The purpose of the following review is to help the Office for Environmental Protection (OEP) obtain a comprehensive understanding of the impact of hydromorphological changes and nutrient enrichment on river biodiversity in Northern Ireland (NI). It will further identify key evidence gaps within this area and provide recommendations for
future focus and action.
The Convention on Biological Diversity (CBD, 1992) defined biodiversity as: ‘The variability among living organisms from all sources, including inter-alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems”. As such, biodiversity refers to the wealth of all life on earth and the links between organisms, including their communities and the habitats which support them. This review focuses on biodiversity in the context of the riverine ecosystem in NI, studying the links between organisms and their habitats within this sphere, along with the key pressures they face. These have been identified as being primarily nutrient enrichment from Phosphorus (P) and Nitrogen (N),
along with hydromorphological modification (i.e. the effects of physical barriers and arterial drainage).
As such, the review presents the key drivers relating to biodiversity impairment and loss in river systems across NI, alongside their origins and evolution. The current state of the river environment is also presented, as documented through national monitoring programmes. Recommendations are subsequently made with regards to addressing these issues in order to protect and restore biodiversity in NI – and why that is so important – with gaps in evidence identified. This review should therefore be viewed as a contribution to the wider work associated with riverine habitats in NI.
With freshwater ecosystems amongst the most biodiverse – supporting more than 10% of all known species – they provide multiple benefits to humans, as well as to a wealth of plant and animal species. From being vital sources of drinking water to assisting with agriculture, irrigation, waste disposal and more, rivers add value to our lives and play a key role in society, both economically and socially. As a result, human settlements have historically been established close to rivers, which has subsequently put pressure on these ecosystems, with their resources exploited. This has created pollution ‘hotspots’ in the surrounding catchments, primarily due to urbanisation and agricultural land use, which has adversely affected the natural character of rivers and resulted in the loss of habitat, biodiversity and wider ecosystem services. These issues have been further compounded by climate and other human-dependant factors such as invasive species and both priority and emerging pollutants, like pesticides and pharmaceuticals.
With the main sources of nutrients within catchments attributed to wastewater, along with diffuse losses from agriculture – including small point sources like farmyards – this review therefore looks at these areas in detail. It presents key information on their impacts upon riverine biodiversity and what is required to manage these – for example, better nutrient source apportionment at catchment scale. Meanwhile, hydromorphological pressures such as flow modification, channelisation, connectivity and physical barriers along the river network are also addressed, along with poor riparian management and land drainage.
With insufficient consideration given to riverine biodiversity to date, this has impeded investment in appropriate policy and management measures, as exemplified through wastewater management in NI. This review therefore highlights the fact that the protection and restoration of ecological integrity and biodiversity requires an
acknowledgement of the holistic nature of rivers, integrating sound scientific principles with management perspectives and policy ambitions which promote sustainable environmental heterogeneity.
Ultimately, rivers are diverse ecosystems which offer an abundance of opportunities to society, as well as to the flora and fauna which live within the riverine environment. They have played a vital role in our culture throughout history and, in order to safeguard this valuable resource and ensure its future success, protecting and sustaining the biodiversity of rivers is of the utmost priority. This review therefore seeks to outline the key factors currently affecting riverine biodiversity – to enhance understanding within this area – and to act as a reference with regards to working towards positive solutions to protect it.