Tunnels into history: algae that bore into calcium carbonate
Channel: New Mexico EPSCoR
Date: 2013-12-09

A video of Dr. Charles O'Kelley's recent seminar on algae and calcium carbonate.

Charley O'Kelly is a well-known research scientist at Friday Harbor and works on microbial communities and primary productivity.  He also works on cell-cell interactions in marine organisms and has also been involved in algal biofuel research. 

SUMMARY: Algae have exploited calcium carbonate ever since the substrate became available to the biosphere.  Presently, several representatives of the green algae, red algae, and cyanobacteria, from marine, freshwater, and terrestrial biomes, actively burrow into carbonate.  Boreholes attributed to these microorganisms occur in rocks dating from the Precambrian onwards, with many "modern" forms making their first historical appearances in the Palaeozoic.  Among the most well-known of these burrowing algae is the red seaweed ("nori") from which sushi wrapper is made, and proper management of the burrowing phase is critical to successful nori cultivation.  The fossil record of these algae has been used to infer aspects of paleoclimate at the sites where they occur.  It's been estimated that the amount of carbon dioxide liberated from carbonates into air and water by these algae presently amounts to about one-fifth of the carbon load derived from fossil fuels, with much of that carbon coming from "fossil" carbonates such as coral reef rock and limestones. The biodiversity among modern carbonate-boring algae is poorly known.  Modern methods such as culture studies and DNA sequencing of cultured and field-collected samples are showing that, typically, there are numerous cryptic species concealed within a single morphospecies.  For example, the green algal genus Ostreobium, with a fossil record dating to ca. 600 MYA, may contain dozens to hundreds of species, with separate temperate and tropical floras, but until 2011, nearly all records were assigned to a single, "worldwide" species, O. quekettii.