Life in the Open Ocean. Joseph J. Torres

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Life in the Open Ocean - Joseph J. Torres


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Gnathophausia ingens, Science, 1968, Vol 160, Issue 3833, figure 1 (p. 1242). Reprinted with permission from AAAS.

Schematic illustration of oxygen consumption rate, percent utilization of oxygen, and ventilation volume in Gnathophausia ingens as a function of oxygen partial pressure, mean of eight runs.

      Source: Figure 4 from Childress (1971), Biol. Bull. 141: 114. Reprinted with permission from the Marine Biological Laboratory, Woods Hole, MA.

Schematic illustration of relationship between percent utilization and ventilation volume in Gnathophausia ingens utilizing the values given in Figure 2.23.

      Source: Figure 5 from Childress (1971), Biol. Bull. 141: 115. Reprinted with permission from the Marine Biological Laboratory, Woods Hole, MA.

      No other oxygen‐minimum‐layer species has been examined as well as G. ingens. Taken together, the several studies on the species’ respiratory physiology paint a complete picture of how it is possible to survive at vanishingly low oxygen concentrations. Nonetheless, a few pieces of the puzzle have been collected in other taxa to suggest that elements of the suite have been employed by other species to achieve the same end. The most important characteristic to look for is a Pc at or below the lowest PO2 encountered in nature. That characteristic has been observed in many of the Crustacea living in the oxygen minimum in the California borderland (8 mm Hg, Childress 1975; Childress and Seibel 1998). It has also been seen in at least one crustacean dwelling in the Eastern Tropical Pacific where the oxygen minimum layer is as low as 3 mm Hg O2: the galatheid red crab Pleuroncodes planipes with a Pc of 3 mm Hg (Quetin and Childress 1976).

      Once an individual reaches its Pc, it responds behaviorally and metabolically. Since metabolism scales positively with activity level, activity is minimized, precipitously dropping metabolic demand for ATP. Any ATP deficit resulting from the inability to meet its needs aerobically must be made up by anaerobic glycolysis. The hypoxia‐induced drop in activity resulting in lowered ATP demand is termed metabolic suppression (Seibel 2011; Seibel et al. 2016) and is not confined to pelagic fauna. It is the first weapon any species can wield to reduce the demand for ATP and is exploited by intertidal species, such as bivalves, during low tide exposure (Hochachka and Somero 1984; Hochachka and Guppy 1987).

      Source: Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer Nature, Experimental Biology Online, Vampire Blood: respiratory physiology of the vampire squid (Cephalopoda: Vampyromorpha) in relation to the oxygen minimum layer, Seibel et al. (1999).

Species VO2 a DGO2 Pg P50 b
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