By Suzanne Egan (University of Tasmania), Angela Russell (University of Adelaide), Aaron Puckeridge (University of New South Wales) and Tony Mott (Charles Darwin University)

Our group from left: authors Angela, Tony, Aaron, Suzanne and one of our trainers, Alice.

Plankton are tiny critters that form the basis of the ocean’s food web, providing essential nutrients to higher levels of marine organisms such as fish, seals, whales and birds. One of the reasons we were interested in visiting this region of ocean was due to the presence of deep-sea canyons and the Bonney Upwelling off the coast of Discovery Bay. Upwellings are a phenomenon where cold, nutrient rich water rises to the surface. Unlike people, who prefer warm tropical waters, plankton love the cold deep ocean water and the nutrients that come with it. Unfortunately, with the motion of the ocean, the influence of the upwelling was not obvious during this trip and there were not copious copepods. Regardless of this though, we were still able to deploy our plankton nets and collect some cute little critters to view under the microscope. We were also able to identify a brittle star collected from the Smith Mac Grab and taken from surface sediments upon the sea floor.

Deployment of Bongo plankton nets from the RV Investigator (left); Retrieval of plankton collected in Bongo nets (right). (Photo credit: April Abbott)

Comparing our data with our mathematically inclined friends in the oceanography department might offer an insight into how this complex system operates. We have included several images from the laboratory however, which include some of the organisms that will be formally identified once we reach dry land.

Angela Russell identifies and counts microscopic species on board RV Investigator (left, photo credit: April Abbott); Brittle stars collected from a deep-sea sediment sample (right, photo credit: Angela Russell)

One of our observations was the detection of microplastics within our plankton samples, which introduces the risk that they may accumulate within the food chain. Even with our careful collection techniques and onboard laboratory conditions, micro-fibres were obviously present. It’s not certain whether these fibres were present within the ocean water column or whether they were introduced to the samples after collection, however this does show how prevalent and easy it is for micro plastics to enter the ocean systems and marine habitats.

Early life stage crustaceans, jellyfish and a squid found in a plankton sample and viewed under the microscope (left); Early stage seastar found in a plankton sample and viewed under the microscope (right). Photo credit: Alice Jones.

Micro plastic fibres were detected in several plankton samples and viewed under the microscope. Photo credit: April Abbott.