Urbanisation living has resulted in massive changes

Urbanisation is one of the most pervasive ways in which humans have altered the global environment. The global shift from rural to urban living has been rapid with the world’s urban population increasing from 746 million in 1950 to 3.9 billion in 2014 (UN, 2014). In 2007 the global urban population exceeded the global rural population for the first time and the world’s population has remained predominantly urban since. Today 54 per cent of the world’s population resides in urban areas and this number is set to increase to 66 per cent by 2050, with the majority of the increase occurring in Asia and Africa (UN, 2014).Although urban areas only account for 2 per cent of the earth’s land surface, they have been shown to have large environmental impacts. For example, Folke et al. found that more than 78 per cent of global greenhouse gases were produced by urban areas. The rapid shift from rural to urban living has resulted in massive changes in land use that have affected the surrounding environment, particularly stream ecosystems (Paul & Meyer, 2001). “Urban streams are common features of the modern landscape that have received inadequate ecological attention” (Paul & Meyer, 2001).Urbanisation has been shown to have detrimental effects on stream ecology and water quality due to pollutants generated by a number of sources including agriculture, industry, transport and domestic dwellings that have the potential to enter a stream through various pathways (European Environment Agency, 2010). This range of pollutants can include industrial and household chemicals, metals, nutrients and pesticides. Rivers and streams are particularly vulnerable to the effects of urbanisation due to their unidirectional nature as any pollutants entering the system have the potential to have damaging effects further downstream (Moyo & Rapatsa, 2016). Another result of urbanisation that can have an impact on streams is the increase in impermeable land cover which has led to increased runoff from urban surfaces flowing into streams, particularly during storm events (Paul & Meyer, 2001). As previously mentioned, the shift from rural to urban living within the last number of decades has been rapid and man made impermeable surfaces are now the predominant type of land use in place of natural land cover (Luo et al., 2017; Schütte & Schulze, 2017). Runoff from these impermeable surfaces results in pollutants such as nutrients, metals and pesticides flowing into streams. These pollutants have been shown to result in consistent declines in the richness of algal, invertebrate and fish communities in urban streams (Paul & Meyer, 2001). Although the ecological impacts of urbanisation have not been as thoroughly studied as the chemical effects, quite a lot of information is known about the effects of urbanisation on macroinvertebrates (Paul & Meyer, 2001). Their sensitivity to pollution and limited mobility make them useful for assessing the health of a stream ecosystem. The use of macroinvertebrates for biomonitoring of streams is widespread and a number of ecological indices have been developed to assess the impacts of human activities on streams (Luo et al., 2017).Dalu et al. noted that biomonitoring using macroinvertebrates is best performed using species-level identification but due to financial and expertise-related constraints this is not always possible. Therefore, taxon-level identification of macroinvertebrates is regularly used to assess the ecological state of streams. Urbanisation has been shown to put pressure on freshwater ecosystems (Grizzetti et al., 2017) and the European Union has implemented legislation to combat this problem. The Water Framework directive (WFD) has been described as the “single most important piece of EU legislation relating to the quality of fresh and coastal waters” (European Environmental Agency, 2010). The WFD aims to reduce these anthropogenic pressures and achieve a good ecological status for all water bodies. Under the WFD, EU member states are required to assess the quality of the water bodies in their country and take appropriate action to improve the quality where necessary (Grizzetti et al., 2017).As an EU member state, Ireland is required to comply with the Water Framework Directive and assess the quality of its streams and rivers. The aim of this study was to assess the ecological status of the Tramore stream in Cork City and investigate if urbanisation has impacted the quality of this stream.