Temperature and immune challenges modulate the transcription of genes of the ubiquitin and apoptosis pathways in two high-latitude Notothenioid fish across the Antarctic Polar Front.

Thermal variations due to global climate change are expected to modify the distributions of marine ectotherms, with potential pathogen translocations. This is of particular concern at high latitudes where cold-adapted stenothermal fish such as the Notothenioids occur. However, little is known about the combined effects of thermal fluctuations and immune challenges on the balance between cell damage and repair processes in these fish. The aim of this study was to determine the effect of thermal variation on specific genes involved in the ubiquitination and apoptosis pathways in two congeneric Notothenioid species, subjected to simulated bacterial and viral infections. Adult fish of Harpagifer bispinis and Harpagifer antarcticus were collected from Punta Arenas (Chile) and King George Island (Antarctica), respectively, and distributed as follows: injected with PBS (control), LPS (2.5 mg/kg) or Poly I:C (2 mg/kg) and then submitted to 2, 5 and 8 °C. After 1 week, samples of gills, liver and spleen were taken to evaluate the expression by real-time PCR of specific genes involved in ubiquitination (E3-ligase enzyme) and apoptosis (BAX and SMAC/DIABLO). Gene expression was tissue-dependent and increased with increasing temperature in the gills and liver while showing an opposite pattern in the spleen. Studying a pair of sister species that occur across the Antarctic Polar Front can help us understand the particular pressures of intertidal lifestyles and the effect of temperature in combination with biological stressors on cell damage and repair capacity in a changing environment.

Cellulosic and microplastic fibers in the Antarctic fish Harpagifer antarcticus and Sub-Antarctic Harpagifer bispinis.

Human settlements within the Antarctic continent have caused significant coastal pollution by littering plastic. The present study assessed the potential presence of microplastics in the gastrointestinal tract of the Antarctic fish Harpagifer antarcticus, endemic to the polar region, and in the sub-Antarctic fish Harpagifer bispinis. H. antarcticus. A total of 358 microfibers of multiple colors were found in 89 % of H. antarcticus and 73 % of H. bispinis gastrointestinal track. A Micro-FTIR analysis characterized a sub-group (n = 42) of microfibers. It revealed that most of the fibers were cellulose (69 %). Manmade fibers such as microplastics polyethylene terephtalate, acrylics, and semisynthetic/natural cellulosic fibers were present in the fish samples. All the microfibers extracted were textile fibers of blue, black, red, green, and violet color. Our results suggest that laundry greywater discharges of human settlements near coastal waters in Antarctica are a major source of these pollutants in the Antarctic fish.

Influence of mating strategies on seminal material investment in crabs.

Reproduction involves high energetic costs which are related to behaviour and gamete production. In females energy allocation to gamete production has been well documented. However, estimations of male investment in seminal material are scarce. The present study aims to assess and compare male investment in four brachyuran species by determining biochemical substrates present in the vasa deferentia to subsequently estimate energetic investment during the reproductive cycle. We identified two groups with contrasting energy investments. Two species, Homalaspis plana and Romaleon setosum, showed high investment due to significant quantities of proteins and lipids. Both species are characterised by large and complex vasa deferentia, and the formation of a remarkably large sperm plug deposited to the female after copulation as a sperm competition avoidance strategy. In contrast, Metacarcinus edwardsii and Taliepus dentatus invested little energy in their smaller-sized and simpler vasa deferentia. Morpho-functional traits may play a key role in determining the investment, which may also be influenced by mechanisms (i.e. mating tactics) to prevent sperm competition and the intensity of polygyny. This study emphasises the high amount of energy males invest in seminal material and highlights the diversity of mating strategies in Brachyura, which are reflected even on the physiological level.

Moderate hypoxia mitigates the physiological effects of high temperature on the tropical blue crab Callinectes sapidus.

