The following link is to an article that looks into the decline of Krill and the impact on Penguins. The rising number of Whales is also having an impact on Penguin numbers because of competition for declining Krill.
For more visit:
http://news.nationalgeographic.com/news/2011/04/110411-penguins-antarctica-decline-krill-whales-warming-environment-animals/
Kevin's Walk on the Wild Side 