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

Abstract

A key difference among marine divers is whether or not they make use of their lung O2 stores while diving. Sea turtles are air‐breathing divers that dive with their lungs full of air. Lung oxygen stores in sea turtles are supplemented by O2 stored in the blood. Olive ridley sea turtles exhibit polymorphic nesting behaviors consisting in either a mass nesting behavior called arribada, where up to 25,000 turtles nest at once, or a solitary nesting behavior. We measured blood volume, hemoglobin concentration, hematocrit, plasma volume and mean corpuscular hemoglobin concentration, and estimated total blood O2 stores in samples collected from olive ridley turtles nesting solitarily or in arribada. There were no significant differences in mean values between nesting periods, but most parameters were more variable in arribada nesting individuals than in those performing solitary nesting. Mass‐specific plasma volume did not vary 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 can confer ~14 minutes of 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 changing ocean temperatures. Support or Funding Information McNair Scholars and Centro Mexicano de la Tortuga

Oxidative Stress Is a Potential Cost of Synchronous Nesting in Olive Ridley Sea Turtles

“…We then conducted correlation analyses using mass, hormones, TG, NEFA, glucose, and lactate [ 28 ]. Glucose and lactate showed a positive association in both nesting modes; however, this association was stronger in arribada (r s = 0.82, p = 0.0006) and not significant in solitary nesters (r s = 0.60, p = 0.067) ( Figure 2 a,b).…”

“…In a previous study we showed that arribada nesters have higher circulating corticosterone and glucose levels than solitary nesters [ 28 ]. Here, we found that arribada nesters are bigger and have higher thyroid hormone levels than solitary nesters.…”

“…Assays were conducted following the manufacturers’ instructions. The glucose, lactate, and corticosterone concentrations included in our correlation analyses were measured in samples obtained from the same animals in our previous study [ 28 ].…”

“…Correlation analyses between hormones, mass, TG, NEFA, glucose and lactate were conducted by calculating Spearman rank correlation coefficients. The glucose, lactate, and corticosterone concentrations included in our correlation analyses were measured in samples obtained from the same animals in our previous study [ 28 ]. Statistical significance was considered at p ≤ 0.05.…”

Ecological and life‐history correlates of erythrocyte size and shape in Lepidosauria

“…Similarly, reptiles use a range of physiological mechanisms, including bradycardia, prolonged apnoea, cardiac shunts and Bohr effects, to support diving behaviour (Anderson, 1966; Millard & Johansen, 1974; Seymour & Webster, 1975). In diving turtles, oxygen is stored both in the lungs and blood (Arango et al, 2021; Lutz & Bentley, 1985), and blood oxygen stores are thought to be important in some squamates (Ferguson & Thornton, 1984). Marine snakes have significantly higher haematocrit levels (Brischoux et al, 2011; Feder, 1980), with the file snake Acrochordus granulatus , the species with the largest recorded erythrocytes, having the largest blood oxygen stores of any reptile (Feder, 1980).…”