Snapshots from the abyss
The smells of ethanol and fish hang in the air as Dr Dianne Bray, Museums Victoria’s senior collection manager for vertebrate zoology, extracts a small, bulldog-faced fish from one of an armada of glass jars. In the Ichthyology and Herpetology Lab at Melbourne Museum, she and Dr Martin Gomon, senior curator of ichthyology, are showing off the spoils of their abyssal survey.
Both scientists spent a month from mid May to mid June aboard CSIRO’s research vessel, the Investigator, working alongside 40 other scientists and support crew on a project spearheaded by Museums Victoria. The Sampling the Abyss expedition surveyed Australia’s east coast abyssal waters from Tasmania to Queensland, mostly at depths between 2500 and 4000 metres beyond the continental shelf. An international team of scientists is now engaged in the lengthy process of preserving,
identifying, labelling and cataloguing the expedition’s deep-sea treasures for researchers present and future.
When deep-sea creatures are hauled from the depths, they rarely emerge alive. On board the ship, their bright colours and bioluminescent features rapidly pale, and they are quickly posed for diagnostic portraits before their life lights completely fade. Working swiftly, scientists “fix” the specimens’ flesh with formalin before decanting them into ethanol for longer-term storage. But Bray and Gomon’s lab feels less like a morgue than a place of lively enquiry.
Bray gestures towards the jars of pickled creatures – squat-bodied fish, nightmarish loosejaws with mouths like praying mantid arms, faceless eels, cookiecutter sharks the length of baking trays – each afloat in its own small preservatory sea. “These are part of our libraries of life, for people who are not yet born.”
Gomon is particularly interested in tripod fish: small, slender, silvery creatures that use their elongated pelvic fins to prop themselves on the ocean floor, their noses pointed into the current. Although they have eyes, these are probably vestigial – there is no light in the abyss by which they might see – and they rely instead on water movements to push prey past them. Carefully angled pectoral fins tilt forwards to form a kind of net, and the fish use their fins to herd any unlucky creatures swept into them towards their mouths.
Sitting alongside the tripod fish is a coffinfish – a pale, boxy-looking creature about the size of a rockmelon – the first of its kind found in Australia, and possibly an entirely new species. Gomon points out a line of conspicuous pores that runs from the fish’s mouth to its tail. These form part of a laterosensory system that picks up movement. In fish from shallower waters, these pores tend to be much smaller, better covered or more sunken, to block out the white noise of everyday fish life – the crash of waves, and the chatter and slosh of thousands of other animals. But in the depths of the abyss, although there are currents, there’s virtually no white noise, and having larger pores allows creatures like the coffinfish to open themselves up to listen to the whispers and clicks of the deep, dark ocean.
It’s expensive to study the abyss. “The number of specimens in [pre-existing] collections is very small for virtually all of the species,” says Gomon of the tripod fish family, and this observation holds for many of the creatures captured by the Investigator.
Vertebrate animals like fish form only a small part of the biota found living within the abyss. Melanie Mackenzie is a collection manager for marine invertebrates at Museums Victoria. When we meet, she apologises for smelling of sea cucumbers. Sea cucumbers, or holothuroids, are her specialty and passion.
Not all sea cucumbers are built alike. The Investigator’s sampling brought up specimens shaped like footballs, one with a cape-like velum, and some covered in papillae sticking out like bristles on a hairbrush. Mackenzie pulls out a jar containing some benthic sea cucumbers, which, as she explains, “sort of work like vacuum cleaners, crawling along the bottom”. The sea cucumbers are off-white, with tube feet and feeding tentacles. “To be perfectly honest, they always look pretty crud once they’re in a jar,” Mackenzie says cheerfully, “but when they’re under the ocean, they’re pretty cool!”
The expedition used underwater cameras, and some of the observed sea cucumber behaviours were quite unexpected. “I’ve always thought of sea cucumbers as crawling,” says Mackenzie, “but a lot of them can actually jump up enough to get caught in a current and move along.”
Not all of the specimens from the abyss were biological in origin. “Unfortunately, we found quite a lot of rubbish, even down to 4500 metres.” Mackenzie points to a tray of debris – bits of old rag, rope, chunks of plastic, an old beer can and some fist-sized lumps of rock. “This is coal, and this is clinker from the steam ships.” Clinker is the residue that formed on the inside of pipes when coal was burned. Steamer crews would have chipped it out of the pipes and thrown it overboard. “You’re talking about a hundred years ago,” says Mackenzie. “Once it goes in, it doesn’t come out.” Adjacent to the rubbish samples is a jar containing two fat ghostly prawns, covered in some kind of sticky, blood-red residue, which the scientists think is probably lead-based anti-fouling paint from ships. Despite the great depths of the abyss, it is not immune to human harm.
“We do affect it a lot,” says Mackenzie. “Anything that’s on the surface of the ocean eventually ends up at the bottom.”
A third of Australia’s marine territory falls within the abyss, and Mackenzie says that while there will be decades of work in the material from the expedition there’s still a lot more to discover.
“It’s important that we keep exploring and keep looking, but we also need to think about how we as humans are affecting that environment, and about how things like climate change might affect it too.
“If we hadn’t been down there and collected these animals now, we wouldn’t be able to go back and say, ‘Oh, these ones are gone,’ or ‘This is what’s changed.’ So it’s important to get a snapshot in time, and in space. And that’s what museums and collections are about.”