Category Archives: Diversity and Biogeography

By Richard A. Ingebrigtsen, Department of Arctic and Marine Biology, University of Tromsø - Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=12614179

Keeping Things the Same

The elemental composition of organic matter is remarkably constant throughout the world’s oceans, but phytoplankton are known to take up nutrients and carbon in quite variable ratios depending on light and nutrient conditions.

In a paper published online in the journal Global Biogeochemical Cycles last month, Darwin Project researchers David Talmy (MIT), Christopher Hill (MIT), Anna Hickman (Univ. of Southampton, England), and Mick Follows (MIT), in a collaboration with Adam Martiny (Univ. of California, Irvine), report on their work  seeking to understand what ecosystem factors could cause the elemental composition of organic matter to remain stable and relatively constant (homeostatic), even when the phytoplankton can have quite variable composition. Continue reading

Dutkiewicz, S., J.J. Morris, M.J. Follows, J. Scott, O. Levitan, S.T. Dyhrman, and I. Berman-Frank, 2015, Impact of Ocean Acidification on the Structure of Future Phytoplankton CommunitiesNature Climate Change, doi: 10.1038/nclimate2722

 

Image credit: Christian Sardet, Tara Expeditions

Uncovering a Diverse Invisible Ocean World

Read this story at oceans.mit.edu

Tara Oceans, an international consortium of researchers that explored the world’s oceans in hopes of learning more about one of its smallest inhabitants, reported their initial findings this week in a special issue of Science. Plankton are vital to life on Earth—they absorb carbon dioxide, generate nearly half of the oxygen we breathe, break down waste, and are a cornerstone of the marine food chain. Now, new research indicates the diminutive creatures are not only more diverse than previously thought, but also profoundly affected by their environment. Continue reading

Villar, E., Farrant, G.K., Follows, M.J., et al, 2015, Environmental characteristics of Agulhas rings affect interocean plankton transport. Science, Vol. 348 no. 6237, doi: 10.1126/science.1261447

NO3, Fe, and diazotroph biomass - observations (left) and model (right) over top 50 m - from Fig 1, Dutkiewicz et al, 2014

Life on the Edge – How shifting marine province boundaries could provide a new metric for global change

In their new competition theory paper, appearing in the 2014 issue of Biogeosciences, Dutkiewicz et al examine the sensitivity of the biogeography of nitrogen fixers to a warming climate and increased aeolian iron deposition in the context of a global earth system model. Continue reading

Dutkiewicz, S., Ward, B. A., Scott, J. R., and Follows, M. J. (2014) Understanding predicted shifts in diazotroph biogeography using resource competition theory, Biogeosciences, 11, 5445-5461, doi: 10.5194/bg-11-5445-2014.

From Figure 5 of Levy et al (2014)

Mixing Down Diversity

Phytoplankton are an extremely diverse set of floating, microscopic organisms, which are freely transported by water movements (current, eddies, etc.) and make up the base of the oceanic food web. This work, published in the September issue of Limnology & Oceanography: Fluids & Environments,  explores how their diversity is affected by dispersal by different scales of motions in the ocean. Continue reading