River delta and the immediate surroundings of Kocasu, hosting the terms of the diversity of natural habitats has unique natural wealth with delta, dune plants, marsh, swamp natural forests and lagoons it host several life. Swamp forests consisting of ash, alder and willow; lilies, sea bean, tamarisk, hyacinths, onions lake, aquatic plants such as oak rabbit; black stork, Ferruginous, pochard, marsh swallow, Kentish Plover, little bittern, the night heron, pied herons, little egret, gray herons, swans, green head, garganey, Hungarian duck, apple head Duck, White-Tailed Eagle, coot, oystercatcher, the tern, little tern and the delta where several woodpecker species, bird species such as the pygmy cormorants and white pelicans are housed during migration. Examination field has earned the status of Important Bird Areas breeding bird populations such as black storks, marsh swallow, cut necklace rain bird. Soil frog, marsh frog, spotted turtle, striped turtles, water snakes, amphibians and reptiles such as the southern crested newt living in the area are other biosphere elements. These lagoons are home to extinct eel with pike, roach, carp, flounder, and fish such as rhodeus sericeus amarusich. The Tatars black chards on the field in terms of endemic species of vegetation are in the high risk category. Sand lilies, rhododendron protection priority; discrete sand, while the lake onion is located in the delicate protected category. The spleen herb is considered endemic in the low-risk group. Swamp forests, dune plants, aquatic vegetation, birds and lagoons of ecotourism and jeomorfoturizm poses potential appeal. Although natural sites in Dalyan, pollution in Poyraz and Arapçiftliği the lagoons, incorrect land use, chemical fertilizer use, Kocasu mixing the river water with the Bursa industrial waste, siltation, eutrophication, sand withdrawal, some wrong practices, such as cutting of trees in the swamp forests leads to compensation impossible degradation.