Sea Jelly Blooms in the UK: research continues to point towards manmade causes

Back in September, I posted an article about the summer invasion of sea jellies in Monterey Bay, CA. I was there to conduct an underwater video workshop for the BLUE Ocean Film Festival and found me and my students surrounded by thousands of sea nettles.



I learned that these mass gatherings of sea jellies of various species were becoming more frequent worldwide. However, scientists were unsure as to the reasons why. There were certainly some likely possibilities including pollution, loss of predators, and climate change, but as far as most scientists were concerned, it was all inconclusive. There's much we don't know about these beautiful invertebrates, so making definitive statements is difficult at best.



But the invasions continue. The BBC News reports of a rise in sea jelly, or jellyfish, swarms in the United Kingdom. And scientists there are beginning to subscribe to the same suspicions I referenced in my previous post.



"It's not only beach-goers who have to watch out. Torness nuclear power plant in Scotland recently had to shut down after moon jellyfish blocked the water intake system. Several tonnes of the creatures had to be cleared out.

Some areas, including the Irish Sea and the east coast of Scotland, have been invaded by so many they now resemble a 'jellyfish soup', says the Marine Conservation Society (MCS). So why do they appear to be on the increase?

According to research there is strong evidence that an increase is linked to three main factors - pollution, overfishing and possibly climate change.

Pollution such as sewage and fertilisers run off the land and into the sea, causing increased nutrients in the water. This can boost jellyfish numbers as the nutrients increase plankton which they feed on, along with fish.

Overfishing means jellyfish do not face their usual predators and competitors, which usually regulate population growth. Large fish, which eat jellyfish, have been drastically reduced by bad fishing practices, says Ocean 2012, a pressure group which campaigns to stop overfishing. So have smaller fish which compete for food with the stingers.

It is argued that climate change can cause more favourable conditions for jellyfish, with their adaptability giving them an advantage over some other sea creatures."

Sea jelly swarms - also known as blooms, like plankton blooms - apparently have occurred in the cold North Atlantic waters from Ireland to Scotland to England. A few research organizations have been conducting tagging studies and surveys to learn more about their distribution, but the sparse data comes in slowly so, once again, conclusions are hard to come by.

Says Dr. Victoria Hobson of Ecojel, a 3-year old research project on the abundance and distribution of sea jellies, "This [the lack of research] also makes it difficult to get a handle on how numbers have changed. Even in recent years people are doing a lot more watersports so are spotting more. With the development of smartphones it is also much easier to report those sightings. It makes it difficult to interpret if there are actually more jellyfish or just more sightings."

Sea jelly invasions can have serious economic consequences. In Nambia, swarms of sea jellies have consumed or pushed out many local fish species, depriving subsistence-level fisherman of any catch whether for sale or for their own consumption. And in developing nations hard hit by either civil strife or severe drought conditions (or both), a loss of a local food source can have grave implications.

In more developed nations, like Japan or Great Britain, sea jelly swarms can spoil entire commercial catches. In 2007, a jellyfish invasion wiped out Northern Ireland's only salmon farm, killing over 100,000 fish.

Beautiful to look at, fascinating to watch, and sometimes dangerous to the touch, sea jellies can be seen as an indicator as to the health of the oceans and whenever they appear en masse, we should all take notice. It could mean a lot more than just the need to be careful where you step on the beach or in the surf.

Read about UK's sea jelly invasion in the BBC News.

Great Britain's Sea Jellies: non-divers get to see jellyfish in the wild

Spending as much time as I do talking about ocean environmental and conservation issues, it's easy to get wrapped up in all the challenges and problems and forget what stirred my interest in the first place: the beauty and the wonder.



So, no warnings or dire predictions today; just a fun video I found on BBC Nature News. In Great Britain, there are large kelp forests, similar to my local California waters - but a darn sight colder. And for those who don't dive, there's a great way to peer into this wet and wild world: boats designed with large windows well below the water line - a variation on the classic glass-bottom boat - giving passengers an expansive view of what is just offshore from their homeland.



In this video, various sea jellies, local to Britain's waters, are featured. From moon jellies to lion's mane jellies, it's a nice "oooh and aaah" moment.

Moon Jellies: mass stranding near San Francisco

Just this past September I reported on a sea jelly invasion in Monterey, California. For a good portion of the late summer, the popular central California ocean community was beset with west coast sea nettles - beautiful to look at but potentially painful, given the numbers that were accumulating from the bay right up to the shoreline.

Another high concentration of sea jellies recently occurred at Ocean Beach, located near San Francisco. This time it was thousands upon thousands of moon jellies that had washed up on the beach overnight this past weekend. But in this instance, it was not so much an invasion as it was a freak occurrence linked to a cyclical event.

Moon jellies are one of the more prolific of all jellies. A popular attraction at many aquariums, they are relatively easier to breed, compared to other species, and do not pose a threat to humans. In the fall, they can have large spikes in their populations along the eastern Pacific coast. These sea jelly "blooms" can go unnoticed for the most part, unless the right tidal and wave conditions push the floating moon jellies ashore. Which is apparently what happened this past weekend.

Gary Williams, a researcher of invertebrates at the California Academy of Sciences described it as a "regular event," “Jellyfish cluster in massive blooms well offshore that we rarely see. But sometimes, with just the right combination of wind and currents, those blooms wash ashore.”

As relatively common as the moon jelly is, there is surprisingly little we know about them. The when, where, and how of their reproduction habits is still predominantly a mystery. Because of that, it makes it difficult for scientists to attribute any apparent rise in population to outside factors such as climate change.

