McLaughlin, E. N.. Academy of Natural Sciences, Estuarine Research Center, enm4838@students.ssu.edu
Breitburg, D. N.. Academy of Natural Sciences, Estuarine Research Center, breit@acnatsci.org
Decker, M. University of Maryland Center for Environmental Science, mbdecker@uci.edu
Purcell, J. E.. University of Maryland Center for Environmental Science, purcell@hpl.umces.edu

 
BEHAVIORAL RESPONSES AND TOLERANCE OF THE CTENOPHORE MNEMIOPSIS LEIDYI TO DISSOLVED OXYGEN AND TEMPERATURE IN A STRATIFIED WATER COLUMN
 
Low dissolved oxygen is common in stratified coastal systems, deep oxygen minimum zones, and lakes. Although gelatinous zooplankton are important predators in many coastal systems characterized by high nutrients and seasonal oxygen depletion, little is known about their tolerance or behavioral responses to oxygen depleted waters. The lobate ctenophore Mnemiopsis leidyi is abundant in bottom waters of the Patuxent River at dissolved oxygen concentrations as low as 1-2mg/L, but is rare or absent at concentrations <1mg/L. Ctneophore densities in the hypoxic bottom layer where prey are scarce can greatly exceed densities in warm surface waters where prey are abundant. Experiments in 1.2m tall tanks that maintained a stratified water column indicated that M. leidyi avoids both low dissolved oxygen levels of 0.5mg/L and high surface temperatures. Survival was 100% in 24 and 96-hour tolerance experiments even at dissolved oxygen concentrations of 0.5mg/L. Our experimental results and field data indicate that M. leidyi can tolerate low dissolved oxygen levels for extended periods of time, but prefer higher oxygen concentrations. Vertical distributions in the field may be a compromise between avoidance of severly hypoxic bottom waters and avoidance of high surface temperatures, as well as interactions with predators and prey.
 
Day: Tuesday, Feb. 2
Time: 02:15 - 02:30pm
Location: Hilton of Santa Fe
 
Code: CS67TU0215H