Sub-Lethal Effects of Hypoxia/Hypercapnia on Callinectes Sapidus in the York River Estuary, Virginia

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SUB-LETHAL EFFECTS OF HYPOXIAIHYPERCAPNIA ON CALLINECTES SAPIDUS IN THE YORK RIVER ESTUARY, VIRGINIA By SANDRA R. HYPES, Masters of Interdisciplinary Science A thesis submitted in partial fulfillment of the requirements for the degree of Master of Interdisciplinary Science at Virginia Commonwealth University. Virginia Commonwealth University, 1999. Major Director: Dr. Peter L. deFur, Affiliate Associate Professor, Center for Environmental Studies This research examined effects of hypoxic environments on blue crabs, Callinectes sapidus in an estuarine environment. Hypoxic conditions were treated as a multiple stressor involving low dissolved oxygen (D.O.), increased carbon dioxide (hypercapnia), and low pH concurrently. The objectives were to: 1) identify hypoxiahypercapnia by monitoring D.O. and pH as an indicator of hypercapnia in shallow regions of the York River, 2) measure blue crab abundance, and 3) describe blue crab responses to hypoxiahypercapnia via field work at Taskinas Creek and lab measurements of respiration. Ambient D.O. and pH were positively correlated in the Taskinas Creek and York River sites (r= .73). Crab abundance (CPUE) was not significantly different among D.O. and pH ranges. It was concluded that hemolymph blood lactate concentration was not considered a good in situ biomarker for exposure to hypoxickypercapnic conditions. Oxygen uptake was not significantly different between normoxic and hypoxic conditions but was significantly affected by pH.