Respiration rates of dominant hydromedusae in the North Inlet tidal estuary during winter and summer

Abstract

The objective of this study was to quantify the respiratory requirements and oxygen consumption rates for seasonal hydromedusae populations in the North Inlet estuary, Georgetown, SC, USA. Respiration rates were determined for hydromedusae collected in January 2006, 2007 and July 2006 using microrespirometry. The numerically dominant gelatinous predators were Nemopsis bachei (January 2006 and 2007) and Bougainvillia muscus (July 2006). Seasonal oxygen consumption rates were low (0.80-1.27 μmol O2 g -1 h-1). Q10 values were high during January 2006 and July 2006 (4.7), but low during January 2007 (0.5), suggesting hydromedusae were sensitive to the exposure temperatures (7-34°C) in this study and well adapted to the temperature range encountered in this estuary. Moreover, the oxygen consumption rates during July 2006 showed significant differences between the two species. The allometric relationship between respiration rate and hydromedusae weight differed seasonally. Our findings suggest hydromedusae can persist in hypoxic conditions and may partially explain the frequently observed increase in these cnidarians under conditions of low dissolved oxygen concentrations. © The Author 2007. Published by Oxford University Press. All rights reserved.