Meeting Abstract
Despite being critically endangered, relatively little is known about the physiological capacities of the Hawaiian monk seal (Monachus schauinslandi). Utilizing data from both wild and captive monk seals we quantified blood, muscle, lung, and total O2 storage capacity as well as diving and swimming metabolic rates for this species. Blood volume (BV; n=1), hemogolobin and hematocrit (Hb, Hct; n=2) were measured in captive male monk seals. BV was determined to be 87.49 ml∙kg-1, while Hb and Hct values were 17.29±0.20 g∙dL-1 and 49.16±0.58%, respectively. Average muscle myoglobin (Mb) was quantified by analyzing major locomotor muscles (longissimus dorsi) sampled from sub-adult (n=2) and adult (n=3) wild monk seals. Average [Mb] was determined to be 5.21±0.19 g∙100g-1 muscle. Diving lung volume was estimated from values of closely related phocid species. Calculated blood, muscle, and lung O2 stores for adult monk seals were 17.27 ml∙kg-1, 23.03 ml∙kg-1, and 4.26 ml∙kg-1, respectively, making total O2 storage capacity 44.57 ml∙kg-1. Diving and swimming metabolic rates were measured in one captive adult male seal using open-flow respirometry. The average submerged swimming metabolic rate was 7.74±1.56 ml O2∙min-1 kg-1. By dividing total O2 stores by O2 demand, the cADL of an adult monk seal was estimated to be between 5.8-13.9 minutes, depending upon activity level underwater. Considered ‘living fossils’ due to their distinct evolutionary history, our study suggests that Hawaiian monk seals are also physiologically unique among pinnipeds, exhibiting characteristics similar to both phocid and otariid species.
