Data from: Physiological, morphological, and ecological tradeoffs influence vertical habitat use of deep-diving toothed-whales in the Bahamas

Dive capacity among toothed whales (suborder: Odontoceti) has been shown to generally increase with body mass in a relationship closely linked to the allometric scaling of metabolic rates. However, two odontocete species tagged in this study, the Blainville's beaked whale Mesoplodon densirostris and the Cuvier's beaked whale Ziphius cavirostris, confounded expectations of a simple allometric relationship, with exceptionally long (mean: 46.1 min & 65.4 min) and deep dives (mean: 1129 m & 1179 m), and comparatively small body masses (med.: 842.9 kg & 1556.7 kg). These two species also exhibited exceptionally long recovery periods between successive deep dives, or inter-deep-dive intervals (M. densirostris: med. 62 min; Z. cavirostris: med. 68 min). We examined competing hypotheses to explain observed patterns of vertical habitat use based on body mass, oxygen binding protein concentrations, and inter-deep-dive intervals in an assemblage of five sympatric toothed whales species in the Bahamas. Hypotheses were evaluated using dive data from satellite tags attached to the two beaked whales (M. densirostris, n = 12; Z. cavirostris, n = 7), as well as melon-headed whales Peponocephala electra (n = 13), short-finned pilot whales Globicephala macrorhynchus (n = 15), and sperm whales Physeter macrocephalus (n = 27). Body mass and myoglobin concentration together explained only 36% of the variance in maximum dive durations. The inclusion of inter-deep-dive intervals, substantially improved model fits (R2 = 0.92). This finding supported a hypothesis that beaked whales extend foraging dives by exceeding aerobic dive limits, with the extension of inter-deep-dive intervals corresponding to metabolism of accumulated lactic acid. This inference points to intriguing tradeoffs between body size, access to prey in different depth strata, and time allocation within dive cycles. These tradeoffs and resulting differences in habitat use have important implications for spatial distribution patterns, and relative vulnerabilities to anthropogenic impacts.

齿鲸亚目（Odontoceti）物种的潜水能力通常随体重增加而提升，该关系与代谢速率的异速缩放紧密相关。然而本研究标记的两个齿鲸物种——布氏中喙鲸（Mesoplodon densirostris）与柯氏喙鲸（Ziphius cavirostris），却违背了简单异速关系的预期：它们拥有极长的单次潜水（平均时长分别为46.1分钟与65.4分钟）与极深的下潜深度（平均深度分别为1129米与1179米），但体重却相对偏小（中位数分别为842.9千克与1556.7千克）。这两个物种的连续深潜间隔同样格外漫长：布氏中喙鲸的间隔中位数为62分钟，柯氏喙鲸则为68分钟。我们基于巴哈马海域5种同域栖息的齿鲸类群，检验了多项相互竞争的假说，以解释由体重、氧结合蛋白（oxygen binding protein）浓度以及深潜间隔所反映的垂直生境利用模式。研究通过卫星标记获取的潜水数据对假说进行评估，标记对象包括两类喙鲸（布氏中喙鲸，n=12；柯氏喙鲸，n=7）、瓜头鲸（Peponocephala electra，n=13）、短肢领航鲸（Globicephala macrorhynchus，n=15）以及抹香鲸（Physeter macrocephalus，n=27）。体重与肌红蛋白（myoglobin）浓度仅能解释最大潜水时长36%的变异。加入深潜间隔变量后，模型拟合度得到显著提升（决定系数R²=0.92）。该结果支持如下假说：喙鲸通过突破有氧潜水极限来延长觅食潜水时长，而深潜间隔的延长则对应着累积乳酸的代谢过程。这一推论揭示了体型、不同深度层的猎物获取机会以及潜水周期内时间分配之间的精妙权衡。这类权衡及其导致的生境利用差异，对物种的空间分布格局以及受人类活动影响的相对脆弱性均具有重要意义。