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Mollusc species collapsing in eastern Mediterranean, finds study
Mollusc species Mollusca is one of the most diverse groups of animals on the planet, with at least 50,000 living species (and more likely around 200,000). It includes such familiar organisms as snails, octopuses, squid, clams, scallops, oysters, and chitons.
The study
- The team gathered over 100 samples from the seafloor to gauge the characteristics of local mollusc populations — the species present, their numbers, etc.
- These were then compared to historical data on the same topic.
- Only around 12 per cent of the shallow-sediment molluscs noted in the historical records are still present today.
- On rocky reefs, that number is only five per cent.
- While the mollusc species originally native to the eastern Mediterranean are on the decline, tropical invaders have increased significantly, the research found.
- The species that migrate via the Suez Canal are well adapted to the warm water in the eastern Mediterranean and can, therefore, settle in large numbers.
- They now form large populations with fully reproductive individuals.
- The researchers estimated that 60 per cent of the remaining local mollusc populations were below their reproductive size.
Reasons
Global Warming, Pollution and the pressures from invasive species
Source: Down To Earth
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