The flow of acidified water derived from rainfall and runoff, leads to the gradual erosion of limestone and the eventual formation of hollows or kamenitzas. The latter collect rainwater in winter, forming shallow freshwater rock pools (Maltese: għadajjar tal-ilma ħelu), which provide a suitable habitat for a number of rare species.

Freshwater rock pools last for only a short period, because in summer they dry up completely and may become colonised by terrestrial vegetation. Therefore, the ecological cycle of this habitat spans over a year, with a wet and a dry stage. Species that are specialised to this habitat type remain dormant in the soil during the dry stage and emerge during the wet stage. Other species move out of the rock pool when it is in the dry state and return when conditions become favourable. Plants and algae that inhabit freshwater rock pools include the Maltese waterwort (Scientific: Elatine gussonei; Maltese: L-elatine) and the Maltese horned-pondweed (Scientific: Zanichellia melitensis; Maltese: Ħarira tal-Ilma). The duration of how long the rock pool remains with water determines the species richness of that particular rock pool. Several aquatic invertebrates are also found in this habitat type, among which microcrustaceans and freshwater shrimps. Certain microorganisms that occur in this habitat are extremely rare such as the tadpole shrimp (scientific: Triops cancriformis; Maltese: Gamblu tal-elmu).

Should you require more information, please contact nature.

requests@mepa.org.mt.