By Mark Kinver Science and environment reporter, BBC News
A number of penguin species found in western Antarctica are declining as a result of a fall in the availability of krill, a study has suggested.
Researchers, examining 30 years of data, said chinstrap and Adelie penguin numbers had been falling since 1986.
Warming waters, less sea-ice cover and more whale and seal numbers was cited as reducing the abundance of krill, the main food source for the penguins.
The findings appear in the Proceedings of the National Academy of Sciences.
Antarctic krill (Euphausia superba) is a shrimp-like creature that reach lengths of about 6cm (2in) and is considered to be one of the most abundant species on the planet, being found in densities of up to 30,000 creatures in a cubic-metre of seawater.
It is also one of the key species in the ecosystems in and around Antarctica, as it is the dominant prey of nearly all vertebrates in the region, including chinstrap and Adelie penguins.
Note: Newswire stories are provided as a courtesy of OceanDoctor.org. Content of these articles is provided by external sources.