Oxygen consumption of the crab Callinectes rathbunae parasitized by the rhizocephalan barnacle Loxothylacus texanus as a function of salinity (original) (raw)
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Journal of Experimental Marine Biology and Ecology, 2002
The osmoregulatory response of the blue crab Callinectes rathbunae parasitized with the rhizocephalan barnacle Loxothylacus texanus, and subjected to sudden salinity changes, was experimentally measured in the laboratory. Parasitized and control crabs were exposed to salinity changes every 3 h and their hemolymph osmolality measured. Two experiments, one with increasing salinity conditions (5x , 12x , 19x , 25x ) and a second one with decreasing salinities (35x , 25x , 15x , 5x ) were conducted. The results show that L. texanus significantly alters the hemolymph osmolality of C. rathbunae maintaining it at lower than normal levels. In the increasing salinity trial, the hypoosmotic hemolymph condition of parasitized crabs was present at all salinities tested, whereas in the decreasing salinity trial a significant effect was found only at salinities of 5x and 15x . Since C. rathbunae is constantly subjected to abrupt salinity changes in the tropical estuaries where it occurs, moving into high salinity areas may be the only way to cope with the impact of L. texanus. D
Behavioral Physiology of Four Crab Species in Low Salinity
Biological Bulletin, 1999
Reports focusing on the behavioral responses of crabs to exposure to low salinity have involved choice chamber experiments or quantification of changes in activity. In addition to describing changes in locomotor activity in four species of crabs of differing osmoregulatory ability, the present study describes six behaviors: increased movement of the mouthparts, cleaning of the mouthparts with the chelae, cleaning of the antennae and antennules with the maxillipeds, flicking of the antennae, retraction of the antennules, and extension of the abdomen. Callinectes sapidus and Carcinus maenas are classed as efficient osmoregulators, and in general, showed an increase in these behaviors with decreasing salinity. Cancer magister, a weak regulator, and Libinia emarginata, an osmoconformer, exhibited these behaviors to a lesser degree and became inactive in the lower salinities, tending to adopt an isolation-type response. The differences in behaviors between the species correlated closely with previously reported changes in cardiovascular function and hemolymph flow. These overt reactions are discussed in relation to the osmoregulatory physiology and ecology of each crab species.
International Aquatic Research, 2014
Carcinoscorpius rotundicauda is one of the four extant species of horseshoe crab, occurring only in Asia: around India, Indonesia, Malaysia, Philippines, Singapore, Thailand and Hong Kong. Virtually nothing is known about the physiology of this Asian species. In the present study, the respiratory physiology in terms of oxygen consumption rate of the trilobite larvae of C. rotundicauda was evaluated under laboratory conditions. The trilobite larvae were exposed to different levels of temperature (10, 20, 30 and 40°C), salinity (10, 20, 30 and 40 ppt), pH (5, 6, 7, 8 and 9) and dark-light conditions for a period of 12 h. Effect of temperature on oxygen consumption in trilobite larvae was not so significant among all the temperatures tested. However, both 10 and 40°C temperature showed comparatively high rate of oxygen consumption at the initial 4 h of experiment. More or less consistent oxygen consumption pattern observed at 20 and 30°C temperature suggested 20-30°C as the best temperature range for rearing trilobite larvae. Trilobite larvae revealed enormous tolerance to temperature and indicated that the temperature is not critical in terms of respiration. The trend in oxygen consumption was more or less uniform at all salinities tested indicating the insignificant influence of salinity on respiration. Though not significant, the oxygen consumption trend was more consistent at 20 ppt as compared to other salinities and thus could be considered as the most suitable salinity for rearing trilobite larvae. There was a positive relationship between oxygen consumption rate and the
Aquaculture, 2006
The blue swimmer crab, Portunus pelagicus, is an emerging aquaculture species in the Indo-Pacific. Two experiments were performed to determine the effects of salinity on survival, growth and haemolymph osmolality of early juvenile P. pelagicus crabs. The salinities tested for the first experiment were 10, 15, 25 and 40 ppt, and for the second experiment 5, 20, 30, 35 and 45 ppt. Each salinity experiment was triplicated, with each replicate consisting of 10 stage 4 juveniles. Each experiment lasted 45 days. Mortalities and incidence of "molt death syndrome" were recorded daily, while the intermolt period, carapace length, carapace width and wet weight were measured at each molt. At the end of the experiments the haemolymph osmolality and dry weights were measured.
