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DNA metabarcoding and stable isotope analysis have significantly advanced our understanding of marine trophic ecology, aiding systematic research on foraging habits and species conservation. In this study, we employed these methods to analyse faecal and blood samples, respectively, to compare the trophic ecology of two Red-billed Tropicbird (Phaethonaethereus; Linnaeus, 1758) colonies on Mexican islands in the Pacific. Trophic patterns among different breeding stages were also examined at both colonies. Dietary analysis reveals a preference for epipelagic fish, cephalopods, and small crustaceans, with variations between colonies and breeding stages. Isotopic values (δ15N and δ13C) align with DNA metabarcoding results, with wider niches during incubation stages. Differences in diet are linked to environmental conditions and trophic plasticity among breeding stages, influenced by changing physiological requirements and prey availability. Variations in dietary profiles reflect contrasting environmental conditions affecting local prey availability.

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Fibropapillomatosis (FP) - tumour-associated chelonid alphaherpesvirus 5 (ChHV5; Scutavirus chelonidalpha5) - is a disease that affect marine turtles around the world, and characterized by the formation of cutaneous tumours that can appear anywhere on the body. We carried out a thorough literature search (from 1990 to 2024) in the feeding sites of North-western Mexico, a region that hosts important habitats for feeding, development, and reproduction for five of the seven existing sea turtle species. We found 18 reports recording a total of 32 cases of FP and/or ChHV5/Scutavirus chelonidalpha5 in coastal and insular areas of North-western Mexico. Baja California Sur resulted with the highest number of cases (75%). While the first case of ChHV5/Scutavirus chelonidalpha5 infection was reported in 2004, the presence of FP tumours was reported in 2014 and became more frequent between 2019 and 2024. The affected species were black, Chelonia mydas (50%), olive ridley, Lepidochelys olivacea (46.8%) and loggerhead turtles, Caretta caretta (3.2%). Tumours occurred mainly in anterior flippers (46.1%) and neck (22.5%), and most had a nodular and verrucous appearance with a rough surface. In the study region, there is a potential sign of the emergence of the ChHV5/Scutavirus chelonidalpha5 infections and FP disease during the last 20 years, with a rapid increase during the last 10 years. As long as infections by ChHV5/Scutavirus chelonidalpha5 and the prevalence of the FP disease may be potentially influenced by anthropogenic activities, a One Health approach is needed to understand and improve sea turtles' health.

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Host phylogeny and ecological convergence are two factors thought to influence the structure of parasite communities. The aims of this study were to determine the diversity of metazoan parasites of 10 sympatric fish species of the family Carangidae from the southeastern Gulf of California, and to analyze their similarity at infracommunity and component community levels, in order to determine if the host species, particularly those congeneric with similar ecological characteristics, exhibit similar assemblages of parasites. In total, 874 fish specimens were examined and 40 parasite species were identified. The component community was composed by 21 parasite species in Caranx caninus, 20 in C. caballus, 11 in C. vinctus, five in Chloroscombrus orqueta, four in Carangoides otrynter, seven in Hemicaranx leucurus, eight in Selene brevoortii, 14 in S. peruviana, and 11 in Trachinotus rhodopus. The metazoan parasite communities of C. vinctus, Ch. orqueta, H. leucurus, and S. brevoortii are reported here for the first time. The parasite communities of the remaining six carangid species have been reported from regions other than the Gulf of California. All fish species differed significantly regarding the diversity of their parasite infracommunities. This possibly is due to different patterns of habitat use among fish species, and because of the differential host specificity among parasite taxa. Nonetheless, when the analysis was restricted to common parasite species, some fish showed similar parasite infracommunities, particularly congeners of the genus Selene as well as C. caballus and C. vinctus. The component communities of species of Selene were highly similar (>65%), but the three species of Caranx were not. This result supports the hypothesis that congeneric fish species with similar ecological filters harbor similar parasite communities. However, the difference observed between C. caninus and C. caballus suggests that these species, despite being evolutionary and ecologically related, have different physiological or immunological characteristics (compatibility filters) that may result in different parasite communities.

