Masters Thesis

Blood Oxygen Stores of Olive Ridley Sea Turtles, Lepidochelys olivacea, Are Highly Variable Among Individuals During Arribada Nesting

Sea turtles are mostly pelagic, air-breathing divers that can become neritic during nesting season. Sea turtles dive with a full lung of air and these O2 stores are supplemented by O2 stored in blood. Olive ridley sea turtles exhibit polymorphic nesting behavior; mass nesting behavior called arribada, where up to 25,000 turtles will nest at once; and solitary nesting behavior. As mostly pelagic and highly migratory species, we hypothesize that newly arrived turtles, nesting in arribadas, will exhibit increased blood oxygen stores as compared to solitary nesting towards the end of the season, where turtles have likely become neritic. We measured blood volume and associated variables to estimate total blood O2 stores including hematocrit and blood hemoglobin content. There were no significant differences in mean values between nesting periods, but arribada nesting individuals were more variable than those performing solitary nesting. Mass specific plasma volume was relatively invariant among individuals, but mass specific blood volume and blood oxygen stores varied widely, 2-fold and 3-fold, respectively. Blood O2 stores represented 32% of total body O2 stores. Under typical mean diving conditions of 26°C and high levels of activity, blood stores confer ~14 min to aerobic dive times and are likely critical for the long duration, deep diving exhibited by the species. Individual differences in blood O2 stores strongly impact estimated aerobic dive limits and may constrain the ability of individuals to respond to changes in ocean climate.

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