Emersion behavior of the semi-terrestrial crab Neohelice granulata during hypoxic conditions: Lactate as a trigger (original) (raw)
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Oceanologia, 1997
The ability to accumulate lactate as result of laboratory exposure to anoxia was determined in the mud crab Rhithropanopeus harrisii tridentatus. Haemolyph lactate levels rose from 0.232 ± 0.13 µmol ml −1 to 25.337 ± 1.6 µmol ml −1 during 32 h of anoxia. High haemolymph lactate levels resulting from anoxia were associated with a number of behavioural responses. The response of R. harrisii tridentatus to very low levels of oxygen < 2 Torr was relatively slow (LT 50 = 24.3 h). Glycogen was found in normoxic concentrations of 15.21 ± 4.68 µmol g −1 d.w. These decreased after 6 h exposure to anoxia. The results are discussed in relation to the metabolic requirements for the survival of other crustaceans under low oxygen conditions.
Marine Biology, 2007
The Dungeness crab, Cancer magister, inhabits areas that are frequently subject to periods of hypoxia. This species can employ physiological mechanisms that allow it to cope with acute hypoxic episodes. When crabs feed there is a general increase in physiological variables; these may pose an additional physiological burden on crabs already attempting to maintain adequate oxygen uptake in hypoxia. In Barkley Sound, British Columbia, the inshore habitats of C. magister ranged in dissolved oxygen from 28 kPa at the water surface to less than 1.0 kPa just above the sedimentwater interface. During short-term hypoxic events, crabs reduced both the amount of food eaten and the amount of time spent feeding. Crabs tended to cease feeding below 3.2 kPa oxygen, but resumed feeding when the dissolved oxygen tensions were rapidly raised to 6 kPa. In a high (10.5-21 kPa) oxygen gradient, both unfed and fed crabs showed no preference for any area of the gradient. In a low (2.5-10.5 kPa) dissolved oxygen gradient, both unfed and fed crabs preferred the highest oxygen regime. In the laboratory, crabs were less likely to enter hypoxic waters (below 3.2 kPa oxygen) to obtain and consume food; those that did moved the food to a higher oxygen regime prior to feeding and settled in higher oxygen regimes for digestion. Crab behaviour was also monitored in the Weld. Fed and unfed crabs were Wtted with ultrasonic telemetry tags and tracked during a tidal cycle. Unfed crabs remained mobile, travelling up to 1,370 m within 6 h, while postprandial crabs settled in areas of high oxygen and moved very little during the Wrst 48 h after release. The present study suggests that C. magister exhibits behavioural responses in order to minimise the use of physiological mechanisms, and maximise foraging and digestive processes. Thus the nutritional state of the individual may be important in regulating both its behaviour and distribution in its natural environment.
Crustacean Research, 2017
We subjected the intertidal hermit crab, Pagurus samuelis (Stimpson, 1857), to various treatments to determine physiological responses of this species to the environmental stress of burial. Hermit crabs were buried with 6 cm of sediment and excavated at 2 h intervals up to a maximum of 12 h. Duration of burial and state (alive or dead) of the crab were analyzed for effects on lactate accumulation in hemolymph. Hermit crab weight, shell weight, weight ratio, lactate, and burial duration were analyzed for their influence on survival. As expected, lactate levels, as well as incidence of death, rose with duration of burial. Significant interaction, however, was also found between burial duration, crab state, and lactate concentration. There was a trend for lactate concentration to be low for surviving crabs, yet higher for dead crabs during shorter burial durations. Conversely and surprisingly, lactate concentrations were very high in surviving crabs, yet lower in dead crabs during long burial durations. Since some surviving crabs were able to develop very high lactate levels, we suggest that lactate buildup itself is unlikely to be the sole cause of death. Further studies are needed to identify factors affecting crab resilience during the stress of burial.
