SummaryIn temperate marine ecosystems, loss of biogenic habitat (i.e., habitat formed by the growth and architecture of particular species) has contributed to declines in fish and invertebrate popilations and loss of species diversity. In estuarine ecosystems, habitat provisioning by eelgrass (Zostero marina) is critical to maintaining the ecological roles played by these estuaries as nursery and foraging habitats. In rocky-bottom ecosystems, canopy-forming kelp species (Macrocystis pyrifera and Mereocystis leutkeana) are primary producers and provide habitat by serving as surface area for sessile organisms and refuges for young fish. <p> Extent and structure (stem density and size structure) of these habitats are important metrics. These can cycle with environmental conditions and herbivore pressure.