Ancient shellfish used for purple dye vanishes from eastern Med

Red-mouthed rock shell was one of main sources of Tyrian purple and study blames its collapse on rising sea temperatures

Peter Beaumont in Jerusalem

Monday 5 December 2016 15.24 GMT

The shellfish that was one of the main sources of Tyrian purple – one of the most storied and valuable trading products in the ancient world – has disappeared from the eastern Mediterranean coast, amid warnings of an ongoing multi-species collapse blamed on global rises in sea temperatures.

Described by Aristotle and Pliny among other ancient writers, Tyrian purple or imperial purple was a dye extracted from shellfish along the Levant coast and favoured by emperors and kings in a trade of huge value. Associated with royalty, clothes with purple in them were believed to convey high status.

A new Israeli survey of shallow water Mediterranean habitats has noted the almost total disappearance of stramonita haemastoma – the red-mouthed rock shell – which was one of the two main sources of the dyes.

In a survey for Nature’s Scientific Reports, the Israeli marine biologist Gil Rilov identified the mollusc as one of a number of species to have vanished in recent decades from shallow eastern Mediterranean coastal waters highly vulnerable to sharp temperature changes. 

Rilov said coastal waters were a “potential hotspot” for species collapse and present-day surveys had failed to find 38 of 59 mollusc species once common on Levant reefs. In addition, he said he found strong evidence for major, sustained population collapses of two urchins, one large predatory gastropod and a reef-building gastropod.

“Temperature trends indicate an exceptional warming of the coastal waters in the past three decades,” he wrote. “Though speculative at this stage, the fast rise … may have helped push these invertebrates beyond their physiological tolerance limits leading to population collapses and possible extirpations. 

“If so, these collapses may indicate the initiation of a multi-species range contraction at the Mediterranean south-eastern edge that may spread westward with additional warming.”

Among the species identified by Rilov as having almost entirely disappeared from areas in Israel and elsewhere in the region where it once existed was the red-mouthed rock shell.

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Squid set to top chippy menus as seawater warms up

Great British cod supper is under threat as cold-water fish are replaced by warm-water species, says researcher

Britons may have to adopt a more continental diet as seawater temperatures rise.

Alexandra Topping

Monday 12 December 2016 07.00 GMT

It is the meal most associated with the UK, along with slurping tea and moaning about the weather. But the great British fish supper could be on the way out, replaced by more continental variations such as squid and chips, as seas continue to warm, the British Ecological Society will be told this week. 

Britons may have to adopt a more continental diet when it comes to fish, as climate change sees cold-water fish such as cod gradually replaced by squid and other warm-water species, according to research led by Dr John Pinnegar of Cefas, the Centre for Environment, Fisheries and Aquaculture Science.

“Our models for 2025 and beyond suggest that seawater temperature may continue to rise in the future,” said Pinnegar. “As a result, UK waters will become more hospitable for some species and less suitable for others, with the overall result that most commercial species will move northwards.” 

Squid numbers have increased dramatically over the past 35 years in the North Sea, according to Cefas, which has monitored North Sea fish populations for the past 114 years. It said squid was found at 60% of its 76 survey stations in 2016, compared with just 20% in 1984.

The organisation analyses records of where fish are caught and water temperature, to monitor the impact of climate change and fishing intensity to long-term changes in abundance.

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Whales, dolphins, seals: newcomers crowd into British waters in pursuit of their prey

Scientists predicts cetaceans from as far away as the Pacific will live here as climate change heats up our waters.

The waters around the British Isles could soon be home to several new species of mammals as a rising number of foreign visitors are being reported around our coasts. Experts believe the rare sightings of cetaceans from tropical climes could mean sea creatures are scouting for new territories to settle as global warming takes effect on sea temperatures.

Animals from the tropics, including the dwarf sperm whale, the pygmy sperm whale, and the Fraser's dolphin have all made recent appearances here, and the Cuvier's beaked whale, another warm-water species, has been recorded increasingly regularly in the west of Britain. The melon-headed whale, a squid-loving relative of the killer whale, has been seen in the Channel, off the coast of Brittany.

Before too long we may see giants such as the 16-metre gray whale nudging into deep water around Cornwall and into the Irish Sea.

"We are now seeing a number of species far from home, and they probably will continue to recur with increasing frequency," said Peter Evans, director of the Sea Watch Foundation. "Several are normally found off west Africa. For the moment they tend to be seen at times of year when our sea temperatures are at their warmest. Whales and dolphins can cope with a wide range of temperatures but their fish and squid prey tend to be more constrained, and their ranges are extending significantly northwards."
He said cetaceans would follow their favourite food, and many species rare in colder waters just a decade ago had moved into British seas. This autumn a dwarf sperm whale was spotted in Mounts Bay, Cornwall, while a pygmy sperm whale, its close relative, was found beached on Seil island, near Oban.

"They were both very big surprises: they are rarely seen even where the populations are known to exist," said Evans. "If the fish are extending their range, as we know many are, then the whales and dolphins will follow. Anchovies, for example, were really quite scarce in the North Sea 10-20 years ago. Now they are widespread and may be why the common dolphin is now a regular in the North Sea.
"The behaviour of different fish, if they shoal or don't shoal, for example, requires a fair bit of understanding, so once a species has learned a feeding strategy they will follow rather than learn a new technique for a new prey."

Evans believes we may soon see a visitor that disappeared from the Atlantic in the 17th century – the grey whale. "They migrate up the west coast of north America, from Mexico and California up to the Arctic and, of course, could go no further. But now the Northwest Passage is open it is very possible they may cross the North Atlantic.

"Gray whales were seen last year off the coast of Israel and off Barcelona this year. Such a remarkable appearance in such a strange location reinforces the pattern we are seeing."

Twenty-nine species of dolphin and whale have been recorded this century in British or Irish territorial waters. The common dolphin, striped dolphin, minke whale and humpback whale are among those species where numbers sighted have increased since 1980.

But it is not just the whales moving north into warmer seas; we are also seeing mammals coming down from colder climes. Bearded seals from the Arctic have been seen off the coast of Fife, east Scotland, said Callan Duck, a senior research scientist at the Scottish Oceans Institute at St Andrews University.

"The change in climate and the food chains is definitely having an impact in the species we are seeing, but I think you have to remember to factor in how much better we are at spotting and recording these mammals. Good digital cameras are really accessible now, and so everybody has the opportunity to identify what they have seen – so the whole process of reporting sightings is much more accurate and efficient."

Tracy McVeigh
The Observer
http://www.guardian.co.uk/environment/2011/dec/04/whales-new-species-britain