Marine Biology, 2010
Episodes of hypoxia are common in the marine environment, and their ecological effects depend, in part, on their severity and duration. Many species of decapod crustaceans reside in areas with fluctuating oxygen regimens. Physiological mechanisms enhance the ability of these crustaceans to cope with acute episodes of hypoxia. Southern king crab, Lithodes santolla, fishery is important in the south of South America, and some data describe fishing zones with low dissolved oxygen (DO) levels (3.5 mgO 2 l-1 , i.e., 8.3 kPa). Our main objective was to evaluate the effect of dissolved oxygen level on respiratory metabolism, nutritional physiology, and immunological condition of L. santolla juveniles. Individual animals were exposed for 10 days to different oxygen tensions (2.1, 4.2, 8.5, 12.7, and 21.1 kPa) to quantify the oxygen consumption rate; thereafter, blood oxyhemocyanin (Hc), protein concentration, as well as hemocytes, were sampled. Freezedried animals were dissected, and digestive gland metabolites (glycogen, protein, glucose, cholesterol, acylglycerol, and lactate) and digestive enzyme activity (general protease, trypsin, and chymotrypsin), as well as gill lactate dehydrogenase (LDH) activity, were quantified. In the present study, Lithodes santolla showed a critical oxygen tension between 4 and 9 kPa, indicating that this crab species is more sensitive to DO than other crustacean species. Protein and Hc concentrations followed a similar pattern to that of oxygen consumption. Digestive gland glycogen and protein concentration did not change after 10 days at different oxygen exposures, but glucose, cholesterol, and acylglycerol concentrations decreased linearly and proportionally to the available oxygen in the water. As in other decapods, chymotrypsin showed over 90% of the total quantified proteases activity. Chymotrypsin activity together with total proteases and trypsin was not affected by the environmental oxygen tension. Gill LDH and digestive gland lactate followed a similar increase at lower environmental oxygen tension but dropped sharply at the lowest tension (2.1 kPa). Dissolved oxygen affected also the immune system through reduction of hemocytes. This could provide a critical window for opportunistic pathogens to become established when crabs are exposed to hypoxic conditions. L. santolla juveniles show a moderate tolerance to low oxygen availability by modifying the concentration of hemolymph proteins, mainly OxyHc, some digestive gland metabolites, and by activating the anaerobic metabolism. This allows L. santolla juveniles to inhabit temporarily low oxygen zones in the deep ocean and suggests an advantage for culture conditions.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2008
The present study showed that the lactate/glucose ratio in the hemolymph of Chasmagnathus granulatus maintained in normoxia (controls) was 4.9, suggesting that lactate is an important substrate for this crab. Periods of hypoxia are part of the biological cycle of this crab, and lactate is the main end product of anaerobiosis in this crab. Our hypothesis was that this lactate would be, therefore, used by gluconeogenic pathway or can be oxidized or excreted to the aquatic medium during hypoxia and post-hypoxia periods in C. granulatus. The concentrations of hemolymphatic lactate in animals in normoxia are high, and are used as an energy substrate. In hypoxia, muscle gluconeogenesis and excretion of lactate to the aquatic medium would contribute significantly in regulating the concentration of circulating lactate. Utilization of these pathways would serve the objective of maintaining the acid-base equilibrium of the organism. Muscle gluconeogenesis participates, during the recovery process, in metabolizing the lactate produced during the period of hypoxia. Lactate excretion to the external medium, was one of the strategies used to decrease the higher hemolymphatic lactate levels. However, oxidation of lactate in the muscle is not a main strategy used by this crab to metabolize lactate in the recovery periods.
The air exposure behavior of the semi-terrestrial crab Neohelice granulata during severe hypoxiawas studied. This study also verified whether this behavior mitigates possible oxidative damage, namely lipoperoxidation, caused by hypoxia and reoxygenation cycles. The lethal time for 50% of the crabs subjected to severe hypoxia (0.5 mgO2·L−1) with free access to airwas compared to that of crabs subjected to severe hypoxiawithout access to air. Crabswere placed in aquaria divided into three zones:water (when the animalwas fully submersed), land (when the animal was completely emerged) and intermediate (when the animalwas in contact with both environments) zones. Then the crabs were held in this condition for 270 min, and the time spent in each zone was recorded. Lipid peroxidation (LPO) damage to thewalking leg muscleswas determined for the following four experimental conditions: a—normoxic water with free access to air; b—hypoxicwaterwithout access to air; c—hypoxic water followed by normoxic water without air access; and d—hypoxic water with free access to air. When exposed to hypoxicwater, N. granulata spent significantly more time on land, 135.3±17.7 min,whereas control animals (exposed to normoxic water) spent more time submerged, 187.4 ± 20.2 min. By this behavior, N. granulata was able to maintain a 100% survival rate when exposed to severe hypoxia. However, N. granulata must still return to water after periods of air exposure (~14 min), causing a sequence of hypoxia/reoxygenation events.Despite increasing the survival rate, hypoxiawith air access does not decrease the lipid peroxidation damage caused by the hypoxia and reoxygenation cycle experienced by these crabs.
