sediments were collected at 37 stations. Grain size exhibited a monotonic trend, with very fine sands and organic carbon low on the inner shelf and high clay content and organic carbon on the continental slope. The accumulation and enhanced preservation of organic carbon can be attributed to the high clay content and its characteristically large surface area, which reduces exposure time to dissolved oxygen. This organic carbon was derived mainly from marine siliceous plankton, with a minor contribution from terrestrial organic matter. Cluster and principal component analyses defined two biogeochemical provinces on the south‐western margin of the Baja California Peninsula: (1) a coastal province with high dissolved oxygen concentrations, fine sands and low clay and organic carbon contents, and (2) an oceanic province with low dissolved oxygen concentrations, high fine clay and organic carbon contents, located within the northeastern Pacific OMZ. Both provinces have high inputs of marine organic matter derived mainly from siliceous plankton, that is, diatoms and silicoflagellates.

Water Masses and Summer–autumn Distributional Patterns of Dwarf Hake (Merluccius productus) in a Tropical-subtropical Transition Zone Off the Baja California Peninsula Pacific Coast