Antarctic parasite found in great numbers, changing scientists’ view of marine ecosystem


Updated

November 05, 2018 17:27:46

A little-known ocean parasite has surprised Antarctic researchers after they found it to be in abundance in southern oceans, a revelation that could change the way the Antarctic ecosystem is understood.

The syndiniales parasite has been found in oceans around the world, but usually only at a level of 1 per cent of the marine life in any sample.

When Tasmanian scientists took water samples from the Southern Ocean and ran them through DNA sequencing, they got a much closer view of things than mere electron microscopes allow.

They found the syndiniales parasite in unprecedented levels. The plankton-killing parasite formed as much as 50 per cent of the living matter in the samples.

Australian Antarctic Division scientist Bruce Deagle said the research aimed to better understand the marine ecosystem via DNA as opposed to looking through a microscope.

“Underneath the microscope, you don’t see these parasites, they’re either in very small forms or they’re cysts that are ready to infect another organism, or they’re actually inside organisms.

“They exist inside of the phytoplankton, so we weren’t expecting to see that.”

He said the parasites were plentiful in the nutrient-rich water near the sea ice.

Larger organisms possibly impacted by small parasite

Dr Deagle said there was lot to discover about how the lethal organisms interacted with phytoplankton — microscopic marine algae.

“Once they’ve infected a cell they will eventually kill that cell — it’ll burst and they will go on to infect other cells,” he said.

He said the discovery of the parasite in such high levels could force scientists to review their study of the Southern Ocean ecosystem.

“Our understanding of that ecosystem is based on models and research that doesn’t include those parasites as a factor,” Dr Deagle said.

“We’ve sort of been modelling these populations and looking at the ecosystems without including parasites as a variable, and the impact of those parasites.

“By understanding them we will get a better view of how the ecosystem is controlled.

“This might be one of the reasons why we see the [phytoplankton] blooms ending, as opposed to running out of nutrients.”

Because the parasites attacked phytoplankton, which forms the base of the marine food chain, it could impact larger organisms like crustaceans, krill, fish and whales.

“All of those larger organisms do depend on the energy that’s coming from the phytoplankton, and this [research] is providing a new factor that really does affect the productivity of that whole ecosystem and the base of the food web, so exactly how that impacts is something that we are going to have to find out,” Dr Deagle said.

Topics:

marine-biology,

antarctica

First posted

November 05, 2018 14:51:59



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