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High temperatures alter the physiological condition of Octopus maya embryos, juveniles, and adults, and the time of exposure could have a key role in their thermal tolerance. The present study evaluates the effects of temperature and exposure time on octopus juveniles obtained from a thermally stressed female and a control female when exposed to optimal (25 °C) and high temperatures (30 °C) for 20 and 30 days, respectively. The results showed a transgenerational temperature effect that was expressed with low survival, depressed routine resting and high metabolic rates. Moreover, a collapse of antioxidant defense enzymes and high levels of oxidative damage products were detected in juveniles from thermally stressed females. Stress was lethal for animals acclimated at 30 °C, while the performance of juveniles acclimated at optimal temperature (25 °C) was conditioned by high oxidative stress levels and a reduction of the high metabolic rate (HMR) even after 30 days of experiment. In contrast, juveniles from the non-thermally stressed female had an optimal performance when acclimated at 25 °C but at 30 °C, they had a comparatively higher HMR during the first 8 days. These results suggest energy surplus in those animals to escape from warming scenarios before experiencing oxidative damage accumulation. Further studies should confirm if epigenetic alterations could be involved.

Anthropogenic global warming generates profound metabolic alterations in marine ectotherm invertebrates capable of leading a wide range of these species to extinction. To evaluate the cross-generational effect of thermal stress on the cephalopod Octopus maya, groups of females were exposed at 24 and 30 °C until spawn. After, embryos of each female group were incubated at 24 and 30 °C allowing for evaluating the transgenerational effects on embryos exposed to high and low temperatures. We analyzed the morphology, oxygen consumption, antioxidant mechanisms, and oxidative stress indicators of the embryos. The results demonstrate that thermally stressed females produced smaller eggs with lower yolk content as observed in nonthermally stressed females. Also was observed that embryos from females acclimated at 30 °C had lower body weight and higher respiratory rates when compared with nonthermal stressed females. Embryos from females acclimated at 30 °C showed a collapse of the antioxidant defense system measured as lower both catalase activity and total glutathione concentrations. Additionally, glutathione-s transferase activity increased in embryos incubated at 30 °C and in females maintained at high temperatures in a clear deleterious and cross-generational effect of thermal stress on this octopus species. No changes were observed in the activity of B-esterases in octopus embryos linked with the thermal stress of females. Embryos from thermally stressed females had smaller sizes, less yolk, and higher metabolic rates. Additionally, a collapse in the antioxidant defense system was observed indicating they were unable to control the high load of ROS and oxidative damage, which was partially acquired by maternal inheritance.

No ecotoxicological information exists on phenanthrene (Phe) exposure in cephalopods, animals of commercial and ecological importance. This study investigated the effect of Phe on two B-esterases, Acetylcholinesterase (AChE) and Carboxylesterases (CbE), in Octopus maya embryos. Octopus embryos were exposed to different treatments: control (seawater), solvent control (seawater and DMSO 0.01%), 10 and 100 µg/L of Phe. AChE and CbE activities were measured at different developmental stages (blastula, organogenesis, and growth). B-esterase activities increased in control and solvent control as the embryos developed, showing no statistically significant differences between them. On the other hand, the embryos exposed to Phe had significant differences from controls, and between the high and low concentrations. Our results indicate that B-esterases are sensitive biomarkers of exposure to Phe in O. maya. Still, complementary studies are needed to unravel the toxicodynamics of Phe and the implications of the found inhibitory effect in hatched organisms.

Current anthropogenic global warming generates profound metabolic alterations in marine ectotherm invertebrates capable of leading a wide range of these species to extinction. The most worrying and devastating consequence may be that the effect of thermal stress overpasses the individual generations. To evaluate the transgenerational effect of thermal stress on the cephalopodOctopus maya, this study experimentally tests morphology, respiratory metabolism, antioxidant mechanisms, and oxidative stress indicators of the embryos incubated at two temperatures (24 and 30°C) produced by females acclimated at 24 and 30°C. The results demonstrate that, regardless of their incubation temperature, embryos from females acclimated at 30°C are smaller, show more accelerated development, and higher respiratory rates than those from females acclimated at 24°C. These embryos confirmed a greater oxidative stress degree, as well as an increased amount of soluble carbonylated proteins and catalase activity as the main enzyme during the activation development stage (even the highest in the embryos incubated at 30°C). Finally, a collapse of the antioxidant defense system was observed, measured as lower both CAT activity and GSH concentrations. Additionally, soluble carbonylated proteins reduced and GST activity increased in embryos incubated at 30°C from females maintained at high temperatures in a clear deleterious and transgenerational effect of thermal stress on this octopus species.

