Ok I wonder what kind of adaptations would the animals need on an environment I plan to make in a fiction. But it's rather believable as far as I can see. The island is rather small like the offshore islands of Singapore but the whole island is in fact a very big mangrove swamp. Every time the tide rises at least 90% of the island is submerged in water. The flowering plants here are mostly mangroves and small shrubs and saltwater grasses.