Swinging seaweed fronds form a peaceful underwater scene in which the spotted sunlight falls. Hidden in the genes of the organisms, however, this can be evidence of the planet’s past geological violence.
In an article published last week in Proceedings of the Royal Society B., Researchers say the bullentang genes along the coast of New Zealand’s South Island show traces of an earthquake that occurred 800 years ago when part of the sea floor rose and wiped out its inhabitants. This made room for newcomers with a different genetic background, the ancestors of today̵
New Zealand lies on a nest of fault lines. After a quake four years ago, the edge of a fault near the city of Kaikoura shot more than a meter out of the water, and Jon Waters, professor of zoology at the University of Otago, and his colleagues wondered what had happened to Kelps such destruction. Those who are stranded above the tide line die quickly, but as the underwater ecosystem changes to a new normal, there are suddenly many vacant properties that new people can enter and take over. And due to the way in which a population of seaweed carpets is an area in the long term and offers little space for newcomers, according to Dr. Waters is an ideal test bed to determine whether the effects of a catastrophe on the gene pool persist over time.
About 800 years ago there was a similar quake along the coast near Dunedin in New Zealand according to geological records. The scientists took kelp samples along a 60-mile stretch of this bank. Each kelp looked similar to the others of its kind. However, when the scientists examined genetics, there were big differences in where the kelps were collected. Bullentang, which lived on a 15-mile route that had been blown up during the earthquake a long time ago, was different from neighbors of the same kind on either side, whose houses had been undisturbed for a long time.
“We were only thrilled when we looked,” said Dr. Waters. “We could see where the buoyancy zone was by just looking at the genetics.”
As migratory bull kelps entered the wasteland left by the earthquake from further down the coast, they were likely to multiply rapidly, dominating the entire footprint of the uplifted area within a few decades before others could penetrate. Your descendants still live there. Their presence is a sign of an old disturbance, but also a renewal.
“One of the things we learned from this is how quickly nature recovers,” said Dr. Waters. “It is comforting that nature has this power.”
The work confirms the idea that after the recovery of the ecosystems from disasters, the genetic makeup of the organisms there can bear signatures for the change for hundreds of years or longer. What is particularly interesting is the fact that 800 years after the earthquake, the new seaweed barely mixed with its neighbors. Researchers wrote. The group is now observing the resettlement of the raised zone of the Kaikoura earthquake and collecting samples as new kelps arrive. Kelps are travelers, as it turns out. Individuals can swim thousands of kilometers and are still viable if they wash off on a distant shore.
And if the kelp grows, many small creatures living in it can return, said Dr. Waters. The intricate strands that attach kelp to rocks form tiny, protected worlds in the surf where small crustaceans and other animals settle.
“They have a sheltered little environment where things can go about their everyday life,” he said.