An international research team use a global sampling of seawater to reveal which tropical reef fish occur where. To identify species and families, they successfully used the residual DNA shed by the animals present in the water. But not all fish can be traced in this way.

Tropical coral reefs are colourful, beautiful – and rich in species. The diversity among fish is particularly high: researchers estimate that coral reefs are home to as many as 8,000 species of fish worldwide.

However, global warming and human activities are causing coral reefs to disappear at an alarming rate, and how many species of reef fish there are and where they are distributed has not yet been accurately quantified.

One reason is that many fish species lead very secretive lives, are very similar to each other or live partly in the open sea and are therefore difficult to detect. To record the presence of fish in an area, biodiversity research has mostly depended on visual observations by divers (or catching fish).

Read more at ETH Zurich

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