Hugh Bollinger / Friday, May 20, 2011

Record keeping

I once used a boring instrument to take core samples from trees at timberline in the Rocky Mountains. When the cores were examined, they showed growth rings over decades and, in some cases, centuries. Counting the rings, I could determine how much time had elapsed since fires had burned through the forest and allowed surviving trees to regrow. The "record keeping" of the rings helped me understand the long-term ecological events I was trying to interpret. Counting layers in various natural materials can tell stories of past environments and climate conditions over consistent time-lines. They are books that can be read by trained eyes. Besides trees, similar approaches have been used by glaciologists to decipher ice cores, archeologists to determine age from teeth enamel layers and stages of bone growth, and geologists to date cave deposits from stalactites and stalagmites. Now corals have been decoded to tell climate records over many years of growth in the marine environment. [caption id="attachment_4128" align="aligncenter" width="473" caption="Coral growth rings under UV. Photo credit: Eric Matson (AIMS)"]

[/caption] Researchers at the Australian Institute of Marine Science (AIMS) -- working with slow growing corals from the Great Barrier Reef -- have shown that the annual density bands in giant corals acted just like tree rings. The rings expressed coral growth rates and also the timing of environmental events affecting the coral’s growth such as bleaching from high temperatures or toppling from tropical cyclones. Measurements of trace minerals in the coral skeletons also indicated sea temperatures, salinity, or the amount of sediment in the water at specific times during the corals growth. Such environmental records are increasingly important as climate change accelerates. However, we will need to start reading the books more closely before they are destroyed, die, or melt away. WHB

Curiouser & curiouser Denmark can suck a (pickled) egg. China too.

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Tags: environment climate change coral reefs climate dating coral dating fire ecology ice cores marine ecology tree cores tree ring analysis

Record keeping

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