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Intertidal adaptations and the constraints on the development of the egg capsules of Nucella spp. (Gastropoda: Muricidae)
SlOl
P14-4
P14-6
Endogenous substrate for energy metabolism and ultrastructural correlates in spermatozoa of the four species of the sea urchin, Echinotnetra tnathaei.
The bioenergetic interactions of thermoregulation, activity, and digestion in Steller sea lions, Eumetopias jubatus. Rosen DAS and Trites AW Marine Mammal Research Unit, University of British Columbia, Vancouver, British Columbia, Canada V6T 124
Mita p> M’,’ Uehara T3 and Nakamura M” ‘Dept. of Biol.. Sch. of Educ., Waseda Univ., ShinJuku-ku. Tokyo 169-8050, ‘Teikyo Jun. Coil., Shibuya-ku, Tokyo 151-0071, ‘Dept. of Biol., Univ. of the Ryukyu, Nishihara, Okinawa 903-0213, “Dept. of Basic Life Sci., Teikyo Univ., Hachioji, Tokyo 192-0352, Japan.
Four different types of the sea urchin Echinometra mathaei are abundant on Okinawa reef flats in southern Japan. Interestingly, sperm size and shape gradually change to become longer and more slender relative to the species of Echinometra sp. (A, B, C and D). To obtain further information Okinawan Echinometra, this study
regarding examined
speciation in the energy production system of spermatozoa of Echinometra sp. A, B, C
and D. All spermatozoa contained cholesterol and several kinds of phospholipids. There were some differences in the lipid and fatty acid components a incubation in seawater, phosphatidylcholine (PC) was
among the four species. After in the level of decrease observed in all spermatozoa.
The hydrolysis of PC correlated with the activity of phospholipase. Lipid bodies within mitochondria of the sperm midpieces became small or disappeared after incubation in seawater. In conclusion, it appears that Echinometra sp. spermatozoa use PC located in the lipid bodies as a substrate for energy metabolism. The results further suggest that Echinometra sp. A, B, C and D are closely-related, but different, species.
P14-5
Intertidal adaptations and the constraints on the development of the egg capsules of Nucellu spp. (Gastropoda: Muricidae) Newel MS and Bourne GB Department of Biological Sciences, The University of Calgary and the Batnfield Marine Station Intertidal gastropods possess morphological, physiological and behavioural adaptations that correspond with their relative position in the intertidal zone. The egg capsules deposited by whelks of the genus Nucella provide an opportunity to study the constraints affecting development in the intertidal zone. Thus, we measured the effects of certain habitat features (i.e., tidal height and wave exposure) on capsule morphology and several measures of physiological performance in the egg capsules of Nucella ostrina and N. lamellosa. The capsules of both Nucella species maintain or increase their relative rates of oxygen consumption during periods of emersion. However, N. ostrina possesses an increased capacity for aerial oxygen uptake compared with that of N. lamellosa. Similarly, after an emersion period the capsules of both species increase their rates of ammonia excretion, including a rapid efflux immediately upon re-immersion. Therefore, in the intertidal the increased oxygen availability may relax diffusive constraints. However, the accumulation ofmetabolic waste products within the capsule may introduce a novel constraint that is reflected in both the snail’s egg capsule morphology and reproductive strategies.
