. Fig. 59. Moulting. Monthly frequency of occurrence of cast skins between the surface and 1000 m., the three hauls from 250 m. to the surface being treated as one. In the East Wind zone the sun's rays strike obliquely with the result that they are deficient in intensity, much ultra-violet radiation is lost and the total available heat is low. All this, quite apart from its adverse effect on photosynthesis, may contribute to the slow growth-rate we find among the high southern krill, much as it affects the annual growth of many deciduous and evergreen plants in the Arctic (Dansereau, 1955). MO
. Fig. 59. Moulting. Monthly frequency of occurrence of cast skins between the surface and 1000 m., the three hauls from 250 m. to the surface being treated as one. In the East Wind zone the sun's rays strike obliquely with the result that they are deficient in intensity, much ultra-violet radiation is lost and the total available heat is low. All this, quite apart from its adverse effect on photosynthesis, may contribute to the slow growth-rate we find among the high southern krill, much as it affects the annual growth of many deciduous and evergreen plants in the Arctic (Dansereau, 1955). MOULTING In the vertical samples I examined I frequently noted complete casts of euphausian skins, or fragments of euphausian skins, which from their large size could readily be referred to E. superba. Only casts that could obviously be referred to this species were recorded, very small casts which, though possibly those of young adolescent krill, might also have been confused with those of other and smaller species,
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