While we typically consider global warming to have detrimental impacts on biodiversity and ecosystems, new research published in Science Advances reports that two species of marine foraminifera are adaptable enough to thrive in hypoxic and anoxic sediments, environmental conditions that are becoming more common as climate change progresses.
Foraminifera, also known as forams, are a kind of protist or single-celled eukaryote that are characterized by a streaming granular ectoplasm that is used to catch food. As seen in the video below, they commonly exhibit an external shell made from a wide range of materials that take many forms.
"Benthic foraminifera represent truly successful microbial eukaryotes with diverse and sophisticated metabolic adaptive strategies," write the authors in their study entitled “Multiple integrated metabolic strategies allow foraminiferal protists to thrive in anoxic marine sediments”. The authors predict that these strategies will increase the expansion of forams in oxygen-depleted marine habitats.
In addition, the paper found that the multiple metabolic strategies that these forams exhibit to adapt to low and no oxygen conditions are changing the classical view about the. That classical view hypothesizes that the rise of oxygen in Earth's system led to the acquisition of oxygen-respiring mitochondria, the part of a cell that generates most of the chemical energy that powers a cell's biochemical reactions.
This study focused on two particular species of forams that represent "typical" mitochondrial-bearing eukaryotes, however, these species are anything but average eukaryotes. The forams the study focuses on respire nitrate instead of oxygen and produce energy in anoxic conditions with high levels of hydrogen sulfide, which is usually toxic to eukaryotes. According to the authors, these distinctions shed light on the ways that scientists understand the evolution and diversity of eukaryotes and can even help construct climatic models of historic oceanographic conditions. Co-author and project leader Joan Bernhard, senior scientist in the Geology and Geophysics Department at the Woods Hole Oceanographic Institution (WHOI) goes so far as to say that finding these nitrate-respiring forams "throws a whole new wrench in interpretations of past environmental conditions on Earth, driven by the foram fossil record."
"We never knew exactly why forams can live where there isn't any oxygen until molecular methods got good enough that we could really start to ask some of these questions,” commented Bernhard. “This is our first paper that's coming out with some of these insights," she said, adding that the potential unknown metabolic strategies used by these organisms could be vast.
This could have serious implications for the role that forams play in the future. "The metabolic variety suggests that at least some species of this diverse protistan group will withstand severe deoxygenation and likely play major roles in oceans affected by climate change," conclude the authors.