For some time there has been a growing worry about the numbers of jellyfish, with massive swarms being reported in Hawaii and the Gulf of Mexico in late 2008 (Science Daily article).

Jellyfish swarming is a natural event, but evidence is mounting that human activities are favouring these occurrences. Nutrients entering seawater from land run-off increases phytoplankton numbers, and over-fishing reduces the competition for this food. The consequence? – a Jellyfish swarm that can be several kilometres across!