How does rising atmospheric CO2 affect marine organisms?

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Competition and Chaos: Sources of Enhanced Ecosystem Species Richness
Hulsman, J. and Weissing, F.J. 1999.  Biodiversity of plankton by species oscillations and chaos. Nature 402: 407-410.

What was done
The authors investigated the "paradox of the plankton" - why the number of coexisting species typically exceeds the number of limiting resources in most oceanic mixed-water environments - via computer model studies of sets of simultaneous equations describing the dependencies of different planktonic species upon different limiting resources in otherwise uniform and undisturbed environments.

What was learned
It was discovered that competition itself often induces a set of non-equilibrium species oscillations that readily allow for the coexistence of more species than would normally be expected on the basis of the number of limiting resources.  Some of these diversity-enabling oscillations are so small they "would probably go unnoticed behind the noise of any real-world data set."  As resource numbers increase, many simulations show irregular species fluctuations; and the pattern of species replacement "never repeats itself."  This continuous divergence of trajectories "is a characteristic feature of chaos."  Yet the authors observed that the chaotic ups and downs of individual species abundances within an ecosystem combine to produce "a near constancy of total community biomass."

What it means
In the words of the authors, their results show that "competition is not necessarily a destructive force" and that "competitive interactions that generate oscillations and chaos may allow for the persistence of a great diversity of competitors on only a few limiting resources."  And with external forcings, such as the ongoing rise in the air's CO2 concentration, stirring up the environmental mix even more, we would expect an even greater tendency for ecosystem biodiversity enhancement, particularly in environments of few and scarce resources.

Reviewed 15 February 2000