Project Rationale
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.
Methodology
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. Additionally, eggs are laid over the course of many months each year, which allows for potentially many experiments each year. Experiments on the effects of temperature on this species have been successfully completed at NOCS.
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.
Necessary home office licenses and ethical approval will be in place before any work commences.
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.
Training
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the University of Southampton. Specific training will
include:
Experimental ecology
Fish larval rearing
Ecophysiology and climate change ecology of marine fish
Molecular biology (including lab work, i.e. DNA/RNA extractions)
Sample clearing and staining to identify skeletal development and ossification (MNHN, France)
Metabolic rate measurements
Bioinformatics
Data analysis and visualization (mainly in R)
Presentation skills (oral and written)
Teamwork
Scientific writing
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