As part of an investigation into the population decline of Steller sea lions in the North Pacific, we are constructing a bioenergetic model to calculate energy demands. While bioenergetic parameters can be quantified independently, the interactions between factors is more ecologically relevant. We used 4 juvenile Steller sea lions (ages 152.0 yr; mass: 7513.5 kg) to determine whether thermogenesis from activity or digestion is used to offset thermoregulatory costs (by examining changes in resting metabolism, diet-induced thermogenesis, and activity with water temperature). The oxygen consumption of the sea lions was measured while freeswimming and resting in a metabolic tank with water temperature set between 2-8 C. Metabolism was measured both pre- and 2 hrs postprandial after consuming 2 kg of herring. There was no indication of increases in pre-meal resting metabolism or activity levels with decreasing water temperature. However, postprandial metabolism decreased with decreasing water temperature for both free-swimming and resting animals. We propose that these results indicate that the sea lions did not utilize heat from activity or digestion to offset thermoregulatory costs. Rather, they restricted “peripheral” processes such as digestion (via decreased blood flow and core body volume) as an initial response to thermoregulatory demands, instead of increasing metabolic output. P14-7
Mechanisms of hypoxia tolerance in Nautilus. Sta&s JF’ Seibel, BA’, Webber, DM3 and Boutilier ‘Dept. of Zoology, Univ. of Cambridge, CB2 3EJ, 2mne Biology and Fisheries, University of Miami, 3Biology Dept. Dalhousie Univ., Halifax, NS, B3H
RG’ UK USA 4JI,
The hypoxia tolerance of Nautilus pompilius is distinctive among cephaplopods. During progressive hypoxia (final PC& - 5 mm Hg) octopine concentrations rise in adductor muscle and heart. However, octopine, lactate and succinate do not change through 1 hour of acute hypoxia (rapid Pa change from air-saturation to 20 mm Hg). After IO minutes of acute hypoxia, tissue concentrations of high-energy phosphates fall Corn normoxic values, but remain stable through a Cn-ther 50 minutes of hypoxia, and recover upon re-oxygenation. During progressive hypoxia, rates of whole animal oxygen consumption (n/roz) remain constant down to a I’@ of approximately 25 mm Hg. Below this P@, A4& decreases sharply. This reduction of M@ is reversed upon reoxygenation. Such reversible metabolic depression is the most effective strategy for surviving environmental conditions that may constrain energy production capacities. Our work also examines the potential for N. pompilius to use 02 contained within the gas-filled chambers of its shell during hypoxia. In addition the effects of hypoxic water layers on the behavioural and metabolic responses of N. pompilius moving freely in a tower-tank mesocosm (10m deep, 3m diameter) are reported.
P14-4
P14-6
Endogenous substrate for energy metabolism and ultrastructural correlates in spermatozoa of the four species of the sea urchin, Echinotnetra tnathaei.
The bioenergetic interactions of thermoregulation, activity, and digestion in Steller sea lions, Eumetopias jubatus. Rosen DAS and Trites AW Marine Mammal Research Unit, University of British Columbia, Vancouver, British Columbia, Canada V6T 124
Mita p> M’,’ Uehara T3 and Nakamura M” ‘Dept. of Biol.. Sch. of Educ., Waseda Univ., ShinJuku-ku. Tokyo 169-8050, ‘Teikyo Jun. Coil., Shibuya-ku, Tokyo 151-0071, ‘Dept. of Biol., Univ. of the Ryukyu, Nishihara, Okinawa 903-0213, “Dept. of Basic Life Sci., Teikyo Univ., Hachioji, Tokyo 192-0352, Japan.
Four different types of the sea urchin Echinometra mathaei are abundant on Okinawa reef flats in southern Japan. Interestingly, sperm size and shape gradually change to become longer and more slender relative to the species of Echinometra sp. (A, B, C and D). To obtain further information Okinawan Echinometra, this study
regarding examined
speciation in the energy production system of spermatozoa of Echinometra sp. A, B, C
and D. All spermatozoa contained cholesterol and several kinds of phospholipids. There were some differences in the lipid and fatty acid components a incubation in seawater, phosphatidylcholine (PC) was
among the four species. After in the level of decrease observed in all spermatozoa.
The hydrolysis of PC correlated with the activity of phospholipase. Lipid bodies within mitochondria of the sperm midpieces became small or disappeared after incubation in seawater. In conclusion, it appears that Echinometra sp. spermatozoa use PC located in the lipid bodies as a substrate for energy metabolism. The results further suggest that Echinometra sp. A, B, C and D are closely-related, but different, species.
