a number of the coastal lagoons, especially those near to the city of rio de janeiro and in neighboring niterói, have seen their natural habitats deteriorate in recent centuries, due to human expansion and pollution. consequently, many of the native ecosystems within the lagoons have degenerated, and in some cases ceased completely. the state authorities are now working to improve the situation, by focusing efforts on the regeneration of the lagoons, with various conservation strategies being put in place.

another particularly rich ecosystem of the coastal zone is the mangrove region, which not only houses a great number of species, but also plays an important role in supplying adjacent systems with biomass and nutrients. there are various species of mangroves found in rio de janeiro, such as the red mangrove, or the rarer white mangroves, which can grow to eight meters high. the mangroves provide an important refuge for fish species as well as other organisms, as well as helping stabilize the coastline from currents and tides.