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Island oak (Quercus tomentella) is a rare relictual island tree species that exists only on six islands off the coast of California and Mexico, but was once widespread throughout mainland California. Currently, this species is endangered by threats such as non-native plants, grazing animals, and human removal. Efforts for conservation and restoration of island oak currently underway could benefit from information about its range-wide genetic structure and evolutionary history. Here we present a high-quality genome assembly for Q. tomentella, assembled using PacBio HiFi and Omni-C sequencing, developed as part of the California Conservation Genomics Project (CCGP). The resulting assembly has a length of 781 Mb, with a contig N50 of 22.0 Mb and a scaffold N50 of 63.4 Mb. This genome assembly will provide a resource for genomics-informed conservation of this rare oak species. Additionally, this reference genome will be the first one available for a species in Quercus section Protobalanus, a unique oak clade present only in western North America.

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The abundance of microplastics (MPs) in the gastrointestinal tract (GT), gills (GI), and exoskeleton (EX) of Litopenaeus vannamei shrimp cultured in a commercial indoor super-intensive controlled (ISCO) system was investigated. Shrimp of 25 days (postlarvae; PL25), and one, three, five, and seven culture months were analyzed. The postlarvae PL25 MP abundance per individual and gram of PL (wet weight) was 0.2 ± 0.0 MPs and 3.5 ± 0.5 MPs/g. For L. vannamei juveniles at one, three, five, and seven culture months, the MP abundance per juvenile shrimp was 10.0 ± 0.3, 27.2 ± 1.6, 32.3 ± 3.1, and 40.3 ± 3.6 MPs/individual, respectively (expressed in MPs/g of tissue were 1.6 ± 0.1, 2.0 ± 0.2, 2.0 ± 0.3 and 1.5 ± 0.2, respectively). Fibers were the most common MP type in all shrimp age classes (42.1-68.7 %), and the predominant color was transparent (46.1-65.0 %). The MP size in all shrimp stages ranged between 15 and 4686 µm. In general, the predominant polymers identified were PE (37.4 %), NY (21.1 %), and PET (18.5 %). The MP variability through the culture cycle showed that as the age of shrimp increased, and the culture advanced the MP abundance and size also augmented. Conversely, there is a higher MP abundance in L. vannamei cultured in ISCO systems compared to shrimp cultured in traditional semi-intensive and intensive ponds and those from wild environments. The latter is probably due to the extensive use of plasticized materials (geomembrane and greenhouse installations) and their degradation, which cause a greater MP exposure to shrimp. The estimated oral MP intake by ISCO shrimp consumption was 647 MPs/capita/year, which can be 178 % more than from wild shrimp.

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The San Quintin Kangaroo Rat, a rodent species microendemic to the San Quintin-El Rosario region in Baja California that was considered potentially extinct in the wild, was recently rediscovered. This stimulated subsequent searches by us throughout its known distribution range and on sites that seemed suitable beyond its limits. We captured the species at 19 out of 42 localities surveyed, of which 6 are beyond its historically known distribution range, expanding the latter by ~60 km. Most sites occupied by the species occur on abandoned farmland in early ecological successional stages. Our data support that in the highly transformed agricultural landscape into which the region was converted in the 20th century, the species was able to survive undetected and colonize/recolonize sites once habitat became adequate after agricultural abandonment. This exhibits that the species is highly resilient and persisted as a metapopulation. Further research and conservation actions must be framed within context of the region's agricultural development.

Quintín­El Rosario, Baja California, considerada potencialmente extinta, se redescubrió recientemente. Ello estimuló búsquedas en todo su rango de distribución conocido y en sitios potenciales que parecían adecuados más allá de sus límites geográficos. Capturamos a la especie en 19 de 42 localidades, de las cuales 6 estaban fuera de su rango de distribución históricamente conocido, expandiendo este rango en ~60 km. La mayoría de los sitios ocupados por la especie se encuentran en tierras de cultivo abandonadas en etapas tempranas de sucesión ecológica. Nuestros datos respaldan la hipótesis de que el paisaje agrícola altamente antropizado, en el que se convirtió la región en el siglo XX, la especie sobrevivió en refugios y colonizó/recolonizó sitios una vez que el hábitat se volvió adecuado después de su abandono agrícola. Esto mostró que la especie es altamente resiliente y persistió como una metapoblación. Las futuras acciones de investigación y conservación deben enmarcarse en el contexto del desarrollo agrícola de la región.

