Assessing the Success of the Lunawa Restoration Project Six Years Post Restoration

Abstract

The Lunawa lagoon, receives large amounts of untreated industrial effluents and domesticwaste water due to its industrialized and urbanized setting. As a result, the once pristinelagoon progressively deteriorated, ultimately becoming a health hazard to those living inclose proximity. Many restoration programmes, of differing magnitudes, were undertakenfrom time to time; the most recent being that by the Coast Conservation Department in 2007.The objective of the present study is to assess the status of the lagoon in terms of waterquality and avifaunal diversity six years after restoration.

This study was conducted from April to July 2013 during which selected water qualityparameters in surface water were monitored at ten stations across the lagoon each month. Anavifaunal survey was also conducted along six transects twice a month over the four months.On each day birds were observed between 0700 and 1000 hrs at equally spaced points alongthese transects. The levels of many of the parameters were significantly different betweensites. The ranges recorded were pH: 7.0 - 10.4, salinity: 0.7-8.1 ppm, conductivity: 4.7 -4058.0 μS, turbidity: 4.29-69.32 NTU, dissolved oxygen (DO): 2.3 – 14.9 mgl-1, BiologicalOxygen Demand (BOD)5day: 7.9 - 23.2 mg l-1, nitrate: 1.4 - 8.4 mg l-1, phosphate: 0.0 - 4.9 mgl-1 and chloride: 461.5 - 2875.5 mg l-1. The mean values for conductivity and BOD weresignificantly lower (p< 0.05) and DO significantly higher (p< 0.05), than the values reportedfor the lagoon prior to restoration. Although recorded previously in lagoon water, the heavymetals, Cr, Pb, and Cu were not detected during the present study. Zn (0.31 mg l-1) was onlydetected from the eastern drainage basin. Thus the present status suggests gradualtransformation of the water quality in the lagoon since restoration. The avifaunal survey didnot show similarly positive trends. A total of 31 resident species of terrestrial and aquaticbirds were recorded during the present survey. The mean abundance of the birds on each daywas 57. Both these values were lower than that reported in previous surveys. It wasnoteworthy though is the re-colonization of some species such as the spot-billed pelican, piedking fisher, white ibis, and the grey heron. It is likely that the major reasons for the lowabundance of birds at present is the absence of riparian vegetation and trees along the banksof the lagoon, which were cleared (but replanted since) during the process of restoration.

The improvement of the water quality of the lagoon over the six years post restorationindicates that these efforts have been successful. It appears that it is too premature to arrive atconclusions with regard to the bird community. But, with time, the re-establishment of thebank vegetation would very likely facilitate recolonization of a more diverse bioticcommunity.