DHABDeep-Hypersaline Anoxic Basin
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Most DHAB interfaces are just one to three yards thick, and within that short space each vertical millimeter presents a different menu of challenges and opportunities to potential residents.
Bernhard, who spearheaded the sediment work, said Jason did a beautiful job collecting material from the beach and the normal seafloor, but had trouble penetrating into a DHAB even with its downward thrusters revved up all the way.
Noted scientist Ed Leadbetter, who investigated microbial metabolism during a 46-year career at Amherst and the University of Connecticut, is helping to piece together an overall picture of how organisms with different metabolic capabilities interact in the DHAB ecosystem.
With its residents unable to travel through normal seawater to other basins, each DHAB has evolved its own unique fauna.
Wherever they came from, whatever their survival strategies, the DHAB eukaryotes have already redefined the limits of life.
What's interesting about the DHABs (pronounced D-habs) is that there are multiple stress factors involved.
When bacteria and archaea, another domain of single-celled life forms, were discovered living in Mediterranean DHABs about ten years ago,
For Edgcomb and WHOI geobiologist Joan Bernhard, who have studied protists from hostile habitats around the planet, figuring out what was really going on in DHABs was an irresistible challenge.
DHABs were discovered in the eastern Mediterranean in the 1980s and have also been found in the Red Sea, the Gulf of Mexico, and a few other locations.
The brine has stayed in the basins ever since, isolated from the less dense water above it and from other DHABs nearby.
Over the past few years, Edgcomb and her colleagues have made several trips to Mediterranean DHABs, most recently with equipment that let them precisely identify their sampling areas in DHABs and preserve the collected cells in situ--at the site of collection.
Both DHABs and interface zones are home to many kinds of bacteria but few archaea.