Size at sexual maturity, seasonal variation by maturity stages, and fecundity of the spotted round ray (Urobatis maculatus) and the thorny stingray (Urotrygon rogersi) from the northern tropical eastern Pacific.

Round rays (family: Urotrygonidae) are commonly caught as by-catch by shrimp trawl fisheries in the tropical eastern Pacific (TEP). However, little information on their life history and catch species composition exists for most round ray species, preventing the evaluation of the impact of fishing on their populations. The mean size at sexual maturity (DW50 ), seasonal variation by maturity stages, and fecundity for two round ray species caught during shrimp trawl research cruises in the south-eastern Gulf of California (northern TEP) were estimated using a multi-model approach and inference for the first time, to determine the part of the population of each species that is being affected by shrimp trawling. Disc width (DW) ranged from 7.0 to 30.9 cm for the spotted round ray (Urobatis maculatus), and 7.2-33.5 cm for the thorny stingray (Urotrygon rogersi), with females reaching larger sizes than males in both species. The DW50 was estimated at 12.8 and 11.8 cm DW for the males and females of U. maculatus, respectively, whereas for U.rogersi, it was 15.0 and 18.4 cm DW for males and females, respectively. Embryos were found in females ≥14.5 cm DW in both species. The maximum fecundity was five embryos for U. maculatus (mean = 3.1 ± 0.2 S.E., mode = 4), and six embryos for U. rogersi (mean = 3.0 ± 0.3 S.E., mode = 2). Fecundity and embryo size did not vary with maternal size. Male and female immature and mature individuals for both species, including pregnant females, were found in the catches in all seasons of the year. Our results can help determine the vulnerability of the studied species populations to fishing pressure from shrimp trawling in the northern TEP and guide the development of future monitoring strategies and conservation actions for these species, if necessary.

Understanding the natural expansion of white mangrove (Laguncularia racemosa) in an ephemeral inlet based on geomorphological analysis and remote sensing data.

The interactions between local tides and river discharges are crucial in the processes related to the recruitment of mangrove propagules in estuarine systems. This investigation aimed to determine the causes of the recent natural recruitment and expansion of Laguncularia racemosa in mudflats within an ephemeral inlet in Mexico. We conducted a fluvial and coastal geomorphology assessment with spaceborne and UAV-based images. We deployed and recorded continuous data loggers in the estuarine system to assess water level and salinity. Depending on the available data, we used a combination of cloud-computing Google Earth Engine, UAV-Digital Surface Models, LiDAR, Google Earth images, and biophysical variables to monitor mangrove forests from 2005 to 2022. When the inlet is open, the estuarine system presents a full tidal range (∼1-1.5 m) with a strong salinity gradient (0-35 mS/cm), in contrast to the strong freshwater influence and minimal water level variability (<10 cm) that prevails for three months when the inlet is closed. Once the mouth of the river closes, there is considerable sediment accumulation, creating mudflat areas adjacent to the mangrove forests where Laguncularia racemosa propagules begin to establish under minimal water level variability and oligohaline conditions. After 16 years, the new forest expanded by 12.3 ha, presenting a very high density (10000 stems/ha), a considerable basal area (54-63 m2/ha), and a maximum canopy height of 15.8 m, which largely surpasses that of other semiarid Laguncularia racemosa forests within permanent open-inlet systems or even in ephemeral inlets with different hydrological conditions. Our study will help to understand the causes of natural Laguncularia racemosa recruitment in extremely dynamic systems.

First report of plastic contamination in batoids: Plastic ingestion by Haller's Round Ray (Urobatis halleri) in the Gulf of California.

The presence of microplastics has been reported in the marine environment and these pollutants have also been reported in food webs. Information about the presence of microplastics in the Haller's Round Ray (Urobatis halleri) and bottom sediments off the east coast of the Gulf of California is non-existent. The digestive tracts of individuals of this species and sediment samples were examined for plastic particles in this region. In total, 107 plastic particles were found in the sediment. All were fibers and 94.4% were microplastics, the rest were mesoplastics. The gastrointestinal tracts of 142 rays were analysed, and it was determined that this is a benthic feeder. A total of 386 plastic particles were recovered from 46 individuals (32.4%). On average 10.2 (±7.4) plastic particles were found per specimen, with plastic lengths ranging from 0.00821 mm to 0.953 mm. The FTIR-ATR analysis revealed the presence of six types of polymers: polyamide or nylon polyethylene, polypropylene, and polyacrylic were found in both sediments and gastrointestinal tracts of Haller's Round Ray. Polyethylene terephthalate and polyacrylamide were only found in the gastrointestinal tracts of the ray. These polymers are consistent with the human activities undertaken in this area, specifically intensive small-scale and industrial fisheries, as they are used for the elaboration of fishing nets, plastic bags, storage containers, clothing, and fishing boats maintenance. Our results show that benthic feeders are exposed to plastic debris, and its presence is another potential threat to batoids, which are already threatened by bycatch, overfishing, and other pollutants. However, studies on the ingestion of plastic debris in batoids and its presence in the sediment are still scarce or non-existent for this region. As such, these studies are necessary to help in the preservation of these species.

