Search Results (45)

Human exploitation has been a major driver of marine turtle population declines, particularly affecting naturally scarce species such as the pantropical hawksbill turtle. Although hawksbill sea turtles have been documented in the Gulf of California since the early 20th century, data on their historical demography during periods of high exploitation in this region are nonexistent. We investigated the size structure of hawksbill turtles from the Western Central Gulf of California by examining a unique sample of decorative taxidermies, corresponding to 31 specimens captured during fishing operations near Santa Rosalía, Baja California Sur, Mexico, between 1980 and 1990. An analysis of the curved carapace measures revealed a length range (nuchal notch to posterior of supracaudals) of 29.5–59.5 cm (mean = 38.75 ± 6.67 cm) and a width range of 25.0–51.5 cm (mean = 33.63 ± 5.66 cm), with 87% of specimens having lengths between 30 and 45 cm. Based on the carapace length measurements, we estimated the ages to be between 7 and 20 years, indicating that the population included juveniles. Our findings provide baseline data for an understudied period and region, suggesting that this area previously served as an important juvenile habitat. These results contribute essential historical demographic information for conservation planning. Full article

The Sonora Estuarine Biocultural Corridor (CBES) is made up of six coastal wetlands with mangrove forest, internationally certified as Ramsar Sites. Four are part of indigenous territories whose inhabitants have serious development lags and low water security. Five are within one or more of six irrigation districts of national relevance. The objective is to learn about the socio-environmental problems of the CBES, focused on the issue of water, as well as community proposals for solutions. Intercultural, mixed methodology approach. Prospecting visits were carried out in the six estuaries of the CBES, and 84 semi-structured interviews were conducted with experts from all social sectors who know the problems of the CBES in three (out of six) estuaries associated with indigenous territories. The main problem is centered on the issue of water: they receive contaminated water from agroindustry, aquaculture, and the municipal service; the fresh water of the rivers is almost nil, rainfall has decreased while the heat increases, and marine and terrestrial biodiversity decreases. This affects the food and economic security of the local population and generates conflicts between the different productive activities. A multisectoral organization that integrates the six estuaries would improve community wellbeing and, in turn, climate resilience. Full article

This paper analyzes phytoplankton communities in the Eastern Tropical Pacific Ocean off Mexico (ETPOM) and the Southern Gulf of California (SGC) during the strong El Niño event of 2023/24. A multidisciplinary research cruise was conducted in the winter of 2024, during which high-resolution hydrographic data and water samples for phytoplankton cell determinations were collected at 33 sites. Additionally, satellite data were obtained to evaluate sea surface temperature and chlorophyll-a levels. A total of 269 phytoplankton species were identified, comprising one hundred and fifty diatoms, one hundred and twelve dinoflagellates, five silicoflagellates, one ciliate and one cyanobacteria. The dominant species included the diatom Pseudo-nitzschia pseudodelicatissima, the dinoflagellate Gyrodinium fusiforme, the silicoflagellate Octactis octonaria, and the ciliate Mesodinium rubrum. The cyanobacterium Trichodesmium hildebrandtii was also identified. In terms of total abundances, diatoms were the most prevalent, with 224,900 cells L⁻¹, followed by dinoflagellates at 104,520 cells L⁻¹, ciliates at 20,980 cells L⁻¹, cyanobacteria at 1760 cells L⁻¹, and silicoflagellates at 1500 cells L⁻¹. Notably, interesting differences emerged in species richness and abundance when comparing both regions. These results enhance our understanding of phytoplankton dynamics associated with strong El Niño events. The ETPOM remains a region that requires further monitoring through in situ observations. Full article

