The mining port of Santa Rosalia presents elevated concentrations of potentially toxic elements (PTEs) in its sediments that exceed ecotoxicological standards, representing a risk to marine biota. In cephalopods, embryonic exposure to PTEs can induce morpho-physiological changes that jeopardize survival and, consequently, reproductive success. The octopus Octopus hubbsorum, resident in the Santa Rosalia region, shows a marked capacity for bioaccumulation of Cd, Mn, Ni, Pb, and Zn, suggesting the possibility of accumulation in embryos and even maternal transfer. The present study evaluated the incidence and type of embryonic abnormalities in O. hubbsorum originating from an area highly contaminated by PTEs. Three portions of egg masses (45 festoons in total) collected in Santa Rosalia were analyzed. Embryonic development was morphologically characterized by using a stereomicroscope and photographic records. To estimate the number of eggs per festoon, unfertilized eggs, and eggs with abnormalities, a 1-cm segment from each festoon was analyzed. The results revealed 3.7% abnormalities, corresponding to 10 types of alterations, classified as defects in the morphology of the yolk sac and embryo, with a higher prevalence of eggs with translucent embryos and yolks. The incidence of abnormalities was low compared with previous reports and suggests that they are related to natural or environmental causes. The egg masses presented 0.84% unfertilized eggs. Despite the high levels of PTEs in Santa Rosalia, the embryonic development of O. hubbsorum is not significantly affected, likely due to the short exposure time during embryonic development (3 to 4 weeks), the low bioavailability of PTEs in the water column, or the low permeability of the chorionic capsule. Nevertheless, additional studies are required to evaluate these mechanisms with greater precision.
A digital bathymetric model was generated for a specific area of the Punta Mita Shallow-Water Hydrothermal System, and the spatial distribution of some active hydrothermal vents was mapped. Bathymetric data acquired with a single-beam echosounder were interpolated at 2 m resolution, and vent locations were analyzed using spatial and kernel density methods. The results provide a first-order, continuous geomorphological approach of the seabed in this area, agreeing in certain aspects with the previously reported fault system, but also showing new lineaments, depressions, and morphological features associated with hydrothermal activity.
Mangrove ecosystems along the American continent represent vital habitats supporting diverse marine life, including elasmobranchs. This study comprehensively examines elasmobranch diversity and their utilization of neotropical mangrove habitats. Through an extensive review of literature, museum collections, and online databases, we compiled records of elasmobranch species inhabiting mangroves across 15 countries, encompassing 29 localities. The findings reveal a rich diversity of elasmobranchs, with 35 shark species representing eight families and four orders and 48 batomorph species from 13 families and four orders. Intriguingly, this diversity is unveiled despite the relatively limited attention that mangrove ecosystems and elasmobranchs have received in scientific research, especially compared to other marine environments. Except for charismatic species, much remains unknown about the utilization of mangrove habitats by various shark and ray species. The study highlights the crucial role of museum collections in verifying and enhancing our understanding of elasmobranch richness in these habitats. Furthermore, the research sheds light on the conservation status of these species, revealing that nearly half of the elasmobranchs cataloged in this study are currently listed as threatened, according to the IUCN Red List. This underscores the urgency of protecting mangrove habitats, which face significant degradation and loss due to human activities. We emphasize the importance of addressing gaps in our knowledge regarding the relationship between mangrove habitats and elasmobranchs and underscore the need for increased research and conservation efforts in these critical ecosystems. Ultimately, this research contributes to understanding the intricate connections between neotropical mangroves and elasmobranchs and highlights their significance in marine biodiversity conservation.
The development of Opistognathus rosenblatti from larvae to juveniles is described using 60 specimens (3.6-47.0 mm LP). Adults were captured in the Loreto Bay Marine Park, Gulf of California, Mexico. They were conditioned and bred in captivity. Changes from larva to juvenile in morphological, meristic, and pigmentation pattern characters were described from specimens preserved in formalin solution (4%). Meristic data of larvae and juveniles were 27-29 total myomeres, XI, 13 dorsal fin, II, 13 anal fin, 8+7-9 caudal fin, and 5 hypural bones. The pigmentation pattern of the larvae from preflexion to postflexion stage consisted of: A cephalic region with small melanophores on the dorsal surface of the brain, on the lower margin of the nasal capsule, on the lateral surface of the lower and upper jaws, on the nape, and the gular region; abdominal region with a series of melanophores on the intestinal sac margins, including the swim bladder; the trunk region with few melanophores in the last myomeres; caudal region with three series of stellate melanophores on the dorsal, ventral margins and medial-lateral section between myomeres 1-14. Other stellate melanophores were present throughout this section, which interlaced towards all margins, providing a very light brown coloration on this section of the body. The juvenile is yellow-orange, with small punctate melanophores that extend across its entire body surface. It also exhibits four discontinuous series of brown spots (circular to oval) extending from the ventral-posterior margin of the eye to the height of the tips of the bases of the dorsal and anal fins. The conjunction of pigmentation patterns, myomeres count, and fin meristics is a distinctive identifier for O. rosenblatti larvae and juveniles, as it is not observed in the larvae of other fish species.
Understanding population-level variation in thermal tolerance is essential for predicting species responses to climate change. This study assessed the lethal low and high temperatures (LT50) of juvenile Pacific lion-paw scallops (Nodipecten subnodosus) from two environmentally contrasting regions of the Baja California Peninsula: Laguna Ojo de Liebre (LOL, Pacific coast) and Bahía de Los Ángeles (BLA, Gulf of California). Individuals were exposed to a 96-h thermal bioassay across seven fixed temperatures (5–35°C) utilizing a precision-controlled marine simulation system. Mortality was recorded hourly, and LT50 values were estimated via Probit regression analysis. Both populations exhibited similar lower LT50 (~6.6°C), but significantly different upper LT50: 30.58°C for LOL and 32.13°C for BLA. Results are evidence of adaptive evolution differences. Comparison with historical environmental data indicate that BLA scallops, despite facing higher thermal stress, exhibit greater resilience, making them promising candidates for aquaculture under climate change scenarios. Future research may consider the LT50 values reported here as instrumental for projecting the climate change impacts and aquaculture planning.
