Search Results (124)

Ocean warming driven by climate change is altering regional circulation patterns and the balance of hydrodynamic forcings in semi-enclosed seas. Understanding how these changes affect ocean circulation and stratification is critical, as they directly influence marine productivity and ecosystem functioning in highly sensitive regions such as the Gulf of California. This study examines the hydrodynamic response of the Gulf of California under three climate change scenarios (SSP1–2.6, SSP2–4.5, SSP5–8.5) projected from 2015 to 2100 using the CNRM-CM6-1-HR global climate model. We evaluate changes in sea surface temperature, surface circulation, and the relative contributions of dominant dynamic forcing mechanisms at annual and interannual scales. Results reveal a basin-wide warming trend accompanied by an increased frequency of extreme heat events. Surface current velocities weaken throughout the Gulf, exhibiting a consistent negative trend, with the strongest decline occurring under SSP5–8.5 in the central basin ($-5.1\times {10}^{-4}$ m s⁻¹ year⁻¹). Wind speed also shows a general decreasing tendency, contributing to reduced circulation intensity and enhanced stratification. The analysis of dimensionless numbers indicates moderate but consistent changes in the relative balance among inertial, baroclinic, and wind-driven processes. Although their proportions vary slightly across scenarios, the dominant forcing hierarchy remains largely preserved, suggesting a gradual modulation in forcing intensity rather than a fundamental reorganization of the hydrodynamic regime. These findings highlight spatial contrasts in climate sensitivity within the Gulf of California and underscore the importance of regional-scale assessments for anticipating future changes in circulation dynamics and marine ecosystem responses. Full article

In recent years, the recording of fish with vertebral malformations has attracted growing interest worldwide, as these malformations may be associated with exposure to xenobiotics. This study aimed to determine the presence and concentrations of pesticide residues (organochlorines and organophosphates) in coastal fish in Nayarit, Mexico, and to assess their potential association with vertebral malformations. From November 2013 to September 2021, 32 fish, with visible malformations were conveniently collected, an equal number of healthy specimens per species was selected for comparative analysis. The fish exhibited vertebral malformations of the following types: kyphosis, lordosis, and scoliosis in 9, 8 and 6 species, respectively, while the total number of malformations was higher across the sampled organisms. Furthermore, pesticide residues were detected in both healthy and malformed fish using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The samples analyzed contained at least one pesticide, with the group of healthy fish showing greater diversity of organochlorine compounds. The most frequent of these were p,p’-DDE, followed by p,p’-DDT (41%), p,p’-DDD (25%), and endrin (25%). The species C. raredonae and A. seemanni exhibited the greatest number of pesticides. The pesticides observed in malformed fish samples were p,p’-DDE (100%), p,p’-DDD (97%), p,p’-DDT (97%), endrin (50%), and BHC delta (31%). Chlorpyrifos was present (56% and 100% in healthy and malformed fish), with the highest frequency observed in A. seemanni and B. panamensis. The highest concentrations were observed in the DDT group. An association was also observed between vertebral malformations and concentrations of p,p’-DDE and chlorpyrifos in the species C. raredonae and A. guatemalensis. Multivariate analysis revealed a clear separation between malformed and healthy fish based on contaminant profiles. Full article

Studies of deep-sea hydrothermal vent systems have generated a spectrum of hypotheses concerning the origin of life on Earth. The present paper integrates recent literature surrounding three separate hydrothermal vent systems (Lost City in the mid-Atlantic, Guaymas Basin in the Gulf of California, and 9°50′ N on the East Pacific Rise) to provide biological, chemical, and geophysical support for these origin-of-life hypotheses. Comparisons between deep-sea hydrothermal vents and impact-generated hydrothermal vent systems may provide further insights into the origin of life. Impact-generated hydrothermal vent systems may have cradled early life. A comprehensive review of studies conducted at Lonar Lake, the Haughton impact structure, and the Chicxulub impact crater provide evidence of long-term hydrothermal activity conducive to the formation of early life, as well as potentially unique DNA structures found in sediment samples—opening the discussion for further investigations into the possible origin (or origins) of life both on Earth and other planetary bodies. Full article

