Feeding and digestion in low salinity in an osmoconforming crab, <i>Cancer gracilis</i> II. Gastric evacuation and motility

McGaw, Iain J.

doi:10.1242/jeb.02442

Cited by 26 publications

(10 citation statements)

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“…This was followed by a rapid return to feeding levels. This pattern was similar 3·h after feeding when food has just started to enter the midgut and 24·h after feeding when the gut is cleared and protein synthesis is well underway (McGaw, 2006b). Our recent work suggests that crabs may be able to suspend the specific dynamic action if they encounter hyposaline environments immediately after a meal (Curtis and McGaw, 2006).…”

Section: Feeding and Low Salinitymentioning

confidence: 56%

“…Cancer gracilis was exposed to low salinity 3·h after feeding while food was still in the foregut and at 24·h after food intake when the gut was cleared and intracellular digestion was underway (McGaw, 2006b). In control conditions Cancer gracilis maintained its heart rate between 70.2 and 71.8·beats·min -1 (Fig.·5A).…”

Section: Feeding and Low Salinitymentioning

confidence: 99%

“…Cancer gracilis can slow food processing in the gut and can even regurgitate food from the foregut in low salinity (McGaw, 2006b). This decrease in food processing is paralleled by a decrease haemolymph flows to the digestive gland via the hepatic arteries (Fig.·5F).…”

Section: Feeding and Low Salinitymentioning

confidence: 99%

“…It is interesting to note that increases in cardiac function and haemolymph flow rates were greater in postprandial crabs when returned to 100%SW. This rapid increase in cardiac function and haemolymph flows was not due to an increase in mechanical digestion, because it takes several hours for gastric processing to resume once 100%SW is restored (McGaw, 2006b). More likely this increase would help repay an oxygen debt (Herried, 1980) caused by the extra demand of intracellular digestion and subsequent protein synthesis (Mente, 2003).…”

Section: Feeding and Low Salinitymentioning

confidence: 99%

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Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis I. Cardiovascular and respiratory responses

McGaw

2006

Journal of Experimental Biology

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SUMMARY The osmoregulatory physiology of decapod crustaceans has received extensive attention. Within this field there is a growing body of literature on cardiovascular and respiratory responses to low salinity. Most species exhibit a tachycardia coupled with an increase in ventilation rate and oxygen uptake. However, these previous experiments were conducted on animals that were starved prior to experimentation in order to avoid increases in metabolism associated with digestive processes. Because organisms are not necessarily starved prior to experiencing environmental perturbations, results from previous experiments may not represent natural physiological responses. The present study investigated how an osmoconforming decapod, the graceful crab Cancer gracilis, balanced the demands of physiological systems(prioritization or additivity of events) during feeding and digestion in a low salinity environment. Cancer gracilis exhibited a typical increase in oxygen uptake and less pronounced increases in cardiovascular variables (heart rate, stroke volume, cardiac output) during feeding in 100% seawater. In 3-day starved crabs, exposure to 65% seawater resulted in a pronounced bradycardia,with a concomitant decrease in cardiac output and haemolymph flow rates and a temporary decrease in oxygen uptake. When crabs were exposed to low salinity,3 h and 24 h after food ingestion, heart rate increased slightly and cardiac output and ventilation rates remained stable. Although oxygen uptake decreased transiently, feeding levels were quickly regained. During a recovery phase in 100%SW there was an overshoot in parameters, suggesting repayment of an oxygen debt. Thus, it appears that feeding and digestion are prioritized in this species, allowing it to survive acute exposure to hyposaline water. Furthermore, the results show that the nutritional state of an animal is important in modulating its physiological responses to environmental perturbations. This underscores the importance of studying physiological responses at the whole organism level under conditions closely approximating those of the natural environment.