Mitochondrial respirometry is key to understand how environmental factors model energetic cellular process. In the case of ectotherms, thermal tolerance has been hypothesized to be intimately linked with mitochondria capability to produce enough adenosine triphosphate (ATP) to respond to the energetic demands of animals in high temperatures. Recent studies made in Octopus maya proposed the hypothesis postulating that high temperatures could restrain female reproduction due to the limited capacity of the animals’ heart to sustain oxygen flow to the body, affecting in this manner energy production in the rest of the organs, including the ovarium. Until now, no reports have shown temperature effects and other environmental variables on cephalopod mitochondria activity because of the lack of a method to evaluate mitochondrial respiratory parameters on those groups of species. In this sense and for the first time, this study developed a method to obtain mitochondrial respirometry data of adult Octopus maya’s heart. This protocol illustrates a step-by-step procedure to get high yield and functional mitochondria of cephalopod heart and procedure for determining the corresponding respiratory parameters. The isolation procedures described here require two hours, demonstrating that confident and replicable results can be obtained with this method.

Observations of wild male O. maya suggest that temperatures below 27 °C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study aimed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28–30 °C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30 °C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa per spermatophore was not affected by temperature, but higher spermatophores production was observed at 30 °C. The paternity analysis showed that the offspring had multiple paternity with an average of 10 males contributing in a single spawn. The paternal contribution was affected by temperature with high, medium, or no paternal contribution in animals maintained at 24 °C (control group), 28 °C and 30 °C, respectively. The temperatures from 28 °C to 30 °C deeply affected the reproductive performance of Octopus maya males, suggesting that, as embryos, reproductive performance of adult males of this octopus species can be used as a tool for monitoring thermal changes in Yucatan Peninsula, located at the entrance of Gulf of Mexico.

The blue crab Callinectes sapidus is a widespread ectothermic species that supports large fisheries. Physiology of temperate and subtropical populations of blue crabs are well studied; however, a lack of information exists on tropical populations. Given the low locomotion capabilities of C. sapidus adult blue crabs, natural selection should favor traits that shape a particular thermal niche reflected through tolerance modulation to dissolved oxygen. This study was designed to evaluate the thermal window and hypoxia sensitivity of the blue crab population in the southern Gulf of Mexico. The effect of acclimation temperatures from 20 °C to 34 °C on thermal preference (TP), critical thermal limits (CT), and thermal metabolic scope (TMS) was assessed in normoxia. Metabolic rate regulation over partial oxygen (pO2) pressure gradient was evaluated through oxygen consumption measurements at different degrees of acute hypoxia. Callinectes sapidus was observed tending to specialize towards higher temperatures, showing a mean TP from 26 °C to 33 °C. The lowest performance of aerobic pathways was observed at the coldest regimes and the highest at the warmest ones with mean TMS value being 35 % greater at 34 °C than 20 °C. Patterns for metabolic regulation were dependent on the interaction between environmental temperature and dissolved oxygen, in which the interval from 29 °C to 34 °C provoked a 50 % reduction in oxygen consumption when exposed to ∼20% air saturation levels. The results obtained showed that blue crabs distributed in the southern Gulf of Mexico could be close to their oxygen-temperature tolerance limits, which has important implications when climate change effects on species re-distribution is considered.

Tropical populations of marine species are predicted to be the most impacted by global warming because they are likely adapted to a narrow range of temperatures in their local environment. In the present study, we investigated the thermal range at which activity metabolic rate (AMR) is maximal, pejus, and critical in the spiny lobster Panulirus argus using different ecophysiological biomarkers. Lobsters were acclimated at constant temperatures (18, 22, 26 and 30 °C; N = 150) at laboratory conditions for 35 days; after that time thermal biology was evaluated. Results obtained demonstrated that, in P. argus the temperature where AMR was maximal does not coincide with temperature that promotes the maximum growth rate (26 °C). In fact, the preferred temperature, determined in a horizontal gradient was around the mean value of 27.5 °C, 5.5 °C above the temperature where animals showed their maximum metabolic scope, growth and thermal preference. Lactate and redox imbalance showed its maximum values in animals acclimated at 30 °C indicating that lobsters where in pejus thermal ranges. Although lobsters are adapted to tolerate temperatures beyond 28 °C, results indicated that temperature and exposure time play important roles in the way organisms respond to thermal challenges. It is likely that the difference in the responses of different ectothermic organisms and the thermal response is linked to the way these effects are measured. These results can help generate predictive models to anticipate changes in the P. argus fishery derived from likely changes in distribution and abundance of this species under warming scenarios of tropical oceans.

