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First published online September 19, 2006
Journal of Experimental Biology 209, 3766-3776 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02441
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Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis I. Cardiovascular and respiratory responses

Iain J. McGaw

School of Life Sciences, University of Nevada, Las Vegas, NV 89154-4004, USA and Bamfield Marine Sciences Centre, Bamfield, British Columbia, VOR 1BO, Canada


Figure 1
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Fig. 1. Cardiovascular parameters of Cancer gracilis (N=10). (A) Heart rate (beats min-1), (B) stroke volume (ml beat-1), (C) cardiac output (ml min-1) and haemolymph flow rates (ml min-1) through the (D) anterior aorta, (E) left anterolateral artery, (F) right hepatic artery, (G) posterior aorta and (H) sternal artery. Crabs were monitored during a 3 h control period in 100%SW, food was administered and cardiac parameters followed for a further 12 h in seawater. Values are means ± s.e.m. The beginning of the feeding periods are marked. In certain cases error bars are small and do not show clearly on figures.

 

Figure 2
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Fig. 2. (A) Ventilation rates (beats min-1) and (B) oxygen uptake rates (mg O2 kg-1 h-1) of 10 Cancer gracilis monitored for a 3 h period in 100% seawater; food was administered and changes in respiratory variables were subsequently followed. Values represent means ± s.e.m.

 

Figure 3
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Fig. 3. Cardiovascular parameters (mean ± s.e.m.) of 10 Cancer gracilis. (A) Heart rate (beats min-1), (B) stroke volume (ml beat-1), (C) cardiac output (ml min-1) and haemolymph flow rates (ml min-1) through the (D) anterior aorta, (E) left anterolateral artery, (F) right hepatic artery, (G) posterior aorta and (H) sternal artery. Crabs were monitored during a 3 h control period in 100%SW, low salinity conditions (65%SW) were initiated for 6 h. Control conditions were then restored for an additional 6 h. The beginning of the low salinity and 100%SW periods are marked. In certain cases error bars are small and do not show clearly on figures.

 

Figure 4
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Fig. 4. (A) Ventilation rates (beats min-1) and (B) oxygen uptake rates (mg O2 kg-1 h-1) of 10 Cancer gracilis monitored for a 3 h period in 100% seawater; low salinity conditions were then initiated for 6 h, following this seawater conditions were restored for an additional 6 h. Values represent means ± s.e.m.

 

Figure 5
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Fig. 5. (A) Heart rate (beats min-1), (B) stroke volume (ml beat-1), (C) cardiac output (ml min-1) and haemolymph flow rates (ml min-1) through the (D) anterior aorta, (E) left anterolateral artery, (F) right hepatic artery, (G) posterior aorta and (H) sternal artery of 10 Cancer gracilis. Crabs were monitored during a 3 h control period in 100%SW, food was administered and cardiac parameters followed for a further 3 h in seawater, after which low salinity conditions (65%SW) were initiated for 6 h. Control conditions were then restored for an additional 6 h. Values are means ± s.e.m. The beginning of the feeding, low salinity and 100%SW periods are marked. In certain cases error bars are small and do not show clearly on figures.

 

Figure 6
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Fig. 6. (A) Ventilation rates (beats min-1) and (B) oxygen uptake rates (mg O2 kg-1 h-1) of 10 Cancer gracilis monitored for a 3 h period in 100% seawater; food was administered and cardiac parameters followed for a further 3 h in seawater before low salinity conditions were initiated for 6 h. Seawater conditions were then restored for an additional 6 h. Values represent means ± s.e.m.

 

Figure 7
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Fig. 7. (A) Heart rate (beats min-1), (B) stroke volume (ml beat-1), (C) cardiac output (ml min-1) and haemolymph flow rates (ml min-1) through the (D) anterior aorta, (E) left anterolateral artery, (F) right hepatic artery, (G) posterior aorta and (H) sternal artery of 10 Cancer gracilis. Crabs that had been fed 21 h previously were monitored during a 3 h control period in 100%SW; low salinity conditions (65%SW) were then initiated for 6 h, after which control conditions were restored for an additional 6 h. Values are means ± s.e.m. The beginning of the low salinity and 100%SW periods are marked. In certain cases error bars are small and do not show clearly on figures.

 

Figure 8
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Fig. 8. (A) Ventilation rates (beats min-1) and (B) oxygen uptake rates (mg O2 kg-1 h-1) of 10 Cancer gracilis that had been fed 21 h previously were monitored for a 3 h period in 100% seawater, before low salinity conditions were initiated for 6 h. Seawater conditions were then restored for an additional 6 h. Values represent means ± s.e.m.

 





© The Company of Biologists Ltd 2006