Many researchers have been attracted to the marine biodiversity and pristine forest as well as the uniqueness of the Karimunjawa archipelago. During the Dutch colonial era, many Dutch botanists such as
Teijsmann (1854),
Koorders (1886),
Schlechter (1910) and Dammerman (1926) came to the Karimunjawa archipelago. Karimunjawa has five types of ecosystems: coral reef, seagrass and seaweed, mangrove forest, coastal forest and low land tropical rainforest. Fresh water is confined to a few small wells and forest streams in the islands.
The coral reefs of Karimunjawa National Park Karimunjawa's
coral reefs are made up of
fringing reefs, barrier reefs and several patch reefs. They have an extraordinary wealth of species: 51 genera with more than 90 species of coral biota and 242 species of ornamental fish. Two protected biota species,
black coral (
Antiphates sp.) and
organ pipe coral (
Tubipora musica), can be found here. Other protected sea biota include the hornet helmet (
Cassis cornuta), triton trumpet (
Charonia tritonis),
chambered nautilus, green shell (
Turbo marmoratus), and six species of clam. Around Kemujan island, the wreck of the Panamanian ship
Indono, which sank to the sea bed in 1955, is now a habitat of coral fish and is a popular site for
wreck diving.
The seagrasses and seaweeds There are 10 genera of
seagrass mostly dominated by
Enhalus and
Thalassia. The seaweed species are grouped into three divisions:
Chlorophyta (Coulerpa and Halimeda),
Phaeophyta (
Padina,
Sargassum and
Turbinaria) and
Rhodophyta (
Eucheuma,
Gracilaria,
Gelidium,
Hypnea and
Acanthopora).
The forests A total of 300 ha of
mangrove forest covers the national park, and is the habitat for 13 genera and 32 species of mangroves, such as the
Rhizophora mucronata. The lowland
tropical forest covers an area of 1,285.50 ha. It provides habitat to a number of endemic species including the mythical
dewadaru tree (
Fagraea elliptica),
setigi (
Pemphis acidula) and
kalimasada (
Cordia subcordata). The local people use these trees as raw material for souvenir handicrafts such as
tasbih,
kris, or staffs. It is generally believed that the wood of the endemic
dewadaru tree has a legendary power of curing diseases or snake bite wounds, protecting house from thieves, or prolonging life. Recently, the population of these three tree species has deteriorated because of the increased extraction. There are about forty different bird species in the island, including the
green imperial-pigeon, (
Ducula aenea),
yellow-vented bulbul (
Pycnonotus goiavier) and
red-breasted parakeet (
Psittacula alexandri). Some migratory birds are also found in this area, such as the
common sandpiper and
whimbrel. The lowland tropical rain forest is the natural habitat of the rare
white-bellied sea eagle. The latest expedition report of the Indonesian Science Institute reveals that there are two endemic butterfly species, and these are the
Euploea crameri karimodjawensis and the
Idea leuconoe karimodjawensis. The diversity of terrestrial animals of this park is not as high in terms of numbers as that of the aquatic animals. However, it is still possible to see
Javan rusa deer (
Cervus timorensis),
Sunda pangolin (
Manis javanica), and the Malayan pit viper (
Calloselasma rhodostoma). Several species of turtles lay their eggs on the islands, e.g.
hawksbill turtle and
green turtle. ==Conservation==