Rivers in peril inside and outside protected areas: a systematic approach to conservation assessment of river ecosystems

Abstract

This paper establishes a framework within which a rapid and pragmatic assessment of river ecosystems can be undertaken at a broad, subcontinental scale, highlighting some implications for achieving conservation of river biodiversity in water‐limited countries. The status of river ecosystems associated with main rivers in South Africa was assessed based on the extent to which each ecosystem had been altered from its natural condition. This requires consistent data on river integrity for the entire country, which was only available for main rivers; tributaries were thus excluded from the analyses. The state of main river ecosystems in South Africa is dire: 84% of the ecosystems are threatened, with a disturbing 54% critically endangered, 18% endangered, and 12% vulnerable. Protection levels were measured as the proportion of conservation target achieved within protected areas, where the conservation target was set as 20% of the total length of each river ecosystem. Sixteen of the 112 main river ecosystems are moderately to well represented within protected areas; the majority of the ecosystems have very low levels of representation, or are not represented at all within protected areas. Only 50% of rivers within protected areas are intact, but this is a higher proportion compared to rivers outside (28%), providing some of the first quantitative data on the positive role protected areas can play in conserving river ecosystems. This is also the first assessment of river ecosystems in South Africa to apply a similar approach to parallel assessments of terrestrial, marine, and estuarine ecosystems, and it revealed that main river ecosystems are in a critical state, far worse than terrestrial ecosystems. Ecosystem status is likely to differ with the inclusion of tributaries, since options may well exist for conserving critically endangered ecosystems in intact tributaries, which are generally less regulated than main rivers. This study highlights the importance of healthy tributaries for achieving river conservation targets, and the need for managing main rivers as conduits across the landscape to support ecological processes that depend on connectivity. We also highlight the need for a paradigm shift in the way protected areas are designated, as well as the need for integrated river basin management plans to include explicit conservation visions, targets, and strategies to ensure the conservation of freshwater ecosystems and the services they provide.

Addressing longitudinal connectivity in the systematic conservation planning of fresh waters

“…The most irreplaceable area and the best solution when setting the CP at high values were especially focused on a single subbasin (Chanza River). This solution highlights the importance of tributaries for conserving freshwater biodiversity (see Nel et al, 2007). The same area had previously C o p y f o r R e v i e w been included in a set of priority areas for conservation through an alternative method based on the reference condition approach (Hermoso et al, submitted).…”

“…Changing the relative emphasis on connectivity causes substantial changes in the spatial prioritisation; our conservation investment could move from one basin to another. (Allan & Flecker, 1993), and being exposed to higher pressures and threats than adjacent terrestrial ecosystems (Malmqvist & Rundle, 2002;Nel et al, 2007), freshwater ecosystems have received less attention by the conservation community (Abell, 2002).…”

Identifying priority areas for ecosystem service management in South African grasslands

“…Data on freshwater biodiversity priority areas consisted of an assessment of the condition and status of river types which Nel et al (2007) used to identify threatened river types. Freshwater priority areas were defined as intact tributaries of critically endangered river types within the grassland biomes (see Reyers et al, 2005).…”

Efetividade de Áreas Protegidas (APs) na conservação da qualidade das águas e biodiversidade aquática em sub-bacias de referência no rio das Velhas (MG)

“…Apesar disso, são capazes de proteger um nú-mero considerável de corpos d'água e, portanto, de grande importância para as espécies aquáticas (Agostinho et al, 2005). Estudando rios dentro e fora de áreas protegidas, Nel et al (2007) verificaram que, apesar de apenas 50% dos rios avaliados dentro das áreas protegidas manterem suas características ecológicas naturais bem preservadas, essa porcentagem é alta, quando comparada à de 28% dos rios localizados fora de áreas protegidas. Sistemas de água doce preservados são cada vez mais raros (Abell et al, 2007).…”