Climate Change effects on the developmental physiology of the small-spotted catshark (Scyliorhinus canicula)

板鳃类（鲨鱼和鳐鱼）是全球海洋生态系统的重要组成部分，但与许多硬骨鱼物种相比，研究很少。气候变化对板鳃类的影响仍然知之甚少，但它们的低繁殖力和相对较长的胚胎发育阶段可能使板鳃类特别容易受到某些气候变化的影响。海洋酸化（OA）已被证明会增加早期幼硬骨鱼的死亡率并诱导发育缺陷，例如（Stiasny等人，2019年），但由于实验室实验相对困难，缺乏关于板鳃类的比较数据。板鳃类的生理、生殖方式、血液化学和呼吸解剖都与硬骨鱼类有明显的不同，因此硬骨鱼类的实验结果不能被假定适用。到目前为止，有限的研究对鲨鱼发育生理学对OA的敏感性给出了对比性的观点，例如（绿色和Jutfelt，2014年），但几乎没有做过什么工作，我们基本上没有实验基础来预测板鳃类的早期发育对气候变化的影响有多大的弹性。因此，该项目旨在探索OA和其他潜在的气候驱动因素对鲨鱼早期发育的长期影响，特别是鳃和骨骼结构的发育，Stiasny等人（2019）表明这在鳕鱼中受到影响。小斑猫鲨（Scyliorhinus canicula）是探索OA对发育生理学影响的理想研究生物，因为它是一种小型物种，并且是卵生的，即它产卵，可以很容易地在实验室环境中进行研究，导致成功实验的机会很高。该项目将以实验为基础，在这些实验中，小斑点猫鲨卵和幼鲨将在整个发育过程中暴露于海洋酸化和控制以及不同的温度。S.在水族箱及本港沃茨内，都有大量的细网藻。我们将从水族馆和野生环境中取样，反应变量将包括基本的健身代理，如生存，身体生长速度和能量代谢。此外，我们将测量血液化学，特别是血液碳酸盐化学，包括稳定同位素方法，鳃的大小和骨骼结构的状况。将对样本进行清洁和双重染色（Schnell、Konstantineland和约翰逊，2016），以研究其骨骼发育并检测脊柱或鳃弓等骨化过程中的阻滞或加速以及变形。根据学生的兴趣，该项目可能包括OA和发育温度对基因表达，生物矿化和/或行为的影响的研究。

Elasmobranchs (sharks and rays) are important components of marine ecosystems worldwide but are poorly studied compared to many teleost species. Effects of climate change on elasmobranchs are still poorly understand, but their low fecundity and relatively long embryonic development stage could make elasmobranchs particularly vulnerable to some climate change effects. Ocean acidification (OA) has been shown to increase mortality and induce developmental defects in early juvenile teleosts, e.g. (Stiasny et al., 2019), but comparative data on elasmobranchs are lacking as laboratory experiments are relatively difficult. Elasmobranch physiology, reproductive style, blood chemistry and respiratory anatomy all differ markedly from teleosts, so that experimental results from teleosts cannot be assumed to apply. Limited studies to date give contrasting views on the sensitivity of shark developmental physiology to OA, e.g. (Green and Jutfelt, 2014), but very little work has been done, and we have essentially no experimental basis to predict how resilient early development of elasmobranchs is to climate change effects. This project therefore aims to explore the long-term effects of OA and potentially other climate drivers on the early development of sharks, in particular the development of gills and the skeletal structures, which Stiasny et al. (2019) showed to be affected in cod. The small-spotted catshark (Scyliorhinus canicula) is an ideal study organism to explore OA effects on developmental physiology, as it is a small-bodied species and oviparous, i.e. it lays eggs, which can easily be studied in a laboratory setting, resulting in a high chance of successful experiments. This project will be based on experiments in which small-spotted catshark eggs and juveniles will be exposed to ocean acidification and a control as well as different temperatures throughout their development. S. canicula is abundant both in aquaria and in local waters. We will sample egg cases from both aquarium and wild settings.Response variables will include fundamental fitness proxies such as survival, somatic growth rate and energy metabolism. In addition, we will measure blood chemistry, especially blood carbonate chemistry including stable isotope approaches, size of the gills and condition of skeletal structures. Specimens will be cleared and double stained (Schnell, Konstantinidis and Johnson, 2016) in order to investigate their skeletal development and detect retardation or acceleration in the ossification process of e.g. the vertebral column or the gill arches as well as deformations. Depending on the interests of the student, the project may include studies of the effects of OA and developmental temperature on gene expression, biomineralisation and/or behaviour.