Population growth has impacted habitat and species adversely and there are a significant number of threats. The environmental problems are similar to many other parts of Africa and it is worth documenting these in some detail (see references - complete text in Louette et al 2004).
The surface area of the forest is liable to become insufficient to support the populations of certain animals
It is essential to save mangrove swamps and forest cover on the massifs, not only in order to avoid erosion and maintain water resources but also to guarantee ecological equilibrium and hence the survival of many species. By plotting the terrain from aerial photographs, forest fragmentation can be seen. At present, even on Grande Comore where the state of natural forest is better, the primary natural forest is localised over even smaller areas on the most inaccessible slopes of Karthala. The rapid degradation and deforestation directly threatens their inhabitants. As an example: big trees supply crevices for the nests of certain species of birds, but also for bats and insects which live in caves. On the other hand, zones which have been heavily influenced by man, such as area of coconut palms, contain a much more ordinary fauna. The dryness of the rivers at present is probably linked to the disappearance of the forest. This is of paramount importance for the well-being of certain local animals.
The quality of vegetation is regressing
Food-producing cultivation and exploitation of the forest hinders the regeneration of the native forest. The conservation of La Grille forest poses more serious problems as it is accessed easily by a tarred road. Near Boboli and Niombadjour on Grand Comore where sawmills were in use some years ago, the forest has almost entirely disappeared and has been replaced by agriculture and by invading plants. The result is a very ordinary vegetation which is uninteresting for fauna. There are other threats and pressures such as deliberate fires, particularly on the summit of Karthala. Campaigns about the dangers of bush fires in the localities at the edge of the forests have had only a limited success. Reforestation programmes are increasing the area of forest and can fulfil the need for timber and thus lessen the pressure of exploitation of natural forests, but they are inferior for the preservation of natural biodiversity. There is, moreover, not much reforestation in the Comoros
Lakes are deteriorating
If the preservation of forests is a priority, lakes are also important as there are few of them. A good example is Lake Dziani Boundouni on Mohéli which is very dry. The water level continues to drop noticeably and the quality is compromised. Unsustainable exploitation including overgrazing, land clearance especially on the slopes causing intense erosion, deforestation of the inflowing pools is putting pressure on the areas. These pressures can seriously harm the lake and in the same way, Lake Dziani Karehani at Mayotte is in danger of drying out (see Louette 1999). The Lakes of Anjouan (Dzialandze and Dzialatsounga) suffer from the same problems.
Exotic species are introduced
The introduction of new species can totally change the ecosystem of the island and it is probable that the loss of the majority of species dates from long ago when man arrived accompanied by domestic animals, rats, mice, insects, cockroaches and invasive plants such as golden alyssum. Even recent introductions made by man can be dangerous: mongoose, House Sparrow Passer domesticus, Common Myna Acridotheres tristis (nowadays the commonest bird in the archipelago), guppy or even the giant mollusc Achatina fulica. Globalisation and international transport genuinely increase the risks of a new wave of introductions.
The ecosystems of the Comoros, both by their diversity and their abundance, represent a unique natural heritage whose conservation is of paramount importance both now and for generations to come. The value of the faunal heritage of the Comoros is as important as the cultural inheritance and requires urgent attention. The interest in the fauna of the Comoros rests particularly in endemic animals linked with the original vegetation. The Comoros still possess well-preserved species which are of prime importance for the conservation of the environment and for science. The creation of nature reserves to protect the national heritage has become an absolute priority. In order to limit and then eliminate exploitation, these reserves will have to bring alternative sources of income to the human population living in the zone e.g. forest wardens and guides for the ecotourism circuits.
Note that at present, the UDC has only one designated National Park (Parc Marin de Mohéli); the Karthala forest park is still under debate. Mayotte has a series of Réserves Forestières (see map in Louette 1999). There are few areas that remain relatively undisturbed: upper levels of Mount Karthala; some islets near Mohéli such as M'Chaco.