M. A. Castellini

Aerobic and anaerobic metabolism during voluntary diving in Weddell seals: Evidence of preferred pathways from blood chemsitry and behavior

SummaryThe salient features of this study in the order of significance as we perceive them are: 1.Post-dive arterial lactic acid concentrations were at no time different from resting levels unless the previous dive exceeded 20 to 25 min (Fig. 5).2.Peak lactate concentration was correlated to dive durations (Fig. 6).3.Only 2.7% of the dives of free-ranging seals exceed 26 min (Table 3 and Fig. 7).4.There was a notable drop in body temperature during prolonged dives to as low as 34.9°C (Table 2).5.Arterial hemoglobin concentrations immediately after dives (22.7%) were significantly higher than concentrations in resting animals (17.4g%) (Fig. 3).6.Blood glucose after dives always rose aboce resting levels.7.pH was in the normal mammalian range except after very long dives; in these cases the pH fell as low as 6.8 (Fig. 4).8.Blood gases were in the normal mammalian range, but based upon resting apneic values

Aerobic diving limits of immature Weddell seals

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THERMAL CONDUCTANCE OF IMMERSED PRINNIPED AND SEA OTTER PELTS BEFORE AND AFTER OILING WITH PRUDHOE BAY CRUDE

may drop to remarkably low levels during prolonged dives.

Heart rates and swim speeds of emperor penguins diving under sea ice

SummaryBuffering capacities (β), measured in slykes (μmoles of base required to titrate the pH of one gram wet weight of muscle by one pH unit, over the pH range of pH 6 to pH 7) due to non-bicarbonate buffers were measured in locomotory muscles from a variety of terrestrial and marine mammals and teleost fishes (Tables 1 and 2). The highest buffering capacities were found in muscles capable of either intense, burst glycolytic function or prolonged, low-level anaerobic function. Marine mammals had higher muscle buffering capacity on the average than terrestrial mammals. Among the fishes studied, warm-bodied species had the greatest β values of all animals examined (Table 2). Deep-sea fishes and shallow-living fishes with sluggish locomotory abilities had low β values. Fish white muscle displayed higher buffering capacity than red muscle (Fig. 1; Table 2), in keeping with the more aerobic poise and higher capillary density of the latter type of muscle. Strong correlations were found between (1) β and muscle myoglobin concentrations in the mammalian species (Table 1; Fig. 2), and (2) β and muscle lactate dehydrogenase (LDH) activities in both the mammals and the fishes (Tables 1 and 2; Fig. 3). No correlation was found between β and the activity of a citric acid cycle indicator enzyme, citrate synthase, in the mammalian species. While strongly correlated with buffering capacity, the amounts of myoglobin and LDH in a muscle are not the principal determinants of β. The results indicate that muscle intracellular buffering capacity is especially critical in locomotory muscles which must function under conditions (burst locomotion and prolonged, low-level anaerobic function) where circulatory perfusion is inadequate to rapidly remove the acidic end-products such as lactic acid that are produced by anaerobic glycolysis. In this respect, the locomotory muscle of diving mammals and the white skeletal muscles of teleost fishes face a common acid-base regulatory problem and utilize a common biochemical strategy to resolve it.

Renal glomerular filtration rate and hepatic blood flow during voluntary diving in Weddell seals

Summary1.Consistent with previous studies on adult seals, post-dive blood lactic acid (LA) concentrations in immature Weddell seals did not increase above resting levels after short voluntary dives (Fig. 1).2.Following longer dives, peak blood LA values increased rapidly according to the duration of the dive (Fig. 1).3.The peak post-dive blood LA concentration relative to dive duration demonstrate that there is a positive relationship between aerobic dive limit (ADL) and body size (Fig. 1 and 3).4.The ADL for 130 to 145 kg seals was about 10 min, and it was 13 min for 185 to 205 kg seals (Fig. 1).5.The calculation of the ADL from available oxygen stores correlates well with the lactate/endurance curve intercept, where peak post-dive LA concentration rises rapidly above resting levels as the dive duration increases in adult and immature animals (Table 2 and Fig. 3).6.Of total dives, 4% of the dive durations exceeded the measured ADL in 130 to 145 kg seals and 8% in the 205 kg seal (Fig. 2).7.Dive depths of immature seals did not exceed 315 m (Table 1).

Muscle temperature and swim velocity profiles during diving in a Weddell seal, Leptonychotes weddellii

SummaryCardiac output was measured by the thermodilution method in three young harbor seals, at rest and while swimming up to the maximum effort for which they could be trained. Stroke volume was determined by counting heart rate simultaneously with determination of cardiac output. Cardiac outputs varied widely between surface breathing (7.8 ml · kg−1 · s−1) and breath-holding while swimming under water (1.8 ml · kg−1 · s−1). Stroke volume while at the surface was almost twice the volume white submerged. Surface cardiac output was always near maximal despite work effort, whereas submerged cardiac output gradually increased at higher work efforts. The cardiovascular performance of seals at the maximum MO2 we could induce from them is equivalent to that of the domestic goat.

Annual cycles of diving behavior and ecology of the Weddell seal

Abstract Thermal conductance (C) of the sea otter and several species of pinniped pelts was determined during immersion, after oiling, and after cleaning. A (C) of 7 Watts · Meter-2 °C-1 ° °C-1 for the sea otter pup was the lowest measured in all controls. The highest was 58 W ° M-2 °C-1 for the California sea lion. Most affected by oiling was the sea otter pup in which (C) doubled. Least affected was the sea lion in which no change in (C) occurred. Washing slightly reduced (C) of the adult otter and fur seal. The results indicate that even a light oiling would have marked detrimental effects on the thermoregulatory abilities of otters and fur seals at sea. The thermal effects of oiling on other adult pinnipeds while at sea would be slight.