The herpetofaunal diversity of northwestern Mexico, encompassing the Californian, Baja California, and Sonoran Desert biogeographic provinces, is characterized by relatively low species richness but a high degree of endemism. This region, particularly the islands of the Gulf of California, is recognized as a biodiversity hotspot. However, amphibian and reptile species in this area, especially those on the Gulf islands, are facing significant threats to their survival, including non-native species, habitat loss, and climate change. These factors pose considerable challenges to their conservation. In this study, we compiled updated lists of amphibian and reptile species across these three provinces, assessed their conservation status, identified the threats they face, and compared them with those in neighboring biogeographic provinces. Our analysis recorded a total of 228 species, comprising 29 amphibians and 199 reptiles, with a notable proportion of endemics, particularly in Baja California. Amphibians, due to the region’s arid conditions, are underrepresented and generally face a lower level of conservation concern. In contrast, reptiles, especially those on the islands, are at higher risk, primarily due to habitat loss, invasive species, and climate change. Of the 228 species, one amphibian and 21 reptiles are classified in a category of conservation concern (Vulnerable, Endangered, Critically Endangered) by the International Union for Conservation of Nature (IUCN) Red List. In addition, 47 species (one amphibian and 46 reptiles) are listed as threatened (A) or at risk of extinction (P) by the Secretaría del Medio Ambiente y Recursos Naturales (SEMARNAT). These findings emphasize the urgent need for conservation strategies, particularly for island reptile species, that involve collaboration among scientists, local communities, and federal and state authorities to address these threats and safeguard the region’s herpetofauna. Similarity analysis revealed significant ecological connectivity among the amphibian and reptile communities across the three provinces. The similarity in species between the Californian, Baja California, and Sonoran Desert provinces highlights the role of historical climatic events, geographic barriers, and ecological factors in shaping species distributions of amphibians and reptiles in northwestern Mexico. Full article

The Gran Acuario Mazatlán (GAM), Mexico’s largest aquarium, is located at the entrance of the Gulf of California. In April 2023, fish in the Ocean Tank (OT) began exhibiting disease symptoms, followed by significant mortality, primarily affecting Caranx caninus, Chaetodipterus zonatus, and Lutjanus colorado. Parasitological examinations identified heavy infestations of Neobenedenia sp. (Monogenea: Capsalidae), with parasites extensively covering body surfaces and gills of some individuals. To control the outbreak, an environmental management strategy was implemented, involving a gradual reduction in water temperature (from 26 °C to 22 °C) and salinity (from 35 ppt to 26 ppt), increased cleaning frequency, and parasite egg abundance monitoring. Over time, egg abundance declined, and by July, fish behavior and feeding rates had returned to normal, with parasite-associated mortality dropping below 2%. Preventive measures, including strict quarantine protocols for new fish, have been implemented to maintain optimal conditions in the OT. This case highlights the challenges of managing parasite outbreaks in large, multi-species aquaria and underscores the importance of environmental control strategies in marine animal care. Full article

Mexico is a well-known seismically active country, which is primarily affected by several tectonic plate interactions along the southern Pacific coastline and by active structures in the Gulf of California. In this paper, we investigate this seismicity using the classical Gutenberg–Richter (GR) law and a non-extensive statistical approach based on Tsallis entropy. The analysis is performed using data from the corrected Mexican seismic catalog provided by the National Seismic Service, spanning the period from January 2000 to October 2023, and unlike previous work, it includes six different regions along the entire west coastline of Mexico. The Gutenberg–Richter law fitting to the earthquake sub-catalogs for all six regions studied indicates magnitudes of completeness between 3.30 and 3.76, implying that the majority of seismic movements occur for magnitudes less than 4. The cumulative distribution of earthquakes as derived from the Tsallis entropy was fitted to the corrected catalog data to estimate the q-entropic index for all six regions, which for values greater than one is a measure of the non-extensivity (i.e., non-equilibrium) of the system. All regions display values of the entropic index in the range $1.52\lesssim q\lesssim 1.61$, slightly lower than previously estimated ( $1.54\lesssim q\lesssim 1.70$) using catalog data from 1988 to 2010. The reason for this difference is related to the use of modern recording devices, which are sensitive to the detection of a larger number of low-magnitude events compared to older instrumentation. Full article

