Effects of combined climate change stressors on coral reef fish offspring

• Applicant: Dr. Björn Illing
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Animal Physiology and Biochemistry
• Term: from 2017 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 393711240

Anthropogenic climate change is already affecting the planet’s ecosystems, in particular the world’s oceans. Here, elevated temperatures, ocean acidification and deoxygenated or hypoxic areas affect, amongst other factors, the growth and survival of marine organisms. Against the backdrop of climate change, marine environments with stable conditions and less pronounced seasonal variability pose an increasing challenge for local organisms as their physiological tolerance thresholds are often less variable or already at their limits. Experimental approaches, simulating projected environmental scenarios, can help shed light on how these marine organisms modify metabolic processes, which are key to biological fitness, so they can cope with future and likely even more extreme conditions. However, there are only few studies testing the coupled effects of the three aforementioned stressors, especially with regard to marine fishes. Their population sizes are, next to fisheries, controlled by the recruitment and survival of their larvae which potentially increases the significance of climate-change affected environmental factors for population dynamics. Hence, the proposed project aims at investigating the interaction and effects of increased temperature, ocean acidification and hypoxia on eco-physiological parameters of the particularly vulnerable early life stages of coral reef fishes. Two sets of experiments will give insight in how larvae of the cinnamon clownfish (Amphiprion melanopus), a key species at the Great Barrier Reef (Australia), respond to projected and simulated environmental conditions. For this, the interaction between increased temperatures, ocean acidification and hypoxia will be investigated on metabolically relevant traits, including oxygen consumption rates, swimming performance, growth and condition, in individual fish. Then, further measurements including a gill structure and surface analysis, as well as aerobic and anaerobic metabolic enzyme activities will assist in completing the picture on how the organism is responding at the tissue and cellular levels. Both sets of experiments span the whole larval development – hatching to post-metamorphosis – to identify windows where fish may be most at risk and support a holistic understanding of how early life history is affected under near-future environmental conditions. This novel and comprehensive approach offers great potential for the conservation of marine fishes’ biodiversity. In addition, the project is promising for further research approaches using models to theoretically upscale the physiological results from an organismal to a population level. Such models could be applied to other systems as well, for example, commercial species from temperate latitudes where efforts are being made to support sustainable fisheries.

• DFG Programme: Research Fellowships
• International Connection: Australia
• Host: Professorin Jodie L. Rummer, Ph.D.