From New Scientist:
Marine life loves a tectonic collision
* 19:00 31 July 2008
* NewScientist.com news service
* Nic Fleming
Today’s marine biodiversity “hotspots” weren’t always so hot, say researchers.
A review of fossil records and molecular evidence found the zones with the greatest variety of fish, molluscs and corals have shifted according to the movement of tectonic plates over three distinct periods during the last 50 million years.
During the late Middle Eocene, 39 to 42 million years ago, the greatest number of families of species existed in seas off southern Europe, northern Africa, and the eastern shore of Arabia.
Between 16 and 23 million years ago – the early Miocene – there were two main maritime hotspots: one covering the Middle East and the coast of north western India, and a region centred around the Philippines and northern Australia.
Since then, the Indo-Australian Archipelago (IAA) has been the most biologically diverse marine environment on Earth.
“There have always been assumptions that a hotspot has always been there and it is an area that produces its own diversity,” says David Bellwood, professor of marine biology at the James Cook University, Townsville, Queensland, Australia. In fact, hotspots can come and go.
The team studied the latest fossil evidence for the first occurrence and rate of DNA changes in large benthic foraminifera – amoeba-like, single-celled, sea-bed-dwelling animals with calcium carbonate shells.
Their prevalence has been shown to correlate with overall diversity in tropical marine environments. They also looked at the fossil records for mangroves, coral reefs, molluscs and cowrie-like gastropods.
They concluded that sea temperature, one of the traditional causes of biodiversity, plays a contributory rather than a primary role.
“Temperature is certainly facilitating diversity, but if it was only temperature in the Eocene, you would have really high diversity in modern Africa,” says lead author Willem Renema of the Natural History Museum in Leiden, the Netherlands.
“We realised these are distinct locations where you have major complex collisions between continents.”
At the early phase of collision, Renema says, a lot of new and different habitats are created, such as rocky and sandy shores, and deep and shallow basins, all of which can accommodate a lot of different species.
The current IAA hotspot lies in the region of convergence between the Eurasia, Australia and the Pacific/Philippine Sea plates.
Journal reference: Science (DOI: 10.1126/science.1155674)
See also the biodiverse life at the vents of the Mid-Atlantic Ridge, where tectonic plates are colliding.
Tropical biodiversity in danger: here.
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- Coral reef research highlights big drop in growth rates (summitcountyvoice.com)
- New marine species discovered in Madang Lagoon (asopa.typepad.com)
- New Marine Species Discovered in Papua New Guinea (natureworldnews.com)
- East Timor conservation (dearkitty1.wordpress.com)
- Tikina prepares for reef survey (fijitimes.com)