The crab fishery of the genus Callinectes is one of the most important fisheries in Mexico. Sonora and Sinaloa are the states on the eastern coast of the Gulf of California, the mainland coast. Sinaloa encompasses the greatest production in Mexico of these species, in particular the Bahía Santa Maria La Reforma (BSMR), supplying the most important catches. A mandatory administrative document for the fishery is the Management Plan of Crab. One of the main weaknesses found in it for Sonora and Sinaloa is the lack of fishery assessment in both states. For this reason, a size-structured method called CASA (Catch-at-Size Analysis) was applied in the BSMR, in the seasons 2000, 2011, and 2014, to C. bellicosus. The first catch size (CW50%) estimated for females was 97.5, 102.5, and 100 mm, while in males, it was estimated at 117.5, 107.5, and 102.5 mm. In the specific case of fishing mortality (F), the algorithm allowed us to find that in the larger sizes, a greater fishing pressure is applied for both females and males, yielding a weighted exploitation rate of 0.047 (2000), 0.119 (2011), and 0.426 (2014) for females and 0.045 (2000), 0.295 (2011), and 0.132 (2014) for males, all below 50% (E = 0.50). The crab C. bellicosus in BSMR is not at risk of overexploitation. Full article

Microplastics (MP) have been evidenced in marine and coastal areas worldwide, including the Gulf of California in Mexico, where the Vaquita Marina refuge area is located, which in turn borders the protected natural area Alto Golfo de California y Delta del Rio Colorado. This research aimed to determine the concentrations of microplastics in the Vaquita protection zone, analyzing samples of ten transects of surface water and samples in the sand of five beaches on the coast surrounding the Vaquita protection polygon. The total concentrations of MP in the surface water transects were from 0.000 to 0.020 MP/m³ and their most recurrent characteristics were fragments (69.0%), the chemical composition of polyethylene (60.0%), the blue color (39.0%) and a size of 2.1–3.0 mm (31.0%). While for the beaches, these corresponded to averages ranging from 28.2 ± 36.4; 17.6 to 200.7 ± 77.9; 193.7 MP/m², the most common characteristics of MP from beaches were filaments (33.2%), PE (32.3%), white (28.0%), and a size of 4.1–5.0 mm (32.0%). The results suggest that part of the MP on the beaches and in the Vaquita Marina refuge area could come from urban areas such as the Gulf of California and activities such as fishing. It is recommended to study all the transects of the Vaquita Marina polygon and more beaches surrounding it in different seasons to better understand the status of MP pollution. Full article

Xyloplax is a genus of three species of sea stars previously found only on sunken wood in the deep ocean. Their circular and petaloid bodies, which lend them their common name “sea daisy”, and their presumed exclusive diet of wood make them an unusual and rare element of deep-sea ecosystems. We describe here the fourth species of Xyloplax from the eastern Pacific Ocean, Xyloplax princealberti n. sp., which ranges from offshore Canada to the Gulf of California (Mexico) and Costa Rica. Though sampled geographically close to another described species of Xyloplax from the northeastern Pacific, X. janetae, this new species is unique morphologically and according to available DNA data. The short abactinal spines are the most obvious feature that distinguishes X. princealberti n. sp. from other Xyloplax. The minimum distance for mitochondrial cytochrome c oxidase subunit I from Xyloplax princealberti n. sp. to the only other available Xyloplax, X. janetae, was 13.5%. We also describe Ridgeia vestimentiferan tubeworm bushes from active hydrothermal vents as a new Xyloplax habitat, the first record of a non-wood substrate, and a new reproductive strategy, simultaneous hermaphroditism, for this genus. We generated the first mitochondrial genome for a member of Xyloplax and analyzed it with other available asteroid data using nucleotide-coding or amino acid (for protein-coding genes) plus nucleotide coding (for rRNA genes). The nucleotide-coding results place Xylopax as part of the clade Velatida, consistent with a previous phylogenomic analysis that included Xyloplax princealberti n. sp. (as Xyloplax sp.), though the placement of Velatida within Asteroidea differed. The amino acid plus nucleotide coding recovered Velatida to be a grade with X. princealberti n. sp. as sister group to all other Asteroidea. Full article