Dissolved oxygen (DO) and water temperature vary in coastal environments. In tropical regions, the ability of aquatic ectotherms to cope with hypoxia and high-temperature interactive effects is fundamental for their survival. The mechanisms underlying both hypoxia and thermal tolerance are known to be interconnected, therefore, the idea of cross-tolerance between both environmental stressors has been put forward. We investigated the combined role of hypoxia and temperature changes on the physiological responses of blue crab Callinectes sapidus living in the southern Gulf of Mexico. We measured oxygen consumption, plasmatic biochemical indicators, total hemocyte count (THC), and antioxidant activity biomarkers in muscle and gill tissues of blue crab acclimated to moderate hypoxia or normoxia and exposed to a thermal fluctuation or a constant temperature, the former including a temperature beyond the optimum range. Animals recovered their routine metabolic rate (RMR) after experiencing thermal stress in normoxia, reflecting physiological plasticity to temperature changes. In hypoxia, the effect of increasing temperature was modulated as reflected in the RMR and plasmatic biochemical indicators concentration, and the THC did not suggest significant alterations in the health status. In both DO, the antioxidant defense system was active against oxidative (OX) damage to lipids and proteins. However, hypoxia was associated with an increase in the amelioration of OX damage. These results show that C. sapidus can modulate its thermal response in a stringent dependency with DO, supporting the idea of local acclimatization to tropical conditions, and providing insights into its potential as invasive species.

The thermal tolerance of a tropical population of blue crab (Callinectes sapidus) modulates aerobic metabolism during hypoxia.

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 (pO2) 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.

Is the southern crab Halicarcinus planatus (Fabricius, 1775) the next invader of Antarctica?

The potential for biological colonization of Antarctic shores is an increasingly important topic in the context of anthropogenic warming. Successful Antarctic invasions to date have been recorded exclusively from terrestrial habitats. While non-native marine species such as crabs, mussels and tunicates have already been reported from Antarctic coasts, none have as yet established there. Among the potential marine invaders of Antarctic shallow waters is Halicarcinus planatus (Fabricius, 1775), a crab with a circum-Subantarctic distribution and substantial larval dispersal capacity. An ovigerous female of this species was found in shallow waters of Deception Island, South Shetland Islands in 2010. A combination of physiological experiments and ecological modelling was used to assess the potential niche of H. planatus and estimate its future southward boundaries under climate change scenarios. We show that H. planatus has a minimum thermal limit of 1°C, and that its current distribution (assessed by sampling and niche modelling) is physiologically restricted to the Subantarctic region. While this species is presently unable to survive in Antarctica, future warming under both 'strong mitigation' and 'no mitigation' greenhouse gas emission scenarios will favour its niche expansion to the Western Antarctic Peninsula (WAP) by 2100. Future human activity also has potential to increase the probability of anthropogenic translocation of this species into Antarctic ecosystems.

Warming and freshening activate the transcription of genes involved in the cellular stress response in Harpagifer antarcticus.

Thermal and saline variations of the Southern Ocean are important signs of climate change which can alter the physiological responses of stenotic species residing at high latitudes. Our study aimed to evaluate the cellular stress response (CSR) of Harpagifer antarcticus subjected to increased ambient temperature and decreased salinity. The fish were distributed in different thermal (2, 5, 8, 11, and 14 °C) and saline (23, 28, and 33 psu) combinations for 10 days. We used qPCR analysis to evaluate the transcription of genes involved in the thermal shock response (HSP70, HSC70, HSP90, and GRP78), ubiquitination (E2, E3, ubiquitin, and CHIP), 26S proteasome complex (PSMA2, PSMB7, and PSMC1), and apoptosis (SMAC/Diablo and BAX) in the liver and gill. The expression profiles were tissue-specific and mainly dependent on temperature rather than salinity in the gill; meanwhile, in the liver, both conditions modulated the expression of these genes. Transcription of markers involved in the heat shock response was much higher in the liver than in the gill and was higher when salinity decreased and the temperature increased. Similarly, the genes involved in the ubiquitination pathway, 26S complex of the proteasome, and the apoptotic pathway showed the same pattern, being mainly induced in the liver rather than in the gill. This is the first study to show that this Antarctic fish can induce the cellular stress response in their tissues when subjected to these thermal/saline combinations.

Freshening effect on the osmotic response of the Antarctic spiny plunderfish Harpagifer antarcticus.

