Distribution and conservation
The lake bottom habitat of Isoetes biafrana in Lake Oku. © Martin Cheek, RBG Kew.
Distribution
Isoetes are often found in springs, seasonal pools and submerged at lake margins.
Isoetes biafrana is only known from 2 localities in west Africa. They are:
- Cameroon (Lake Oku)
- Bioko Island (Lake Moka)
It is a submerged aquatic quillwort species found in slowly-shelving montane crater-lakes with a gravel substrate, in water less than 1m deep, at about 1,600m to 2,200m altitude.
Western Cameroon and the Gulf of Guinea region is the richest area of tropical Africa for plant species.
Conservation
Isoetes biafrana has been assessed as vulnerable (Cheek et al 2000) because only a small fraction of the original rain forest still exists around Lake Oku in Cameroon and this is threatened by increased grazing by goats in the lake's crater. This in turn increases soil erosion around the lake and may cover the gravel bottom, preventing Isoetes biafranum from becoming established since it does not root in mud-bottomed lakes.
Conservation efforts should include stopping forest clearance and livestock grazing, and a thorough survey of population sizes of Isoetes biafranum should be undertaken around the perimeter of the lake.
Several hundred plants were recorded in Lake Oku, below the Baptist Rest House, in November 1996, but there is no record of the number of individuals found in Lake Moka on Bioko. Due to its very restricted range and number of locations, and the threats known to occur in the range of Isoetes biafrana, this species has been assigned the category of vulnerable.
