We still know very little about the benthic megafauna (animals large enough to be seen with the naked eye) present in the deep waters around Cabo Verde. During iMirabilis2, we will use the remotely operated vehicle (ROV) Luso to explore the Cabo Verdean seafloor in order to find out which species live there, with a special focus on the charismatic cold-water corals and deep-sea sponges.
These animals represent true biodiversity oases in the deep sea and the videos and images collected by the ROV will enable us to answer many ecological questions about their presence in Cabo Verde. With the data collected during the expedition, we will be able to detail, for the first time, species composition, abundance, density, area of coverage and distribution patterns of the unexplored deep-sea benthic megafauna of Cabo Verde.
Find out more about seafloor image collection using ROV Luso
Understanding trophic interactions between species (i.e., who eats who!) is crucial in understanding the functionality of a habitat and how it might be affected by disturbance to the ecosystem. Because of the remoteness of the deep sea, applying some of the techniques commonly used in dietary studies can be challenging, either due to the high cost or practical difficulties of performing them in the deep-sea environment.
For many decades, analysis of δ13C and δ15N stable isotopes have been widely used to investigate the trophic ecology of terrestrial and marine ecosystems. Stable isotopes do not decay as they go through the food web, allowing us to infer diet and the trophic levels occupied by consumers and their food sources (i.e., where they sit in the food chain). This means that – as first explained by DeNiro and Epstein in 1976* – “you are what you eat”.
Stable isotope analysis has proven to be a great tool capable of overcoming logistical challenges associated with working in the deep sea, and can provide information on the dietary sources and trophic positions occupied by organisms in the food web.
During iMirabilis2, we will collect samples of different species present in the deep-sea benthic habitats around Cabo Verde, as well as their potential food sources, such as suspended particulate organic matter and sediment. After the expedition, at our home laboratories, we will be able to analyse the δ13C and δ15N isotopic ratios of the collected samples and subsequently decipher the trophic ecology of the deep-sea benthic habitat of Cabo Verde.
*DeNiro, M. J., and Epstein, S.. “YOU ARE WHAT YOU EAT (PLUS A FEW ‰): THE CARBON ISOTOPE CYCLE IN FOOD CHAINS.” (1976), GEOL. SOC. AMER., ABSTR. PROGRAMS; U.S.A.; DA. 1976; VOL. 8; NO 6; PP. 834-835, Conference Paper.