Global warming is having a significant impact around the world, modifying environmental conditions in many areas, including in zones that have been thermally stable for thousands of years, such as Antarctica. Stenothermal sedentary intertidal fish species may suffer due to warming, notably if this causes water freshening from increased freshwater inputs. Acute decreases in salinity, from 33 down to 5, were used to assess osmotic responses to environmental salinity fluctuations in Antarctic spiny plunderfish Harpagifer antarcticus, in particular to evaluate if H. antarcticus is able to cope with freshening and to describe osmoregulatory responses at different levels (haematological variables, muscle water content, gene expression, NKA activity). H. antarcticus were acclimated to a range of salinities (33 as control, 20, 15, 10 and 5) for 1 week. At 5, plasma osmolality and calcium concentration were both at their lowest, while plasma cortisol and percentage muscle water content were at their highest. At the same salinity, gill and intestine Na+ -K+ -ATPase (NKA) activities were at their lowest and highest, respectively. In kidney, NKA activity was highest at intermediate salinities (15 and 10). The salinity-dependent NKA mRNA expression patterns differed depending on the tissue. Marked changes were also observed in the expression of genes coding membrane proteins associated with ion and water transport, such as NKCC2, CFTR and AQP8, and in the expression of mRNA for the regulatory hormone prolactin (PRL) and its receptor (PRLr). Our results demonstrate that freshening causes osmotic imbalances in H. antarcticus, apparently due to reduced capacity of both transport and regulatory mechanisms of key organs to maintain homeostasis. This has implications for fish species that have evolved in stable environmental conditions in the Antarctic, now threatened by climate change.

Integrative depiction of the male reproductive system of the commercial purple crab Homalaspis plana (Platyxanthidae): Structure and function.

The information available on structures and function of reproductive systems are female-biased in many animal groups and crabs are not an exception. However, knowledge about the male reproductive system can help us to understand evolutionary and ecological processes such as the mating system and mating behavior. This study focuses on an integrative description of the principal regions of the male reproductive system of the purple crab, Homalaspis plana, a commercially exploited crab from the southeastern Pacific. For this description a combination of morphological observation, gravimetric records, histological and histochemical techniques and biochemical analysis were used. Also, a gross description of the seminal receptacle of the female was performed. The male reproductive system of H. plana was highly extended and complex, with a great capacity to produce and store spermatophores and secrete, at least, two kinds of seminal fluids. Sperm production, sperm packaging in spermatophores, storage of spermatophores and seminal liquid secretion were functions localized in specific regions. The vasosomatic index was the highest recorded to date in crabs, symptomatic of a high investment in reproduction. All these traits allow identification of H. plana as an internal sperm plug producer, which matches well with the highly extensible seminal receptacle of females. The great quantity of seminal material transferred to females during mating indicates that males may be able to mate only one time in the reproductive season and thus this species could be vulnerable to sperm depletion in males and sperm limitation in females if the fishery substantively reduced the abundance of males in the populations.

Temperature-dependent seminal recovery in the southern king crab Lithodes santolla.

Male-biased fishery management can provoke depletion of seminal reserves, which is the primary cause of sperm limitation. Therefore, identifying factors which contribute to the vulnerability to depletion of seminal reserves is a priority. The present study aimed to determine the effect of temperature on the recovery rate of sperm and seminal reserves after their depletion in Lithodes santolla, an important fishery resource in southern Chile. Sperm and seminal reserves were not fully recovered within 30 days. Temperature significantly affected seminal recovery: after 30 days the recovery index increased to 40% and 21% at 9°C and 12°C, respectively. The twice as fast seminal recovery at 9°C may be explained by the zone of origin of the individuals in this study (northern distributional limit), and 12°C may be close to the threshold of temperature tolerance. Lithodes santolla populations subject to intense male-only fisheries may be vulnerable to depletion of seminal reserves and a climate change scenario could additionally aggravate the risk of seminal depletion in L. santolla in its northern distributional limit.

Decreased Metabolic Rate in the Mole Crabs, Emerita analoga, Infected with the Acanthocephalan Profilicollis altmani.

The relationship between a parasite and its host will have an energy cost for the host at some point; however, this basic hypothesis has seldom been evaluated. Using Emerita analoga as a model species, we investigated the aerobic metabolism, ammonia excretion rate, and locomotor performance patterns of crabs both uninfected and infected with the acanthocephalan Profilicollis altmani. Our results show that infected Emerita had a lower metabolic rate compared to uninfected ones. Whether or not this decrease is a result of the pathology of the parasite infection or due to manipulation of the host by the parasite is still unknown. We discuss the importance of using anaerobic and aerobic metabolism and more-complex scenarios in order to understand the effects on host fitness and not only on the immediate response of the host.

Comparison of Aerobic Scope for Metabolic Activity in Aquatic Ectotherms With Temperature Related Metabolic Stimulation: A Novel Approach for Aerobic Power Budget.

