The economic importance of our coastal resources cannot be over-estimated. And yet, we are all aware that such resources, including our natural heritage in the form of marine life and seascapes are threatened by our own activities. Nowhere is this more evident that in the release of millions of cubic metres of untreated wastewaters and sewage along our shorelines.

Fortunately, this practice will become a thing of the past, since very soon all our domestic and industrial wastewaters reaching our sewers will be treated prior to being discharged into the sea. In the meantime, and until then, there is an urgent need to assess the present state of the marine environment in the vicinity of public sewer outfalls in order to be able to judge the level of damage done, as well as the rate of recovery in the environment once the situation is under control.

In order to contribute to such efforts, the HSBC Cares For The Environment Fund sponsored a research monitoring project to assess the extent of the environmental impact of discharging raw sewage from the Cumnija outfall.

The work, undertaken by the university’s Marine Ecotoxicology Laboratory of the Department of Biology under the supervision of Prof. Axiak, has now been completed and the first results made available to the relevant authorities. The project extended over a period of nine months and included chemical and biological monitoring in the area under immediate influence of this outfall.

The Cumnija sewage outfall is located in a pristine part of our northern coast in the vicinity of Anchor Bay and Cirkewwa. From here, an estimated 1.6 million m3 of untreated sewage from the northern Malta catchments are discharged per year. Preliminary work in 2003 had shown that the extent of contamination by sewage, and the resultant microbes, might be quite extensive in the area.

The HCEF project has shown that marine sediments in the vicinity of the outfall were mostly polluted by lead and zinc and less so by cadmium and copper. However, in terms of environmental impact the levels of cadmium were of particular concern. Petroleum hydrocarbons from oils and fuel remains showed up in fairly small concentrations and marginally exceeded levels which may harm the environment only in the closest proximities of the outfall.

Degraded sea grass meadows with signs of stress and unhealthy conditions were evident from 250 to 300 metres away from the outfall. In the immediate vicinity of the outfall there was a relatively impoverished sandy habitat, typified by small opportunistic worms adapted to living in stressed environments. However, the extent of this damage to the marine environment was rather limited with a relatively rich benthic biodiversity being recorded at 500 metres of the outfall.

This data provides a first contribution on our baseline knowledge of the current state of sediment quality and benthic life in the impacted zone at Ic-Cumnija. It is against such baseline data that the rate of recovery can be monitored when the discharge of untreated sewage in the locality is discontinued by 2007.

Prof. Victor Axiak is head of the Department of Biology in the Faculty of Science at the University of Malta.