Deep-diving sharks in a warming world
Jorge is interested in the life below 200 metres (656 feet), where the largest fish biomass on earth inhabits meso-pelagic waters down to 1,000 metres (3,280 feet). From its inky darkness, communities of fish migrate each night into shallower waters in a process called diel vertical migration. This is essential for the cycling of nutrients and carbon, and many sharks and rays rely on meso-pelagic prey. Jorge wants to understand the extent of this reliance, and what impact fishing and climate change will have on these predators and their prey. He is developing new animal-borne tags with video cameras and sensors to study the ocean’s twilight zone affordably and effectively.
Jorge Miguel Rodrigues Fontes
I was born on the small island of Faial in the Azores archipelago, Portugal. Growing up just steps from the ocean, I have been connected to the water for as long as I can remember. My journey as a naturalist and marine ecologist probably began at the age of five or six when I first used my brother’s snorkel. Throughout my childhood, I spent as much time as possible in the ocean, sailing, free-diving, fishing, swimming, playing, observing and learning.
After high school, I moved to mainland Portugal to study marine biology and fisheries at the University...
INNOVATE - The importance of the twilight-zone for oceanic sharks and rays in a changing ocean
INNOVATE aims to understand how deep-diving sharks and rays depend on meso-pelagic prey, and the effects of ocean warming and prey extraction on these species. This will be achieved by developing groundbreaking animal-borne tags with micro sonar-triggered video cameras that provide detailed data to improve ecological predictions and inform conservation efforts.
INNOVATE will contribute to understanding the dependence of deep-diving sharks and rays on meso-pelagic prey and the impacts of prey extraction and ocean warming. By developing advanced animal-borne tags and predictive models, the project will provide detailed data to inform smart management and conservation strategies.
The ocean’s twilight or meso-pelagic zone, at between 200 metres (656 feet) and 1,000 metres (3,280 feet) deep, contains the largest fish biomass on earth. These communities migrate up to shallower waters at night, a process known as diel vertical migration. The migration plays a crucial role in helping to recycle organic matter and transport carbon to deep-sea habitats, which is essential for maintaining ocean health and regulating climate.
Many large oceanic predators, such as sharks and rays, are believed to rely heavily on meso-pelagic prey. Evidence suggests that some species, like the endangered sicklefin devil ray and whale sharks found in the Azores, feed on meso-pelagic organisms and make deep dives beyond the twilight zone, indicating a greater reliance on these resources than previously understood.
The meso-pelagic zone faces three significant threats: increasing pressure to exploit its resources due to global food security concerns; the impact of sea-floor mining; and a changing ocean biochemistry in response to climate change. Understanding how these changes affect higher trophic levels is challenging because studying the meso-pelagic zone is complex and expensive.
To address this, we can use models to predict the distribution of zooplankton and micronekton biomass. However, these models require validation through in situ observations to compare predictions with reality. Marine animals carrying sensors are a creative solution to provide valuable information about ocean conditions and animal behaviour and interactions.
Improving our understanding of the twilight zone’s importance for large predators is vital to assess the impact of disturbances on biodiversity, especially for under-studied oceanic filter-feeding sharks and rays. More detailed sampling of the meso-pelagic zone is necessary to validate biological models and evaluate the ecological consequences of ocean warming and large-scale biomass extraction in this critical ecosystem.
- To understand how deep-diving sharks and rays rely on meso-pelagic prey, and the effects of ocean warming and extensive prey extraction on these species.
- To develop new animal-borne tags with video cameras and sensors to study the ocean’s twilight zone affordably and effectively. This technology will provide high-resolution data to improve ecological models, helping scientists predict climate and exploitation impacts on meso-pelagic communities and oceanic predators.
- To enhance biologging, deepen our understanding of oceanic predators and support conservation efforts.