Aurelia sp. missing form Palau's jellyfish lake

While snorkeling in Palau's jellyfish lake on April 14th 2010 I noticed that Aurelia sp. jellies were not present amongst the millions of Mastigias sp. There were three of us looking for over 2 hours without seeing any. On this day I met Lori Colin, from the Coral Reef Research Foundation in Palau and two of her assistants who were sampling jellies in the lake and they confirmed that Aurelia has been missing from the lake for quite some time. A year ago in April of 2009 the Aurelia sp. were common by the hundreds.