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.

Species Migration: Humboldt squid - a hungry predator moves northward

When we think of "invasive species," one might think of the example of the Lionfish that has invaded Florida waters due to being initially released from a home aquarium. Or perhaps algae, seaweeds or other parasites or bacteria that get discharged from the bilges of freighters and tankers, thousands of miles away from its point of origin.

But there is also species migration, wherein a species enters into a new region sometimes because of a change in its typical prey diet or because of a change in its environment - such as temperature change.

Both factors enter into the migration that has occurred over the past several years by the Humboldt Squid - a large and particularly voracious predator.

I have had the pleasure of working on several potential projects with Scott Cassell, CEO of the Undersea Voyager Project and one of the leading experts on Humboldt Squid, a distinction borne out of his having spent more time face-to-face with these creatures than anyone else. Scott has made the rounds of many news programs to express his concern with the recent regional habitat changes of the Humboldt Squid and what it represents to the balance of the marine and terrestrial ecosystems and even the safety of humans.

The Humboldt Squid is a large deep water predator, typically found along the west coast of Mexico and South America. But over the past several years, there have been two major changes that have impacted this animal. One factor: the overfishing of shallower-water predators that either feed on the squid or on the squid's food supply - thereby establishing territorial boundaries based on depth. Without these shallower predators, the squid can and has begun to roam in search of food. The second factor: increasing water temperatures which have allowed the squid to migrate up the coast and as far north as Washington and Alaska. Another possible variable is that changing temperature and acidification upwardly expands the low-oxygen water column that the squid seems to favor.

Moving into shallower water is of concern to Scott as that can increase the likelihood of a Humboldt Squid encountering curious divers or even swimmers. This past summer, divers were regularly seeing Humboldt Squid during night dives at La Jolla, CA, near San Diego. Whether on the hunt or simply being curious, these animals are not to be taken lightly - they have powerful suckers, a beak that can break bones, and the speed and strength to drag a diver around in the depths.



The squid's migration northward is also of concern because of its ability to disrupt the food supply for other animals. They have been cited by some as being responsible, along with commercial fishing, for a reduction in the northwest population of salmon. And this can impact other animals that depend on this particular food source. As an example, Grizzly Bears count on the fat-rich salmon for building up their stores to survive the winter.

There have been other invasive species migrations due to changing ocean temperatures; in particular, several jellyfish species that have moved into both Northern Atlantic and Pacific waters and doing considerable damage to commercial fishing or aquaculture operations - their stinging tentacles spoil the catch.

But the Humboldt Squid is just not someone you want to bump into in the middle of the night. He's just doing what evolution has taught him to do, but this is one critter than can really give you the willies!

Marine Life & Climate Change: possible species invasion & extinction

Seaweb.org recently reported on a study published in the journal Fish and Fisheries which provided projections as to marine species invasion and extinction due to climate change, specifically the increasing ocean temperatures. The projections were based on climate change models including those of the Intergovernmental Panel on Climate Change. The results of William Cheung and his colleagues at Canada's University of British Columbia were also presented at a recent Chicago meeting of the American Association for the Advancement of Science.

What the report postulated was that with increasing ocean temperatures, many marine species would migrate towards the temperate to sub-polar regions. Extinctions would occur in tropical regions because of a species inability to migrate, while species in colder waters would be faced with both the same negative impact due to temperature increase plus the impact of invasive species (increased predation and competition). Semi-closed bodies of water (ex: the Mediterranean, the Red Sea), could experience high levels of extinction because of the species' inability to migrate due to geography.

The study pointed out the rate of extinction would be much lower than for terrestrial animals, the theory being that marine animals have a higher dispersal ability and can more easily migrate to suitable habitats. However, the impact by and to human populations can also enter into all of this in the form of decreased fishing in low income tropical economies - economies that depend on seafood on a very basic subsistence level, and in decreased fish populations in colder waters due to industrialized fishing for moderate to high income economies.

We often look to the Arctic and Antarctic for critical signs of climate change, indicators of profound changes. But we must realize it is a worldwide change which challenges all of nature, including man, on many different levels.