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Diving behaviour of two Australian bimodally respiring turtles, Rheodytes leukops and Emydura macquarii , in a natural setting
Author(s) -
Gordos Matthew,
Franklin Craig E.
Publication year - 2002
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1017/s0952836902001474
Subject(s) - biology , turtle (robot) , morning , respiration , zoology , ecology , botany
Time‐depth recorders were used to investigate the diving performance and behaviour of two bimodally respiring turtle species, Rheodytes leukops and Emydura macquarii , known to have a high and low reliance on aquatic respiration, respectively. Significant differences in diving performance between R. leukops and E. macquarii were observed in the number of dives/day (39.3±5.38 vs 112.2±11.73 dives/day; mean± se ), mean dive length (33.1±7.33 min vs 9.6±2.26 min) and maximum dive length (623±104.74 min vs 67.1±8.14 min), respectively. Differences in diving performance between R. leukops and E. macquarii are attributed to the species' reliance (or lack thereof) upon aquatic respiration. Rheodytes leukops displayed a weak bimodal pattern of increased surfacing frequency in the early morning (05:00–07:00) and late afternoon (14:00–18:00), while E. macquarii displayed a strong bimodal pattern of elevated surfacing frequency over similar time periods. Daily patterns of increased surfacing frequency for both species failed to correlate with fluctuating aquatic P o 2 levels or water temperature, and may instead be explained by the heightened activity levels of both species during twilight.