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.

Differences in the respiratory response to temperature and hypoxia across four life-stages of the intertidal porcelain crab Petrolisthes laevigatus.

For aquatic breathers, hypoxia and warming can act synergistically causing a mismatch between oxygen supply (reduced by hypoxia) and oxygen demand (increased by warming). The vulnerability of these species to such interactive effects may differ during ontogeny due to differing gas exchange systems. This study examines respiratory responses to temperature and hypoxia across four life-stages of the intertidal porcelain crab Petrolisthes laevigatus. Eggs, megalopae, juveniles and adults were exposed to combinations of temperatures from 6 to 18 °C and oxygen tensions from 2 to 21 kPa. Metabolic rates differed strongly across life-stages which could be partly attributed to differences in body mass. However, eggs exhibited significantly lower metabolic rates than predicted for their body mass. For the other three stages, metabolic rates scaled with a mass exponent of 0.89. Mass scaling exponents were similar across all temperatures, but were significantly influenced by oxygen tension (the highest at 9 and 14 kPa, and the lowest at 2 kPa). Respiratory responses across gradients of oxygen tension were used to calculate the response to hypoxia, whereby eggs, megalopae and juveniles responded as oxyconformers and adults as oxyregulators. The thermal sensitivity of the metabolic rates (Q10) were dependent on the oxygen tension in megalopae, and also on the interaction between oxygen tension and temperature intervals in adults. Our results thus provide evidence on how the oxygen tension can modulate the mass dependence of metabolic rates and demonstrate changes in respiratory control from eggs to adults. In light of our results indicating that adults show a good capacity for maintaining metabolism independent of oxygen tension, our study highlights the importance of assessing responses to multiple stressors across different life-stages to determine how vulnerability to warming and hypoxia changes during development.

Interspecific variation in the physiological and reproductive parameters of porcelain crabs from the Southeastern Pacific coast: potential adaptation in contrasting marine environments.

Porcelain crabs inhabit from upper intertidal to subtidal habitats. These environments are characterized by highly variable environmental conditions, which subject species found in these habitats to stress. In this study, we compared reproductive traits of mothers [i.e. fecundity, reproductive output (RO), dry weight, organic matter] and physiological parameters of their offspring (i.e. wet weight, water content, dry weight, organic matter, lactate content of embryos) of three species of porcelain crabs that inhabit the Southeastern Pacific: Petrolisthes laevigatus (upper intertidal); P. violaceus (low intertidal); Allopetrolisthes punctatus (subtidal). Overall, female P. laevigatus had lower fecundity (802 ± 115 vs. 4181 ± 1097 embryos) and amount of organic matter in their embryo masses (0.053 ± 0.006 vs. 0.27 ± 0.025 g) but higher RO values (1.34 ± 0.34 vs. 0.20 ± 0.07) than Allopetrolisthes punctatus. In addition, P. laevigatus embryos had higher organic matter content (81.09 ± 28.8 vs. 64.54 ± 6.1 µg), higher water content (188.6 ± 91.9 vs. 152.4 ± 30.8 µL) and higher lactate content (0.26 ± 0.04% vs. 0.07 ± 0.01% dry weight) than that found in A. punctatus embryos. Furthermore, females and embryos of P. violaceus showed low values and similar to those observed in P. laevigatus. As a potential strategy to increase survival of the offspring, P. laevigatus seems to invest a large portion of its energy in production of high quality embryos, despite costs to fecundity. This study reveals that porcelain crabs have physiological adaptations during their ontogeny that allow them to survive in fluctuating environments.

Lethal and sub-lethal effects of commonly used anti-sea lice formulations on non-target crab Metacarcinus edwardsii larvae.

