Gastric Emptying Rate and Return Of Appetite In Lesser Spotted Dogfish,<i>Scyliorhinus Canicula</i>(Chondrichthyes: Elasmobranchii)

Sims, David; Davies, Simon J.; Bone, Q.

doi:10.1017/s002531540003068x

Cited by 34 publications

(20 citation statements)

References 32 publications

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“…Interestingly, food remnants had not reached the anus by this time, so initial concerns (Series 1) about defecation contaminating N-flux measurements proved unfounded. A slow time course (relative to that of teleosts) for digestion, assimilation and gut passage appears to be characteristic of elasmobranchs (Jones and Geen, 1977;Wetherbee et al, 1987;Schurdak and Gruber, 1989;Wetherbee and Gruber, 1990;Cortes and Gruber, 1990;Sims et al, 1996). Fig.·1.…”

Section: Discussionmentioning

confidence: 98%

Alkaline tide and nitrogen conservation after feeding in an elasmobranch(Squalus acanthias)

Wood

Kajimura

Mommsen

et al. 2005

Journal of Experimental Biology

114

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We investigated the consequences of feeding for acid-base balance, nitrogen excretion, blood metabolites and osmoregulation in the Pacific spiny dogfish. Sharks that had been starved for 7·days were surgically fitted with indwelling stomach tubes for gastric feeding and blood catheters for repetitive blood sampling and were confined in chambers, allowing measurement of ammonia-N and urea-N fluxes. The experimental meal infused via the stomach tube consisted of flatfish muscle (2% of body mass) suspended in saline (4% of body mass total volume). Control animals received only saline (4% of body mass). Feeding resulted in a marked rise in both arterial and venous pH and HCO 3 -concentrations at 3-9·h after the meal, with attenuation by 17·h. Venous P O ∑ also fell. As there were negligible changes in P CO ∑, the response was interpreted as an alkaline tide without respiratory compensation, associated with elevated gastric acid secretion. Urea-N excretion, which comprised >90% of the total, was unaffected, while ammonia-N excretion was very slightly elevated, amounting to <3% of the total-N in the meal over 45·h. Plasma ammonia-N rose slightly. Plasma urea-N, TMAO-N and glucose concentrations remained unchanged, while free amino acid and β-hydroxybutyrate levels exhibited modest declines. Plasma osmolality was persistently elevated after the meal relative to controls, partially explained by a significant rise in plasma Cl -. This marked post-prandial conservation of nitrogen is interpreted as reflecting the needs for urea synthesis for osmoregulation and protein growth in animals that are severely N-limited due to their sporadic and opportunistic feeding lifestyle in nature.

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Section: Discussionmentioning

confidence: 98%

Alkaline tide and nitrogen conservation after feeding in an elasmobranch(Squalus acanthias)

Wood

Kajimura

Mommsen

et al. 2005

Journal of Experimental Biology

114

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“…However, as other experiments indicate that the factor limiting food intake is stomach 825 fullness (Grove and Crawford, 1980;Sims et al, 1996;Hossain et al, 1998; and as stomach fullness depends on both intake rate and stomach evacuation rate, evacuation rate and maximum food intake are intrinsically linked. The results from the study of Andersen and Riis-Vestergaard (2003) can hence not be used directly in the present study, as the whiting in the present study had a varied diet 830 consisting of both rapidly and slowly evacuated prey.…”

Section: Estimation Of Maximum Daily Ration Of Whitingmentioning

confidence: 95%

Functional and aggregative response of North Sea whiting

Rindorf

Gislason

2005

Journal of Experimental Marine Biology and Ecology

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15The functional response of whiting (Merlangius merlangus L.) to clupeid and gadoid prey was determined from estimates of food intake and prey density at five locations in the North Sea. The intake of most prey types was well described by a type II (decelerating) response, although in some cases a type III (sigmoid) response provided a slightly better fit. Though a saturation level was reached for all types of 20 fish prey, none of the levels corresponded to the maximum digestive capacity of the predator. This was not caused by ingestion of other prey as the amount of other food and fish prey ingested were not negatively correlated. An investigation of the occurrence of fresh fish in the stomachs revealed that fish was ingested almost 2 exclusively during dawn and dusk and the lack of negative correlation between the 25 intake of fish and other prey may thus be a result of the limited time in which fish prey was vulnerable to predation. No aggregative response of the predators was detected towards any of the prey and catches of prey and predators were slightly negatively correlated. There was evidence of an increase in mortality with density at low clupeid densities, but mortality decreased to virtually zero at high densities. 30Whiting seem therefore unlikely to impose a regulatory effect on their fish prey outside a narrow range of prey densities.