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Section: Feeding and Low Salinitymentioning

confidence: 56%

Section: Feeding and Low Salinitymentioning

confidence: 99%

Section: Feeding and Low Salinitymentioning

confidence: 99%

Section: Feeding and Low Salinitymentioning

confidence: 99%

See 2 more Smart Citations

Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis I. Cardiovascular and respiratory responses

McGaw

2006

Journal of Experimental Biology

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“…A seasonal shift in diet was also reported in female terrapins, coincident with movements between habitats (Butler et al 2012;Alleman and Guillen 2017). Although these analyses provided evidence of terrapin resource use, they may be biased towards food items that are less easily digested such as crab carapaces (McGaw 2006), while simultaneously underestimating contributions of soft-bodied prey. Additionally, these studies provide only a snap-shot of an individual's diet at any given time.…”

Section: Introductionmentioning

confidence: 83%

Stable Isotope Analysis Enhances Our Understanding of Diamondback Terrapin (Malaclemys terrapin) Foraging Ecology

Denton

Demopoulos

Baldwin

et al. 2018

Estuaries and Coasts

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Dietary studies on generalist predators may provide valuable information on spatial or temporal changes in the structure of ecological communities. We initiated this study to provide baseline data and determine the utility of stable isotope analysis (SIA) to evaluate the foraging strategies of an opportunistic reptilian predator, the diamondback terrapin (Malaclemys terrapin), which specializes in salt marshes and mangrove estuaries along the Atlantic and Gulf coasts. We evaluated stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope values of multiple tissues from terrapins inhabiting mainland and island mangrove habitats in south Florida and potential food sources to examine spatial and temporal variations in terrapin resource use. We fit linear regression models to determine the best predictors of isotopic values for both terrapins and their prey, and Stable Isotope Bayesian Ellipses in R (SIBER) analysis to examine terrapin isotopic niche space and overlap between groups. We identified differences in terrapin isotopic δ 13 C and δ 15 N values among all sites. Blood and scute tissues revealed different isotopic compositions and niche overlap between sites, suggesting diets or foraging locations may change over time, and amount of variation is site specific. Niche overlap between size classes was larger for blood (short term) versus scute (long term), suggesting greater variability in food habits or resource isotopes over the long term versus short term. These results demonstrate the usefulness of SIA in examining the spatial and temporal variability in diamondback terrapin resource use within estuary systems and further define their niche within these dynamic food webs.

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Acute metabolic responses of two marine brachyuran crabs to dilute seawater: The aerobic cost of hyper regulation

Rios

Freire

2023

J Exp Zool Pt A

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Hepatus pudibundus ("flecked box crab") is a stenohaline osmoconfomer, and restricted to marine habitats. Callinectes danae ("swimming crab Dana") lives in coastal/estuarine waters and is a weak hyper regulator. There is no consensus on which strategy is more expensive metabolically face salinity challenges: conformation with higher dependence on cell volume regulation, or hyper regulation, alleviating the need for intense cell volume regulation. Crabs were probed for their acute response to dilute seawater through exposures to salinities 35‰, 30‰, 25‰, and 20‰ for 2, 4, and 6 h. Hemolymph osmolality, lactate, and ions (chloride, sodium, magnesium, potassium) were assayed, as well as muscle water content.Water dissolved oxygen, ammonia, and pH levels were also measured. H. pudibundus conformed for osmolality and displayed increase in muscle hydration along the decrease in salinity down to 25‰, while C. danae efficiently maintained hemolymph osmo ionic stability, consumed more oxygen, acidified more the water, and released more ammonia. In 25‰, both species spent energy: H. pudibundus putatively controlling cell volume, and C. danae regulating hemolymph concentrations. In 20‰, H. pudibundus closed itself, avoiding the contact of the interface epithelia with the external environment and producing much lactate, whereas C. danae spent more energy (aerobic) in extracellular osmo ionic stability. Under these conditions, anisosmotic extracellular regulation (together with additional cell volume regulation) is more oxygen consuming than osmoconformation with a putatively more intense challenge to cell volume. The exposure to hyposalinity limits the occupation of estuarine environments by H. pudibundus in short and middle term.

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Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis II. Gastric evacuation and motility

Cited by 26 publications

References 50 publications

Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis I. Cardiovascular and respiratory responses

Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis I. Cardiovascular and respiratory responses

Stable Isotope Analysis Enhances Our Understanding of Diamondback Terrapin (Malaclemys terrapin) Foraging Ecology

Acute metabolic responses of two marine brachyuran crabs to dilute seawater: The aerobic cost of hyper regulation

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