Blooms of seagrass epiphytes have potentially important economic and ecological consequences in Tampa Bay, one of the Gulf of Mexico’s largest estuaries. As part of a Tampa Bay Pilot Study to monitor the impact of environmental stresses, precise characterization of epiphyte diversity is required for efficient management of affected resources, and thus may be used as a rational basis for assessment of ecosystem health. Fixed monitoring sites were selected north of Port Manatee, composed of dense and sparse Thalassia testudinum seagrass sites. A total of 13 epiphytic species encompassing green, brown and red macroalgae were manually collected in May 2001 from dense seagrass beds, versus 9 species from sparse beds. Epiphytes only collected in the dense beds were Enteromorpha flexuosa, Sphacelaria rigidula, Ceramium byssoideum, and Herposiphonia tenella; epiphytes only occurring in the sparse beds were Griffithsia and Stylonema alsidii. A correlation seems to emerge among attachment mode of epiphyte to host, presence of cortication and epiphyte length. A main goal of this ongoing study is the determination of indicator species for both healthy and stressed seagrass bed environments using both taxonomic and gene sequencing techniques.

Key words: epiphytes, Florida, floristics, Gulf of Mexico, macroalgae, Tampa Bay, Thalassia