(full paper is archived in the Miller Library)
Title: Respiratory and tolerance responses of the copepod, Tigriopus californicus, after rapid induction of torpor by high salinites
Student Author(s): Senko, J. Thomas
Faculty Advisor(s): Phillips, John
Location: Final Papers Biology 175H
Date: June 1977
Keywords: high tide pools
Abstract: Tigriopus californicus, a splash pool copepod of the intertidal zone, enters into a state of torpor in response to high salinites. Tolerance to, recovery from, and QO2 of the torpor state were studied. After 3 hours exposure to hypersaline conditions an ED-50 of 88.82 ppt was found. Acclimatization to salinity change occured rapidly with a 64 percent decrease in torpor at 120 ppt in 20 hours. Recovery from 3, 6, 24, 34, and 48 hours exposre to 120 ppt showed greatest recovery occuring in a solution of 25 ppt. Recovery was rapid. All animals able to resume normal activity after torpor did so in 30 to 60 minutes. QO2 was determined over a range of salinites during 5 hours exposure. QO2 is inversely related to salinity in the range tested. QO2 ranged from a high of 7.78 uL/mg-dry weight/hr. at 16 ppt to a low of .78 uL/mg-dry weight/hr. at 145 ppt. animals aggregated at 34 ppt respired at a significantly lower rate when compared to free swimming animals at 34 ppt. The aggregated animals provided a Basal Metabolic Rate of 2.89 uL/mg-dry weight/hr. This allowed the calculation of the percent increase due to activity and the percent decrease by salinity. The values ranged from +169 percent at 16 ppt to -73 percent at 145ppt. The results indicate topor maybe the result of an inability to osmoregulate and the decrease in QO2 in torpor could be the combination of decreased activity and a decreased ability to metabolize oxygen by a direct effect of salinity.