However, further south from San Francisco in San Diego, California, a rare black sea nettle has been making more frequent appearances along that Southern California coast. Actually deep purple in color, the black sea nettle is much larger than the west coast sea nettle, reaching 3 feet across and with up to 30 feet of trailing tentacles.

Though not yet seen in invasion-size numbers, the black sea nettle, according to some oceanographers, could be increasing in numbers due to warming temperatures or a consistent increase in the primary food source, plankton - which also "blooms" with warmer water temperatures.

Beautiful, fascinating, and in many ways a mystery, sea jellies are basic predatory invertebrates (and, technically, by definition not a fish - as in "jellyfish"), simple in structure with no brain or heart but exhibiting behaviors that have yet to be fully explained.

Read about San Francisco's moon jelly stranding.
Read about San Diego's black sea nettle.

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.

Filmmaker's Journal: BLUE Festival and the ocean comes alive

Sunny weather is greeting the first arrivals to the BLUE Ocean Film Festival & Conservation Summit. The Monterey area (Monterey, Pacific Grove, Seaside, and more) is one of those great places on the California coast where, given the work opportunity, I would certain consider relocating.

First up on the day's agenda was my underwater video workshop, an opportunity for beginning and aspiring videographers to get a chance to hone their underwater skills with 2 dives in Monterey Bay and a classroom session. The water conditions were, perhaps, a bit typical for Monterey: the water can have an emerald green hue to it with some reduced visibility from incoming particulates. But that did not detract us from what turned out to be the big attraction of the dives.

The past week there had been a large influx of West Coast Sea Nettles - a small but beautiful sea jelly with w 3- to 4-inch dome, trailing white fleshy appendages, and dark red tentacles that trailed up to 18-inches. Did I say a large influx? Well, congregating in a layer from the surface to about 25 feet, they were in the hundreds if not thousands. Getting below them and looking up through the emerald water, it reminded me of the fresh water jellies of Palau - on steroids!

I had told the workshop participants that on this first dive I would have them focus getting key shots for building a video: master wide shots, tighter medium shots, close-ups, etc. Once we submerged and saw the gelatinous panorama laid out before us, I think class was immediately postponed on account of something that divers just don't get to see every day.

See or feel. It was impossible to not come in contact with the trailing tentacles of the sea nettles and that meant we were going to get stung. Fortunately, not badly; we would exit the water with a bit of a rash on the face or some puffy lips, but it would dissipate quickly. But the images in our minds - and hopefully our cameras - of these amazing jellies would last much longer.

That evening saw several receptions opening the festival. Famed photographer, David Doubilet, had a wonderful gallery exhibit of his work and it became the focal point of the evening with filmmakers and ocean conservationists talking shop over wine and cheese. David has become one of the uncontested masters of the above and below shots - half in the water, half out - and he was telling me he was not quite sure what made him gravitate often to this type of shot but thinks it may have to do with what impressed him with the ocean as a child. Above is the world we live in, and just below is the world we dream in.
I told him what impresses me with his above and below shots is how, in one frame of film, he is bringing together these two worlds; that they are not separate, a place that people cannot relate to, but are actually two worlds that share an important connection, a bond that is crucial to our future.

Well, I did say there was wine. . .

Today, the festival and conservation summit begins in earnest with industry discussion groups and more meet-and-greets. Friday through Saturday will see more of the sames along with a barrage of wonderful ocean films. It's shaping up to be a great week. More reports to come.

Sea Jelly Invasion: Japan's next monster movie...for real

Japanese fishermen working the Sea of Japan are preparing for what has been called "a huge jellyfish typhoon." Swarms of the giant Nomura sea jelly, which can reach six feet in width, have been sighted. They first appeared in large numbers in 2005, poisoning the fish being caught as they were hauled up together in nets. The problem was so severe that salmon fishermen would not go out to sea and lost up to 80% of their income.

While sea jellies can congregate in large numbers normally, the increasing size and frequency of these aggregations is of major concern to fishermen, public officials (public safety), and researchers.

Researchers at the University of Queensland, Australia, reporting in Trends in Ecology and Environment, have theorized that these aggregations can well be due to human activities. Fertilizer runoff can add excessive nutrients which negatively impact many fish species but can allow sea jellies to flourish because of the associated increase in phytoplankton (a primary food source). Then the die off of the phytoplankton blooms produce decomposition that increases bacteria, causing a reduction in oxygen - again impacting fish but sea jellies are better able to survive in low oxygen environments.

Overfishing also can lead to increased sea jelly aggregations. There have been documented cases of sea jelly blooms when fish such as sardines and anchovies, which feed on the same food sources as sea jellies, are overfished, thereby upsetting the balance of food source competition that normally controls species populations. This has occurred in as disparate areas as off the coast of Nambia in Africa to the Black and Caspian Seas.

And finally, sea jelly larvae can be transported in the ballast water of large ships and, as an invasive species, can take hold in new marine ecosystems where plankton-eating fish are being commercially caught in large numbers, providing the sea jelly with a foothold to grow in numbers.

Increasing sea jelly populations can reach a "tipping point" where they overwhelm the ability of predators to control their numbers, while at the same time feeding on the fish eggs and larvae of those very same predators. When that happens, human management of the situation is made extremely difficult. Researchers are recommending that prevention - controlling runoff, avoiding overfishing, better methods for controlling invasive species - would be a better long-term strategy than eradication.