Most of our understanding on embryonic development in cephalopods comes from studies using constant temperature. Even though spawning generally occurs at relatively stable environments, eggs and embryos can be exposed over short periods of time to high temperature anomalies caused by oceanic warming. Therefore, in this study we examined the effects of increasing temperatures on growth, respiratory metabolism, and antioxidant defense mechanisms to define the thermal limits of Octopus maya embryos in a changing environment. Ramp temperatures consisted in increments of 1 °C every 5 days from 24 °C to 30 °C. The thermal limit of embryos at ramp temperatures was detected at 27 °C with metabolic rate increments between 63% and 69%, compared with the metabolic rate observed at control temperature (24 °C). Based on the calculated integrated biomarker response (IBR) was possible to detect that at the thermal limit, an increment on oxygen consumption was observed joint with reactive oxygen species (ROS). The IBR analysis indicated that above 27 °C embryos experienced changes in the oxidative system and were not able to recover. This study suggests that in a scenario of rapidly increasing temperatures after a short winter, O. maya embryos may suffer irreversible effects that are likely to negatively affect recruitment and the population dynamic. The thermal sensitivity of O. maya embryos, revealed in the present work, indicates that this species has an important potential for biomonitoring of the effects of environmental warming. Changes in the population dynamics of this species should be further studied since they can be used as a proxy for warming of the southern Gulf of Mexico ecosystems.

Octopus maya supports an important fishery in Yucatan Peninsula (YP) where this species is highly abundant. Considering that temperatures in the tropics are increasing (IPCC, 2013), there are several scenarios that can modify the dynamic of the O. maya population in YP: i) prolonged summer and short winter seasons, and/or ii) fast temperature increases and high temperatures after a winter season, both affecting the survival of hatchlings and the performance of juveniles. The present study was designed to evaluate the effect of maternal temperature stress over hatchling and juvenile performance in terms of their energetic plasticity and thermoregulatory behaviour, when they were exposed to a gradual temperature increase (TI) from 24 to 30 °C and compared with hatchlings maintained at preferred and constant temperature (24 °C). Hatchlings from stressed females were smaller, and had a lower growth rate compared to those from unstressed females providing evidence that temperature stress experienced by females has consequences on the performance of hatchlings, with effects on the biomass production and survival. Results also demonstrated that hatchlings exposed to TI (24–30 °C) had a growth rate and oxygen consumption similar to those maintained at preferred temperature (24 °C), in both female groups indicating that a gradual temperature increase of 1 °C every 5 days is probably enough to allow the organisms to make physiological adjustments without an excessive energetic cost.

Octopus maya is one of the most promising candidates for octopus aquaculture due to its holobenthic development. The objectives of this study were to investigate: i) whether the time required for embryonic development of this species can be reduced; ii) whether high or low temperatures affect the size and physiological characteristics of embryos; iii) whether temperature affects the time taken to reach stage XX, using thermal time; and iv) the effects of incubation temperature on hatchling performance, measured as survival after 10 d fasting. Eggs were acclimated at 18, 22, 26 and 30 °C. Embryos incubated at 30 °C reached stage XX 50 d before embryos incubated at 18 °C. A mean value of 596 degrees day − 1 was obtained for embryos incubated at 22 and 26 °C where embryo development was optimum. Principal component analysis showed that arm length was the morphological characteristic that separated embryos incubated at 22 °C from the rest of the treatments. Embryos in stage XIX and incubated at 26 °C had a higher metabolic rate than embryos maintained at other experimental temperatures. The best hatchling performance was obtained with embryos incubated at 22 °C. Results indicated that the optimal temperature for O . maya incubation is in the range of 22–26 °C. Statement of relevance Octopus maya is one of the most promising species for octopus aquaculture due its holobenthic development. This study will be useful when design production facilities because it gives key information to obtain the hatchlings with the best performance.