Although sandy islands in arid environments are vital protection sites for endemic species, they face constant natural and anthropogenic hazards, such as storm surge impacts and the occasional presence of off-road vehicles. Monitoring the sedimentary dune-beach displacement and balance is essential because sediment transportation usually does not depend on external sources, such as rivers. The latest generation of geomatic applications may be relevant to understanding coastal vulnerability due to their ability to acquire and process spatial data at unprecedented scales. The objective of this study was to analyze the sedimentary dynamics of a distinctive dune corridor on Altamura Island in the Gulf of California, Mexico. We compared three ultra-high spatial resolution digital surface models (DSMs) with geomorphic change detection (DoD), covering the 1150 m coastal stretch. We used light detection and ranging (LiDAR) data and analyzed changes in the coastline with the semi-automatic CoastSat tool. Although the orthomosaics and the DSM collected in April, June, and October 2021 show different conditions in sediment distribution along the beach-dune interface, depending on the direction and intensity of the wind, the two DoDs showed a constant sediment distribution balance of ~13 M m³ between April and June and June and October. LiDAR data along the 40-km length of the sandy island indicate that the entire island could present a similar sedimentation pattern between the dune and beach interface. The CoastSat data indicate a constant accretion of 125 m in the beach-ocean interface between 2015 and 2022. This study demonstrates that the sediment balance between the dune and the beach on arid sandy islands is vital for conserving their shoreline and all associated coastal ecosystems. Full article

Fishing sector fuel subsidies are designed to increase profitability by reducing costs. However, despite the number of liters of fuel subsidized in 2018 in Mexico, there is no information available on the effectiveness of the subsidies in reducing cost inefficiencies. The purpose of this study was to estimate the cost efficiency of shrimp fishing companies in Mexico, as well as measure the impact of fuel subsidies on the cost inefficiency of the sector from 2003 to 2018. The True Fixed Effects model was used to represent a Cobb–Douglas stochastic production frontier, which included a shrimp fishing inefficiencies model. The results indicate that shrimp fishing companies could reduce their costs by 25% without reducing their catch levels. Fishing companies in the Gulf of Mexico were more efficient than those operating in the Gulf of California and the South Pacific. Fuel subsidies reduce cost inefficiencies, with a greater effect when the subsidy reaches a level of 20% of the total liters of subsidized fuel. Full article

The herpetofauna of the insular systems of Mexico is composed of 226 species, of which 14 are anurans, two are salamanders, and 210 are reptiles, comprised of two crocodilians, 195 squamates, and 13 turtles. Although the surface of the Mexican islands is only 0.26% of the Mexican territorial extension, these 226 species constitute 16.1% of Mexico’s documented herpetofauna of 1405 species. We classified the Mexican islands into five physiographic regions: the islands of Pacific Baja California; the islands of the Gulf of California; the islands of the Tropical Pacific; the islands of the Gulf of Mexico; and the islands of the Mexican Caribbean. The highest species richness among these regions is in the Gulf of California, with 108 species, and the lowest richness is 40 for the islands of the Pacific Baja California and 46 for those of the Gulf of Mexico. We identified introduced species, risk of wildfires, climate change, and urban/tourist development as the main environmental threats impinging on these species. In addition, we assessed the conservation status of the native species by comparing the SEMARNAT (NOM-059), IUCN Red List, and the Environmental Vulnerability Score (EVS) systems. The comparison of these systems showed that the NOM-059 and the IUCN systems seriously underestimate the degree of threat for insular endemics, being particularly concerning for those insular species that are known only from their respective type localities. The EVS system proved to be practical and indicated that 94 species have a high vulnerability status, 62 a medium status, and 56 a low status. The Relative Herpetofaunal Priority system, which contrasts the number of endemic and threatened species among different physiographic areas, indicates that the regions with the highest priority are the Islands of the Gulf of California, followed by the islands of the Tropical Pacific. Finally, we discussed the completeness of the Mexican Natural Protected Areas on the insular systems of the country; the result is outstanding since Mexico is already close to achieving the goal of having all their islands under some degree of federal protection. Full article

