Coral Reef Dynamics Across Longitude, Latitude, and Depth

Investigating coral reef dynamics across three global biodiversity gradients—Latitude, Longitude, and Depth— my fellowship examines the drivers and consequences of biodiversity assembly and redistribution across three dimensions in one of the world’s most diverse, valuable, and vulnerable ecosystems. Working from the scale of atoms to ecosystems, I will uncover mechanisms shaping the ecological and evolutionary trajectories of coral reef fish, incorporating unprecedented scales of knowledge from across the entire coral reef depth gradient, 0 – 120 meters. As severe and persistent warming forces rapid ecosystem change, reef fish from tropical shallow-waters may mitigate climate-related pressures by shifting poleward, or to deeper depths. Understanding the ecological dynamics controlling potential shifts towards cooler ranges, and effects on the functioning of ecological networks and ecosystem services is critical to understanding coral reef futures. However, studies of coral reef macro-ecological dynamics are typically focused on shallow water assemblages (<20m), ignoring steep depth-related transitions in community structure. Technological developments have recently facilitated unprecedented access to deeper reefs. My recent pioneering research is at the forefront of demonstrating strong depth-modifications of previously established ecological patterns and processes, and depth-related interactions with other macro-gradients, such as longitudinal distance from biodiversity centres. Yet, large gaps remain in understanding the spatial scales, and evolutionary and life-history traits of communities that these modified processes act on, and the consequences of these modifications on the redistribution of biodiversity in future coral reefs. Leveraging a new and unprecedented multi-gradient reef fish abundance dataset spanning from tropical to subtropical reefs across the Atlantic and Pacific oceans, advanced technical diving and quantitative analysis capabilities, and elemental and molecular research techniques, I will identify controls on community assembly, changes in energy and productivity pathways, and the structure of ecological networks along interacting biodiversity gradients related to longitude, latitude, and depth. Firstly, I will determine if the rate at which new fish species evolve differs along the coral reef depth gradient and whether species predominantly move from shallow to deep reefs, or vice versa. I will compare these evolutionary dynamics between the Pacific and Atlantic oceans and between tropical and subtropical locations. This will identify species 'pumps' that may be disproportionately important for the maintenance of future biodiversity. Secondly, I will identify the spatial scales and depths at which deterministic ecosystem processes shape evolutionary and ecological distinctness of reef fish assemblages along the three principle spatial gradients. Thirdly, I will determine for the first time how reef fish food webs and energy pathways are connected along the full coral reef depth gradient and what this means for reef productivity at different depths. Finally, I will identify depth-related changes in the structure and robustness of the ecological networks that support fish communities at different positions along depth, latitude, and longitude biodiversity gradients; challenging these networks under hypothesized future assemblages. Combining understandings across multiple scales and the full spatial extent of coral reefs will provide a groundbreaking framework with which to assess the shape, robustness, connectivity, and consequences of future reassembly of coral reef biodiversity. The results of my fellowship will provide a sea-change in our understanding of coral reef assembly process across multiple dimensions. Strategically, it will further pave the way for coral reef biodiversity redistribution research and conservation efforts to align with three-dimensional global change investigations and management strategies utilised in other ecosystems.