The impact of climate change on intertidal species, camouflage and predation

To understand the impact of climate change on ecosystems we need to know not only how individual species will be affected, but also the relationships between them. Predator-prey relationships determine the structure and function of ecosystems worldwide, governing the abundance of populations, the distribution of different species within habitats and, ultimately, the composition of communities. Many predator-prey relationships are shifting as a result of environmental change, with climate change causing both mismatches in the abundance and distribution of species and changes in predator and prey behaviour. However, few studies have addressed how climate change might impact the interactions between species, particularly the development of anti-predator defences, which enable prey to limit their predation risk. One of the most widespread defences in nature is camouflage, with many species capable of changing colour to match their background to avoid being seen and eaten. The impact of climate change on this process is largely unknown, save for studies on species that exhibit seasonal changes in coloration. Using behavioural assays with predatory rock gobies (Gobius paganellus) and chameleon prawn prey (Hippolyte varians), I first demonstrate how background matching affects survival, shedding light on the fitness benefits of camouflage. Building on this fundamental understanding, this project explores how defensive coloration may be affected by anthropogenic climate change. Through a series of laboratory studies I test what impact ocean warming and ocean acidification have on the development of camouflage in intertidal crustaceans (chameleon prawns and common shore crabs, Carcinus maenas). Camouflage is modelled according to the visual systems of relevant predators, allowing us to understand what implications their coloration has for detectability, predation risk, and associated trophic links. Finally, this project investigates how camouflage can be applied to conservation and aquaculture. By rearing juvenile European lobster (Homarus gammarus) on different backgrounds, I show that they are capable of colour change for camouflage, as well as colour change throughout ontogeny. This capacity could be harnessed to help improve survival on release into the wild. As such, this thesis explores the fundamental science of camouflage, anthropogenic impacts on this process and its applications for conservation