GLOBAL CHANGES IN PAMPEAN LOWLAND STREAM (ARGENTINA): IMPLICATIONS FOR BIODIVERSITY AND FUNCTIONING

RODRIGUES CAPÍTULO, A.; GÓMEZ, N.; GIORGI, A.; FEIJOO, C.

HYDROBIOLOGIA

SPRINGER

Lugar: Bruselas; Año: 2010 p. 53 - 70

0018-8158

The rivers and streams in the pampeanplains are characterized by a low flow rate due to thelow slope of the surrounding terrain, high levels ofsuspended solids, silty sediment in the benthos, andreduced rithron; the riparian forest of this region hasbeen replaced by low-altitude grasslands. Many ofthese environments contain a wide coverage of aquaticreeds, both submerged and floating, making thepampas limologically extraordinary. These terrainshave undergone a gradual transformation in responseto the progress of urbanization and agricultural activityin recent years with a resulting loss of biodiversity,leaving only few sites that continue to reflect theoriginal characteristics of the region. Because ofhuman activities in combination with the globalclimate change, variations have occurred in biologicalcommunities that are reflected in the structure andfunction of populations and assemblages of algae,macrophytes, and invertebrate fauna or in the eutrophicationof affected ecosystems. The objective of thisarticle is to describe the principal limnologic characteristicsof the streams that traverse the Buenos AiresProvince and relate these features with the predictedfuture global changes for the area under study.Considering the future climate-change scenarios proposedfor the pampean region, the projected incrementin rainfall will affect the biological communities.Higher rainfall may enhance the erosion and generatefloodings; increasing the transport of sediments, nutrients,and contaminants to the ocean and affecting thedegree of water mineralization. Changes in dischargeand turbidity may affect light penetration in the watercolumn as well as its residence time. The modificationsin the use of the soil will probably favor the input ofnutrients. This latter effect will favor autotrophy,particularly by those species capable of generatingstrategies for surviving in more turbid and enrichedenvironments. An accelerated eutrophication willchange the composition of the consumers in preferenceto herbivores and detritivores. The increase in globalpopulation projected for the next years will demandmore food, and this situation coupled with the new scenarios of climate change will lead to profoundsocioeconomic changes in the pampean area, implyingan increase in demand for water resources and landuses.Keywords Pampean streams Biotic communitiesFisico-chemical Primary and secondary producersLandscape