Aspects of the ecology of seasonal watercourses in the island of Gozo

Abstract

A preliminary survey of the basic physical, chemical and ecological characteristics of seasonal watercourses in Gozo has been conducted. Measurements of nitrates, phosphates, conductivity, pH, flow rate and maximum discharge were carried out between October 1996 and April 1997. The biota was also measured and effects of human interference noted. Flow rate in most valleys depended directly on rainfall since there could be strong run off following heavy rain and this was gradually reduced into a series of isolated pools. Only Xlendi valley had constantly flowing water. The water in the valleys was alkaline and had high levels of nitrates and phosphates, probably due to leaking from surrounding fields. The biota of the watercourses was affected by the duration of flooding. The stable habitat had more complex communities than those that dried out after a short while. Human interference also affected the communities present. Dumping of organic waste caused a decline in diversity, while the building of dams led to the invasion of territorial vegetation into the valley system. It is proposed that conservation of the valleys requires less dumping, reduced abstraction of water and a greater emphasis on educating the public so as not to further destroy the beauty and biota of the valleys. Rehabilitation of the valleys can be conducted by the removal of silt, household and construction waste and invasive vegetation.