The effects of starvation and acute low salinity exposure on food intake in the Dungeness crab, Cancer magister |
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Authors: | Daniel L Curtis Cheryl H Vanier Iain J McGaw |
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Institution: | (1) School of Life Sciences, University of Nevada, Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154, USA;(2) Bamfield Marine Sciences Centre, Bamfield, BC, V0R 1B0, Canada;(3) Ocean Sciences Centre, Memorial University of Newfoundland, St. John’s, NL, A1C 5S7, Canada |
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Abstract: | 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. |
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