Mangrove forests are an important feature of the Balinese coastline, providing nursery grounds for young fish, shrimp and other marine creatures and helping to prevent coastal erosion by absorbing onshore waves. The soil in mangrove forests is waterlogged and without oxygen, so native plant species have evolved elaborate root systems which allow to ‘breathe’. The stilt roots of Rhizophora species are one solution to this problem, while Bruguieraspecies have developed roots which loop in and out of the soil forming aerated ‘knees’ above ground level. Other local specialisations include self—planting fruit of Rhizophoraspecies. Unusually, the seed actually germinate: whilst still attached to the parent tree. A long torpedo—like root soon develops and when the seedling, with its first leaves emerging, drops from the branch, this structure readily penetrates the soft mud below.
Coral reefs are extremely complex communities built around the compacted and cemented skeletal remains of marine creatures and the limestone secretions of sedentary organisms, some of which are the coral itself. The latter requires lots of light and warm temperatures, which is why coral reefs are only found in tropical waters and usually not below depths of 100-120 metres.