Description: In the context of global warming, the present study aimed to identify at which stages the embryos of the holobenthic species Octopus maya are the most sensitive to temperature. We used temperature as a tool to induce minimum (TIMR-min: 11°C) and maximum metabolic rates (TIMR-max: 30°C) on embryos that came from three wild females caught off Sisal harbor (21°10'N, 90°02'W; Yucatán, Mexico) in March 2016. Higher metabolic rate values were recorded at stages XV and XVI, when the three hearts start beating, compared to stage X, when organogenesis begins. The factorial metabolic scope (FMS = TIMR-max ? TIMR-min) was higher at stages XV and XVI than the more mature stages, establishing stage XVII as the most vulnerable. High temperature exposure applied only during the earliest developmental stages (until stage XV) could have adaptive advantages if spawning occurs during hot waves in tropical coastal zones where the embryos are incubated or used for aquaculture purposes by shortening the time before hatching without physiological costs.

Description: Morphological changes of Octopus mimus females were evaluated during ovarian development. Digestive gland (DG) and ovaries wet weight were assessed to obtain gonadosomatic and hepatosomatic indices. Obtained from a group of females placed in tanks until spawn, embryos were incubated and sampled during development. Females (DG and ovaries), embryos (at different stages of development) and paralarvae (one and three days old) were preserved for energetic metabolites (glucose, glycogen, cholesterol, triacylglycerides, and protein concentrations), digestive enzyme activities (acidic proteases, alkaline proteases, trypsin and lipases), detoxification (acetylcholinesterase and carboxylesterase activities), and oxidative stress indicators (catalase activity, glutathione-s-transferase activity, superoxide dismutase activity, redox potential, total glutathione and lipid peroxidation).

Description: Sexual maturation and reproduction influence the status of a number of physiological processes and consequently the ecology and behaviour of cephalopods. Using Octopus mimus as study model, the present work was focused in the changes in biochemical compound and activity that take place during gonadal maturation of females and its consequences in embryo and hatchlings characteristics. To do that, a total of 31 adult females of Octopus mimus were sampled to follow metabolites (ovaries and digestive gland) and digestive enzyme activities (alkaline and acidic proteases) during physiological and functional maturation. Levels of protein (Prot), triacylglyceride (TG), cholesterol (Chol), glucose (Glu) and glycogen (Gly) were evaluated. Groups of eggs coming from mature females were also sampled along development and after hatching (paralarvae of one and three days old) to track metabolites (Prot, TG, Glu, Gly, TG, Chol), digestive enzymes activity (Lipase, alkaline proteases, and acidic proteases), and antioxidant defence indicators with embryos development. Based on the data obtained, we hypothesised that immature females store Chol in their ovaries, probably from the food they ingested, but switch to TG reserves at the beginning of the maturation processes. At the same time, results suggest that these processes were energetically supported by Glu, obtained probably from Gly breakdown by gluconeogenic pathways. Also, was observed that embryos metabolites and enzymes (digestive and detoxification/antioxidant enzymes) where maintained without significant changes and in a low activity during the whole organogenesis, meaning that organogenesis is relatively not energetically costly. In contrast, after organogenesis, a mobilization of nutrients and activation of the metabolic and digestive enzymes was observed, together with increments in consumption of yolk and Gly, and reduction in lipid peroxidation. Derived from our results we also have the hypothesis that reactive oxygen species (ROS) were produced during the metabolic processes that occurs in ovarian maturation. Those ROS may be in part transferred to the egg provoking a ROS charge to the embryos. The elimination of ROS in embryos started when the activity of the heart and the absorption of the yolk around stages XIV and XV were evident. Altogether, these processes allowed the paralarvae to hatch with buffered levels of ROS and with the antioxidant defence mechanisms ready to support further ROS production derived from paralarvae higher life stage requirements (feeding and metabolic demands).

Description: Considering that swim-flume or chasing methods fail in the estimation of maximum metabolic rate and in the estimation of Aerobic Scope (AS) of sedentary or sluggish aquatic ectotherms, we propose a novel conceptual approach in which high metabolic rates can be obtained through stimulation of organism metabolic activity using high and low non-lethal temperatures that induce high (HMR) and low metabolic rates (LMR), This method was defined as TIMR: Temperature Induced Metabolic Rate, designed to obtain an aerobic power budget based on temperature-induced metabolic scope which may mirror thermal metabolic scope (TMS = HMR—LMR). Prior to use, the researcher should know the critical thermal maximum (CT max) and minimum (CT min) of animals, and calculate temperature TIMR max (at temperatures −5–10% below CT max) and TIMR min (at temperatures +5–10% above CT min), or choose a high and low non-lethal temperature that provoke a higher and lower metabolic rate than observed in routine conditions. Two sets of experiments were carried out. The first compared swim-flume open respirometry and the TIMR protocol using Centropomus undecimalis (snook), an endurance swimmer, acclimated at different temperatures. Results showed that independent of the method used and of the magnitude of the metabolic response, a similar relationship between maximum metabolic budget and acclimation temperature was observed, demonstrating that the TIMR method allows the identification of TMS. The second evaluated the effect of acclimation temperature in snook, semi-sedentary yellow tail (Ocyurus chrysurus), and sedentary clownfish (Amphiprion ocellaris), using TIMR and the chasing method. Both methods produced similar maximum metabolic rates in snook and yellowtail fish, but strong differences became visible in clownfish. In clownfish, the TIMR method led to a significantly higher TMS than the chasing method indicating that chasing may not fully exploit the aerobic power budget in sedentary species. Thus, the TIMR method provides an alternative way to estimate the difference between high and low metabolic activity under different acclimation conditions that, although not equivalent to AS may allow the standardized estimation of TMS that is relevant for sedentary species where measurement of AS via maximal swimming is inappropriate.