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As a function of the water quality provided by square, circular and oval experimental ponds, the growth, survival and oxygen requirements in epibenthic postlarvae of Farfantepenaeus aztecus were analysed in relation to their routine metabolism and apparent heat increment. Temperature, oxygen concentration, pH and salinity were measured daily in two experimental ponds of each shape. The postlarvae oxygen consumption during two 24-h cycles, their growth, physiological condition and survival and the productivity in the ponds were estimated. Low values of pH, oxygen concentration and phytobenthos productivity, and reduced postlarvae relative growth and survival were observed in the square ponds. We suggest that the latter results from a deficient water circulation related to the effect of the pond's shape on dissolved oxygen levels and, consequently, on growth and survival. The postlarvae routine metabolism, including feeding, varied between 1.91 and 2.25 mg O2 h−1 g−1 wet weight, whereas the minimum oxygen concentration needed in the ponds is approximately 4.25 mg O2 L−1. These conditions were achieved in the oval ponds concurrent with higher survival and growth values, in which individuals distributed randomly, for which we suggest that oval-shaped ponds could be the most adequate for the culture of this and other penaeid species. [ABSTRACT FROM AUTHOR]

To assess the health status of aquatic ecosystems, specialized tools and strategies are needed to study the changes induced in oceanic systems by human activity. The Gulf of Mexico has a tremendous ecological importance because of its biological diversity. The present paper defines baseline levels of blood metabolites and immune components for wild tropical populations of F. duorarum: an important shrimp species of the Gulf of Mexico. Osmotic pressure (OP), osmotic capability (OC), oxy hemocyanin (OxyHc), glucose, digestive gland glycogen, proteins, cholesterol, lactate, acylglycerols (AG) were used as indicators of physiological and nutritional status; phenoloxidase activity, quantification of hemocytes, as well as respiratory burst, were used to assess the immunological status. There were no differences between sexes in either live weight or physiological and nutritional conditions. Only total blood protein, oxy hemocyanin, and digestive gland glycogen showed normally distributed data. All the remaining blood parameters were right- or left-skewed. A median live weight of 9.5 g was registered for the sampled population. Median values of 955 and −91.85 mOsm/kg (OP and OC, respectively) were obtained, indicating that shrimp were slightly hypo-osmotic in relation to sea water. A proportion of 27% of OxyHc of the total protein (OxyHc/Prot) was calculated for the F. duorarum population. ProPO and PO showed no normal distribution and were not different between sexes. A right-skewed distribution was observed. Total hemocytes, hyaline (HC) and granular cells (GC) showed differences between sexes, with higher values in females than males. A similar proportion of HC (69%) and GC (30%) of total cells were observed between sexes. Basal and activated respiratory burst showed differences between sexes with higher values for females than for males. The current results provide indicators of the nutritional and immune status of F. duorarum that can be used to detect changes in trophic relations and health at a population level. [ABSTRACT FROM AUTHOR]

An Octopus briareus specimen was recorded off Port Sisal, Yucatán, Mexico. This finding represents the first record of O. briareus in the southern Gulf of Mexico, expanding the currently known westernmost distribution area for this species on the American continent. The specimen was captured by scientific divers performing routine maintenance at underwater facilities in the area of the discovery. The collected specimen was an adult female weighing 25.3 g. The presence of O. briareus could be related to changes in the environmental conditions in the Caribbean Sea and the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Octopus maya is an endemic species located on the continental shelf of the Yucatán peninsula. This area is located between the Caribbean Sea and the Gulf of Mexico, two ecosystems linked by the Yucatán 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 Yucatán 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 Yucatán 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 Yucatán peninsula environment. Early juveniles (age: 20days) of O. maya were individually acclimated at 18, 22, 26 and 30°C during 20days. 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 (RAHI) 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. [ABSTRACT FROM AUTHOR]

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 (DO). 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 oxygen partial pressure (p O 2) 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 DO, 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. • Aquatic ectotherm oxy-regulation capacity is influenced by local adaptation. • Thermal tolerance of tropical blue crabs was measured in normoxia. • Routine metabolic rate was measured in acute hypoxia. • Crabs in higher temperatures elicited specialization. • Future temperatures may induce structural changes of tropical benthic communities. [ABSTRACT FROM AUTHOR]

