This study was carried out to provide detailed information on species diversity and community structure of Gokceada Salt Lake Wetland (brook feeding the lake, neighboring sea and terrestrial area around the wetland). Aquatic species diversity (algae, invertebrates, and fish) at 9 different stations in freshwater, brackish water and marine ecosystems, and terrestrial species diversity (plants, amphibians, reptiles, birds and mammals) in the surrounding wetland were studied seasonally in 2016. A total of 195 taxa of terrestrial vascular flora and 134 species of aquatic flora (97 species of phytoplankton, 37 species of benthic algae); a total of 23 macrobenthic invertebrate taxa from the lake and 131 invertebrate species from the sea were identified. Also, 4 fish, 14 reptiles, 3 amphibians and 71 bird species were observed in the study area. While one species of phytoplankton was determined as a new record for the Turkish aquatic flora, a total of 71 marine invertebrate species were reported for the first time in the marine fauna of Gokceada. The obtained data will not only provide a solid basis to expand the understanding of the island's ecosystem, but also will serve as an important tool in the action plans for wetland conservation.