and is fed only by rainwater, there being no rivers at all in Nauru. Thus, between the monsoon season from November to February, when most of the rain falls (this is on average some 2,126 mm each year) and the dry season, especially in years when La Niña is present, the low-water level can sink as far down as five metres below sea level. The lake’s greenish waters are slightly brackish, with a salt concentration of 2‰, and slightly basic with a pH of 8. Flora Very little information is available about the Buada Lagoon's lacustrine flora, even though the presence of water hyacinth (Eichhornia crassipes) was confirmed not long ago. The vegetation along the lake's edge to a great extent represents a relic of the tropical forest that occupied 90% of the island before the phosphate ore began to be exploited in the 20th century. Covering 40 hectares and growing on a fertile, waterlogged soil, it is made up mostly of tamanu (Calophyllum inophyllum) along with a few Rubiaceae like Guettarda speciosa, and also Premna serratifolia, sea almond, Adenanthera pavonina, kapok, Mimosa pudica, mango, sea mango, coconut, while the undergrowth is mainly made up of Scaevola (notably Scaevola taccada), noni, hopbush, Physalis angulata, ferns like monarch fern and giant swordfern, and parasitic plants like Cassytha filiformis, or Psilotum nudum. Glochidion societatis is found in open areas while Cyperus (specifically Cyperus javanicus and Cyperus compressus, species close to papyrus), Portulaca oleracea and Ipomoea aquatica are found in the wetlands, much of which was destroyed during the Japanese Occupation during the Second World War. Further, exotic plants such as guava, lantana, Grona triflora and Chamaesyce hirta have colonized places that have experienced disturbances. Within this forest, on small parcels of land, are grown fruit trees such as pandan, breadfruit, banana, mango, guava and soursop, as well as vegetables such as cabbage and bitter melon for consumption. Also grown are ylang-ylang, Cassia grandis, Crotalaria spectabilis, Samanea saman, seagrape and, for ornamentation, some Asteraceae such as Ageratum conyzoides and Synedrella nodiflora. Fauna Insects The lagoon's depression is one place on Nauru where insects proliferate, mostly because of the nearby expanses of stagnant freshwater such as the Buada Lagoon itself and also the rainwater cisterns found at dwellings and farms. Thus, three species of mosquito, Culex quinquefasciatus, Culex sitiens and Aedes aegypti, proliferate in the monsoon season from November to February near expanses of