Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Potential threats to benthic macroinvertebrate fauna in Lake Ohrid watershed: water pollution and alien species.

Abstract

Two of the key pressures and drivers of biodiversity loss in the aquatic ecosystems are the excessive nutrient load and pollution and the invasive alien species. The aims of our study were to assess the ecological status of the water based on the composition and structure of benthic macroinvertebrate community and to examine the occurrence of alien macrozoobenthic species in the littoral of Lake Ohrid and its watershed. The study was conducted in Lake Ohrid littoral area, six tributaries and the Crni Drim River, in 2013. A total of 79 taxa were recorded. The highest number of taxa (52%) belonged to Insecta, which was presented mostly in the tributaries, followed by Gastropoda (20%), presented in the lake littoral. All taxa were native, there was no any alien species recorded either in the lake or in its tributaries and outflow. The most abundant were the representatives of lower indicative value to pollution, such as Tubifex tubifex, Chironomus plumosus, and Gammarus roeseli. The ecological status of the lake littoral sites was significantly lower (bad and poor) in comparison with that of the sites along the tributaries (from poor to very good) and the Crni Drim River (good). These results may indicate a general decrease in the stability and functionality of the lake ecosystem, which would consequently reduce its natural resilience and resistance capacity against introduction and spread of invasive alien species.