June 7, 2004
Bloater Works Harder Under Pressure
Ann Arbor, Mich. — Placing bloater in an environment with high water pressure increases the metabolism of this abundant deep-water salmon-like fish from the Great Lakes.
Under pressure, the swimbladder is squeezed and becomes smaller. The swimbladder is an internal balloon-like gas sac that prevents fish from sinking. In contrast to many other fish, bloater cannot easily add gas to enlarge their swimbladder. As a result they must swim harder to stay afloat, which means they use more oxygen. So, when wild bloater swim deeper, where water pressure is higher, they have to 'tread water' to prevent sinking as their swimbladder shrinks.
"Bloater are thought to move between shallow and deep water on a daily basis so the knowledge that they use more oxygen in deep water gives a more accurate picture of their metabolism," said Daniel Lingwood, a researcher in the Department of Zoology at the University of Guelph in Ontario. "This information is useful in a variety of ways, from calculating how much food bloater consume, to developing sustainable fisheries models."
Hatchery-raised bloater were used in this study because uncontrollable expansion of swimbladder gas causes wild-collected bloater to be hauled up in a 'bloated', and typically dead, state. The fish were placed in a sealed chamber that could be pressurized using a high-pressure pump. By measuring the oxygen content in water entering and exiting the chamber, the researchers could gauge how much oxygen the fish were using. They compared oxygen usage as pressure was increased and then as it was decreased between simulated depths of 0m to 30m and found that oxygen use by the fish increased as pressure increased and then returned to normal values as pressure decreased.
Original Publication Information
Results of this study, "Effects of temperature and hydrostatic pressure on routine oxygen uptake of bloater (Coregonus hoyi)," are reported by Ben Speers-Roesch, Daniel Lingwood, and E. Donald Stevens in the latest issue (Volume 30, No. 1, pp. 70-81) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2003.
Contacts
For more information about the study, contact E. Don Stevens, Department of Zoology, University of Guelph, Ontario N1G 2W1; dstevens@uoguelph.ca; (519) 824-4120 ext. 52137.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; marlene.evans@ec.gc.ca; (306) 975-5310.
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.