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Daylight occurrence of humpback dolphins Sousa chinensis in Algoa Bay, South Africa
Author(s) -
Karczmarski Leszek,
Thornton Meredith,
Cockcroft Victor G.
Publication year - 2000
Publication title -
african journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.499
H-Index - 54
eISSN - 1365-2028
pISSN - 0141-6707
DOI - 10.1046/j.1365-2028.2000.00215.x
Subject(s) - daylight , bay , evening , morning , geography , cape , nocturnal , fishery , oceanography , environmental science , ecology , biology , archaeology , geology , botany , physics , astronomy , optics
This paper describes the pattern of daylight occurrence of humpback dolphins Sousa chinensis in Algoa Bay, the Eastern Cape, South Africa, between May 1991 and May 1994. Two indices, the Sighting Index (SI) and the Total Recorded Dolphin Presence (TRDP), were used to quantify the dolphins' daylight occurrence. Humpback dolphins display a clear pattern of daylight occurrence in Algoa Bay and can be seen mostly in the morning, and, to a lesser extent, in the evening. This pattern varies little between seasons (with possible exception for the evening hours), follows the time of the solar day, is not related to the tidal cycle and is probably governed by the diurnal cycles of dolphins' prey.