|Diel cycles of activity, metabolism, and ammonium concentration in tropical holothurians|Wheeling, R.J.; Verde, E.A.; Nestler, J.R. (2007). Diel cycles of activity, metabolism, and ammonium concentration in tropical holothurians. Mar. Biol. (Berl.) 152(2): 297-305. hdl.handle.net/10.1007/s00227-007-0683-3
In: Marine Biology. Springer: Heidelberg; Berlin. ISSN 0025-3162, more
|Authors|| || Top |
- Wheeling, R.J.
- Verde, E.A.
- Nestler, J.R.
Movement rate, oxygen consumption, and respiratory tree ammonium concentration were measured in situ in the holothurians Pearsonothuria graeffei and Holothuria edulis in the Agan-an Marine Reserve, Sibulan, Philippines (9°20'30?N, 123°18'31?E). Measurements were made both day and night for both species during April–July 2005. P. graeffei had significantly higher movement rate during the day than at night (1.14 and 0.27 m h-1, respectively; three-way ANOVA, P < 0.05) while H. edulis had higher movement rate at night compared to the day (0.83 and 0.07 m h-1, respectively), spending the daylight hours sheltering under coral. More than 80% of H. edulis had movement rate of zero during the day. Oxygen consumption of P. graeffei was significantly higher during the day than at night (1.61 and 0.83 µmol O2 g-1 h-1, respectively; two-way ANCOVA, P < 0.05), but the reduction at night was not as pronounced as the reduction in movement. H. edulis had a 75% reduction in oxygen consumption during the day compared to night (0.51 and 1.96 µmol O2 g-1 h-1, respectively), matching this species’ reduced movement rates during the day. Ammonium concentration in water withdrawn from the respiratory trees of P. graeffei during the day (12.0 µM) was three times higher than in respiratory tree water sampled at night (4.3 µM) and 15 times higher than ambient seawater (0.8 µM; three-way ANOVA, P < 0.05). Ammonium concentration in the respiratory tree water of H. edulis was six times higher at night (14.6 µM) than during the day (2.2 µM) and 16 times higher than that of ambient seawater (0.9 µM). Even though H. edulis and P. graeffei are found within the same coral reef environment, they may affect different substrates and reef organisms due to their different habitats and distinct but opposite diel cycles.