Meeting Abstract
Hypoxia in Chesapeake Bay from anthropogenic activities is a major concern. For obligate aerobes like juvenile striped bass, incursion into these increasingly prevalent hypoxic zones creates additional metabolic pressure when performing energetically expensive activities such as swimming. When in these hypoxic waters, the Darwinian fitness of these fish may depend on their tolerance of hypoxia (HT) and/or ability to escape the hypoxic region by swimming away from it. Here we measured the relative HT of 18 juvenile striped bass twice, 11 weeks apart, and their oxygen consumption rate while swimming in low flow (10.2 cm s-1) and high flow (estimated 67 % Umax) under normoxia (>90% air saturation, AS) and hypoxia (20% AS). The rank order of individual HT was significantly repeatable over the 11-week period, and HT increased significantly in most individuals. Oxygen consumption was lower while swimming against low flow regardless of available oxygen levels, but was significantly lower in hypoxic water under high flow. There were no clear relationships or trade-offs between an individual’s relative HT and their oxygen consumption while swimming under any conditions. Only an individual’s increase in HT after multiple hypoxia exposures and oxygen consumption rate in low flow were significantly-negatively correlated. Importantly, both HT and oxygen consumption rate were repeatable and varied substantially among individuals suggesting that they may be targets of natural selection in fish occupying hypoxia-prone waters
