OCE-PFR Understanding macroalgal community structure: a trait-based and phylogenetic approach

Award Period
Award Amount
Agency Name
National Science Foundation
Award Number
PI First Name
PI Last Name
Robert Miller
Area/s of Research
Ecology and Evolution

Macroalgae forests, such as the giant kelp beds off the Pacific coast of North America, are highly productive ecosystems yet we do not know much about how component algae species perform ecologically, which is necessary to predict how species, or groups of species, might respond to climate change. This is important to understand because climate change has already caused an increase in environmental stressors such as more intense storms, larger waves, increased run-off from terrestrial sources, and changes in temperature, disturbance, nutrient availability, and light levels in coastal habitats in the Santa Barbara Channel and around the world. This study will measure functional traits of algae species, traits that affect an organism’s performance, which can then enable predictions about how species distributions might vary with climate change. For example, suppose toughness is identified as an important functional trait, as wave height and wave force increase with more frequent and powerful winter storms, it could be predicted that algae assemblages might shift from weakly to firmly attached species. As well as being highly productive, macroalgae at temperate latitudes form the basis of food webs and provide habitat for rich ecological communities. It is important that we understand community structure in these key marine ecosystems which provide goods and services for many at the regional and global level.

This project will engage undergraduates who will help with field and lab work, conduct honors theses, and receive scientific diver training. Aspects of this project will also inform the LTER Schoolyard program which educates K-12 students and teachers via school visits, field trips, and an on-campus residential program. Additionally, there will be opportunities to share the results of the project via public lecture series held at the Santa Barbara Natural History Museum and the Channel Islands National Park.

Kelp forests are key marine ecosystems yet the community structure of macroalgae in these assemblages is little understood. By measuring an extensive suite of functional traits of key algae species that span important ecological performance axes—resource acquisition, grazer resistance, and tolerance to disturbance—macroalgae will be assigned to functional groups. Hypotheses can then be tested about how functional groups and community structure vary along an environmental gradient, which, in turn, can then enable predictions to be made about how community structure might vary with climate change induced environmental stressors. Using a molecular phylogeny, it will also be investigated if there is an evolutionary component to the functional groupings and if closely related species have similar functional traits. Results will enable general statements to be made about community structure, general statements being more useful than species specific ones. The results will facilitate our understanding of how key ecosystems will respond to climate change and will also bring our understanding of these important primary producers in-line with that of their terrestrial angiosperm counterparts and more recently, marine phytoplankton, where measurements of meaningful traits have enabled predictions to be made about community-level responses to environmental stressors.  Indeed, a more holistic understanding of the forces driving these diverse and critical ecosystems is necessary if we are to predict change due to human impacts.