The pesticides used by the salmon industry to treat sea lice, are applied in situ via a bath solution and are subsequently discharged into the surrounding medium. The effects of cypermethrin, deltamethrin, azamethiphos and hydrogen peroxide were assessed on the performance of Metacarcinus edwardsii larvae, an important crab for Chilean fishery. All larvae were dead or dying after 30 min of exposure to cypermethrin and after 40 min to deltamethrin at concentrations 100 and 20 times lower (0.15 and 0.1 µg L-1, respectively) than the concentrations and exposure times recommended by the manufacturers (CRM) to treat sea lice. Azamethiphos affected all larvae at a concentration 10 times lower than CRM. Hydrogen peroxide had the lowest detrimental effects, but at the CRM, 100% of the larvae were affected. Sub-lethal effects, i.e prolonged developmental time, were observed at concentrations lower than CRM. Repeated exposure to azamethiphos (0.0625-0.5 µg L-1) and hydrogen peroxide (188-1500 mg L-1) had effects on survival. In conclusion, the pesticides used against parasitic copepod tested here, negatively affect non-target crustacean larvae. Due to the product's characteristics, the lethal effects of the pyrethroids probably are restricted to the time and area of application, while the action of azamethiphos may extend to a wider area. Current data are insufficient to accurately dimension the effects of these compounds in the field. More research is required to evaluate the consequences of prolonged developmental times and/or reduction in appendage mobility, so as the effects of these compounds on the pelagic and benthic communities.

Tide-related biological rhythm in the oxygen consumption rate of ghost shrimp (Neotrypaea uncinata).

The effects of tidal height (high and low), acclimation to laboratory conditions (days in captivity) and oxygen level (hypoxia and normoxia) were evaluated in the oxygen consumption rate (OCR) of the ghost shrimp Neotrypaea uncinata We evaluated the hypothesis that N. uncinata reduces its OCR during low tide and increases it during high tide, regardless of oxygen level or acclimation. Additionally, the existence of an endogenous rhythm in OCR was explored, and we examined whether it synchronized with tidal, diurnal or semidiurnal cycles. Unexpectedly, high OCRs were observed at low tide, during normoxia, in non-acclimated animals. Results from a second, longer experiment under normoxic conditions suggested the presence of a tide-related metabolic rhythm, a response pattern not yet demonstrated for a burrowing decapod. Although rhythms persisted for only 2 days after capture, their period of 12.8 h closely matched the semidiurnal tidal cycle that ghost shrimp confront inside their burrows.

Thermal biology of the sub-polar-temperate estuarine crab Hemigrapsus crenulatus (Crustacea: Decapoda: Varunidae).

Optimum temperatures can be measured through aerobic scope, preferred temperatures or growth. A complete thermal window, including optimum, transition (Pejus) and critical temperatures (CT), can be described if preferred temperatures and CT are defined. The crustacean Hemigrapsus crenulatus was used as a model species to evaluate the effect of acclimation temperature on: (i) thermal preference and width of thermal window, (ii) respiratory metabolism, and (iii) haemolymph proteins. Dependant on acclimation temperature, preferred temperature was between 11.8°C and 25.2°C while CT was found between a minimum of 2.7°C (CTmin) and a maximum of 35.9°C (CTmax). These data and data from tropical and temperate crustaceans were compared to examine the association between environmental temperature and thermal tolerance. Temperate species have a CTmax limit around 35°C that corresponded with the low CTmax limit of tropical species (34-36°C). Tropical species showed a CTmin limit around 9°C similar to the maximum CTmin of temperate species (5-6°C). The maximum CTmin of deep sea species that occur in cold environments (2.5°C) matched the low CTmin values (3.2°C) of temperate species. Results also indicate that the energy required to activate the enzyme complex (Ei) involved in respiratory metabolism of ectotherms changes along the latitudinal gradient of temperature.

Physiological responses of the ghost shrimp Neotrypaea uncinata (Milne Edwards 1837) (Decapoda: Thalassinidea) to oxygen availability and recovery after severe environmental hypoxia.

Hypoxia is a common and widespread phenomenon in aquatic ecosystems, imposing a significant challenge for the animals that inhabit such waters. In different habitats, however, the characteristics of these hypoxic events may differ, therefore imposing different challenges. We investigated the tolerance of adult ghost shrimp Neotrypaea uncinata (an intertidal mudflat dweller) to different partial pressures of oxygen (pO2), severe hypoxia (2 kPa) and recovery from hypoxia after different exposure times, mimicking the natural tidal cycle (6 h and 12 h). We calculated critical oxygen tension and categorize the adult ghost shrimps as oxyregulators (R value=75.27%). All physiological measurements (metabolic rate, oxyhemocyanin, hemolymph protein and lactate concentrations) were affected by exposure to low partial pressures of oxygen, but most of them recovered (with exception of metabolic rate) control values (21 kPa) after 6h under normoxic conditions. Low metabolic rate, high release of hemolymphatic proteins and anaerobic metabolism are suggested as response mechanisms to overcome hypoxic events during low tide.

