Foul play has been ruled out after about seven kilos of various fish were found dead in the marshland of il-Magħluq ta’ Marsaskala, following reports that individuals had been seen dumping in the area.
Speaking to Times of Malta, a spokesperson for Nature Trust Malta, which manages the site, said CCTV footage had not revealed any foul play and that the fish had likely died due to a lack of oxygen in the ponds.
Bodies of water can sometimes become too rich in nutrients, which results in a depletion of oxygen levels, a natural process that is known as eutrophication. When this occurs the water becomes too toxic for survival, causing the fish to die.
Nature Trust has since cleaned the ponds and removed the fish, which had clogged gills. Footage also indicated that the fish struggled to breathe before dying.
The NGO said that the site would soon be equipped with aerators to improve water circulation and increase oxygen in the water, particularly during the summer months when water loses its capacity to store oxygen.
However, Natura Trust said it has not been uncommon for live animals and litter to be dumped in the marshland, with employees having been faced with instances of dumping of non-native fish species, live ducks as well as innumerable large pieces of litter such as pushchairs and traffic cones.
Il-Magħluq is a protected Natura 2000 site and one of only two saline marshlands in the south of Malta where the Maltese killifish (bużaqq) is found.
Native killifish populations declined severely in the 1990s due to pollution and predators, however, a breeding programme in 2018 reintroduced about 500 fish back to the site.
The site was first built during the Knight’s period and was used for aquaculture purposes. Diverse populations of grey mullet, sea bass, sea bream and the freshwater eel live beneath the surface of the brackish waters. Fishing is not allowed at the site today, other than to manage fish populations.
Times of Malta last week reported that a Swiss study had Malta topping its chart for fragile biodiversity, with the majority of Malta’s ecosystems ranked as “comparatively fragile, with further use potentially accelerating a decline”.
Marine biologist Alan Deidun said that protected areas like Natura 2000 sites only made up some 13 per cent of the island’s terrestrial area and that even a small loss of protected area would denote a large percentage of biodiversity loss.