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This study assessed the concentrations of trace metals in tissues of Mytilus californianus from the west coast of Baja California, Mexico, during the cold and warm seasons. The concentrations of silver, cadmium, copper and zinc in mussel tissues were measured using Atomic Absorption Spectrophotometry. Silver concentrations ranged from 0.03 to 0.48 µg/g dry weight (d.w.) with significantly higher values registered at sites close to densely populated areas. Cadmium, copper, and zinc concentrations ranged from 0.57 to 7.83 µg/g d.w., 3.71 to 621 µg/g d.w., and 57.54 to 124.55 µg/g d.w., respectively. According to the WHO, values of copper and zinc were within acceptable limits. The maximum values of cadmium, however, exceeded the recommended limits set by the European Commission (2014). The human health risk of the metals analyzed was low (THQ and HI < 1). The regular monitoring of trace metals in M. californianus is recommended for a more definitive evaluation of contaminants.

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Background: Parasphaerosyllis Monro, 1937 is a syllid genus, currently composed of four species: P.indica Monro, 1937 from the Arabian Sea, P.uschakovi (Chlebovitsch, 1959) from the Kurile Islands, P.ezoensis Imajima & Hartman, 1964 from Japan and P.malimalii Capa, San Martín & López, 2001 from the Pacific coast of Panama. The distribution of P.indica is circum-tropical to temperate waters, but the presence of species complexes has been suggested. In order to clarify the distribution of P.indica in many areas of the world, a re-description, based on examination of the type material, is required as a first step to a better understanding of its diagnostic features. New information: Parasphaerosyllisindica is re-described, based on holotype examination, a new species is established from the Gulf of California and Parasphaerosyllismalimalii is reported for the first time since its description in 2001. Parasphaerosyllisirregulata sp. nov. is distinguished from its congeners by the following features: 1) Palps are free at their base; 2) Two types of dorsal cirri are present: spherical to bulbous and moniliform cirri; 3) Both types of cirri are distributed irregularly. A spherical/bulbous and moniliform cirrus may appear together within the same segment (asymmetrical segment) or only a spherical/bulbous cirrus may appear in several consecutive segments (not alternating as occurs in congeners); 4) The spherical/bulbous cirri may have distal knobs with 1-3 terminal articles; and 5) Bidentate falcigers with short, sub-triangular blades with a proximal tooth slightly larger that the distal one. A taxonomic key to species of Parasphaerosyllis species is included.

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Alexandrium tamiyavanichii is a marine dinoflagellate known to produce Paralytic Shellfish Poisoning (PSP) toxin. Thus, a strain was isolated from La Paz Bay, Baja California Sur, Mexico and used to explore whether stress conditions, such as phosphorus limitation (PL) and nitrogen enrichment (NE) modulate population growth and PSP toxin production in the GSe medium. Growth kinetics showed that the PL treatment produced a 3.4-fold increase in cell density versus control at day 30 of the culture cycle. The highest PSP concentration was found in the control culture (309 fmol cell-1) on day 21. Saxitoxin (STX) was the main analog in all the treatments (> 40 % mol). In conclusion, PL and NE treatments promoted growth kinetics in the species studied but did not affect the PSP toxin production. For the first time, the present research describes A. tamiyavanichii high toxicity strain isolated from Mexican coasts relative to the South-Atlantic strains.

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BACKGROUND: This paper examines the association between drinking context use by Whites and Hispanics on and off the US/Mexico border and alcohol problems. METHODS: Data come from a household sample of 1209 adults 18 to 39 years of age resident in Imperial County on the California/Mexico border; and Kern, Tulare, and Madera in California's Central Valley. Data were collected on the phone or online and analyzed with an ordinal generalized linear model. RESULTS: The pattern of statistically significant associations between the frequency and the volume of drinking in different contexts varies across problem types. Furthermore, some contexts of drinking are associated with problems in more than one area. For instance, frequency of drinking at bars/pubs is associated with social problems, risky sex, and fights, but not with injuries. Injuries are associated with the frequency of drinking at home alone or with family and at restaurants. Volume of drinking at bars/pubs is also significantly associated with three different contexts: social problems, injury, and fights. But the volume of drinking at the home of friends or relatives is associated with fights only. Border location is an effect modifier, changing the effect of frequency of drinking at bars and pubs from protective to a factor of risk for social problems and fights. CONCLUSION: These results provide support for the social ecology of drinking and micro environmental factors or risk. The effect of border location on frequency of drinking in bars/pubs underlines the importance of the macro environment in problem generation.

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