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The biomass of a species can be estimated in an ecosystem by calculating its abundance with its average individual size.

A high biomass means a large number of fish, which can indicate a healthy reef.

Flourishing reefs can keep bad microbes in check.

Certain algae found on damaged reefs release food for bacteria and can cause bad bacterial to grow out of control.


Flint Island, in the South Pacific, is four kilometres long and less than a kilometre wide.

Flint Island is the top of an ancient volcano, surrounded by deep ocean.

In the 1870s, native plants were stripped from Flint Island and tens of thousands of palm trees were planted to produce coconut oil.

Around 1900, Flint Island was abandoned.

Coral and algae can be a barometer of a health of an ecosystem.

If a coral is stressed, it can turn white or bleach.

Coral covers 90% of the sea floor of the Flint Island reef. This is over three times more that other reefs in the Indo-Pacific.

Flint’s reef is beautifully coloured and healthy.

The reef’s algae use sunlight to create energy, some of which it gives to the coral.

Sharks keep fish populations under control.

Fishing has affected the shark population on Flint Island.


Vostok Island was first sited in 1820 and named by a Russian explorer, after his ship.

Vostok is less than 2.5 square kilometres.

Vostok Island has never had human habitation.

Sharks and abundant life in Vostok’s reef indicate a healthy and undisturbed system.

Vostok is one of the few places left that looks like the Pacific did 200 years ago.

Vostok’s forest ecosystem is natural, unlike almost every other South Pacific island.

Vostok’s forest contains a mat of pure guano.

Guano, or bird dung, is rich in phosphates and nitrogen.

In the mid 1800s, surrounding islands were mined for guano to be used as fertilizer.

Vostok’s small size saved it from being mined for guano.


Starbuck Island is nearly 600 kilometres northwest of Vostok Island.

Starbuck is over eight kilometres long and three kilometres at its widest.

Starkbuck has only a handful of palm trees.

In 1872, more than 100 guano miners laboured on Starbuck, abandoning it in 1920.

Starbuck’s reef is half covered by algae, mostly Halimeda, a type of algae that coexists with corals.

Starbuck’s reef is abundant with fish and sharks.

Starbuck has the second largest biomass of all studied coral reefs.

The biomass of predators on Starbuck is larger than that of the fish they eat.


Malden Island is 200 kilometres northeast of Starbuck Island.

Malden Island is almost 39 square kilometres and roughly triangular in shape.

Malden Island was mined for guano between the 1850s and 1920s.

Malden Island was the test site for three low altitude nuclear bombs in 1958.

Malden’s reef contains at least ten times more sharks than other reefs around the world.

Parrot fish graze on the reef and break down dead coral skeleton to sand.

Development, fishing, and pollution can upset the delicate balance between algae and coral.

There are 10 times more microbes on reefs degraded by man.


Millennium Atoll is a lagoon surrounded by a string of islands.

Millennium Atoll is about 800 kilometres away from Malden Island.

Blacktip reef sharks swarm the flats of Millennium’s lagoon.

Sharks are among the first species to go away when humans arrive, and the abundance of sharks in the Millennium lagoon indicates a healthy system.

Millennium’s reef contains a large amount of one species of branching coral – Acropora.

Millennium’s reef contains giant clamps with electric green and blue colours.

On the islands, native plants compete with imported coconut trees for space.



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