Marine Biology, 2010
Episodes of hypoxia are common in the marine environment, and their ecological effects depend, in part, on their severity and duration. Many species of decapod crustaceans reside in areas with fluctuating oxygen regimens. Physiological mechanisms enhance the ability of these crustaceans to cope with acute episodes of hypoxia. Southern king crab, Lithodes santolla, fishery is important in the south of South America, and some data describe fishing zones with low dissolved oxygen (DO) levels (3.5 mgO2 l−1, i.e., 8.3 kPa). Our main objective was to evaluate the effect of dissolved oxygen level on respiratory metabolism, nutritional physiology, and immunological condition of L. santolla juveniles. Individual animals were exposed for 10 days to different oxygen tensions (2.1, 4.2, 8.5, 12.7, and 21.1 kPa) to quantify the oxygen consumption rate; thereafter, blood oxyhemocyanin (Hc), protein concentration, as well as hemocytes, were sampled. Freeze-dried animals were dissected, and digestive gland metabolites (glycogen, protein, glucose, cholesterol, acylglycerol, and lactate) and digestive enzyme activity (general protease, trypsin, and chymotrypsin), as well as gill lactate dehydrogenase (LDH) activity, were quantified. In the present study, Lithodes santolla showed a critical oxygen tension between 4 and 9 kPa, indicating that this crab species is more sensitive to DO than other crustacean species. Protein and Hc concentrations followed a similar pattern to that of oxygen consumption. Digestive gland glycogen and protein concentration did not change after 10 days at different oxygen exposures, but glucose, cholesterol, and acylglycerol concentrations decreased linearly and proportionally to the available oxygen in the water. As in other decapods, chymotrypsin showed over 90% of the total quantified proteases activity. Chymotrypsin activity together with total proteases and trypsin was not affected by the environmental oxygen tension. Gill LDH and digestive gland lactate followed a similar increase at lower environmental oxygen tension but dropped sharply at the lowest tension (2.1 kPa). Dissolved oxygen affected also the immune system through reduction of hemocytes. This could provide a critical window for opportunistic pathogens to become established when crabs are exposed to hypoxic conditions. L. santolla juveniles show a moderate tolerance to low oxygen availability by modifying the concentration of hemolymph proteins, mainly OxyHc, some digestive gland metabolites, and by activating the anaerobic metabolism. This allows L. santolla juveniles to inhabit temporarily low oxygen zones in the deep ocean and suggests an advantage for culture conditions.
When are resting water-breathers lacking O2? Arterial PO2 at the anaerobic threshold in crab
Respiration Physiology, 1992
The minimum arterial 02 partial pressure (Pao:) at which, in resting conditions, O2 consumption (I~1o.,) can be maintained and below which anaerobic metabolism is initiated was studied in the crabs Eriocheir sinensis and Carcinus maenas at 15 °C. Arterial Po:, 1~1o2 (in E. sinensis), blood lactate concentration ([lact]b) and blood copper concentration ([Cu]b, an index of the blood O2 carrying capacity) were determined after 24 h exposure to inspired Po: (Pro,) ranging from 2.7-2.1 kPa. They were compared to normoxic controls. in normoxia, the most frequently measured Pao2 ranged between I and 3 kPa in both species. In hypoxia, the threshold for blood lactate appearance was Pao: = 2.1 kPa in E. sinensis and 1.3 kPa in C. maenas, but in many individuals anaerobic metabolism was initiated at lower Pao:'S. The lowest Pao: with [lact]b approx. 0 was 0.7 kPa in both species. I~c~, was maintained in 4 E. sinensis out of 6 with Pao: ranging from 0.7-1.2 kPa (Pro., = 2. I kPa). The arterial Pc): at which anaerobic metabolism occurred was not related to blood O., carrying capacity.