Biologists call for network of protected rivers

An international research team has used the Guadiana River basin, in which 92% of the species are under threat, as a reference point to measure the loss of aquatic biodiversity and its conservation value. A new study reveals that the state of fragmentation of Iberian river basins is 'seriously endangering' the freshwater fish that inhabit them, and highlights the need to create new protected aquatic reserves.

'At present, conservation of waterways is both insufficient and inefficient, as water courses within nature reserves are nearly always used simply as administrative boundaries that do not guarantee the conservation of aquatic biodiversity,' Virgilio Hemoso, chief author of the new study and a researcher at the University of Queensland, Australia, tells SINC.

The study, which has been published in the latest issue of Hydrobiologia, is based on the premise that there are few nature reserves for the conservation of aquatic biodiversity. 'Rivers have been treated as being of secondary importance, unless they represent an opportunity to conserve the land environment,' Hermoso adds.

To date, the criteria used to select protected areas have had 'nothing to do with conservation,' the scientist points out. Factors such as scenic value, lack of development, inaccessibility and low potential for commercial use are applied to select areas, resulting in 'conservation strategies focused on areas that are the easiest to protect and with the least need for short-term protection.'

In order to design a reserve system that protects aquatic biodiversity, the biologists evaluated the fish communities in the Guadiana River basin. With so few resources being devoted to conservation, and conservation itself competing with other human uses, the researcher stresses that 'it is more sensible to focus conservation efforts on water courses with healthy populations.'

In order to do this, the team measured potential biodiversity loss and calculated the conservation value. Their method highlights areas that have not suffered significant losses of biodiversity and which 'are therefore worthy of special attention.'

In the context of the Mediterranean, the Guadiana River basin stands out due to both its richness in freshwater fish species, 'which is only comparable to that found in two other river basins: the River Po in northern Italy and the River Orontes in southern Turkey,' and the degree to which it is threatened. 'This makes it an ideal place to hone tools and processes which could be applied to other Mediterranean river basins,' Hermoso states.

One of the main problems in the conservation of aquatic ecosystems is the lack of any evaluation of the biodiversity in areas under threat. Hermoso stresses: 'Given the high degree of fragmentation of Iberian river basins, we need new studies to analyse the importance of the best-conserved areas and to design a system of reserves to protect all the species.'

The team is now studying how to incorporate criteria relating to connectivity, ecological processes and the effects of climate change into the design of aquatic reserves. 'These aspects are essential in order to ensure our reserves are able to react to future changes and to consolidate the long-term survival of species,' Hermoso insists.

However, according to the scientist, 'the best-conserved areas are not necessarily representative, and do not cover the needs of all the species in the reserves, such as migratory species or those which live downstream, experiencing high stress levels in areas where conservation is poor.'

The biologists are in no doubt: incorporating degraded areas into the current aquatic reserve system would provide new opportunities for the conservation of biodiversity.