. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . Fig. 77.—Longitudinal section of the Baltic Sea, from Skagen to Lulea, with isohalines, in %e, according to Ekman; depths in meters at the left. After Brandt. at more than 150-m. depth 2 species of worms, Harmothoe sarsi and Priapulus caudatus, occur, and at greater depths than 230 m. all animal life is absent. The reason for this condition lies in the low oxygen content and the accumulation of carbon dioxide. The water at 0-60 m. depth is about one-third saturated with oxygen,
. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage . Fig. 77.—Longitudinal section of the Baltic Sea, from Skagen to Lulea, with isohalines, in %e, according to Ekman; depths in meters at the left. After Brandt. at more than 150-m. depth 2 species of worms, Harmothoe sarsi and Priapulus caudatus, occur, and at greater depths than 230 m. all animal life is absent. The reason for this condition lies in the low oxygen content and the accumulation of carbon dioxide. The water at 0-60 m. depth is about one-third saturated with oxygen, in the deeps of East Gotland at a depth of 100 m. only one-fifth, and at 200 m. only one-fifteenth. On the other hand, while only 32 cc. of carbon dioxide per liter is present at a depth of 0-60 m., 36 cc. is present at 100 m. and 41 cc. at 200 m. Rarely, on the occasion of continuous easterly storms, does the surface water recede in the east and an under- current of water rich in oxygen and salt advances farther toward the east, bringing fresh supplies to the depressions. After such storms richer animal life becomes possible in these local deeps; thus, 3 species of maldanids (Annelida) were taken in the Danzig deeps in February, 1904, while only 1 species of annelid normally occurs in the western Baltic Sea.,i:{ Geologically speaking, the Baltic is still young. It has retained a
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Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology
