Particles at the ocean surface and seafloor aren't so different
Although scientists often assume that random variations in scientific data fit symmetrical, bell-shaped normal distributions, nature isn't always so tidy. In some cases, a skewed distribution, like the log-normal probability distribution, provides a better fit. Researchers previously found that primary production by ocean phytoplankton and carbon export via particles sinking from the surface are consistent with log-normal distributions.
In a new study, Cael et al. discovered that fluxes at the seafloor also fit log-normal distributions. The team analyzed data from deep-sea sediment traps at six different sites, representing diverse nutrient and oxygen statuses. They found that the log-normal distribution didn't just fit organic carbon flux; it provided a simple scaling relationship for calcium carbonate and opal fluxes as well.
Uncovering the log-normal distribution enabled the researchers to tackle a longstanding question: Do nutrients reach the benthos—life at the seafloor—via irregular pulses or a constant rain of particles? The team examined the shape of the distribution and found that 29% of the highest measurements accounted for 71% of the organic carbon flux at the seafloor, which is less imbalanced than the 80:20 benchmark specified by the Pareto principle. Thus, although high-flux pulses do likely provide nutrients to the benthos, they aren't the dominant source.
B. B. Cael et al, Can Rates of Ocean Primary Production and Biological Carbon Export Be Related Through Their Probability Distributions?, Global Biogeochemical Cycles (2018). DOI: 10.1029/2017GB005797