Tag Archives: Diazotrophs

Collecting snow in the tropics

R/V Atlantic Explorer at sea

After 2 months of packing, planning, prepping, and fretting, I finally boarded a plane to Bermuda in mid August to take part in a research cruise aboard the R/V Atlantic Explorer. This was set to be the third and final research expedition of my PhD, and I had firm plans to tie up some loose ends from previous sampling and to [hopefully] confirm a few hypotheses I’ve been juggling about for the past year. Like any research expedition, we faced a few hurdles with engine troubles and impending tropical storms, but managed to leave port only 2 days late, and were able tack on an extra day of sampling on the end to make up for lost time. All in all there was no harm done, except maybe to my ever-dwindling research training and support grant, which certainly took a few hard knocks with flight changes. Continue reading Collecting snow in the tropics

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Marine nitrogen fixation: the players

This is the second of two articles written by Elizabeth Sargent on the marine nitrogen cycle; the first article covered some of the basics and can be found here

A trichodesmium 'puff'. Oh, and watch out for this image in the April version of Scientific American

There are three main groups of nitrogen fixing organisms in the ocean: filamentous, heterocystous, and unicellular diazotrophs. The unicells are relatively new to the research scene (discovered in 1998), and are difficult to image due to their size, distribution, and our lack of knowledge about their lifestyle. I have some epifluorescent microscope images of unicellular diazotrophs, but you can get a good idea of what that looks like by picturing the night sky; it’s a whole lot of darkness and some tiny yellow dots. Continue reading Marine nitrogen fixation: the players

The marine nitrogen cycle

This is the first of two articles to be written by Elizabeth Sargent on the marine nitrogen cycle; the second article will go into more depth on nitrogen fixers (or, as Liz refers to them: ‘the diazotrophic organisms I hold near and dear’).

The marine nitrogen cycle (modified from http://bit.ly/wC3xZo)

The marine nitrogen cycle is one of the most complicated biogeochemical cycles in the ocean.  Nitrogen is a biologically limiting element and changes in its form, or concentration, can cause changes in the cycling of other elements, such as carbon and phosphorus. Marine nitrogen cycling has been and will continue to be an integral component of ocean biogeochemistry, so everyone should know at least the basics. Continue reading The marine nitrogen cycle