This Week in the Deep

New and noteworthy publications in deep-sea science for the week of December 31st, 2012.

PLoS One: How Deep-Sea Wood Falls Sustain Chemosynthetic Life

Large organic food falls to the deep sea – such as whale carcasses and wood logs – are known to serve as stepping stones for the dispersal of highly adapted chemosynthetic organisms inhabiting hot vents and cold seeps. Here we investigated the biogeochemical and microbiological processes leading to the development of sulfidic niches by deploying wood colonization experiments at a depth of 1690 m in the Eastern Mediterranean for one year. Wood-boring bivalves of the genus Xylophaga played a key role in the degradation of the wood logs, facilitating the development of anoxic zones and anaerobic microbial processes such as sulfate reduction. Fauna and bacteria associated with the wood included types reported from other deep-sea habitats including chemosynthetic ecosystems, confirming the potential role of large organic food falls as biodiversity hot spots and stepping stones for vent and seep communities. Specific bacterial communities developed on and around the wood falls within one year and were distinct from freshly submerged wood and background sediments. These included sulfate-reducing and cellulolytic bacterial taxa, which are likely to play an important role in the utilization of wood by chemosynthetic life and other deep-sea animals

Read More

Ocean of Pseudoscience Shorty – Chemosynthetic ecosystems and independence from the sun

One of the many frequent claims that crop up in both popular and scientific reports about deep-sea hydrothermal vents is that chemosynthetic ecosystems are independent of photosynthetic ecosystems. Even high quality scientific reporting have been guilty of making this claim: “These animals live completely independent of sunlight” (NOAA Ocean Explorer).

But are chemosynthetic systems totally independent of the sun?

Recall the basic equation for chemosynthesis:

CO2 + O2 + 4H2S -> CH20 + 4S + 3H2O

Now, this is a basic chemosynthesis reaction using hydrogen sulfide as the electron donor, this is not the only possible chemical pathway for chemosynthesis. Notice that one of the required molecules is O2. Where did that oxygen come from? Photosynthesis!

So while chemosynthetic ecosystems are not directly dependent on the sun for energy, a critical part of the chemosynthetic pathways requires a byproduct of photosynthesis, therefore, it is inaccurate to state that “These animals live completely independent of sunlight”

~Southern Fried Scientist