Species interactions, trophic structure and food web dynamics
Experiments on species interactions
One of the predictions for climate change during the next several decades is for increased winter storm activity in California. Such changes are likely to have profound effects on giant kelp forest ecosystems because winter storms are a major source of disturbance that removes kelp and other biota. An increasing frequency of severe winter storms would likely result in large losses of giant kelp every winter. Giant kelp is the foundation species of the ecosystem and our long-term monitoring shows that the dynamics of the benthic community of understory algae and sessile invertebrates are directly linked to the dynamics of giant kelp.
Specifically, giant kelp (which is a dominant competitor for light) has a direct negative effect on understory algae and a indirect positive effect on sessile invertebrates (which compete with algae for space). To investigate the ecological consequences of regular kelp loss during winter to the structure and function of kelp forest communities in the Santa Barbara Channel, we initiated a long-term experiment in winter 2008 in which giant kelp is removed once per year in winter from permanent plots to simulate the effects of increased storm frequency on giant kelp. Adjacent plots where kelp is left undisturbed serve as controls. Changes in the structure (e.g. species abundance, diversity) and function (e.g. primary production of understory algae, detrital accumulation) of the benthic community are being followed over time with bimonthly monitoring.