Pacific Coast Of Mexico Research Articles

A new species of the genus Monstrilla (Copepoda: Monstrilloida: Monstrillidae) from the Gulf of California, Mexico

Based on deep-water (700-750 m) biological samples obtained from the southern Gulf of California, Pacific coast of Mexico, a new species of the monstrilloid copepod genus Monstrilla Dana, 1849 is described based on a single subadult female collected close to the bottom with an epibenthic sledge. Monstrilla hendrickxi sp. n. is distinguished by a unique combination of characters including: 1) no trace of eyes; 2) strong, thick antennules with segments 2-4 partly fused; 3) strongly developed apical elements on antennular segment 5 and spinous processes on segments 2-5; and 4) bilobed fifth legs with 2 apical setae on the exopodal lobe and a digitiform, unarmed endopodal lobe. The new species exhibits some affinity with surface-dwelling species of Monstrilla that have 2 setae on the exopodal lobes of the fifth legs. This is the fifth record of a species of the order Monstrilloida in the Gulf of California. The present discovery in deep oceanic waters significantly adds to our knowledge of the habitat range of this copepod order and likely anticipate further interesting findings of monstrilloids in deep waters worldwide.

Prediction of Fourier Amplitude Spectrum of Ground Motion in Mexico City from Subduction Thrust Earthquakes

Mexico City, one of the largest cities in the world, experiences frequent, devastating interplate earthquakes that originate on the subduction thrust along the Pacific coast of Mexico more than 250 km away. A notorious example is the 19 September 1985 Michoacán earthquake (Mw 8.0) which killed ~ 10,000 persons and caused wide-spread destruction in the city. The main cause of seismic damage in Mexico City is its subsoil that amplifies the ground motion. In view of the seismic hazard faced by the city, a reliable estimation of ground motion during future earthquakes is of vital importance. We present a new ground motion prediction equation (GMPE) for the Fourier amplitude acceleration spectrum (FAS) from subduction thrust earthquakes along the Pacific coast of Mexico at the reference station, CU, located in the firm zone of Mexico City. The GMPE is derived via Bayesian regression analysis and is based on an enlarged set of recordings (1965-2020; 40 earthquakes; 250 ≤ R≤ 500 km; 5 ≤ Mw ≤ 8.0). An important feature of the new GMPE is that it includes a term to model different attenuation along different ray paths. The inclusion of this term leads to a reduction in the aleatory variability of the GMPE, particularly at high frequencies. Since spectral amplification of seismic waves with respect to CU is known at many sites in the city, the FAS at these sites can be computed if it is known at CU. The new GMPE has been incorporated in a fully Fourier-based probabilistic seismic hazard analysis of Mexico City.

The systematics of the amphidromous shrimp Macrobrachium tenellum (Smith, 1871) (Decapoda: Caridea: Palaemonidae) from the Mexican Pacific slope

Abstract We had previously revised the systematics of four species of MacrobrachiumSpence Bate, 1868 from the Pacific coast of Mexico, including the Baja California Peninsula (BCP): M. americanumSpence Bate, 1868, M. digueti (Bouvier, 1895), M. hobbsi Nates & Villalobos in Villalobos Hiriart & Nates Rodríguez, 1990, and M. occidentale Holthuis, 1950. Genetic analyses of the mitochondrial markers 16S ribosomal RNA (16S) and cytochrome oxidase I (COI) of individuals of these morphological species from BCP have shown that, even facing the Gulf of California (Sea of Cortés) as an apparent marine ecological barrier, they are conspecific to their respective genetic lineages (species) found from the Pacific slope of mainland Mexico. We discuss the systematics of the fifth species of Macrobrachium from the Mexican Pacific slope, M. tenellum (Smith, 1871) to test the hypothesis that individuals of the putative M. tenellum from BCP belong to the same species from the Pacific slope of mainland Mexico. We revised the morphological characters of taxonomic importance using material obtained in the field and voucher material deposited in Mexican scientific collections, and performed molecular genetic analyses with newly generated fragments of the mitochondrial markers 16S and COI. We conclude, as in our previous studies on Macrobrachium species of the region, that the examined specimens of the putative M. tenellum from BCP belong to the same species found on the Pacific slope of mainland Mexico, and that oceanic dispersal is responsible for the distribution of the species of Macrobrachium in the peninsula rather than by vicariant events.

Distribution, eco-climatic characterization and modelling of suitable soursop cultivation zones in Mexico

Soursop (Annona muricata L.) is a tropical fruit tree highly valued for its organoleptic characteristics, and is the most important Annonaceae species in Mexico. This study aimed to generate maps of the natural geographic and eco-climatic distribution where soursop grows in Mexico, and to model potential zones according to climate change scenarios estimated for 2050. The natural distribution model showed that this species is found in most tropical and some subtropical areas of Mexico. This fruit tree grows in three different eco-climatic regions (two tropical and one temperate): Aw1 (found on the edges of the Balsas basin, and in the south, southeast and central north of the Veracruz region, as well as in the center of the Mexican Pacific coast), Am (north and central south of the Veracruz region, and the Yucatán peninsula) and C(w0) (east of the Trans-Mexican Volcanic Belt). Modelling of suitable climate adaptation zones showed that the Pacific coast of Mexico and Veracruz, as well as some areas of the Balsas basin and the Yucatán peninsula, have potential for soursop cultivation. Likewise, in the scenario of global climate change, beneficial effects on the adaptation of this species are predicted.

Records of the non-native alga Acanthophoraspicifera (Rhodophyta) and their colonial epibionts in La Paz Bay, Gulf of California.

Acanthophoraspicifera, a red alga considered an alien species, was discovered for the first time on the Pacific coast of Mexico in 2006 from a locality inside La Paz Bay, Gulf of California. Since then, more records have shown its presence, 17 localities having been added up to 2015. A two-year field study (2020-2022) visiting 31 sites along the coast of La Paz Bay, complemented with data from literature and citizen science, resulted in a database of 709 entries that spans the data from 2004 to 2023. These data showed a distribution that goes from Punta Coyote, close to Boca Grande, the northern entrance to the Bay to Playa Tecolote in the south, more than 100 km of coastline, including Espiritu Santo Archipelago, an area considered a natural reserve since 2007. Anthropogenic activity and environmental variables did not present statistical differences that explain A.spicifera spreading. It represents a naturalised alien species without evidence of a negative impact. Still, it soon could acquire the status of invasive species together with its epibionts Bryozoa and Hydrozoa detected in this study.

Microplastics in Sandy Beaches of Puerto Vallarta in the Pacific Coast of Mexico

In this research, the abundance and physical and chemical characteristics of microplastics (MPs) in coastal sediments from three beaches of Puerto Vallarta in Mexico were investigated. The objective of characterizing and finding MPs in sand is to generate information that is useful to manage macroplastic waste, prevent its additional generation, and thus reduce environmental pollution and achieve sustainable development. The MPs were classified according to their physical characteristics such as color, size, and shape under a stereoscopic microscope, and their wear and surface were observed using a scanning electron microscope. The chemical composition of the most representative types of polymers were detected by Fourier-transform infrared spectroscopy. It can be observed that Los Muertos beach presents the highest number of MPs (97.5 particles/m2) followed by Boca de Tomates beach (69.75 particles/m2) and Oro beach (28.75 particles/m2). The differences found between the beaches are attributed to the tourist influx and proximity to the mouth of a river. In total, 37% of MPs were white, followed by 19% yellow, and 11% transparent. The shape distribution of microplastics of sizes < 5 mm and 1 mm was fragmented, the greatest abundance was microfibers, microfragments, and microfilms for MPs between <1 mm and 1 µm, and these corresponded to polyester, polyethylene, cellophane, and polystyrene, respectively.

Machine learning based anomaly detection for sedimentological data: Application to a Holocene multi-proxy paleoenvironmental reconstruction from Laguna Boquita, Jalisco, Mexico

Paleoenvironmental reconstructions are critical to determine past climatological and hydrological conditions, such as sea-level rise (SLR) and extreme events including hurricanes and tsunamis. While established quantitative methods, such as principal components analysis and discriminant analysis, have effectively aided reconstructions by demarcating stratigraphic zones, they suffer from limitations due to the underlying assumptions (linearity, normality). Here, we introduce the machine learning technique anomaly detection for sedimentological reconstructions, capable of objectively pinpointing events (anomalies) in sediment cores. We tested this technique on five sediment cores extracted from Laguna Boquita, located along the Pacific coast of Mexico. Each core was subjected to high resolution loss-on-ignition, while the most representative core (core 1) was deemed the training core and scanned with a handheld XRF unit. In general, the sediment cores were dominated by thick units of peat and/or clay, and most cores contained sand layers. This reconstruction represents many environmental settings, ranging from a sandy terrestrial environment (∼6830- ∼ 6370 cal yr BP), organic-rich wetland (∼6370- ∼ 5170 cal yr BP), and clastic-rich backbarrier lagoon (∼5170 cal yr BP to present). The anomaly detection technique proved effective in marking many events, including marine transgression, evidence of SLR, transitions separating dominant depositional environments, and, perhaps most notably, a faded blue clay layer with minimal LOI variability that may represent a shift in backbarrier water level. The anomaly detection also registered anomalies when events were not visually distinct nor present in the LOI datasets (false positives), which represent sediment core sections that require further investigation with multiple proxies. However, anomaly detection failed to register anomalies in certain core sections that should have registered as events due to their distinct nature. Future efforts will look to improve anomaly detection by choosing different train cores and adding additional proxy datasets.

Conquering the Pacific: An Unknown Mariner and the Final Great Voyage of the Age of Discovery

Conquering the Pacific: An Unknown Mariner and the Final Great Voyage of the Age of Discovery

Crambe insularis sp. nov. (Crambeidae: Poecilosclerida) a New Crambeid from the Eastern Tropical North Pacific: Morphological, Molecular and Ontogenetic Approach

Specimens of Poecilosclerida taxa, collected from an insular coral community on the Pacific coast of Mexico, were identified as members of the family Crambeidae Lévi, 1963. They were associated with larvae and rhagon phases by using morphological characters, the nucleotide relationship and genetic divergence of three independent loci, two mitochondrial (COI and 16S rDNA) and one ribosomal (28S rDNA C3–C5). Crambe insularis sp. nov. differs from the general skeletal architecture in the genus Crambe Vosmaer, 1880, by its reduced spiculation defined by the presence of ectosomal and choanosomal monactinal megascleres, and the absence of microscleres. Bayesian and Maximum–Likelihood analyses of three loci supported the clustering of larvae, rhagon and adult sponge, all closely related to Mediterranean Crambe crambe (type species of the genus Crambe), and with South American Crambe species (C. chilensis, C. maldonadoi and C. amarilla) as sister species. The larva of C. insularis sp. nov. corresponded to the typical parenchymella larvae poecilosclerid species but with the presence of subtylostyles and styles. Ontogenetic process about the larval and rhagon of this new crambeid are provided. The morphological characters and molecular affinities of Crambe insularis sp. nov. are similar to Monanchora genus, and the implications are further discussed. This is the first taxonomic and molecular study with an integrative approach that includes other diagnostic features such as larval and rhagon development for the description of new species in Porifera.

Lizard species on three islands off the Mexican Pacific Coast: effects of insularity

This study provides a descriptive panorama of the lizard communities on 3 islands and the mainland on the Pacific coast of Mexico, estimating the effect of insularity (ecological changes between lizards on the islands and on the mainland) on lizard populations. The panorama included the number of species, encounter frequency and age classes. The insularity effects were estimated by comparing these variables, as well as basking behavior, activity related to microclimate, and perch height among the islands and the mainland. Of 11 species recorded, 8 occurred on the islands; however, every insular community was composed of 3 to 5 species (4 are protected by Mexican law). The encounter frequency for all species ranged between 11 and 0.1 individuals per hour. Lizard communities were predominantly composed of adults. Only 2 lizard species, Aspidoscelis communis and A. lineattissima, were shared among all sites, showing no insularity effects on the encounter frequency nor basking behavior. There were signs of insularity, however, on age classes and a clear effect on perch height, suggesting niche expansion. The study contributes to the regional knowledge of lizard species, as well as to ecological theories such as niche expansion and density compensation.

