Salvador Emilio Lluch-Cota

The IPCC reports decreasing trends in global and regional pH, which diminish aragonite ([[EQUATION]]) saturation states, approaching levels that could lead to shell dissolution in commercial gastropods and bivalves. In the north-eastern Pacific, high-value abalone fisheries, which are sensitive to pH variations, require knowledge of in situ pH to properly assess the bioeconomic effects of their possible dynamic trajectories under alternative exploitation rates. In this study, daily and seasonal pH values obtained from an in situ HOBO Data Logger for the period Oct 2023 - Oct 2024 in La Bocana, Baja California Sur, México (located at 26°46’32.1 N and 113°42’47.9 W) were analysed. The HOBO pH range observed was [7.54, 8.35], with lower values in August and September and higher values in April and June. These pH values were used to calculate the corresponding [[EQUATION]]values using the software CO2SYS v2.5©. Trajectories of intra-annual pH and [[EQUATION]]both show a seasonal pattern of aragonite saturation state in the La Bocana coastal area, BCS. The mean [[EQUATION]]value was [[EQUATION]]2.55, ranging from 1.44 to 3.15. A dynamic, environmentally driven, bioeconomic age-structure model was built to account for changes in the saturation states ([[EQUATION]]) in the study region, where a fishery targets a high-priced calcifying species (i.e., abalone, Haliotis corrugata). This was done by making the constant age-specific vectors of individual growth and natural mortality into dynamic functions of pH over time. With predetermined limit reference points (LRPs) for stock biomass and resource rent, the associated risks of possible IPCC pH trajectories and alternative exploitation rates were calculated over time through a Monte Carlo analysis. Under the Sustainability IPCC scenario (SSP1 – 2.6), results indicated a negligible risk of falling below LRPs for H. corrugata over time. On the other hand, the long-run risks for stock biomass under the IPCC SSP2-4.5 scenario are 14%, 23%, and 55% for the three exploitation rates considered. Additionally, for the IPCC SSP5-8.5 Fossil-fuel Development scenario, the mid-term risks are 13%, 23%, and 48%, respectively. In the long run, a 100% risk of falling below LRP (species moratorium) was calculated.

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.

Marine heatwaves (MHWs) have become increasingly frequent and intense, raising concerns about their impacts on fisheries production and economic value. We present a global assessment of MHW-related impacts across 2088 marine fisheries from 1985 to 2022. Using high-resolution satellite data and standardized catch production and catch value, we identified significant reductions in catch and ex-vessel value during years of elevated thermal stress. A total of 322 fisheries (15%) showed statistically significant declines during years with high MHW activity, with regional disparities indicating that the Northeast Atlantic and Southeast Pacific experienced the highest cumulative losses, while country ranking highlighted Norway, China, Japan, and Peru as the most affected. Estimated accumulated global losses since 1985 exceeded 5.6 million tonnes and USD 6.6 billion (2005 USD equivalents), nearly 40% of which occurred during 2013–2022. These findings emphasize the need to incorporate extreme thermal events into fisheries risk assessments and adaptation strategies, especially in highly productive or strategic regions.

Objetivo: analizar la evolución histórica, el estado actual y el potencial de la acuacultura en Baja California Sur, identificando los principales desafíos y oportunidades para su desarrollo. Metodología: se empleó un enfoque mixto que combinó el análisis de fuentes secundarias, incluyendo datos de Conapesca, Sagarpa e INEGI, con entrevistas semiestructuradas a productores, académicos y funcionarios gubernamentales. Para el análisis de los datos cualitativos se utilizó el software ATLAS.ti, aplicando análisis de contenido y codificación cualitativa para identificar patrones clave. Resultados: revelan que las principales barreras para el desarrollo de la acuacultura en la región incluyen el acceso limitado a financiamiento, deficiencias en infraestructura y una regulación ineficiente. No obstante, se identificaron ventajas como las condiciones ambientales favorables y la creciente demanda de productos acuícolas sustentables. Limitaciones: el estudio se centra únicamente en Baja California Sur, lo que podría restringir la generalización de los hallazgos a otras regiones. Conclusiones: para consolidar el sector acuícola en la región es necesario mejorar el acceso a financiamiento, fortalecer la infraestructura y optimizar la regulación. Asimismo, se recomienda la implementación de políticas públicas que fomenten la diversificación de especies y la capacitación técnica, con el fin de impulsar un desarrollo acuícola sostenible.

Understanding how thermal variability affects marine ectotherms is essential for predicting species resilience under climate change. We investigated the physiological responses of juvenile Nodipecten subnodosus (lion’s paw scallop), offspring of two genetically distinct populations (Bahía de Los Ángeles and Laguna Ojo de Liebre), reared under common garden conditions and exposed to three temperature regimes: constant, regular oscillation, and stochastic variability. After 15 days of exposure, scallops underwent an acute hyperthermia challenge. We measured metabolic rates, scope for growth (SFG), tissue biochemical composition, and oxidative stress markers (SOD, CAT, GPx, TBARS). No significant differences were detected between populations for most traits, suggesting that phenotypic plasticity predominates over evolutionary divergence in thermal responses. However, the temperature regime significantly influenced metabolic, biochemical and oxidative stress markers, indicating that scallops in variable conditions compensated through improved energy balance and food assimilation but also showed higher oxidative stress compared to the constant regime. Following acute hyperthermic exposure, energy demand escalated, compensatory mechanisms were impaired, and scallops attained a state of physiological maintenance and survival under stress, irrespective of their population or prior thermal regime exposure.

Understanding how thermal variability affects marine ectotherms is essential for predicting species resilience under climate change. We investigated the physiological responses of juvenile Nodipecten subnodosus (lion’s paw scallop), offspring of two genetically distinct populations (Bahía de Los Ángeles and Laguna Ojo de Liebre), reared under common garden conditions and exposed to three temperature regimes: constant, regular oscillation, and stochastic variability. After 15 days of exposure, scallops underwent an acute hyperthermia challenge. We measured metabolic rates, scope for growth (SFG), tissue biochemical composition, and oxidative stress markers (SOD, CAT, GPx, TBARS). No significant differences were detected between populations for most traits, suggesting phenotypic plasticity predominates over evolutionary divergence in thermal response. However, the temperature regime significantly influenced metabolic, biochemical and oxidative stress markers, indicating that scallops in variable conditions compensated through improved energy balance and food assimilation but also showed higher oxidative stress compared to the constant regime. Following acute hyperthermic exposure, energy demand escalated, compensatory mechanisms were impaired, and scallops attained a state of physiological maintenance and survival under stress, irrespective of their population or prior thermal regime exposure.