Study Systems
Marine forests generally are created by the large, three-dimensional structure of brown seaweeds in the class Phaeophyceae, primarily the “kelps” (order Laminariales) and fucoids (order Fucales). Generalized terms used to describe functional groups within these systems are not consistent, thus, for the sake of clarity we will use “canopy-forming species” to describe brown seaweeds that create three-dimensional habitat. This includes all canopy species referred to as floating, stipitate, and prostrate canopies in Dayton et al. (1984), also termed surface, understory, and bottom canopies (Schiel & Foster 2015). Algal turfs are a diverse functional group that includes species from all three algal phyla, but refer to shrub-like, filamentous, and branched species that can be opportunistic and provide very little structure (Filbee-Dexter & Wernberg 2018). Alternately, algal crusts are low-lying, prostrate species that closely adhere to the substrate (Steneck & Dethier 1994). These two functional groups can further be divided by whether or not the species is calcified (Steneck & Dethier 1994). These delineations result in four functional groups that interact with canopy-forming species: coralline turf, coralline crust, non-coralline turf, non-coralline crust. Throughout the manuscript, we often refer to “turfs”, given their increasing importance in transforming coastal environments (Filbee-Dexter & Wernberg 2018), but we consider the interactions of each of these four functional groups that live below the canopy.