Mangrove wetlands in northwestern Mexico have been highlighted due to their ecological relevance and ecosystem services. This study evaluated the mortality and natural regeneration of mangroves located in six coastal lagoons in Sinaloa, considering five plots each (400 m²), during a warm–strong (2015–2016) and cold–weak (2017–2018) El Niño–Southern Oscillation. The highest mean mortality was recorded in Huizache–Caimanero—the southern coastal lagoon—during the second stage (390 stems ha⁻¹; 22% corresponding to logging). While an increasing latitudinal (north–south) mortality trend was observed, differences between sites and stages were not statistically significant. Natural recovery was also observed due to higher abundance of seedlings, e.g., the largest increase from one stage to another was recorded in Santa María–La Reforma. Mortality and seedling regeneration are discussed in this study, particularly in relation to anthropogenic stressors, logging, and climate variability. Full article

The whale shark aggregation area in La Paz has given rise to vital wildlife tourism activity since the mid-1990s, which has been consolidated during the first decade of the 21st century. La Paz Bay is one of the three sites in Mexico where whale shark wildlife tourism is practiced. Biological and ecological research of whale sharks in the La Paz Bay is extensive. However, there is a considerable lack of knowledge about the socioeconomic implications of this activity. Understanding the recreational values of whale shark area users is fundamental to formulating an effective management policy. Using the individual travel cost method, we estimate the recreational value of whale sharks in La Paz Bay—the estimated individual’s willingness-to-pay ranges from 8 to 27 USD per trip. The recreational value of whale shark wildlife tourism ranges from 304,600 to 1,028,025 USD/season. The recreational value per whale shark ranges from 2361 to 14,083 USD. These results serve as a baseline for implementing economic and environmental policies and/or instruments to collect financial resources, strengthening actions oriented towards site and species conservation. Community-based management options, limitations, and opportunities are also discussed. Full article

The Sharpchin Slickhead, Bajacalifornia burragei, is a rarely collected bathypelagic fish endemic to the eastern tropical Pacific Ocean, and its genetic diversity remains undocumented. This study characterizes mitochondrial diversity in a localized deep-basin collection from the Carmen Basin of the Gulf of California by sequencing complete mitochondrial genomes from four individuals collected simultaneously at 1300 m in a single Tucker trawl. A high-quality reference mitogenome was assembled using PacBio HiFi long reads, and three additional mitogenomes were generated from Illumina PE150 libraries mapped to this reference. The mitogenome of B. burragei exhibits the canonical 37 gene architecture and conserved gene order typical of teleost mitogenomes. Overall mitogenome divergence was low (Range: 0.21–0.29%), with most protein-coding and rRNA genes exceeding 99.5% identity. Slightly elevated variation occurred in atp8, nad6, and several tRNA genes. This study provides the first genetic characterization of B. burragei and establishes a baseline for evaluating mitochondrial diversity within a localized collection of individuals and provides a point of comparison for future studies assessing connectivity among deep basins. Full article

Evaluations of recreational beaches are necessary to guide their management. In this study, we conducted a socio-ecological evaluation to propose management guidelines for San Francisco beach in northwestern Mexico, using a beach quality index and recording user perceptions. The results showed that the beach quality is high, based on the recreational, natural, and protection functions considered in the beach quality index. This finding was consistent with user perceptions of beach services, environmental conditions, and cleanliness. The findings of this study can be applied to strategies focused on the use and preservation of San Francisco Beach, aiming to maintain the natural landscape and sanitary quality, provide public services, ensure cleanliness, subdivide recreational areas, and implement year-round surveillance. Full article

Mesoscale eddies play a key role in oceanic transport, yet their characterization in marginal seas like the Gulf of California remains challenging due to complex coastlines and bathymetry that hinder conventional detection methods. This study addresses this gap by presenting a robust hybrid framework—integrating dynamical (Okubo–Weiss), velocity geometry (Nencioli), and closed-contour (Chelton) criteria—applied to the high-resolution (${0.01}^{\circ }$) Neural Ocean Surface Topography (NeurOST) altimetry product (2010–2024). Temporal continuity is ensured through a cost-based tracking algorithm optimized to tolerate observational gaps and track quasi-stationary features. This census, representing the first systematic, high-resolution sea surface height anomaly (SSHA)-based characterization for this region, identified 344 persistent trajectories (≥14 days) and revealed a fundamental dichotomy in the Gulf’s dynamics: a transient, tidally dominated regime in the north (dominated by short-lived features) contrasting sharply with a persistent, topographically trapped regime in the south. Focusing on the long-lived population (lifetimes $>30$ days), our analysis confirms that multi-year, quasi-stationary cyclonic eddies are trapped in the southern basins, while a subset of energetic tracks exhibits coherent poleward propagation consistent with advection by the Mexican Coastal Current. Cyclonic structures dominate the ten longest-lived tracks (90%) and include two events with lifetimes confirmed to exceed 500 days. We also identify a robust seasonal decoupling between SSHA and sea surface temperature anomalies (SSTA) in spring, when surface heating masks the thermal signature of cyclones. This census, which documents multi-year structures and distinguishes the two regional regimes, establishes a new baseline for quantifying mesoscale transport and serves as a transferable framework for the new generation of satellite altimetry observations (i.e., the Surface Water and Ocean Topography, SWOT, mission). Full article

