Respiration and Thermal Tolerance of the Phyllopod Crustacea Triops longicaudatus and Thamnocephalus platyurus Inhabiting Desert Ephemeral Ponds

• Published in: Physiological zoology 1972-07, Vol.45 (3), p.189-195
• Main Authors: Hillyard, Stanley D., Vinegar, Allen
• Format: Article
• Language: English
• Subjects: Animals; Dead animals; Flasks; Freshwater; Immatures; Larvae; Oxygen; Oxygen consumption; Ponds; Respiration; Water temperature
• ISSN: 0031-935X
• DOI: 10.1086/physzool.45.3.30152497

(1) Oxygen consumption and thermal tolerances were measured in the phyllopod crustacea T. longicaudatus and T. platyurus inhabiting desert ephemeral ponds in southeastern Arizona and southwestern New Mexico. Measurements were made during consecutive 1-hour exposures to 26, 30, 34, 38, 40, 42 and 44 degree C in order to approximate the continual rise in temp that occurred in the ponds during the day. Both larvae and adults were used in the experiments. (2) The mean O sub(2) consumption of the larvae increased markedly between 26 and 30 degree C, with Q sub(10) values of 4.12 for Triops and 11.81 for Thamnocephalus. Oxygen consumption of the adults increased very little over the temp span of the experiment. (3) Larvae and adults of each species showed similar thermal tolerances to 1-hour exposures to the experimental temps. All of the Triops had died after 1 hr exposure to 42 degree C while some of the Thamnocephalus survived until 20 minutes of exposure at 44 degree C. (4) The animals were observed to come to the surface regularly with their respiratory appendages stirring the top layer of the ponds. For this reason, O sub(2) levels are probably seldom a limiting factor. (5) We never observed the water temp to be as high as the thermal maxima determined experimentally. Horne (1971), however, recorded a water temp of 43 degree C in a shallow pond, indicating that lethal temps can exist in nature. (6) We feel that the near maximal levels of respiration observed in the adults over the range of experimental temps and the high Q sub(10) values for O sub(2) consumption of the immatures between 26 degree and 30 degree are related to the rapid growth rate that these animals must sustain in order to become sexually mature and reproduce in the transient ephemeral pond habitat.