Review of available data for a South African Inventory of Inland Aquatic Ecosystems (SAIIAE)

Review of available data for a South African Inventory of Inland Aquatic Ecosystems (SAIIAE) Heidi van Deventer1,2*, Lindie Smith-Adao1, Chantel Petersen1, Namhla Mbona3, Andrew Skowno3 and Jeanne L Nel4,5 Council for Scientific and Industrial Research (CSIR), PO Box 395, Pretoria 0001, South Africa School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa 3 South African National Biodiversity Institute, Private Bag x101, Pretoria, 0001, South Africa 4 Institute for Environmental Studies, Faculty of Science, Vrije Universiteit Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands 5 Sustainability Research Unit, Nelson Mandela University, Private Bag X6531, George 6530, South Africa 1 2 ABSTRACT The National Biodiversity Assessment of 2011 found freshwater ecosystems to be highly threatened and poorly protected. However, a number of studies have shown that the National Wetland Map (NWM) Version 4 represents less than 54% of wetlands mapped at a fine scale. A more comprehensive South African Inventory of Inland Aquatic Ecosystems (SAIIAE) would greatly improve the assessment of wetland ecosystem types and their condition and conservation status, and is crucial for monitoring trends to inform decision making and planning. In preparation for the third National Biodiversity Assessment of 2018, a review was undertaken to identify possible data sources that could contribute to the SAIIAE. The objectives of the study were to (i) assess which type of information is available for developing a SAIIAE; and (ii) list and understand the availability of fine-scale wetland data for updating the NWM. A variety of data related to species occurrence and distribution, extent and type of inland wetlands and rivers, as well as datasets which describe regional settings of inland aquatic ecosystems, were found across a number of institutions. Fine-scale spatial data amounted to more than double the extent of inland wetlands mapped by remote sensing at a country-wide scale. Nearly 5 million ha of fine-scale data were collected from a diverse number of institutions, with the majority (73%) of these data mapped by Government (3 681 503 ha or 3% of South Africa). It is estimated that < 8% of the sub-quaternary catchments of South Africa had complete wetland data sets, primarily in the Gauteng, Mpumalanga and Western Cape Provinces. Accuracy assessment reports and confidence ratings were however not consistently available for the wetland datasets. Inland wetlands in the majority of South Africa (84%) therefore remain poorly represented. We recommend future steps to improve the SAIIAE, including improving the representation of inland wetland ecosystem types and focusing on accuracy assessment. Keywords: wetland inventory, National Wetland Map, river/wetland ecosystem types, inland aquatic ecosystems, National Biodiversity Assessment INTRODUCTION South Africa is considered one of 17 megadiverse countries in the world (Mittermeier et al., 1997). The diversity of inland aquatic ecosystem types in South Africa, formerly referred to as ‘freshwater ecosystems’ are recognised in a framework for wetland types, titled the Classification System for Wetlands and other Aquatic Ecosystems in South Africa (Ollis et al., 2013; SANBI, 2009), which was implemented through the National Wetland Map (NWM) Version 4 (Nel et al., 2011). The biodiversity of river ecosystems of South Africa was first assessed in the National Spatial Biodiversity Assessment in 2004, while wetlands were included with the river ecosystems in the National Biodiversity Assessments (NBA) of 2011 (Driver et al., 2005; Nel et al., 2011; Driver et al., 2012). Inland aquatic ecosystems support a high diversity of aquatic species which provide direct benefits in the form of water, food, building material and medicine, as well as indirect benefits such as water filtration and flood control (Darwall et al., 2009; Kotze et al., 2009). Inland aquatic ecosystems in South Africa, as in many other countries, are however under threat from a * To whom all correspondence should be addressed.  +27 12 841 2507; Fax: +27 12 841 3909; e-mail: Received 25 August 2017; accepted in revised form 12 March 2018 http://dx.doi.org/10.4314/wsa.v44i2.05 Available on website http://www.wrc.org.za ISSN 1816-7950 (Online) = Water SA Vol. 44 No. 2 April 2018 Published under a Creative Commons Attribution Licence number of pressures, including an increased demand for water, urbanisation, changes in climatic conditions, and invasive species. The NBA of 2011 (NBA 2011) found inland aquatic ecosystems to be highly threatened and poorly protected, and therefore the accurate inventorying of inland aquatic ecosystems in South Africa is crucial for monitoring trends, and informing decision making and planning (Nel et al., 2011). The inventory of South African inland aquatic ecosystems has thus far focused only on the extent and types of rivers and wetlands, which is often referred to as a National Wetland Map. A wetland inventory is defined by Finlayson et al. (1999 p. 718) as ‘the collection and/or collation of core information for wetland management, including the provision of an information base for specific assessment and monitoring activities’. Whereas a wetland directory is considered to be a list of coordinates of wetland location and possibly type, an inventory would consist of core datasets which would support the typing of ecosystems, as well as additional information related to landuse, impacts, conservation and management (Finlayson et al., 1999). A wetland inventory therefore encompasses more information than the extent and type of wetland ecosystems, which are generally included in a wetland map. The first directories of inland wetlands of South Africa date to the early 1970s and of rivers to the 1980s (Noble and Hemens, 1978; O’Keeffe, 1986). A more comprehensive inventory of priority wetlands was undertaken for the 184 KwaZulu-Natal Province, mapping as far as possible the historical extent and pressures on these systems (Begg, 1988). The study showed that 58% of wetlands in the Mfolozi catchment had been altered or lost, reducing the extent of wetlands from 5% to 2.1% of the surface area of the catchment. Subsequent to these initial efforts, the Department of Environmental Affairs and Tourism compiled a directory of wetland types in 1998 (Cowan and Van Riet, 1998). Efforts to update these initial wetland directories extended to mapping the spatial extent of rivers and inland wetlands at a national scale for the NBAs, and formalising the framework for the Classification System. South Africa defines an aquatic ecosystem as ‘an ecosystem that is permanently or periodically inundated by flowing or standing water, or which has soils that are permanently or periodically saturated within 0.5 m of the soil surface’ (Ollis et al., 2013:1). Three broad systems are recognised, incl (...truncated)