Sea Jellies: a summer swarm in Monterey!

Imagine slipping into the cool, late summer waters of Monterey Bay in central California, expecting to settle to the bottom and film kelp beds and the sealife associated with this unique marine ecosystem. As you descend into the Bay's emerald green water laden with nutrients, you find yourself surrounded, engulfed by sea jellies reaching two feet in length. An invasion of sea jellies is in full assault in Monterey Bay.



But it's not as hostile as it seems. Aggregations of sea jellies have occurred around the world, to the extant that scientists were able to see cyclical patterns. But now they are beginning to scratch their heads as more and more population outbreaks of various species are happening worldwide. The potential for a sea jelly to become an invasive species is always there, possibly transported in the bilges of international freighters as has been the case for some species of algae and seaweed. And their increased presence can destabilize local fish populations as fish seek locations free of the sea jellies' stinging tentacles.

But marine biologists are also considering man-made factors like climate change and ocean pollution. Increasing water temperatures due to climate change can stimulate sea jelly growth. And sea jellies also thrive in areas of low oxygen as a result of pollutants.

Additionally, you have the impact of overfishing on some of the sea jellies' natural predators, whether they are a commercially sought species or not. The loss of tuna and sea turtles, among others, removes an important control mechanism to sea jelly populations. And in turn, swarms of sea jellies can envenom and spoil entire commercial catches.

Sea jelly invasions. It's a topic that raises more questions than there are definitive answers at this time. Some scientists are hesitant to correlate human actions with sea jelly populations, while others pose the possibility that sea jellies could become the dominant species in the ocean. And in several Asian countries, sea jellies are already on the menu; an indication that their increasing numbers could prove a viable food source (I'll pass, if you don't mind.)

One thing is for sure; to be in the midst of thousands of these fascinating invertebrates, slowly weaving along with the currents, is an awesome sight. That is until you feel the burning, itching sensation around your unprotected face and you give leeway to these gelatinous invaders.

Video produced for Google Earth's Ocean layer.