Fisheries play critical roles in food supply and income for human communities worldwide. Unfortunately, the fishery distribution have been changing due to anthropogenic climate change (CC). In this sense, this study analyses were directed to predict the suitability and distribution of red octopus (Octopus maya), an endemic and commercially important species of the Yucatan Peninsula (YP) in Mexico under different CC scenarios. For this purpose, a correlative (CNM) and mechanistic (MNM) niche models based on temperature and salinity and on metabolic scope, respectively, were projected to different Representative Concentration Pathway (RCP) scenarios (2.6, 4.5, 6, 8.5) for the 2040–2050 and 2090–2100 periods. The CNM results suggest that red octopus suitability and potential distribution (PD) could be slightly reduced for the RCP 2.6 scenario. Whereas, RCP 4.5 shows higher suitabilities at the northern region of the YP, which is characterized by a seasonal upwelling which could act as climate refugia. In contrast, a significant suitability and PD reduction occurs during 2090–2100 for the RCP 6 and 8.5 scenarios. On the other hand, MNM indicates the red octopus could retain most of its PD except for the most catastrophic scenario, finding climate refugia north of the YP and deeper waters. Overall, the CNM is more pessimistic than MNM regarding forecasts. Differences between outputs could be based on the MNM using a single variable as proxy to a multivariate niche and the statistical weight of surface environmental variables in the CNM compared to MNM, which considered only bottom temperature data. In addition, coastal data may be overrepresented, which may bias the CNM. Regardless of the differences in the results, both approaches usually predicted suitability reduction in all RCP scenarios showing that temperatures of ~30 ° C are detrimental for the red octopus. Assuming that a relationship between abundance and the niche suitability exists, landings in the region will be reduced and less accessible for small-scale fisheries, which is especially important since Mexican regulations assume this species will benefit from CC. • The Octopus maya is vulnerable to strong warming scenarios. • A loss in suitability in the region is always predicted. • Weaker warming scenarios allows to Octopus maya to retain its distribution. [ABSTRACT FROM AUTHOR]

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 to models, a warming scenario would cause a restriction of the available thermal niche of O. maya , while O. 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. insulari s will increase in the future, replacing the heavily exploited O. maya in the coasts of the southern Gulf of Mexico. Regarding O. americanus, no inference might be made until thermal tolerances of locally adapted populations can be studied. • Thermal optimum and pejus were used to predict octopus distribution. • Octopus insularis may benefit in some warming scenarios. • Warming scenarios may be a detriment for Octopus maya. • No inferences could be made for Octopus americanus. [ABSTRACT FROM AUTHOR]

The abundance of the alien, Indo-Pacific damselfish Neopomacentrus cyanomos on an oil-loading platform in the southwest Gulf of Mexico indicates that widely distributed platforms could facilitate the expansion of its geographic range across the western and northern fringes of the Gulf. From there it likely will spread to other areas of the Greater Caribbean. The lionfish example demonstrates that it eventually happens, and can do so rapidly. Reduced temperature effects on the physiology of this species were examined to better predict its survivability in the northern Gulf during winter, when sea surface temperatures fall as low as 15 °C along the coast. Overall, our results show that when the degree of experimental temperature decline was large and rapid, no compensation occurred and the stress response observed mostly reflected cellular processes that minimized damage. Integrated biomarker response values were significantly different between fish rapidly exposed to colder vs. warmer temperatures (declines of −4 °C each day, from 26 to 14 °C), reflected in higher values of blood metabolites and routine metabolic rates observed in fish exposed to 14 and 18 °C respectively, and lower activity of all enzymes, lower protein carbonylation, and higher oxidative damage to lipids in fish exposed to 14 °C. While the physiological proxies responded to minimize damage during the rapid-decrease experiment, the same proxies reflected the consequences of compensation when fish were thermally challenged after a 45 days acclimation at 18 °C. In this case, lower values of blood metabolites and high antioxidant levels and indicators of damages underpinned its pejus lower range. Based on the results of the present work, it seems clear that low winter SSTs in the northern Gulf will slow down the colonization of the inshore area of N. cyanomos. We suggest that the use of physiological cellular stress markers on specimens acquired at the beginning of an invasion should be implemented in new standardized experimental protocols, including both rapid increases/decreases of temperature and post-acclimation temperature challenges, to assess the invasiveness potential of aquatic species such as this. Unlabelled Image • Species native's data are often used to predict its invasion potential as alien. • Reduced temperature on alien Neopomacentrus cyanomos' physiology was examined. • Higher routine metabolic rates were noted at 18 °C under rapid temperature decrease. • Pejus occured after a thermal challenge following 45 days acclimation at 18 °C. • Inshore waters' invasion may slow down due to cold winter sea surface temperature. [ABSTRACT FROM AUTHOR]