Using data related to thermal optimal and pejus of the embryos of Octopus americanus from Brazil and O. insularis and O. maya from Mexico, this study aimed to project the potential distribution areas in the Gulf of Mexico and predict distribution shifts under different representative concentration pathway scenarios (RCP 6 and 8.5) for the years 2050 and 2100. The different thermal tolerances elicited different responses to current and future scenarios. In this sense, O. insularis and O. maya thermal niches stretch from the Caribbean to Florida. Nevertheless, O. insularis may inhabit warmer areas than O. maya. Surprisingly, no area was considered thermally habitable for O. americanus, which could have been associated with the use of data of populations thermally adapted to temperate conditions south of Brazil. According with models, a warming scenario would cause a restriction of the available thermal niche of O. maya, whileO. insularis could expand under RCP 6 scenarios. This restriction was more substantial in the RCP 8.5 scenario. Nevertheless, under the RCP 8.5 scenario, the temperature in 2100 may negatively affect even O. insularis, the species most thermal tolerant. If our results are accurate, the fishing yield of O. insularis will increase in the future, replacing the heavily exploited O. maya in the coasts of the southern Gulf of Mexico. Regarding O. americanus, the results obtained from the population in Brazil did not match with the environmental conditions found in the Gulf of Mexico, which suggested that no inference might be made until physiology and thermal tolerances of locally adapted populations can be studied.

Sexual maturation and reproduction influence the status of a number of physiological processes and consequently the ecology and behavior of cephalopods. Using Octopus mimus as study model, the present study was focused on the changes in biochemical composition that take place during gonadal maturation of octopus females and its consequences in embryo and hatchlings characteristics, putting special attention to energetic metabolites, digestive enzymes, and antioxidant defense mechanisms. To do that, a total of 32 adult females of Octopus mimus were sampled during ovarian maturation and the biochemical composition (metabolites and digestive enzymes) of digestive gland (DG) and ovaries (only metabolites) were followed during physiological and functional maturation. Levels of protein (Prot), triacyl glycerol (TG), cholesterol (Chol), glucose (Glu) and glycogen (Gly) were evaluated. In DG also the activity of alkaline and acidic enzymes was measured. Simultaneously, groups of eggs coming form mature females were also sampled along development, and metabolites (Prot, TG, Glu, Gly, TG, Chol), digestive enzymes activity (Lipases, alkaline and acidic), antioxidant defence mechanisms and radical oxygen species (ROS) were evaluated. Results obtained showed that ovarium is a site for reserve of some nutrients for reproduction. Presumably, TG where stored at the beginning of the maturation processes followed by Chol, both at the same time were energetically supported by Glu, derived from Gly following gluconeogenic pathways. Also, was observed that embryos during organogenesis nutrients and enzymes (metabolic, digestive and REDOX system) where maintained without significant changes and in a low activity. Results obtained in the present study shows that that activity could be not energetically costly. In contrast, was observed that during the embryo growth there were mobilization of nutrients and activation of the metabolic and digestive enzymes, joint with increments in consumption of yolk and glycogen, and reduction in molecules associated with oxidative stress, allowing paralarvae hatch with the antioxidant defence mechanisms ready to support the ROS production.

In female Octopus maya the reproductive success has well-defined thermal limits; beyond which, spawning, number of eggs, fecundity, and the viability of the embryos are reduced. Observations of wild male O. maya suggest that temperatures below 27°C favour their reproductive performance. From these observations we hypothesize that, as in females, the temperature modulates the reproductive performance of adult O. maya males. The study was directed to evaluate the physiological condition, reproductive success, and histological damage in testis of male O. maya exposed to thermal stress, to determine the implications of ocean warming over their reproductive performance. High temperatures (28-30°C) negatively affect the growth and health of male O. maya. In octopuses maintained at 30°C, as a consequence of the thermal stress we observed an increment in the haemocytes number, a reduction in the oxygen consumption rate, and an inflammatory process in the testis. The number of spermatozoa per spermatophore was not affected by temperature, but higher spermatophores production was observed at 30°C. The paternity analysis showed that the offspring had multiple paternity with an average of 10 males contributing in a single spawn. The paternal contribution was affected by temperature with high, medium, or no paternal contribution in animals maintained at 24°C (control group), 28°C, and 30°C, respectively. The temperatures from 28°C to 30°C deeply affected the reproductive performance of Octopus maya males.

Culture of octopuses is still in an experimental stage due to a lack of knowledge about their digestive physiology. This study aimed to determine the temporality of nutrient digestion, absorption and assimilation in 2 species of octopus: the tropical Octopus maya (habitat temperature 22 to 26°C) and the subtropical-temperate O. mimus (15 to 21°C). In both species, the chyme volume displayed 2 peaks over time along the digestive tract: one at the beginning of digestion and a second at the end of the digestion process. These phases were observed in gastric juice (GJ) enzymes, in the flow of nutrients in the digestive gland (DG), in the appearance of metabolites in the hemo lymph, and in muscle protein and glycogen levels. The soluble nutrient flow throughout the digestive tract into the DG was similar in both species. How ever, intracellular digestion was different in O. mimus compared to O. maya; lipids were mobilized faster than proteins in O. mimus, whereas proteins were mobilized faster than lipids in O. maya. This suggests that at low temperatures, the mobilization of lipids could be a biological priority due to their role in membrane protection. In addition, O. mimus displayed more digestive enzyme activity in the GJ and DG compared with O. maya, suggesting that adaptive differences may be related to environmental temperatures.