Chaetognaths play an essential role in zooplankton communities and significantly contribute to their overall biomass. Changes in the hydrographic properties of the water column, driven by hydrodynamic processes, affect their species richness and abundance. This study investigates the species richness and abundance of chaetognaths, as well as their relationship with circulation patterns at the boundary of the Pacific Ocean and the Gulf of California, Mexico. The analysis is based on high-resolution hydrographic data and zooplankton samples collected during the early summer of 2019. The results revealed a cyclonic circulation pattern that impacted the chaetognath community at depths greater than 200 m. This pattern resulted in higher chaetognath densities along the peninsular coast compared to the mainland coast. A total of 15 species from three different families were identified. Among these, Flaccisagitta enflata had the highest density, recorded at 16,143 ind 100 m⁻³, while Aidanosagitta neglecta exhibited a significantly lower density of only 48 ind 100 m⁻³. Multivariate statistical analyses indicated that hydrographic variables were key factors influencing the distribution of the chaetognath community during the sampling period. Given the significant research gap regarding this group in the region, our findings contribute to a deeper understanding of chaetognath communities and their relationship with circulation patterns in the Southern Gulf of California, recognized as an oasis of marine life. Full article

When designing spatial planning programs for processes in coastal zones, it is essential to consider the connections between marine and terrestrial environments and to coordinate institutional work in their implementation. This study examines the environmental policies of two planning processes in the coastal zone, one terrestrial and one marine, which were formally developed and adopted through decrees in the State of Sonora (NW Mexico). The Gulf of California Marine Spatial Planning (MSP-GC) was decreed in 2006, and the Sonora Coast Land Spatial Planning (LSP-SC) was decreed in 2009 and updated in 2015. This study reviewed, compared, and spatially analyzed the environmental policies established by both planning processes. The results show that both planning processes contain environmental policies with limited links between the marine and terrestrial environments in practice. Both planning processes were enacted with effort, resources, and stakeholder participation, but have not been implemented effectively. It is essential to review the mandates of the decrees, conduct an integrated assessment of environmental policies, and seek ways for federal and State institutional structures to drive the implementation of these planning processes. Considering the dates of the MSP (2006) and LSP-SC (2015) decrees, now it is the right time to evaluate them. Full article

A mark–recapture experiment was conducted off Mazatlán in the entrance of the Gulf of California to evaluate the growth of juvenile spiny lobsters (Panulirus inflatus). A total of 40 post larvae of spiny lobster were captured, marked, and maintained in plastic cages for 180 days in seawater off Mazatlán, Sinaloa, Mexico (23°12′32.4″ N 106°25′33.2″ W). Carapace length (CL in mm) was measured. Growth was estimated using the Schnute model, which encompasses four primary cases. In this study, two additional variants equivalent to the von Bertalanffy and Logistic models were also incorporated. These six models were parametrized using normal and log-normal distributions of errors. The selection of the best distribution and best model was based on the Akaike information criterion (AIC). The AIC selected the normal distribution of error and sigmoid-shaped curve as best representative of the growth pattern of juvenile spiny lobster P. inflatus. By identifying the asymptotic sigmoidal curve as the best descriptor of juvenile growth, this study offers a reliable foundation for subsequent assessments of population dynamics, resource management, and aquaculture development of P. inflatus. Full article