In utero elemental tags in vertebrae of the scalloped hammerhead shark Sphyrna lewini reveal migration patterns of pregnant females.

Vertebral microchemistry recently allowed to infer the migration patterns of the scalloped hammerhead shark Sphyrna lewini in the Mexican Pacific, however conclusions regarding the movements of reproductive females were hindered by the small sample size. Considering that S. lewini is a placental viviparous species, maternal supply of nutrients to the embryos might influence their vertebral microchemistry while in utero and provide intrinsic markers of the pregnant female environmental histories. This hypothesis was tested before attempting to infer the migration patterns of pregnant females through the analyses of the in utero elemental profiles quantified in the vertebrae of coastal young-of-the-year ('YOY'). Vertebrae were obtained from sharks captured along the Mexican Pacific coast in 2016. Vertebral microchemistry was quantified using laser ablation inductively-coupled plasma mass spectrometry. Elemental signatures at vertebral edge were consistent between each pregnant female and her embryos demonstrating the viability of employing in utero elemental signatures as a maternal tag of the gestation-related environmental histories. Analyses of the YOY in utero Sr:Ba and Pb:Ca profiles suggested that pregnant females either (1) progressively migrated offshore before quickly returning to coastal habitats before term or (2) remained nearshore during complete gestation. Considering the endangered status of S. lewini, current management measures may be insufficient for the sustainable management of the population as pregnant females may be particularly susceptible to fisheries when remaining nearshore or entering coastal habitats prior to pupping.

Cadmium, mercury, and selenium in muscle of the scalloped hammerhead Sphyrna lewini from the tropical Eastern Pacific: Variation with age, molar ratios and human health risk.

With the aim of assessing health risk to shark consumers, cadmium, mercury, and selenium were measured in muscle of Sphyrna lewini from four coastal states (Baja California Sur, Sinaloa, Nayarit, and Colima) in western Mexico. According to length of specimens, three age modes were found: juveniles and neonates (the majority of the individuals), preadults and adults. Average concentrations (µg g-1 dry weight) in all the studied individuals followed the order cadmium (0.06), selenium (0.94), and mercury (1.56). The mean concentrations of cadmium and mercury increased significantly (p < 0.001) with mean length of specimens. Overall, hazard quotient and hazard index values were below one so there is no health risk to consumers. According to molar ratios of Hg and Se in the edible portion (muscle) of sharks, and depending on the areas of collection, individuals from Baja California Sur might not be beneficial to consumers.

Larval fish assemblages in nearshore waters of southeast Gulf of California: vertical and temporal patterns

The influence of salinity and temperature on larval fish assemblages, as well as, temporal and vertical patterns on larval fish assemblages off the inlet of the Presidio River, southeast coast of the Gulf of California were evaluated. Samplings for ichthyoplankton and environmental parameter measurements were carried out at three depths, in five sampling sites, during September and December 1994, and April and June 1995. Anchovies and herrings (Clupeiformes) were the most abundant larval fish accounting for 77% of the total abundance. A significant relationship between salinity and the abundance of larval herrings (Opisthonema medirastre and O. dovii) and between the water temperature and the abundance of the weakfish (Cynoscion reticulatus) was found. Anchovies (Anchoa lucida, A. walkeri, and A. nasus) were present in all sampled months, while O. medirastre and O. dovii occurred in December and June, and C. reticulatus in September. Larvae of pelagic fish were more abundant near the surface, while larvae of demersal fish were more abundant near the bottom. The present study, by emphasising the importance of considering temporal and vertical changes in larval fish assemblages in coastal environments with ecological and economic importance, will be useful for designing more efficient sampling programs.(AU)

Se evaluó la influencia de la salinidad y la temperatura, así como patrones temporales y verticales en la comunidad de larvas de peces enfrente del río Presidio, costa sudeste del Golfo de California. Los muestreos de ictioplancton y las mediciones de los parámetros ambientales fueron realizados a tres profundidades, en cinco sitios de muestreo, durante septiembre y diciembre de 1994, y abril y junio de 1995. Las anchoas y sardinas (Clupeiformes) fueron las larvas de peces más abundantes representando el 77% de la abundancia total. Se encontró una relación significativa entre la salinidad y la abundancia de larvas de sardinas (Opisthonema medirastre and O. dovii), y entre la temperatura del agua y la abundancia de la corvina rayada (Cynoscion reticulatus). Las anchoas (Anchoa lucida, A. walkeri y A. nasus) estuvieron presentes en todos los meses muestreados, mientras que O. medirastre y O. dovii ocurrieron en diciembre y junio, y C. reticulatus en septiembre. Las larvas de peces pelágicos fueron más abundantes cerca de la superficie, mientras que las larvas de peces demersales fueron más abundantes cerca del fondo. El presente estudio, al enfatizar la importancia de considerar los cambios temporales y verticales en el ensamblaje de larvas de peces en ambientes costeros con importancia ecológica y económica, será útil para diseñar programas de muestreo más eficientes.(AU)

Periodicity of the growth-band formation in vertebrae of juvenile scalloped hammerhead shark Sphyrna lewini from the Mexican Pacific Ocean.

