During recent years, massive jellyfish congregations have appeared along the Northeast U.S. coast, in the Gulf of Mexico, in the Mediterranean, in the Black and Caspian Seas, and in South-East Asian coastal waters.

“Dense jellyfish aggregations can be a natural feature of healthy ocean ecosystems, says Dr Anthony Richardson of the University of Queensland, but a clear picture is now emerging of more severe and frequent jellyfish outbreaks worldwide.”

A new study by Richardson and his colleagues at the University of Miami, Swansea University and the University of the Western Cape, presents convincing evidence that these massive jellyfish populations are supported by the release of excess nutrients from fertilisers and sewage, and that fish populations depleted by over-fishing no longer are capable of keeping them in check.

“Fish normally keep jellyfish in check through competition and predation but overfishing can destroy that balance,” Dr Richardson says. “For example, off Namibia intense fishing has decimated sardine stocks and jellyfish have replaced them as the dominant species. Mounting evidence suggests that open-ocean ecosystems can flip from being dominated by fish, to being dominated by jellyfish. This would have lasting ecological, economic and social consequences.”

In addition to this, the distribution of many jellyfish species may extend as a response to global warming and an increased water temperature could also favour certain species by augmenting the availability of flagellates in surface waters.

The study, which was lead by CSIRO Climate Adaptation Flagship, has been published in the journal Trends in Ecology and Evolution.

You can find more information about CSIRO Climate Adaptation Flagship here:

450 pound blobs filling up the Sea of Japan

The changing ecosystems affect a long row of different jellyfish species, but some of the most spectacular jellyfish congregations observed during recent years have involved the Nomura jellyfish (Nemopilema nomurai) living in the Sea of Japan (Also known as the East Sea). This colossal species, which can reach a size of 2 metres* across and weigh up to 220 kg**, is also present in the Yellow Sea as well as in the rest of the East China Sea.

After becoming a major problem in the region, the Nomura jellyfish population is now combated by a special committee formed by the Japanese government. Killing jellyfish or ensnaring them in nets will however only prompt these animals to release billions of sperm or eggs; aggrevating the problem rather than reducing it. Coastal communities in Japan have started to harvest jellyfish and sell them as a dried and salted snack, and students in Obama, Fukui have started making jellyfish cookies and jellyfish-based tofu.

* circa 6 feet 7 inches

** circa 450 pounds

A Greater Weever (Trachinus draco) has been found in a stretch of the Thames estuary in Great Britain. The species, which is native to the Eastern Atlantic, the Mediterranean, and the Black Sea, is one of many signs of the improving health of the Thames estuary.

The weever was found after a two-year investigation carried out by the Environment Agency and Zoological Society of London and is the 60th new species found in the Thames since 2006. “The diversity and abundance of fish is an excellent indicator of the estuary’s health”, says Environment Agency Fishery Officer Emma Barton.

Flowing through London and several other urban areas, the Thames has a long history of being heavily polluted. In the so called ‘Great Stink’ of 1858, pollution in the river was so severe that sittings at the House of Commons at Westminister had to be abandoned.

So, should we fear this semi-new addition to the Thames estuary? No, there is no need to panic. This fish can deliver a very painful sting and should be handled with care, but the sting is rarely dangerous to humans – especially not if you seek medical attention.

The Greater Weever has venom glands attached to both of the spines on its first dorsal fin, and to the spines of the gill cover. The spines are equipped with grooves through which venom is driven up if the spines are pressed. A person that receives a sting from a Greater Weever can develop localized pain and swelling, and the result has – in a few rare cases – been fatal. Fortunately, there are several things you can do to make the situation less dangerous for a stung victim.

· If the wound bleeds, allow the wound to bleed freely (within reason of course) to expel as much venom as possible.

· Soak the affected limb in warm water because the toxin produced by the Greater Weever is sensitive to heat. There is no need use extremely hot water it and risk scalding the skin, because the toxin will deteriorate at a temperature of 40° C / 104° F.

· Seek medical attention.

The pain is normally at its most intense during the first two hours after being stung and even without treatment, the severe pain normally goes away within 24 hours. It is however possible for some pain to last for up to two weeks, and it is also possible for the spine to break off and get stuck inside the stung limb where it can continue to cause problems until it is removed.