African Zoology, 2007
The aquatic oxygen consumption of the estuarine brachyuran crab, Cyclograpsus punctatus, was investigated after a 24-hour acclimation period at different temperature (12.5, 20, 30°C) and salinity (9, 17.5, 35, and 44‰) combinations. Salinity had no significant effect on oxygen consumption at 12.5 and 20°C in both large and small crabs. At 30°C and 44‰, however, the rate of oxygen consumption declined in large crabs (from 0.233 to 0.176 mg O 2 g wwt/h) and increased in small crabs (0.300 to 0.469 mg O 2 g wwt/h). There was also a significant increase in the oxygen consumption (0.300 to 0.536 mg O 2 g wwt/h) of small crabs at the high temperature/low salinity combination. Temperature had a significant effect on the rate of oxygen consumption at all salinities, with Q 10 values ranging from 1.16 to 2.85. In all cases the mass-specific oxygen consumption rate of small crabs was higher than that of large crabs. The results suggest that the confinement of this species to the lower reaches of estuaries may, in part, be due to physiological constraints on juveniles and small individuals.
Journal of Experimental Biology, 1995
Callinectes sapidus and C. similis co-occur in estuarine waters above 15 salinity. Callinectes sapidus also inhabits more dilute waters, but C. similis is rarely found below 15 . Previous work suggests that C. sapidus may be a better hyperosmoregulator than C. similis. In this study, energy metabolism and the levels of transport-related enzymes in excised gills were used as indicators of adaptation to low salinity. Oxygen consumption rates and mitochondrial cytochrome content of excised gills increased in both species as acclimation salinity decreased, but to a significantly greater extent in C. similis gills. In addition, C. similis gills showed the same levels of carbonic anhydrase and Na+/K+-ATPase activities and the same degree of enzyme induction during low-salinity adaptation as has been reported for C. sapidus gills. However, hemolymph osmolality and ion concentrations were consistently lower in C. similis at low salinity than in C. sapidus. Therefore, although gills from low...
Journal of Experimental Marine Biology and Ecology, 2008
The specific metabolic rate (SMR) and haemolymph osmolality (HO) of the mud crab Rhithropanopeus harrisii Gould, 1841 from Baltic brackish waters were measured at a habitat salinity of 7 psu (T = 15°C, full air saturation) and after step-wise acclimation to a salinity range of 3-27 psu. Values of SMR at 7 psu varied between 0.40 and 3.89 J g − 1 WW h − 1 (n = 25, wet weight range 0.051-1.142 g) and were significantly ( p b 0.05) related to the specimen's wet weight (WW) according to the power regression SMR = 0.94 WW − 0.41 (R 2 = 0.68). The SMR of females did not differ significantly ( p N 0.05) from those of males. When exposed to higher salinities, the SMR of R. harrisii decreased significantly ( p b 0.05) and reached a minimum value at 23 psu (0.55 ± 0.05 J g − 1 WW h − 1 , n = 6). Mean haemolymph osmolality at 7 psu amounted to 581 ± 26 mOsm kg − 1 (n = 5) and was 2.9 times higher than that of the external medium. R. harrisii hyperosmoregulated its body fluids up to 24 psu (727 mOsm kg − 1 ) at which salinity the isosmotic point was reached.
