Meeting Abstract

P1.57  Thursday, Jan. 3  Metabolism in the Mudminnow (Umbra limi): Effects of temperature, hypoxia and ammonia MARKS, C.M.*; LEARNER, A.D.; WRIGHT, P.A.; CURRIE, S.; BAGATTO, B.; Univ. of Akron; Univ. of Akron; Univ. of Guelph; Mount Allison Univ.; Univ. of Akron cm14@uakron.edu

The mudminnow (Umbra limi) is a common fish in central North America occupying still waters that vary greatly in temperature, dissolved oxygen, and components of nitrogenous waste. They are also continuous but facultative air breathers using the swimbladder as an accessory respiratory organ. Few studies have addressed the full range of metabolic responses of the mudminnow to the complex and extreme environment it occupies. This study begins to address the effects of temperature, dissolved oxygen level, and ammonia level on the metabolism of the mudminnow. It also begins to investigate the interaction of these abiotic factors in their metabolism. Mudminnows were placed individually in opaque containers and metabolism was measured via closed system respirometry. Although a previous study concluded there was no temperature effect on metabolism in mudminnows, we found the opposite. Metabolism in mudminnows increased five-fold over a 16 C increase in water temperature. Mudminnows responded to hypoxia by increasing their frequency of air breathing. Their aquatic respiration significantly decreased in hypoxia even when access to the surface was denied. Mudminnows are very tolerant of high ammonia levels. Their increased metabolism in response to ammonia is only detected at the highest treatment levels of 20 mmol.It remains unclear how hypoxia and high ammonia interact in affecting the metabolism of the mudminnow.