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“…Averaged on a daily basis, consumption appears to be in the range of 0.5-2.5% (Jones and Geen, 1977) or 0.8-4.1% of body mass (Tanasichuk et al, 1991) in Squalus acanthias, with substantial year-to-year and seasonal variation. Gut passage time is calculated to be more than 5·days in Squalus acanthias (Jones and Geen, 1977) and 8·days in Scyliorhinus canicula (Sims et al, 1996), with estimates of 3-4·days in other elasmobranch species at warmer temperatures (Menon and Kewalramani, 1959;Wetherbee et al, 1987;Wetherbee and Gruber, 1990;Cortes and Gruber, 1990;Cortes, 1999). All authors except Menon and Kewalramani concur that the digestive process is much slower in sharks than in similarly sized teleost carnivores at comparable temperature (Menon and Kewalramani, 1959).…”

Section: Introductionmentioning

confidence: 93%

Osmoregulation, ionoregulation and acid–base regulation by the gastrointestinal tract after feeding in the elasmobranch (Squalus acanthias)

Wood

Kajimura

Bucking

et al. 2007

Journal of Experimental Biology

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SUMMARY In order to study the physiological consequences of voluntary feeding in the gastrointestinal tract of a ureotelic marine elasmobranch, dogfish (fasted for 96 h) were sampled at various times up to 360 h after consuming a 5–6% ration of teleost fish (hake) under natural feeding conditions. Digestion and absorption were completed between 120 and 360 h post-feeding. The tissue masses of different segments of the gastrointestinal tract increased and decreased markedly as the chyme moved through, mainly because of fluid engorgement rather than hyperplasia. In fasted dogfish, the cardiac and pyloric stomachs contained only small volumes of highly acidic fluid (pH 1.77±1.12, 2.05±0.08) similar in composition to seawater. Feeding resulted in gastric pHs of 3.20±0.31 and 3.95±0.40 at 6 h, followed by slow declines through 60 h. An alkaline tide in the blood also occurred at 6 h. In the face of large changing masses of highly acidic chyme in the stomachs, the pH (6.50±0.10), ionic composition and volume of chyme in the intestine (spiral valve) were precisely regulated from 6 to 60 h post-feeding at very different values from those in the stomachs, and intestinal HCO –3 remained low (5.12±0.83 mmol l–1). The colon was usually empty and its pH constant at 7.20±0.16 at all times. Despite the ingestion of strongly hypo-osmotic teleost tissue, the osmolality of the chyme remained in equilibrium with that of the blood plasma in all segments at all times after feeding. Much of the osmotic equilibration was because of the secretion of urea into the chyme,particularly in the intestine. After feeding, gastric fluid concentrations of Na+ and Mg2+ declined, K+ and Ca2+increased, whereas Cl– exhibited little change, indicating that additional drinking of seawater was minimal. Na+,K+, water and especially Cl– were absorbed in the intestine, whereas Mg2+ and Ca2+ were largely excluded. Our results illustrate the complex integration of digestive and ionoregulatory function in the elasmobranch digestive tract, and marked differences from the teleost pattern.

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Gastric Emptying Rate and Return Of Appetite In Lesser Spotted Dogfish,Scyliorhinus Canicula(Chondrichthyes: Elasmobranchii)

Cited by 34 publications

References 32 publications

Alkaline tide and nitrogen conservation after feeding in an elasmobranch(Squalus acanthias)

Alkaline tide and nitrogen conservation after feeding in an elasmobranch(Squalus acanthias)

Functional and aggregative response of North Sea whiting

Osmoregulation, ionoregulation and acid–base regulation by the gastrointestinal tract after feeding in the elasmobranch (Squalus acanthias)

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