Seagrasses are important communities in undisturbed shallow coastal ecosystems, providing essential habitat for many species of marine animals. The distribution and abundance of seagrasses have greatly diminished in nutrient-enriched coastal waters, such as Chesapeake Bay and Danish estuaries, where water transparency and light availability to rooted plants have declined as result of phytoplankton growth and fouling of the grass blades by epiphytes and biofilms. These habitat changes propagate through food webs, and the abundance and species diversity