The Pacific thread herring, Opisthonema libertate, is a fishery resource in the eastern tropical Pacific, yet its population dynamics are poorly understood. The aims of this work were to document the metazoan parasite species in O. libertate from the Gulf of California in Mexico, determine latitudinal changes in their infection levels, and assess their potential as biological tags. Six parasitic species were identified: Myosaccium ecaude and Parahemiurus merus digeneans, Cribromazocraes cf. travassosi and Mazocraeoides georgei monogeneans, Pseudoterranova sp. nematodes, and Lepeophtheirus sp. copepods. The monogenean and copepod species are reported for the first time in O. libertate. Many fish were infected with digeneans, and there was a rare occurrence of other parasites. While the prevalence and median intensity of M. ecaude and P. merus significantly varied among sampling localities, a multivariate analysis revealed a distinct separation between some localities; these results suggest that individual fish form several discrete populations. However, the utility of these parasites as biological tags will be further probed because they cannot satisfy all requirements for good biological tags. The present results might be helpful in complementing other techniques to determine the movement and stock structure of O. libertate, albeit with certain limitations. Full article

The genus Amphidinium Clap. & J. Lachm. comprises a high diversity of planktonic and benthic (epiphytic and sand-dwelling) dinoflagellates from marine and freshwater ecosystems. High morphological plasticity and vaguely defined genus characteristics (e.g., a small epicone size) have complicated the clear delineation of species boundaries. Although six Amphidinium morphospecies have been reported from Mexican coastal waters, species identifications are uncertain and not generally supported by molecular phylogenetic data. In this study, seven isolates of Amphidinium from diverse benthic coastal locations on the NE Pacific, Gulf of California, and southern Gulf of Mexico were subjected to critical morphological analysis using photonic and scanning electron microscopy. The phylogenetic reconstruction was based on nuclear-encoded, partial large-subunit (LSU) rDNA and internal transcribed spacer I and II (ITS1 and ITS2) sequences. The revised phylogenetic analysis was consistent with the traditional subdivision of the genus Amphidinium into two sister groups: Herdmanii and Operculatum clades. This study provided the first confirmed records of A. theodorei and A. massartii from coastal waters of Mexico. The molecular phylogenetic evidence indicated that the morphologically described A. cf. carterae from Baja California was in fact more closely allied with A. eilatiensis sequences. A few Amphidinium species are known to form toxigenic (i.e., fish-killing) harmful algal blooms worldwide, and therefore knowledge on species diversity and biogeography is critical in developing effective strategies for evaluating the potential emerging threat in Mexican coastal waters. Full article

The synthesis and optimization of polymeric inclusion membranes (PIMs) for the transport of Cd(II) and Pb(II) and their separation from Zn(II) in aqueous saline media are presented. The effects of NaCl concentrations, pH, matrix nature, and metal ion concentrations in the feed phase are additionally analyzed. Experimental design strategies were used for the optimization of PIM composition and evaluating competitive transport. Synthetic seawater with 35% salinity, commercial seawater collected from the Gulf of California (Panakos^®), and seawater collected from the beach of Tecolutla, Veracruz, Mexico, were employed. The results show an excellent separation behavior in a three-compartment setup using two different PIMs (Aliquat 336 and D2EHPA as carriers, respectively), with the feed phase placed in the central compartment and two different stripping phases placed on both sides: one solution with 0.1 mol/dm³ HCl + 0.1 mol/dm³ NaCl and the other with 0.1 mol/dm³ HNO₃. The selective separation of Pb(II), Cd(II), and Zn(II) from seawater shows separation factors whose values depend on the composition of the seawater media (metal ion concentrations and matrix composition). The PIM system allows S(Cd) and S(Pb)~1000 and 10 < S(Zn) < 1000, depending on the nature of the sample. However, values as high as 10,000 were observed in some experiments, allowing an adequate separation of the metal ions. Analyses of the separation factors in the different compartments in terms of the pertraction mechanism of the metal ions, PIMs stabilities, and preconcentration characteristics of the system are performed as well. A satisfactory preconcentration of the metal ions was observed after each recycling cycle. Full article