A new study challenges the ‘norm’ on predator-prey interactions and the ecosystem of the deep-sea invertebrate communities in Antarctica.

Newnham PhD student Ming Khan and her supervisor Newnham Fellow and Director of Studies Dr Emily Mitchell are the first and senior authors respectively, on a new study on predator-prey interactions and ecological structure on the deep sea invertebrate communities of Antarctica. 
 

Antarctica is unique in the world for not having shell crushing predators, which means that the seafloor is dominated by soft bodied sponges, corals, and slow-moving echinoderms like brittle stars and starfish.

In the shallow Antarctic ecosystem, where the seafloor is generally muddy, starfish are important predators that regulate the community structure, and are in fact "keystone" groups. Curiously, on the deep, Powell Basin, a rocky basin approximately 2200m deep, in the western Weddell Sea, Antarctica, of the 30,000+ individual organisms they identified, they found that only about 160 of them were predators.

Within their ecological network, they discovered that suspension feeding organisms like sponges and soft corals were very important to the ecosystem, and that ecological redundancy was maintained in the ecosystem, i.e., many organisms perform the same ecological role. Not one single group of organisms controlled the ecological network structure, so there were no central points of vulnerability for the ecosystem as a whole.

Crucially, starfish, which are normally important predators, were disconnected from the network - which suggests that predation by starfish was not an ecosystem structuring role. This finding could have crucial implications for ecosystem functioning on Powell Basin slope.

With climate change, there is a potential for the range expansions of currently excluded predators like crabs and lobsters. It is unknown how these deep rocky ecosystems will be affected by the potential introduction of novel predators, but it is likely to be significant.

Their work focused on the study of invertebrate predator-prey interactions and the ecosystem structure between the animals that live on the seafloor on the slope of the Powell Basin. They were able to study this ecosystem using seabed photographs (taken by the OFOBS - Ocean Floor Observation and Bathymetry System), and then analyse the community using Bayesian Network Inference, a method that helps model an ecosystem as a network with "nodes", which are connected to each other by "edges".

In further exciting news, as a student in Dr Mitchell’s Deep Time Ecology Group in the department of Zoology, Ming's supervisors at Cambridge and the British Antarctic Survey facilitated a polar data collection learning experience for Ming this summer. She is currently part of the PS143-1 research expedition in the Arctic on the RV Polarstern. This expedition (FRAM 2024) is the 25th annual long term ecological monitoring project of the Fram Strait, which is the only deep-water connection area between the Atlantic and the Arctic Oceans. Ming is responsible for operating the OFOBS, the Ocean Floor Observation and Bathymetry System, as mentioned earlier, to image the deep-sea animal life in the Arctic.

The Hausgarten Observatory is studying the long-term effects of climate change in the Arctic. Underwater photos help assess how the seafloor megafauna changes over time.  Ming and her Polarstern supervisor, Dr Autun Purser, who was also a co-author on the Powell Basin study, have written a blog post about the deep sea life she has imaged so far Glimpses of the Deep.