Contrasting the reproductive potential of Narcine entemedor and Rhinoptera steindachneri: 2 viviparous batoid species with different reproductive strategies

Narcine entemedor and Rhinoptera steindachneri are 2 viviparous batoid species of commercial importance on the Pacific coast of Mexico. However, no adequate management plan has been set forth for either of them to ensure sustainable use. The aims of this study were to assess the reproductive potential and the potential rate of population increase (rʹ) of both species, as well contrasting their reproductive strategies, to infer how susceptible they are to fishing exploitation. Comparatively, among batoids, N. entemedor females have an early age at maturity, relatively high fecundity, and an intermediate lifespan, while R. steindachneri females have an early age at maturity, low fecundity, and a relatively short lifespan. According to our estimates, however, both species have relatively high reproductive potential, which N. entemedor exhibits by investing energy in maximizing fecundity and R. steindachneri by increasing the embryo’s body mass. Therefore, N. entemedor has better capacity to recover from relatively high overfishing (rʹ = 0.48) in comparison with R. steindachneri (rʹ = –0.18). The methodology used in this study proved to be a good option to assess the risk of overfishing in species for which there is limited data.

Aphananthe Planch. (Cannabaceae) flower preserved in the Mexican amber

Cannabaceae (Urticalean Rosids clade) is a small family with ten genera and a wide distribution in tropical and temperate regions worldwide. A complete understanding of the history of the lineage is fundamental to the integration of its fossil record, which needs to be better documented in low latitudes of North America. This work recognizes a new species, Aphananthe manchesteri Hernández-Damián, Rubalcava-Knoth et Cevallos- Ferriz sp. nov. (Cannabaceae), from the Miocene amber deposits of Simojovel de Allende, Chiapas, Mexico, based on a flower analyzed with reflected light and CT-scanning. Flowers of Cannabaceae are generally staminate or pistillate and small; staminate flowers have five sepals and opposite five stamens, and a pubescent pistillode, such as the fossil. However, the presence of three unguiculate and two ovate sepals with a puberulent surface are characteristics that allow its recognition as Aphananthe, the fossil is morphologically similar to Aphananthe monoica, an extant species that grows along the Pacific coast of Mexico. The presence of Aphananthe manchesteri sp. nov. in southern Mexico during the middle-early Miocene, ~23–15 Ma ago, supports the history of the lineage in lowlatitude North America, representing an expansion of the Boreotropical Flora. It adds to the taxonomical diversity of angiosperms preserved in Mexican amber, comparable with amber deposits from the Dominican Republic, where another anemophilous extinct species member of the Urticalean Rosids clade has been reported. This coincidence further supports the development of similar plant communities between these fossiliferous localities.

New records of invasive tubeworms (Ficopomatus, Serpulidae) in Mexico

AbstractFicopomatus Southern, 1921 is a serpulid genus currently composed of six species, two of which (F. enigmaticus and F. miamiensis) are reef-builders. The former has invaded subtropical and warm-temperate estuaries worldwide, causing environmental and economic harm. In this study, Ficopomatus miamiensis and F. uschakovi are reported from brackish-water coastal localities in both Atlantic and Pacific sides of Mexico, including a Biosphere Reserve, estuaries, as well as shrimp and oyster farms. Ficopomatus miamiensis is reported from Veracruz (southern Gulf of Mexico, Mexico territory) and Sinaloa (southern Gulf of California). Ficopomatus uschakovi is reported for the first time in the southern Gulf of Mexico (Mexico territory) and repeatedly recorded in Chiapas (southern Mexican Pacific). There are no phenotypic differences between specimens of F. miamiensis from both coasts of Mexico. Comparison of mitochondrial cytochrome b (Cytb) DNA sequences further support the notion that F. miamiensis from the type locality (Florida) and Atlantic coasts of Mexico is also found along the Pacific coast of Mexico. Morphological variability within specimens of F. uschakovi from a single locality (either Laguna del Ostión or La Encrucijada) in Mexico suggest potential presence of multiple cryptic species. Molecular genetics studies are needed to confirm the taxonomic and invasive status of F. uschakovi.