Digestive physiology is one of the bottlenecks of octopus aquaculture. Although, there are successful experimentally formulated feeds, knowledge of the digestive physiology of cephalopods is fragmented, and focused mainly on Octopus vulgaris. Considering that the digestive physiology could vary in tropical and sub-tropical species through temperature modulations of the digestive dynamics and nutritional requirements of different organisms, the present review was focused on the digestive physiology timing of Octopus maya and Octopus mimus, two promising aquaculture species living in tropical (22–30°C) and sub-tropical (15–24°C) ecosystems, respectively. We provide a detailed description of how soluble and complex nutrients are digested, absorbed, and assimilated in these species, describing the digestive process and providing insight into how the environment can modulate the digestion and final use of nutrients for these and presumably other octopus species. To date, research on these octopus species has demonstrated that soluble protein and other nutrients flow through the digestive tract to the digestive gland in a similar manner in both species. However, differences in the use of nutrients were noted: in O. mimus, lipids were mobilized faster than protein, while in O. maya, the inverse process was observed, suggesting that lipid mobilization in species that live in relatively colder environments occurs differently to those in tropical ecosystems. Those differences are related to the particular adaptations of animals to their habitat, and indicate that this knowledge is important when formulating feed for octopus species.

Digestive physiology is one of the bottlenecks of octopus aquaculture. Although, there are successful experimentally formulated feeds, knowledge of the digestive physiology of cephalopods is fragmented, and focused mainly on Octopus vulgaris. Considering that the digestive physiology could vary in tropical and sub-tropical species through temperature modulations of the digestive dynamics and nutritional requirements of different organisms, the present review was focused on the digestive physiology timing of Octopus maya and Octopus mimus, two promising aquaculture species living in tropical (22–30°C) and sub-tropical (15–24°C) ecosystems, respectively. We provide a detailed description of how soluble and complex nutrients are digested, absorbed, and assimilated in these species, describing the digestive process and providing insight into how the environment can modulate the digestion and final use of nutrients for these and presumably other octopus species. To date, research on these octopus species has demonstrated that soluble protein and other nutrients flow through the digestive tract to the digestive gland in a similar manner in both species. However, differences in the use of nutrients were noted: in O. mimus, lipids were mobilized faster than protein, while in O. maya, the inverse process was observed, suggesting that lipid mobilization in species that live in relatively colder environments occurs differently to those in tropical ecosystems. Those differences are related to the particular adaptations of animals to their habitat, and indicate that this knowledge is important when formulating feed for octopus species.

A formulated diet for Octopus maya that provoked a growth rate and survival higher than that observed when animals were fed diet based only on freeze-dried crab is reported for first time. Early juveniles (0.37 g wet weight; ww) of O. maya were used. Diets were made by mixing freeze-dried ingredients (crab paste; Callinectes spp. meal; (Cr), squid meal; Dosidicus gigas (Sq) and silages (Si)) all enriched with a mix of vitamins and minerals, and bound with gelatin, forming a paste. At the end of the experiment, Crab–Squid (CrSq) was the only diet that showed 100% survival, followed by Crab (Cr) (55%). The highest specific growth rate (SGR, % day − 1 ) was obtained in animals fed CrSq (3.04% day − 1 ) followed by animals fed Cr (1.96% day − 1 ) and Squid (Sq) (1.09% day − 1 ). Marginal (0.36% day − 1 ) and negative (− 0.73% day − 1 ) SGR values were observed in animals fed Silage–Crab–Squid (SiCrSq) and Silage–Squid (SiSq). Principal component analysis (PCA) showed that muscle glycogen and DG protein contents had the strongest influence on the separation of groups in a canonical analysis and were positively related with growth indicating that CrSq diets have the best nutritional characteristics to satisfy growth requirements. These results were confirmed when energy balance was measured.

Sexual maturation and reproduction influence the status of a number of physiological processes and consequently the ecology and behaviour of cephalopods. UsingOctopus mimusas a 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 ofO. mimuswere 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 1 and 3 days old) to track metabolites (Prot, TG, Glu, Gly, TG, Chol), digestive enzymes activity (Lipase, alkaline proteases, and acidic proteases), and antioxidant/detoxification defence indicators with embryos development. Based on the data obtained, we hypothesized 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 enzyme activities (digestive and antioxidant/detoxification 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).