Marine Biology, 2010
Adult Cancer magister make forays into hyposaline estuarine habitats during times of high food abundance. However, as weak osmoregulators, they are poorly equipped to deal with the concurrent demands of osmoregulation and digestion. Therefore, the potential interaction between nutritional status and feeding in a physiologically challenging environment was investigated. Changes in the proportion of crabs feeding, the amount of food consumed, the time spent feeding, and the efficiency with which a meal was consumed were examined in response to the length and severity of hyposaline exposure, and the duration of starvation. Reductions in the (a) number of animals feeding, (b) the amount of food consumed, and (c) the time spent feeding were observed in salinities where C. magister actively osmoregulates the concentration of its internal fluids. Although this reduction in feeding was likely a stress response, the crabs were able evaluate the level of salinity stress: there was a dose-dependent reduction in feeding, and they were able to discriminate between salinities separated by as little as 3.5%. The likelihood that animals would feed in low salinity increased with starvation. Thus, the aversion to food uptake in physiologically stressful conditions may be overridden by the need to procure nutrients. In the natural environment, we suggest that C. magister are employing an 'eat and run' strategy, moving into the estuary, consuming a meal, and retreating to higher salinities to digest.
Acute response of the estuarine crab Eurypanopeus depressus to salinity and desiccation stress
Hemolymph osmolality changes following exposure to abrupt salinity change in the range of 5–40 ppt (T = 26°C, full air saturation) and upon exposure to air (T = 23°C, r.h. = 30%) were investigated in the flatback mud crab Eurypanopeus depressus (Smith, 1869), a dominant species on oyster reefs in Southwest Florida. During salinity trials, hemolymph osmolality of E. depressus ranged from 751 ± 123 mOsmol kg−1 at 5 ppt (214 ± 32 mOsmol kg−1) to 1188 ± 81 mOsmol kg−1 at 40 ppt (1188 ± 29 mOsmol kg−1). In the salinity range of 5–15 ppt E. depressus exhibited a hyperosmotic pattern of osmoregulation while at 30 and 40 ppt it conformed. In all cases stable hemolymph osmotic concentration was reached in less than 24 h. During desiccation trials, hemolymph osmolality of E. depressus ranged from 971 ± 121 mOsmol kg−1 for unexposed crabs to 1132 ± 169 mOsmol kg−1 after 90 min of exposure. The information obtained from this study adds to knowledge of crustacean stress physiology and may give a clearer picture of the important factors involved in population distribution and the consequences of multiple stressors that may affect the crabs or their oyster-reef habitat.
Journal of Experimental Marine Biology and Ecology, 2002
The effects of individual larval biomass, and salinity experienced during embryogenesis (i.e., prehatching salinity) on starvation tolerance and growth of zoea 1 of the estuarine crab (Chasmagnathus granulata) were evaluated in laboratory experiments. Freshly hatched zoeae 1 were obtained from broods maintained at three salinities (15x , 20xand 32x), and cultured at 20xunder different initial feeding periods and subsequent food deprivation (''point of reserve saturation'' experiment: PRS) or under initial periods of food deprivation and subsequent feeding (point of no return experiment: PNR). Another group of larvae were used for determination of biomass (dry weight, carbon, and nitrogen) of zoea 1. Larval survival and duration of development depended on the length of feeding period: no larvae reached the second instar under complete starvation; survival was higher and duration of development shorter as the feeding period lengthened. After different initial feeding periods (PRS experiment), zoeae 1 that hatched from eggs incubated at the prehatching salinities of 15xand 20xshowed higher survival and shorter duration of development than those at 32x. Prehatching salinity also affected the amount of reserves accumulated during the first 2 days after hatching, with larvae from 15xand 20x showing the highest percentage of total accumulation of carbon and nitrogen. Initial larval biomass did not affect survival, but it had a slight effect on duration of development, with larger larvae (in terms of biomass) developing faster. After different initial starvation periods (PNR experiment), prehatching salinity did not affect survival, but it affected duration of development: larvae from 15xand 20xreached the second instar earlier. Variability in survival and duration of development