Marine macrophytes (macroalgae, seagrasses, and mangroves) comprise thousands of species distributed in shallow water areas along the world’s coastlines. They play a key role in marine ecosystems regarding biodiversity and energy flow. A large proportion of macrophyte species can be characterised as ecosystem engineers—organisms that directly or indirectly affect the availability of resources to other species by modifying, maintaining, and creating habitats. This book is divided into three main themes: • Marine macroalgae and seagrasses as sources of biodiversity gives an overview of the diversity of the main organisms associated with macrophytes, and their functional role and interactions within their hosts. • Primary and secondary production of Macrophytes synthesizes research on food web structures derived from/or associated with, macrophytes and the transfer of macrophytic primary and secondary production from one ecosystem to another. • Threats to macrophytic ecosystem engineers addresses human-induced effects including eutrophication, physical destruction, invasive species, and global warming. The book is among the first one to concentrate on the value of macrophytes for the well-being of marine habitats. The book is aimed at academics but may be useful for students, policy makers, and laymen alike.

Section 1: Marine Macroalgae and Seagrasses as Sources of Biodiversity The role of chemically defended seaweeds as biodiversity source; Renato C. Pereira, Bernardo A. Perez da Gama Microbial assemblages associated with macrophytes; Franz Goecke, Johannes F. Imhoff Epibiont associated with Marine Macrophyte Assemblages; Carol S. Thornber, Emily Jones, Mads S. Thomsen Free-living invertebrate assemblages associated with macrophytes; Emil Ólafsson, Hilmar Hinz The role of floating plants in dispersal of biota across habitats and ecosystems; Martin Thiel, Ceridwen Fraser The role of drift plants; Lara Arroyo, Erik Bonsdorff Section 2: Production of Macrophytes Primary production; Ken Dunton, Michael H. Graham Secondary production; Hartvig Chistie, Kjell M. Norderhaug Section 3: Human Threats to Macrophytic Ecosystem Engineers Eutrophication and the challenge of changing biotic interactions; Eva Rothäusler, Veijo Jormalainen Physical threats to macrophytes as ecosystem engineers; Diana I. Walker, A Bellgrove Ecological interactions between marine plant and alien species; Mads S. Thomsen, Thomas Wernberg, Peter A. Staehr, David Schiel Effects of climate change on macrophytes; Th