Optimal Design of Hybrid Renewable Energy Systems Considering Weather Forecasting Using Recurrent Neural Networks

Lack of electricity in rural communities implies inequality of access to information and opportunities among the world’s population. Hybrid renewable energy systems (HRESs) represent a promising solution to address this situation given their portability and their potential contribution to avoiding carbon emissions. However, the sizing methodologies for these systems deal with some issues, such as the uncertainty of renewable resources. In this work, we propose a sizing methodology that includes long short-term memory (LSTM) cells to predict weather conditions in the long term, multivariate clustering to generate different weather scenarios, and a nonlinear mathematical formulation to find the optimal sizing of an HRES. Numerical experiments are performed using open-source data from a rural community in the Pacific Coast of Mexico as well as open-source programming frameworks to allow their reproducibility. We achieved an improvement of 0.1% in loss of load probability in comparison to the seasonal naive method, which is widely used in the literature for this purpose. Furthermore, the RNN training stage takes 118.42, 2103.35, and 726.71 s for GHI, wind, and temperature, respectively, which are acceptable given the planning nature of the problem. These results indicate that the proposed methodology is useful as a decision-making tool for this planning problem.

Preliminary information for the small-scale yellowfin tuna fishery management in Nayarit, Mexico

The small-scale tuna longline fishery operating on the coast of Nayarit started recently in 2013. We provide the first detailed report on some biological parameters for the yellowfin tuna (YFT) in Nayarit (Mexico). We sampled 584 YFT, representing a catch of 25.5 t. We fit the length–weight relationship, used the t-test to determine the type of growth, and estimated the selectivity curve. The total length data varied from 73.0 to 228.0 cm, with a mean of 153.0 ± 23.5 cm (mean ± SD). Weight ranged from 5.8 to 128.0 kg, with a mean of 43.7 ± 19.4 kg. Length–weight fitting results and the t-test suggested negative allometric growth. Selectivity fitting results suggested that selectivity follows an asymptotic pattern. Our results represent the first step into gathering information to establish research and monitoring programs for the YFT on the Pacific coast of Mexico. The information provided in this study could help develop proper regulations to assure a well-managed fishery and the sustainable exploitation of YFT in Nayarit.

Roccella ramitumidula (Roccellaceae), a new species from the tropical dry forest of Mexico

The new species Roccella ramitumidula is described from a tropical dry forest in the Pacific Coast of Mexico. The new species is characterized by fertile thalli, saxicolous habit, irregularly swollen branches and erythrin and lecanoric acid as lichen products. It differs from R. decipiens by its narrower and longer ascospores, irregularly swollen branches, uneven surface, and smaller branches. Sequences of the genetic markers ITS, nuLSU and RPB2 from the new species were added to a phylogenetic tree based on four genetic markers that included all the Roccella species known for the Americas. The biogeography and ecology of the species is discussed. We reported R. gracilis for the first time for the state of Jalisco, Mexico.