The age of 296 juvenile scalloped hammerhead sharks Sphyrna lewini caught by several fisheries in the Mexican Pacific Ocean from March 2007 to September 2017 were estimated from growth band counts in thin-sectioned vertebrae. Marginal-increment analysis (MIA) and centrum-edge analysis (CEA) were used to verify the periodicity of formation of the growth bands, whereas elemental profiles obtained from LA-ICP-MS transect scans in vertebrae of 15 juveniles were used as an alternative approach to verify the age of the species for the first time. Age estimates ranged from 0 to 10+ years (42-158.7 cm total length; LT ). The index of average percentage error (IAPE 3.6%), CV (5.2%), bias plots and Bowker's tests of symmetry showed precise and low-biased age estimation. Both MIA and CEA indicated that in the vertebrae of juveniles of S. lewini a single translucent growth band was formed during winter (November-March) and an opaque band during summer (July-September), a period of faster growth, apparently correlated with a higher sea surface temperature. Peaks in vertebral P and Mn content spatially corresponded with the annual banding pattern in most of the samples, displaying 1.19 and 0.88 peaks per opaque band, respectively, which closely matched the annual deposition rate observed in this study. Although the periodicity of growth band formation needs to be verified for all sizes and ages representing the population of the species in the region, this demonstration of the annual formation of the growth bands in the vertebrae of juveniles should lead to a re-estimation of the growth parameters and productivity of the population to ensure that it is harvested at sustainable levels.

Cadmium and lead concentrations in hepatic and muscle tissue of demersal fish from three lagoon systems (SE Gulf of California).

We determined the levels of Cd and Pb in liver and muscle of demersal fish from three lagoon systems (Urías, Huizache, and Teacapán) in the SE Gulf of California with the purpose of comparing the studied metals in fish from the three ecosystems and to assess the potential human health risk. Considering the number of individuals, the sequence of fish abundance was Teacapán > Huizache > Urías. Length and size at maturity of collected species showed that 76.5% of the individuals were juveniles. Overall, Cd and Pb were more accumulated in liver than in muscle. After multivariate analyses, considering fish tissue and locality, Cd and Pb levels were different (p < 0.05) between fish from Teacapán and Huizache. In general, the hazard quotients (HQs) of Pb were higher than the corresponding values of Cd; the highest HQ for Cd (0.0051) corresponded to Mugil curema, and the highest HQ for Pb (0.0099) was estimated in Diapterus peruvianus. With respect to the hazard index (accumulative risk from Cd and Pb), the most elevated value (HI = 0.0124) was estimated for Pomadasys macracanthus. Estimated HI does not represent a health risk at the consumption rates of the Mexican population.

Feeding habits and trophic level of the Panama grunt Pomadasys panamensis, an important bycatch species from the shrimp trawl fishery in the Gulf of California.

The Panama grunt is an abundant and commercially important species in the southeastern Gulf of California, but the research undertaken on this species is scarce despite its ecological and economic importance. We studied the feeding habits of Panama grunt through stomach content analyses as a first step towards understanding the biology of this species in the study area. Our results indicate that the Panama grunt is a benthic predator throughout its life cycle and feeds mainly on infaunal crustaceans. Diet differences among grunt were not found according to size, diet, or season. Shannon diversity index results indicate that Panama grunt has a limited trophic niche breadth with a diet dominated by a limited number of taxa as crustaceans. The estimated trophic level of this species is 3.59. Overall, the Panama grunt is a carnivorous fish occupying the intermediate levels of the trophic pyramid.

Síndrome de insuficiencia respiratoria aguda (SIRPA) (Primera de dos partes) / Acute respiratory distress syndrome (ARDS). (first of two parts)

Al síndrome de insuficiencia respiratoria progresiva del adulto (SIRPA) se le denomina actualmente síndrome de insuficiencia respiratoria aguda. Es un término descriptivo que se aplica a muchas lesiones pulmonares agudas, infiltrativas y difusas, de tiología diversa, que se acompañan de hipoxemia severa. El SIRPA se caracteriza por lesiones de la membrana alveolo-capilar que consisten en escape de líquidos y elementos formes de los vasos sanguíneos al espacio intersticial y a los alveolos, y permeabilidad vascular aumentada a las proteínas. Los objetivos del tratamiento son mantener la disponibilidad de oxígeno en niveles óptimos (apoyo ventilatorio convencional y no convencional, oxigenación de membrana extracorpórea, gasto cardiaco adecuado) y restricción de líquidos. Otras acciones terapéuticas de esta entidad (decúbito prono, aumento de la precarga ventricular, surfactante exógeno, antioxidante, ketoconazol, eicosanoides y pentoxifilina) están en proceso de evaluación; el empleo de corticoesteroides, es controversial en la actualidad