Night moves
Martina is deploying remotely operated vehicles (ROVs) to survey sharks and rays at night. She hopes to develop best practices and standardised methodologies so that this technique can be widely used to study sharks and rays on coral reefs at night. Research shows that sharks and rays are often most active at night, but the limitations on scientific nocturnal diving restrict the consistent surveying of coral reefs when it’s dark. Martina will be exploring the Great Barrier Reef, using this novel technique to gain completely different insights into the lives of sharks and rays, which we might be missing by surveying predominantly during the day.
Martina Lonati
I was born in Italy and grew up sailing across the Mediterranean Sea, learning about the ocean and the winds and exploring the unique temperate ecosystems of my home waters. I had stubbornly decided to become a marine biologist when I was very young, fighting the prejudice against such a choice and reassuring my parents that I would find a place in this career that they did not really understand. As soon as I graduated from high school, I left my home town and travelled to Fiji to volunteer in a shark conservation programme. Conducting underwater surveys, shark...
Underwater drones can shine a light on the night-time side of shark science.
To explore the capability of underwater remotely operated vehicles (ROVs) to perform nocturnal surveys to count and observe reef sharks and rays.
Many shark and ray species are known to be most active at dawn and dusk and during the night, but safety limitations on scientific diving allow only daylight surveys to take place. This means that little is known about the nocturnal life of sharks and rays. Underwater ROVs represent an innovative technology to overcome the safety limitations of scuba and collect accurate and representative night-time data on shark and ray populations.
The conservation status of elasmobranchs is often limited or unavailable. This is due mostly to the challenges and restrictions typically encountered in field-based elasmobranch science, namely the cryptic and highly mobile nature of most species. Worldwide assessments have found that many elasmobranch species are threatened with extinction, while coral reef ecosystems suffer the consequences of a changing climate and the impacts of human activities. As a result, elasmobranchs inhabiting coral reefs in the tropical region are disproportionally more threatened with extinction.
Elasmobranchs play important trophic roles as apex predators and mesopredators that regulate, balance and strengthen food webs and ecosystem processes. Conservation measures currently rely heavily on data collected during underwater surveys, which have been the preferred non-extractive method to count and observe elasmobranchs. However, many elasmobranch species are most active at dawn and dusk and during the night, and underwater surveys are restricted to daylight hours due to the limitations on scientific diving for reasons of safety. As a result, the current knowledge of these species is incomplete and likely to misrepresent the true behaviour, ecology and overall population status of cryptic and nocturnal elasmobranch species.
Recent applications of underwater ROVs highlighted the potential of this technology to conduct underwater inspections in the field of marine construction. As often happens, new tools currently used by the industry can be successfully adapted by researchers for a specific purpose. In this case, ROVs can be adopted and perfected for nocturnal underwater surveys that collect new data on elasmobranchs.
There is as yet no standardised, research-focused method to perform underwater visual surveys at night using ROVs. The cryptic and nocturnal nature of elasmobranchs and the well-researched Great Barrier Reef environment provide the perfect stage to launch this technique as a new tool to observe species that could be misrepresented by traditional day-time surveys.
- To use underwater ROVs to perform nocturnal surveys for counting and observing reef sharks and rays.
- To compare the performance of ROVs with the widely used underwater visual census technique.
- To develop best practices, methodologies and standard operating procedures to be used for future studies using ROVs for nocturnal surveys on coral reefs