Chemosynthetic symbionts can fix atmospheric nitrogen

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In a study published today (24/10/16), Jillian Petersen, my colleagues and I show that sulfur-oxidizing autotrophic symbionts of marine clams and nematodes are capable of fixing atmospheric nitrogen (see Petersen et al., 2016). Strikingly, in a parallel study, another group also found out that the same capability is present in the symbionts of a different but closely related species of lucinid clams (see König et al., 2016). The two studies were published back to back in Nature Microbiology.

This discovery is remarkable for a number of reasons. At the very least, these studies show how omics is beginning to reveal the remarkable metabolic ‘talents’ of chemosynthetic symbioses, which go far beyond sulfur oxidation and carbon fixation.

If you want to know more about this topic and the stories behind the papers, you can also read the blog posts that were published in the Nature Microbiology Community to describe and disseminate the results of our study (see here), and of the parallel study from the Markert lab (see here).

Also, you can see the Division of Microbial Ecology website for links to the press release of the University of Vienna, etc.

BMC Ecology Image Competition 2016

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A photo of sand bubbler crabs I have taken in Lombok, Indonesia, in April 2015 has been picked by the expert panel of BMC Ecology Section Editors as one of 18 “highly commended” images chosen out of over 140 total entries.

My wife and I were in Indonesia on holidays and traveled between Bali and Lombok by scooter and public ferries. While enjoying the amazing landscape and sea view at Selong Belanak Beach, we noticed the crabs moving on the sand, and took this among other pictures.

Sand bubbler crabs live on soft shores of the tropical Indo-Pacific. They live in burrows in the sand, where they hide during high tide. During low tide, while searching the sand for food, they form characteristic sand pellets which cover the sand. They play an important ecological role as deposit feeders and bioturbators, and have been shown to affect the productivity of sandy shores. They move in large groups and scout the beach radially from their burrows, creating intricate and characteristic patterns of pellets as they proceed.

As the BMC Editors commented in their Editorial, the image illustrates well the interplay between predator, prey, and environment in a single ecosystem.

Citation and link:

Simundza J, Palmer M, Settele J, Jacobus LM, Hughes DP, Mazzi D, Blanchet S (2016) BMC Ecology Image Competition 2016: the winning images. BMC Ecology 16:1-10

“Nutrient-providing” bacteria help coral reefs flourish

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Figure from the article

In a study that we recently published open access in the journal Ecosystems, my colleagues and I report on a large dataset of physiological measurements for all key photosynthetic organisms and their associated nitrogen-fixing bacteria from a Red Sea fringing reef in Aqaba (Jordan).

We analyzed and extrapolated our results to the entire reef habitat using complex geospatial analyses, demonstrating that the ecosystem productivity relies on the “nutrient-providing” activity of nitrogen-fixing bacteria when other sources are scarce.

Among other results, we also showed that the process of nitrogen fixation is prone to strong climatic control. This implies that climate change may impact this particular process more than others, with repercussions on the reef biogeochemical cycles.

We hope that the estimates presented in this paper can prove useful for environmental managers planning or evaluating the effects of nutrient management actions on the reef ecosystem biogeochemical cycling.

Click here if you want to read the original article!