Octopus maya is an endemic species located on the continental shelf of the Yucatan peninsula. This area is located between the Caribbean Sea and the Gulf of Mexico, two ecosystems linked by the Yucatan Channel, in which the temperature in the benthos community is regulated by summer upwelling. Despite being part of a tropical ecosystem, O. maya 's niche on the Yucatan peninsula is relatively cold, favoring both growth and reproduction of this octopus species. The present study was designed to test the effects of temperature on the energy balance of early juveniles of O. maya in an attempt to determine the physiological mechanisms related to adaptation at relatively low temperatures that are common in the Yucatan peninsula and favor growth of this tropical octopus species. Fatty acid profiles were also analyzed in attempt to understand how experimental temperatures modulate the lipid metabolism of O. maya , and to explore if fatty acid profiles can be used as a tool to explain the physiological mechanisms that support growth of this cephalopod species in the Yucatan peninsula environment. Early juveniles (age: 20 days) of O. maya were individually acclimated at 18, 22, 26 and 30 °C during 20 days. Growth rate, survival, ingestion rate, and fasting and feeding oxygen consumption were measured at the end of the experiment. Growth rate was affected by temperature, with high growth rates for animals maintained between 18 and 26 °C, and low rates for octopuses maintained at 30 °C. Routine and total metabolism increased exponentially with temperature, while apparent heat increment (R AHI ) was higher for octopuses maintained at 18 °C than in the rest of the treatments. The energy challenge into biomass production was higher for octopuses maintained at 18 to 22 °C than 26 °C or 30 °C, demonstrating that low temperatures favor growth, probably due to several factors acting simultaneously: 1) a reduction of basal metabolism and consequent reduction in overall activity; 2) more time available for digestion and thus a better utilization of nutrients from food (fatty acids, among others); and 3) an increased time period in which to eat a greater quantity of food. Our study provided evidence that adaptive mechanisms such as a high ingestion rate and efficient use of fatty acids, among others, operate at low temperatures, beyond the mechanistic effect that temperature has on the enzymatic kinetics of O. maya .

In the present study, digestive dynamics, measured through the changes in the in situ pH along the digestive tract, was evaluated along with the glycogen concentration in the digestive gland (DG) and the proteolytic enzyme activity of the gastric juice (GJ) (both acid and alkaline proteases) to obtain useful information that will allow for the understanding of the DG’s function and the role that it plays as an extracellular digestive enzyme source and for energy storage, providing new information on the digestive physiology of Octopus maya. The results showed that pH along the digestive tract changed according to the postprandial time following the food transit. At the beginning, the pH on crop (St) was 5, changing to 6 when the food arrived. Similar changes were observed on the caecum (Ce) and DG. Glycogen from DG is used as a source of energy during digestion and recovered 8 h after feeding. Maximum activities of digestive gland GJ enzymes were observed 6 h after feeding, indicating that chyme enzymes are still active when they arrive at the DG’s lumen. The presence of food in the digestive tract modi¢es the pH, which, in combination with GJ, favours the activity of the released enzymes of O. maya.

We examined changes in the histology, physiology and enzymatic activity of the diges- tive gland — as well as changes in morphology and feeding behavior — of Octopus maya during rear- ing, to define the phases characterizing post-hatching development. Morphometric changes showed that juvenile O. maya exhibited a non-growth phase during the first 10 d post-hatching (DPH). Histo- logical analysis revealed that the digestive gland morphology changed with age, from a simple tubu- lar gland in octopuses 2 DPH to a tubulo-acinar and vacuolar structure with digestive cells character- ized by vacuoles in octopuses 45 DPH. Digestive enzyme activity was erratic until 14 DPH, after which the activity started to stabilize. O. maya at 2 and 3 DPH rarely presented attack responses to either visual or both visual and chemical stimuli from prey. In contrast, at 4 DPH, octopuses responded to visual stimuli from crabs and palaemonids, but did not display preference in attacking either prey type. Based on our results, we have defined for the first time 2 phases in the early life his- tory of O. maya: post-hatching and juvenile.

