'Missing link' in food chain may explain why white sharks are flocking to Great Australian Bight

The mystery as to why the Great Australian Bight supports so many marine predators may have been explained, with scientists claiming they have found a "missing link" in the food chain.

Year-round apex predators such as great white sharks and orcas, flock to the southern coastal waters with shark sightings in particular said to be on the increase.

For the first time a team of Australian oceanographers have described "substantial" subsurface phytoplankton layers deep beneath the eastern part of the Bight.

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Integrated Marine Observing System (IMOS) data uncovered this "missing link" of subsurface phytoplankton at water depths of 30m to 70m.

Until now the tiny organisms had gone undetected, even by satellite imagery.

It's claimed a "seasonal upwelling of nutrient-rich water" fuels the production of phytoplankton.

The findings were published in a new study in Continental Shelf Research.

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Associate Professor Jochen Kaempf, study co-author and Flinders University researcher, said the finding proves the Bight is one of the most important marine ecosystems in the country.

''Our observation of subsurface phytoplankton layers is the missing key explaining the high productivity of the region," he said.

''This study demonstrates how little we actually know about the functioning of marine ecosystems.

"And how important real field observations are".

Phytoplankton are important as they form the "base" of the food chain, providing food for small to large fish as well as whales.

This in turn attracts the larger predators who feast on them.

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