Understanding the physiological mechanisms that facilitate invasion success is critical for predicting the persistence and spread of non-native species under increasing thermal variability. We examined thermal tolerance, acclimation capacity, and metabolic performance in juveniles of the invasive red swamp crayfish Procambarus clarkii (Girard, 1852) under controlled laboratory conditions. Juveniles were acclimated for 30 days to four ecologically relevant temperatures (20, 24, 28, and 32°C), and upper and lower critical thermal limits (CTmax and CTmin), thermal tolerance breadth (thermal polygon area), acclimation response ratios (ARR), and thermal metabolic scope (TMS) were quantified. Both CTmax and CTmin increased significantly with acclimation temperature, indicating pronounced thermal plasticity. CTmax rose from 37.4 to 40.1°C, whereas CTmin increased from 8.5 to 16.4°C across the acclimation range. The resulting thermal polygon area (286.0°C²) revealed a broad thermal tolerance consistent with a eurythermal strategy. ARR analysis showed asymmetric acclimation capacity, with greater plasticity at lower than at upper thermal limits. Aerobic metabolic performance, expressed as TMS, exhibited a unimodal response across acclimation temperatures, peaking at 28°C and declining at the thermal extremes, yet remaining consistently high and far from physiological collapse across all treatments. Together, these results demonstrate that juvenile P. clarkii combines broad thermal tolerance, asymmetric acclimation capacity, and sustained aerobic performance across a wide thermal range. This suite of ecophysiological traits likely enhances survival, establishment, and spread in thermally heterogeneous freshwater environments, providing mechanistic insight into the invasion success of this globally invasive crayfish under current and future climate variability.

Plant-based formulations supplemented with probiotics are a promising strategy to improve nutrient bioavailability in aquaculture, yet mechanistic understanding of microbial modulation of host metabolism remains limited. We evaluated whether supplementation with Bacillus velezensis (Sp1) and B. amyloliquefaciens (Sp3) influences metabolic efficiency and energy allocation in sub-adult red abalone (Haliotis rufescens). Over 180 days, animals were fed a plant-based or a fishmeal-based diet—both probiotic-supplemented and matched in protein and energy—and compared with fresh kelp (Macrocystis pyrifera) as a control. Metabolic performance was assessed from oxygen consumption, relative specific dynamic action (SDA) index, ammonia excretion and Oxygen-to-nitrogen ratio (O:N) ratio. The Bacillus-supplemented plant-based diet achieved metabolic efficiency comparable to M. pyrifera, with minimal SDA (4.7% vs. 4.3%) and commercially viable growth (2.07 mm/month). The O:N ratio indicated diet-specific, time-dependent shifts in substrate use. The fishmeal-based diet—despite identical macronutrient and probiotic composition—produced a markedly higher postprandial metabolic cost (SDA = 21.0%), consistent with reduced compatibility between high animal protein and herbivorous digestive physiology. Overall, probiotic supplementation may help convert plant-based ingredients into metabolically efficient functional feeds, offering a more sustainable approach that reduces dependence on marine-derived ingredients.

Aquaculture in Latin America has grown; however, it continues to rely on a limited number of species, which limits its potential for diversification and innovation. The white snook (Centropomus viridis), a high-value species native to the eastern tropical Pacific, with strong demand in local and international markets, remains underutilized due to gaps in our understanding of its physiology. The present study provides the first detailed thermal profile of C. viridis, identifying temperature conditions that could enhance survival, growth, and aquaculture performance. After 30 days of thermal acclimation at 20, 23, 26, 29, and 32°C, 230 juveniles (46 per temperature; 15 ± 3.4 g at acclimation start; two replicate tanks of 23 fish each) were assessed for their upper and lower critical thermal limits (CTmax and CTmin), thermal window area, preferred temperature, and thermal metabolic scope (TMS). Tolerance to higher temperatures increased with acclimation temperature, reaching CTmax values of 36.9 to 41.9°C. CTmin increased from 9.9 to 16.4°C across the acclimation gradient. These results show a narrow thermal window area (228°C2). The overall preferred temperature was 27.3°C. The maximum TMS was observed at 29°C, indicating that this temperature may represent a thermally favorable condition for maximizing aerobic performance. These findings establish a crucial physiological foundation for optimizing C. viridis aquaculture and will contribute to the diversification and resilience of native species for future marine farming in Mexico.