The present research showed, for the 1st time, the effect of formulated diets for broodstock of Octopus maya. Reproductive response of O. maya females fed prepared diets and a control diet (crab) was evaluated according to reproductive performance and hatchling quality. Females were fed three formulated most diets based on: 1) crab and squid (CS), 2) crab, squid and fish heads (CSF) and 3) crab, squid and SELCO ® (CSS). Fresh crab (Callinectes sapidus) (Diet 4, C) was used as a control diet. A total of 10 females were used for each experimental diet (n = 40). Females were fed 5% body weight d− 1 until spawning. The feeding period of females was 50 days on average to natural spawning (p < 0.05). Eggs laid by each female were placed in separate incubators with similar temperature, light and water quality, which were thoroughly controlled. Total egg number, egg batches, fecundity, spawning, newly hatched weight and survival after 10 days unfed were determined for each spawn. Egg and hatchling biochemical composition, as well as soluble protein content from the perivitelline was determined for each spawn. Embryonic development of eggs was also studied. No differences in reproductive performance were observed between the four diets. Contrary, PCO analysis showed marked differences on fatty acid composition of the yolk and hatchlings. Palmitic acid (16:0) and arachidonic acid (20:4n6) were the main contributors for the first coordinate (eigenvalues, λ of 0.54 and 0.55 for embryo and hatchlings yolk, respectively). Females fed the control diet (C) produced hatchling with higher weight (p < 0.05). Diet 3 (CSS) delivered the largest hatchlings (p < 0.05) among the prepared diets. There were no differences (p > 0.05) in soluble protein content of the perivitelline or newly hatched survival after 10 days unfed. Morphometric differences on 40 days old embryos were associated with females (p < 0.05) but not with each diet (p > 0.05). Results obtained indicate that O. maya female's present marked adaptation to the diets ingested prior to egg laying, without compromising reproductive performance., 2,0410

On the Yucatan Peninsula there is an upwelling which allows access to a body of cold water that controls temperature in this area. This modulates the ecology and distribution of organisms that inhabit the continental shelf. The objective of this study was to determine the effect of different acclimation temperatures on the thermal biology of prey as mollusc, crustacean (Melongena corona bispinosa, Strombus pugilis, Callinectes similis, Libinia dubia) and predators as fish (Ocyurus chrysurus, Centropomus undecimalis) of Octopus maya. Octopus prey preferred temperatures between 23.5°C and 26.0°C, while predators preferred temperatures 26.4-28.5°C. The species with largest thermal windows were M. corona bispinosa (328.8°C(2)), C. similis (322.8°C(2)), L. dubia (319.2°C(2)), C. undecimalis (288.6°C(2)), O. chrysurus (237.5°C(2)), while the smallest thermal window was for S. pugilis (202.0°C(2)). The acclimation response ratios (ARR) estimated for prey ranged from 0.24-0.55 in animals exposed to CTMax and 0.21-0.65 in those exposed to CTMin. Amongst predators, ARR ranged from 0.30 to 0.60 and 0.41 to 0.53 for animals exposed to CTMax and CTMin, respectively. Correlating the optimal temperature limits of prey and predators with surface temperatures on the continental shelf and those 4m deep showed that the main prey, Callinectes similis and L. dubia, shared a thermal niche and that an increase in temperature could force these species to migrate to other sites to find optimal temperatures for their physiological functions. As a consequence the continental shelf community would undergo a structural change. Predators were found to be near their optimal temperatures in surface temperatures on the continental shelf. We conclude that they would remain in the area in a warming scenario. The size of the thermal window was related to the type of ecosystem inhabited by these species. These ARR intervals allowed us to categorize the species as temperate or tropical, according to the oceanographic conditions that prevail on the Yucatan Peninsula.

A recent revival in using cephalopods as experimental animals has rekindled interest in their biology and life cycles, information with direct applications also in the rapidly growing ornamental aquarium species trade and in commercial aquaculture production for human consumption. Cephalopods have high rates of growth and food conversion, which for aquaculture translates into short culture cycles, high ratios of production to biomass and high cost-effectiveness. However, at present, only small-scale culture is possible and only for a few species: the cuttlefish Sepia officinalis , the loliginid squid Sepioteuthis lessoniana and the octopuses Octopus maya and O. vulgaris . These four species are the focus of this chapter, the aims of which are as follows: (1) to provide an overview of the culture requirements of cephalopods, (2) to highlight the physical and nutritional requirements at each phase of the life cycle regarded as essential for successful full-scale culture and (3) to identify current limitations and the topics on which further research is required. Knowledge of cephalopod culture methods is advanced, but commercialization is still constrained by the highly selective feeding habits of cephalopods and their requirement for large quantities of high-quality (preferably live) feed, particularly in the early stages of development. Future research should focus on problems related to the consistent production of viable numbers of juveniles, the resolution of which requires a better understanding of nutrition at all phases of the life cycle and better broodstock management, particularly regarding developments in genetic selection, control of reproduction and quality of eggs and offspring.

