Roussouw Natasha, van Vliet Tara, Naidoo Kristina, Rossouw Gideon, Plön Stephanie
Bayworld Centre for Research and Education (BCRE), Port Elizabeth, South Africa.
Nelson Mandela University, Port Elizabeth, South Africa.
J Morphol. 2022 Nov;283(11):1411-1424. doi: 10.1002/jmor.21511. Epub 2022 Sep 12.
Blubber is a highly specialized and dynamic tissue unique to marine mammals and presents a reflection of the individuals' nutrition, environment, and life history traits. Few studies have investigated the histomorphology of cetacean blubber in subtropical environments. The aim of this study was to investigate the blubber histomorphology of three different dolphin species off the subtropical KwaZulu-Natal coast, South Africa, using adipocyte cell size, number, and density. Blubber tissue samples from the saddle area of 43 incidentally bycaught animals (four Sousa plumbea, 36 Tursiops aduncus, and three Delphinus delphis) were used to compare cell parameters between blubber layers. Samples were divided into the upper third (corresponding to the superficial layer closest to the epidermis), middle third, and lower third (corresponding to the deep layer). For T. aduncus, factors potentially affecting blubber histomorphology, such as sex, age class, and season, were also assessed. Our results showed that no stratification was present in S. plumbea, which could be ascribed to the species' warmer inshore habitat, large body size, and apparent lower mobility. For T. aduncus and D. capensis, however, blubber stratification was determined, characterized by a gradual transition of cell size, number, and density between layers rather than clearly defined layers. Significant differences in adipocyte cell number and density were found for different sexes and age classes of T. aduncus. However, there were no significant differences between seasons, which was attributed to the small temperature differences between seasons. This study represents the first investigation of odontocete blubber histomorphology in subtropical waters. It is recommended that future studies investigate blubber lipid content, while also taking into consideration the reproductive status of the females and the temperature range of their study area. It is hoped that our results, in conjunction with histopathology and other health indicators, could assist in assessing health and body condition.
鲸脂是海洋哺乳动物特有的一种高度专业化且动态变化的组织，反映了个体的营养状况、环境及生活史特征。很少有研究调查亚热带环境中鲸类动物鲸脂的组织形态学。本研究的目的是利用脂肪细胞大小、数量和密度，调查南非夸祖鲁 - 纳塔尔亚热带海岸外三种不同海豚物种的鲸脂组织形态学。从43头偶然误捕动物（4头铅色真海豚、36头糙齿海豚和3头瓶鼻海豚）鞍部区域采集鲸脂组织样本，用于比较各鲸脂层之间的细胞参数。样本分为上三分之一（对应最靠近表皮的表层）、中三分之一和下三分之一（对应深层）。对于糙齿海豚，还评估了可能影响鲸脂组织形态学的因素，如性别、年龄组和季节。我们的结果表明，铅色真海豚不存在分层现象，这可能归因于该物种较温暖的近岸栖息地、较大的体型以及明显较低的活动能力。然而，对于糙齿海豚和海角瓶鼻海豚，确定存在鲸脂分层现象，其特征是各层之间细胞大小、数量和密度逐渐过渡，而非明显界定的分层。在糙齿海豚的不同性别和年龄组中，脂肪细胞数量和密度存在显著差异。然而，不同季节之间没有显著差异，这归因于季节间较小的温度差异。本研究是对亚热带水域齿鲸类鲸脂组织形态学的首次调查。建议未来的研究调查鲸脂脂质含量，同时考虑雌性的繁殖状况及其研究区域的温度范围。希望我们的结果与组织病理学和其他健康指标相结合，有助于评估健康状况和身体条件。
