Comparative Aerial Metabolism and Water Relations of the Intertidal Limpets Patella granularis L. (Mollusca: Prosobranchia) and Siphonaria oculus Kr. (Mollusca: Pulmonata)
1992; University of Chicago Press; Volume: 65; Issue: 5 Linguagem: Inglês
10.1086/physzool.65.5.30158558
ISSN1937-4267
AutoresDavid J. Marshall, Christopher D. McQuaid,
Tópico(s)Marine and coastal plant biology
ResumoWhen exposed to air, the phylogenetically distant intertidal limpets Patella granularis (Prosobranchia) and Siphonaria oculus (Pulmonata) displayed diferent levels of survival and metabolic adjustment. Siphonaria oculus lost water at a significantly higher rate, a response probably relating to its less domed shell Despite this, lethal exposure time and lethal water loss (LT50 = 158 h; LD50 = 59%) were considerably higher than for P. granularis (LT50 = 89 h; LD50 = 34%). Oxygen uptake rates (V̇o2) for both species remained constant over 12 h in air of 100% relative humidity (RH), when water loss was presumably negligible, but declined significantly in P. granularis after longer (24 h) exposure. Desiccation at 0% RH led to a marked decline in V̇o2 in both species. The V̇o2 of S. oculus fell to as low as 18% of the initial nondesiccated rate, whereas in P. granularis V̇o2 never declined below 38% of the initial rate. When reimmersed after 12 h desiccation at 0% RH, S. oculus showed no "oxygen debt" repayment. The comparatively limited depression of aerobic metabolism of P. granularis, followed by early mortality, is interpreted as a stress-related response to impairment of gas exchange. High survivorship of S. oculus, despite drastic reduction in V̇o2, may indicate adaptive depression of metabolic rate. The extension of vertical distribution by S. oculus further up the shore than P. granularis is discussed with regard to their respective water relations and metabolic characteristics during progressive aerial exposure.
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