The present study aims to determining the isolated and combined effects of stocking and prey densities on growth and survival of Octopus maya hatchlings both at experimental level and in a pilot scale system (8 m2 ; 2700 L). Octopus survival was not related to prey density. Gained wet weight resulted in a significant interaction between initial stocking density and prey density indicating that octopus growth under low and high density was affected in a different manner depending on the density in which prey were offered. Prey density did not have a significant effect on growth and octopus fed with all three prey densities gained wet weight in a similar way. Results indicate the use of culture densities of 140 octopus m-2, and at least 0.27 g prey octopus-1 d-1 can be used to cultivate octopuses in small tanks. In tanks of 8m2 a higher growth rate was obtained with both 25 and 50 octopus m-2 densities were used. Survival was not affected by stocking density between 25 to 75 octopus m-2.

We propose two hypotheses to explain the inexistence of adequate prepared diet for Octopus maya at this date: Hypothesis 1 is related to changes in protein structure during protein cooking, which affects the digestibility. Hypothesis 2 is related to changes on nutritional characteristics during ingredient process, which affects the nutritional composition of diet. To test hypothesis 1, experiments one and two were directed to determine if protein cooking reduces digestibility and growth of animals when compared to fresh or lyophilized protein sources. For hypothesis 2, three experiments were conducted, testing seven different dietary protein sources offered in isolation or combined in artificial diets fed to O. maya. Results demonstrated that the diets that promoted growth were the ones based on fresh crab paste, and both lyophilized crab and squid tentacles paste. In consequence hypothesis 1 was accepted. The cooking process also changed nutritional characteristics of protein sources, affecting the growth of O. maya. Results obtained when squid and crab were mixed suggest that nutritional requirements of octopuses were covered with that diet in similar forms compared to when using fresh or lyophilized crab, also confirming hypothesis 2. Based on growth rates obtained, we can conclude that nutritional requirements of O. maya must be between 80% and 86% Protein (P), 5.1–5.6% Lipids and a protein: energy ratio between (P/E) 38.9 and 42.2 g MJ−1., 1

Thermopreference, tolerance and oxygen consumption rates of early juveniles Octopus maya (O. maya; weight range 0.38-0.78g) were determined after acclimating the octopuses to temperatures (18, 22, 26, and 30°C) for 20 days. The results indicated a direct relationship between preferred temperature (PT) and acclimated temperature, the PT was 23.4°C. Critical Thermal Maxima, (CTMax; 31.8±1.2, 32.7±0.9, 34.8±1.4 and 36.5±1.0) and Critical Thermal Minima, (CTMin; 11.6±0.2, 12.8±0.6, 13.7±1.0, 19.00±0.9) increased significantly (P0.05) with increasing acclimation temperatures. The endpoint for CTMax was ink release and for CTMin was tentacles curled, respectively. A thermal tolerance polygon over the range of 18-30°C resulted in a calculated area of 210.0°C(2). The oxygen consumption rate increased significantly α=0.05 with increasing acclimation temperatures between 18 and 30°C. Maximum and minimum temperature quotients (Q10) were observed between 26-30°C and 22-26°C as 3.03 and 1.71, respectively. These results suggest that O. maya has an increased capability for adapting to moderate temperatures, and suggest increased culture potential in subtropical regions southeast of México.

The effects of feeding two alternative live prey Hyalella azteca (freshwater gammarids) and Hyale media (marine gammarids) to Octopus maya hatchlings were compared with feeding adult Artemia sp., traditionally used during the first weeks of the life cycle. Hatchlings were fed ad libitum these three live preys during the first 15 days, and a paste elaborated with fresh squid and shrimp during the next 15 days when hatchling can be fed prepared diets. Weight (g) and specific growth rates (% day 1 ) were determined every 15 days. Octopus maya hatchlings fed with marine gammarids grew larger (6.9 ± 0.2% day 1 ) compared with hatchlings fed Artemia sp. or freshwater gammarids (4.8 ± 0.2% and 5.0 ± 0.3% day 1 respectively). Survival was also higher (92.2 ± 6.8%) for hatchlings fed marine gammarids, than for those fed Artemia sp. (74.5 ± 23.8%) or freshwater gammarids (41.2 ± 21.2%). The content of acylglycerides, cholesterol and proteins in O. maya fed marine gammarids suggested a better nutrient assimilation by the hatchlings. Also, polyunsaturated fatty acids levels (EPA and DHA) were more abundant in marine gammarids, possibly contributing to the higher growth rates observed. This is the first study revealing a successful use of marine gammarids as alternative prey for octopus hatchlings culture.