Morphology of the marine, planktonic, thecate dinoflagellate Gonyaulax areolata (Dinophyceae), a species causing red tides in the tropical Mexican Pacific

ABSTRACT Blooms of marine planktonic dinoflagellates are usual along the Pacific coast of Mexico, sometimes producing toxic red tides. The thecate dinoflagellate Gonyaulax areolata was found to produce a red tide event in the tropical Mexican Pacific. The species was originally described in 1911 by Kofoid and Michener without an illustration. The morphology of G. areolata was studied here by LM and SEM. Photosynthetic, solitary cells were fairly small, polyhedral, with a short apical protrusion and ‘shoulders’ on the epitheca, and two short, asymmetrical antapical spines. The cingulum was approximately median, cavozone, with the ends fairly displaced but with no, or only slight, overhang. The thecae were strongly ornamented with striae, areolae and pores. The plate formula was Po, 4ʹ, Q, 6ʹʹ, 6c, 4s, 6ʹʹʹ, 1p, 1ʹʹʹʹ, as recently attributed to some species of Gonyaulax. Details of important plates are given. Gonyaulax areolata seems to be morphologically closely related to other small species with a slight cingulum displacement and overhang, such as G. minima and G. striata, and more distantly related to G. spinifera. The maximum concentration of G. areolata was 1.74 × 106 cells l–1, in association with lower numbers of other dinoflagellates and diatoms. Yessotoxins were not detected. Oceanographic conditions during the bloom indicated moderate to weak upwelling, confirmed by both relatively low surface temperature and high Chl a concentration (14 µg l–1).

Dynamics of Hurricanes and Tropical Storms along the Pacific Coast of Mexico: A View from a Seismic Station

This study presents the analysis of seismic signatures generated during passage of hurricanes Newton(September 2016) and Willa (October 2018), recorded on the daily helicorders of a short-period seismic station at thedistances about 450 km from the tracks of events. This view from seismic station allowed to obtain the following results.Periods of passage of these tropical storms and hurricanes were identified. Analysis of the dynamics of sequences ofthese seismic signals allowed to separate the time intervals of increase and decrease in the development of atmosphericdisturbances. The spectral analysis of the signals of tropical storm Newton and hurricane Willa showed that the spectralamplitudes of signals, recorded during the maximum stage of activity of the tropical storm, were larger than the samefor the maximum stage of activity of the hurricane. This may be related to the presence of intensive hailstorms duringtropical storm.

Description of a new species of Liropus (Crustacea, Amphipoda) from Puerto Vallarta, Pacific coast of Mexico.

A new species of the genus Liropus Mayer, 1920 (Amphipoda, Caprellidae) is described from the Mexican Tropical Pacific coast. Liropus alarconi n. sp. is described on the basis of four specimens collected in association with the tropical marine sponge Trikentrion helium Dickinson, 1945, near to coralline patches, between 2330 m depth. Liropus alarconi n. sp. can be distinguished from its congeners for the following characters: pereonites 25 each with one dorsodistal projection and pereonite 3 with a mediolateral projection.

Feeding habits of the snapper Lutjanus peru in the central Gulf of California

A biological basis for survival and development, the diet of fish represents a baseline for research on ecological aspects related to the structure and function of marine communities. This study focused on the feeding habits of the Pacific red snapper, Lutjanus peru, in Santa Rosalía, Baja California Sur (Mexico), during August 2016 through October 2017. A total of 403 specimens were analyzed and categorized by sex, sexual maturity, and season. The size interval ranged from 21 to 60 cm total length, and the weight ranged from 195 to 1,920 g. A total of 29 prey items were identified, including fish (13 items), crustaceans (11 items), mollusks (4 items), and tunicates (1 item). According to the index of relative importance, the main prey were Sardinops sagax (47.65%), Nycthiphanes simplex (38.50%), Harengula thrissina (11.21%), Myctophidae (0.68%), and Benthosema panamense (0.52%). Prey were consumed in different proportions according to sex (F = 2.01, P < 0.049), sexual maturity (F = 4.99, P < 0.001), and season (F = 45.52, P < 0.001). The trophic width was narrow (Bi = 0.16); this was consistent with the Costello graph, which showed the consumption of mainly pelagic-coastal and mesopelagic gregarious prey. The Pacific red snapper in Santa Rosalía functioned as a tertiary consumer. Its opportunistic diet included few highly abundant prey items, and the diet composition differed from that of L. peru in other areas of the Gulf of California and the Pacific coast of Mexico.