Sedimentation is recognized as a significant environmental stressor in aquatic ecosystems and high amounts of suspended sediments (SS) in streams are known to negatively affect aquatic organisms. In particular, it has been hypothesized that many fish species mayexhibit increased respiration rates when exposed to elevated SS. To evaluate this hypothesis, we evaluated the acute response (3 hour exposure) of two small, freshwater fish species exposed to high suspended sediment loads using experimental respirometry chambers which measure oxygen consumption as a proxy of metabolism. Our results indicate that Japanese Medaka (Oryzias latipes) did not exhibit a significantly greater oxygen consumption, as compared to control fish, when exposed to chamber sediment of 0.17 g/L (p-value of 0.41), though oxygen consumption was higher for sediment treatments. However, mosquitofish (Gambusia affinis) exposed to 0.17 g/L did exhibit noticeably greater oxygen consumption compared to fish in no-sediment control test, but not at statistically significant levels (p-value of 0.07). Further study is needed with increased sample sizes and across SS levels to determine the threshold of increased metabolic rate among freshwater species exposed to SS.

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