Intertidal and subtidal communities are characterized by habitat-forming species (e.g., macroalgae, corals, eelgrass, sponges) that perform essential ecosystem services such as provide food, shelter and nursery habitats for a variety of organisms, including economically important shellfish and fish species. Habitat-forming species are spatially dominant organisms whose biogenic structure enhances species co-existence through the creation of fine-scale, complex matrices in which smaller organisms find refuge from competitors or predators. Given that habitat-forming species are critical for ecosystem function, conservation strategies are prioritizing them for protection and restoration. This talk centers around three studies of habitat-forming species. The first study uses ROVs to map and characterize habitat-forming species and their associated species in the Antarctic. The second uses experimental approaches to investigate the consequences of seaweed habitat-forming to ecosystem processes in salt marshes. The third study involves recent studies using acoustic techniques to identify and characterize seaweed species in the Gulf of Maine.