P14-5
Intertidal adaptations and the constraints on the development of the egg capsules of Nucellu spp. (Gastropoda: Muricidae) Newel MS and Bourne GB Department of Biological Sciences, The University of Calgary and the Batnfield Marine Station Intertidal gastropods possess morphological, physiological and behavioural adaptations that correspond with their relative position in the intertidal zone. The egg capsules deposited by whelks of the genus Nucella provide an opportunity to study the constraints affecting development in the intertidal zone. Thus, we measured the effects of certain habitat features (i.e., tidal height and wave exposure) on capsule morphology and several measures of physiological performance in the egg capsules of Nucella ostrina and N. lamellosa. The capsules of both Nucella species maintain or increase their relative rates of oxygen consumption during periods of emersion. However, N. ostrina possesses an increased capacity for aerial oxygen uptake compared with that of N. lamellosa. Similarly, after an emersion period the capsules of both species increase their rates of ammonia excretion, including a rapid efflux immediately upon re-immersion. Therefore, in the intertidal the increased oxygen availability may relax diffusive constraints. However, the accumulation ofmetabolic waste products within the capsule may introduce a novel constraint that is reflected in both the snail’s egg capsule morphology and reproductive strategies.
As part of an investigation into the population decline of Steller sea lions in the North Pacific, we are constructing a bioenergetic model to calculate energy demands. While bioenergetic parameters can be quantified independently, the interactions between factors is more ecologically relevant. We used 4 juvenile Steller sea lions (ages 152.0 yr; mass: 7513.5 kg) to determine whether thermogenesis from activity or digestion is used to offset thermoregulatory costs (by examining changes in resting metabolism, diet-induced thermogenesis, and activity with water temperature). The oxygen consumption of the sea lions was measured while freeswimming and resting in a metabolic tank with water temperature set between 2-8 C. Metabolism was measured both pre- and 2 hrs postprandial after consuming 2 kg of herring. There was no indication of increases in pre-meal resting metabolism or activity levels with decreasing water temperature. However, postprandial metabolism decreased with decreasing water temperature for both free-swimming and resting animals. We propose that these results indicate that the sea lions did not utilize heat from activity or digestion to offset thermoregulatory costs. Rather, they restricted “peripheral” processes such as digestion (via decreased blood flow and core body volume) as an initial response to thermoregulatory demands, instead of increasing metabolic output. P14-7
Mechanisms of hypoxia tolerance in Nautilus. Sta&s JF’ Seibel, BA’, Webber, DM3 and Boutilier ‘Dept. of Zoology, Univ. of Cambridge, CB2 3EJ, 2mne Biology and Fisheries, University of Miami, 3Biology Dept. Dalhousie Univ., Halifax, NS, B3H
RG’ UK USA 4JI,
The hypoxia tolerance of Nautilus pompilius is distinctive among cephaplopods. During progressive hypoxia (final PC& - 5 mm Hg) octopine concentrations rise in adductor muscle and heart. However, octopine, lactate and succinate do not change through 1 hour of acute hypoxia (rapid Pa change from air-saturation to 20 mm Hg). After IO minutes of acute hypoxia, tissue concentrations of high-energy phosphates fall Corn normoxic values, but remain stable through a Cn-ther 50 minutes of hypoxia, and recover upon re-oxygenation. During progressive hypoxia, rates of whole animal oxygen consumption (n/roz) remain constant down to a I’@ of approximately 25 mm Hg. Below this P@, A4& decreases sharply. This reduction of M@ is reversed upon reoxygenation. Such reversible metabolic depression is the most effective strategy for surviving environmental conditions that may constrain energy production capacities. Our work also examines the potential for N. pompilius to use 02 contained within the gas-filled chambers of its shell during hypoxia. In addition the effects of hypoxic water layers on the behavioural and metabolic responses of N. pompilius moving freely in a tower-tank mesocosm (10m deep, 3m diameter) are reported.