Immune response of the Antarctic sea urchin Sterechinus neumayeri: cellular, molecular and physiological approach / Respuesta inmune del erizo de mar Antártico Sterechinus neumayeri: un enfoque celular, molecular y fisiológico

Abstract In the Antarctic marine environment, the water temperature is usually between 2 and - 1.9 °C. Consequently, some Antarctic species have lost the capacity to adapt to sudden changes in temperature. The study of the immune response in Antarctic sea urchin (Sterechinus neumayeri) could help us understand the future impacts of global warming on endemic animals in the Antarctic Peninsula. In this study, the Antarctic sea urchins were challenged with lipopolysaccharides and Vibrio alginolitycus. The cellular response was evaluated by the number of coelomocytes and phagocytosis. A significant increase was observed in red sphere cells and total coelomocytes in animals exposed to LPS. A significant rise in phagocytosis in animals stimulated by LPS was also evidenced. Moreover, the gene expression of three immune related genes was measured by qPCR, showing a rapid increase in their expression levels. By contrast, these immune genes showed a depression in their expression by a thermal effect at 5 and 10 °C. In addition, during bacterial injection, the oxygen consumption was higher in challenged animals. Our results showed that the immune response in the Antarctic sea urchin may be affected by acute thermal stress and that this immune response has a metabolic cost. Rev. Biol. Trop. 63 (Suppl. 2): 309-320. Epub 2015 June 01.

Resumen En el medio ambiente de la Antártica la temperatura del agua es de entre 2 y - 1.9 °C. Por consecuencia ciertas especies han perdido la capacidad de adaptarse a los cambios repentinos de la temperatura del agua. El estudio de la respuesta inmune del erizo antártico (Sterechinus neumayeri) podría ayudar a comprender los futuros impactos en los animales endémicos del cambio climático en la Península Antártica. En este estudio nosotros hemos evaluado la respuesta inmunitaria de S. neumayeri respecto de estimulaciones con bacterias (Lipopolisacáridos y Vibrio alginolitycus) asi como durante el estrés térmico a 5 y 10 °C. La respuesta del erizo fue evaluada en relación al número de celomocitos circulantes, capacidad fagocítica de estos y por el análisis de la expresión de tres genes inmunitarios. Después de la estimulación con LPS un aumento significativo de células esferoidales rojas, de amebocitos fagocíticos y de celomocitos totales fue observado después de las primeras horas de estimulación, de la misma manera que la capacidad fagocítica. Por otra parte los tres genes inmunes medidos mostraron un aumento significativo de su expresión por qPCR después de la estimulación con LPS. El estrés térmico de 5 °C produjo un aumento de la expresión de estos tres genes inmunitarios, por el contrario a una temperatura más alta (10 °C) se produce la reducción de dos de entre ellos. Adicionalmente un aumento del consumo de oxígeno fue observado durante la estimulación bacteriana. Nuestros resultados muestran que la respuesta inmunitaria en el erizo antártico puede ser afectada por el estrés térmico agudo y que la respuesta inmune en invertebrados antárticos tendría un costo metabólico.

Rearing and growth of the Octopus Robsonella fontaniana (Cephalopoda: Octopodidae) from planktonic hatchlings to benthic juveniles.

Globally, octopus larviculture is one of the challenges faced in the attempt to diversify aquaculture and achieve cephalopod farming. Currently, only juveniles of Octopus vulgaris, Octopus joubini, and Enteroctopus dofleini have been obtained at an experimental level. This is the first study to look at the characteristics of planktonic and benthic Robsonella fontaniana juveniles in an effort to analyze the morphometric changes occurring during their planktonic and benthic phases and to explore the feasibility of obtaining settlement under controlled conditions. The morphometric measurements varied exponentially over time and did not show different tendencies before and after settlement. Mantle growth in relation to total length fit a logarithmic regression, whereas arm length and eye diameter increased linearly with respect to total length throughout the entire paralarval and juvenile periods. This suggests that the size of the mantle decreases with age in proportion to the total octopus length, whereas the organs more directly involved in catching prey tend to increase in direct proportion to the total length. The present study shows that R. fontaniana can be reared from hatching through the final paralarval stage on a diet of Lithodes santolla (king crab) zoeae; after settlement, the juveniles can be reared on a diet of crab such as Petrolisthes.