Ancient shellfish used for purple dye vanishes from eastern Mediterranean
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.
|Stramonita haemastoma [Credit: H. Zell/WikiCommons]|
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.
“In all … surveys conducted along the entire coast over the past seven years not a single live individual was recorded, and only three very large and seemingly old individuals were found in a shallow artificial lagoon at Akko [also known as Acre, in Israel] in 2010.”
The mollusc was one of the two major shellfish sources of the dye, which formed an ancient trade that was centred on the Levantine coast around the city of Tyre in modern-day Lebanon, from where it took its name. The dye’s origin was shrouded in mythology, not least the suggestion it was discovered by Heracles’ dog after it ate the shellfish and its mouth turned purple.
The dye was hugely valuable because it has been estimated that it took thousands of shells to produce a single kilo. It was produced by collecting thousands of dye-producing molluscs, crushing them and allowing them to rot in large vats before the colour was boiled out.
Rilov’s survey confirms other recent research describing the risk of sharply rising sea temperatures in the eastern Mediterranean basin.
Author: Peter Beaumont | Source: The Guardian [December 13, 2016]