Ciliate infestations in aquatic organisms are commonly associated with aquaculture, yet their impact on natural ecosystems remains largely understudied. This study describes a mobilid peritrich species infesting the gills of Octopus bimaculatus from the Gulf of California, Mexico. All 76 examined hosts (100%) exhibited infestation, with a mean intensity of 687 ± 228 (279–1077) urceolariid cells per gill. The ciliate cells displayed morphological traits consistent with those of the genus Urceolaria: turban-shaped cells measuring 44.2 ± 13.2 (31.3–88.6) µm in diameter; an adhesive disc of 36.5 ± 10.7 (29.2–74.6) μm in diameter; 18–19 plates measuring 11.0 ± 0.86 (9–12) µm in length; and 166–169 radial pins. Phylogenetic analysis of 18S rDNA sequences placed this species within the genus Urceolaria, a sister group to Urceolaria urechi and Urceolaria serpularum, with a genetic distance of 1.0% with respect to the previously described species. Combined morphological and molecular data support the description of a new species, Urceolaria carmenae n. sp. This is the first record of a mobilid peritrich in cephalopod mollusks, thereby enhancing our understanding of the diversity of ciliates among marine invertebrates in their natural habitats. Full article

Bahía de La Paz is the largest bay in the southern Gulf of California. This bay is an important area with a variety of commercial fish species and other natural resources and recreational activities. Epibenthic dinoflagellates are common inhabitants of harbors, inlets and semi-enclosed coastal lagoons; they produce potent toxins that may negatively affect human health and marine biota. The purpose of the present study was to identify potentially harmful epibenthic dinoflagellates growing on macroalgae from different coastal sites of the bay to determine their species composition, abundances, seasonal distributions, interannual and spatial variations. A total of 153 quantitative samples were collected in 2015–2019 (at 10 sites during four samplings in May, June and December) mainly from macroalgae. About 23 dinoflagellate species from the genera Prorocentrum, Ostreopsis, Sinophysis, Gambierdiscus, Fukuyoa, Amphidinium, Blixaea, Bysmatrum, Cabra, Coolia, Durinskia and Plagiodinium were found as epiphytes on at least 58 macroalgal species of 42 genera. Toxigenic genera, such as Gambierdiscus, Ostreopsis, Coolia and Prorocentrum, were widespread throughout the study area. Playa El Tecolote and Playa Costa Baja were the best habitats for dinoflagellates; therefore, the two locations can be considered the beaches with the greatest risk to human health. Full article

There has been an increasing interest in studying species of the thecate dinophysoid dinoflagellates, especially the genera Dinophysis and Phalacroma, all around the world. Abundant net phytoplankton material collected from coasts of the western coast of Baja California, the central Mexican Pacific (including the Gulf of California), and the Gulf of Mexico was analyzed, and the diversity and morphology of planktonic species of dinophysoids were studied in certain detail by LM and SEM. Particular morphological characteristics, which can be critical, such as the structure of the cingulum and cingular lists, union of sulcal lists, and theca ornamentation, were observed using SEM. Seventy-five (75) taxa (73 species and two varieties) were found and identified, which belong to the following 10 genera: Amphisolenia, Citharistes, Dinofurcula, Dinophysis, Histioneis, Metaphalacroma, Ornithocercus, Oxyphysis, Phalacroma, and Pseudophalacroma. We also included the following four new records: three for the Mexican Pacific (Amphisolenia brevicauda, A. deltiana, and Phalacroma stenopterygium) and one for the Gulf of Mexico (Phalacroma ornamentatum). Descriptions, illustrations, measurements, and distribution data are provided for each species. Taxonomical remarks concerning synonymies of species of the genus Phalacroma were added. Phalacroma whittingiae (Balech) Esqueda-Lara et Hernández-Becerril nov. comb. is a new taxonomic proposal. Full article

The genus Sargassum is taxonomically complex and poorly studied in the Eastern Tropical Pacific. We analyzed specimens collected along the Pacific coast of Central America and compared them with historical records and herbarium material to clarify species identities. Using detailed morphological analyses with molecular phylogenetic reconstruction based on concatenated ITS2 (Internal Transcribed Spacer 2) and COX3 (Cytochrome Oxidase Subunit 3) sequences, we identify two distinct morphotypes corresponding to two well-supported clades. One clade matches the morphology and molecular profile of Sargassum liebmannii. We provide the most comprehensive description of this species to date, including the first published ITS2 and COX3 sequences. Since Taylor’s 1945 work on the tropical Pacific of the Americas, S. liebmannii has been widely reported and considered the predominant species. It forms a genetic clade with other species from the Gulf of California; therefore, we propose a new section, Herporhizum/Sinicola. The second clade represents a previously unrecognized taxon from Central America, which we describe as a new species: Sargassum lacrucense, within the subgenus Sargassum, section Sargassum. Contrary to previous reports, Sargassum brandegeei—now recognized as Sargassum herporhizum—was not found in the region. This study underscores the importance of integrating morphological and molecular data to resolve Sargassum taxonomy in Central America. Full article