Studying Stability Under the Sea

By UC Santa Barbara

An ecosystem arises from the effects of many different levels of organization. There are the species, their populations, the communities they live in, and the network of these communities over the entire region. But scientists are still exploring how the dynamics at different levels combine to determine the properties of the ecosystem as a whole.

Now a team let by UC Santa Barbara researchers has published a study detailing the factors at play in the understory of giant kelp forests in the Santa Barbara Channel. The results appear in the journal Ecology.

“We wanted to understand which factors were most important in stabilizing the regional biomass of the macroalgae that thrive beneath the canopy of giant kelp,” said lead author Thomas Lamy, a postdoctoral scholar at UC Santa Barbara’s Marine Science Institute (MSI). A stable community might see changes in its composition over time, but the overall mass of the plants and animals will remain relatively constant.

Scientists associate stability with two general characteristics: the diversity of different species and the number of patches in the region. If a region has many species, at least some will do well under a given set of conditions. Having a large number of independent communities can also promote stability. In this case, the health of each patch rises and falls independently, so they tend to average out, increasing the overall stability of the ecosystem.

Comparing an ecosystem to an investment portfolio, the stability provided by biodiversity would be like have a very diverse portfolio of companies. The spatial stability would be like investing over a large geographic region. Both aspects stabilize the system in different ways and to different extents.

Lamy and his colleagues were surprised to find a great deal of synchrony between the health of different patches of reef.

Read more here: