Zooplankton diversity of a protected and vulnerable wetland system in southern South America (Llancanelo area, Argentina)

D Sabina D’Ambrosio,Adriana García,María C Claps

doi:10.1007/s40071-016-0125-2

Abstract

In arid regions, climatic conditions exert a great control on the aquatic systems present, but recent changes in climate have produced an enhanced salinization of the aquatic environments located there. Consequently, a major reduction in biodiversity would be expected in those wetlands that were originally fresh water. Salinity is a principal cause of reduced biodiversity particularly in zooplankton because few of those species can adapt to the salt pressure of saline environments. Therefore, the aim of this study was to gain essential information on the diversity of aquatic invertebrates in Llancanelo basin by focussing the analysis on the zooplankton community and exploring seasonal and spatial differences in the zooplankton assemblages of this vulnerable wetland system within an arid region of Argentina. Seasonal samples were taken at nine sites in the basin (a shallow lake, 4 springs, streams, and the Malargue River). A total of 45 species were identified. The zooplankton abundance in the lake displayed a clear seasonal contrast and was higher than that recorded in the springs and lotic environments. Boeckella poopoensis, Fabrea salina, and Brachionus plicatilis predominated in the lake, indicating their halophilia. The presence of the crustaceans Alona sp., Macrocyclops albidus, and Paracyclops fimbriatus was restricted to the springs; whereas Notholca labis and Notholca squamula were found only in running water. The zooplankton species richness in the Llancanelo area is low because of both the salt content in the lake and the irregularity of freshwater entry in all locations during the annual cycle.

Highlights

In arid regions, climatic conditions exert a great control on the aquatic systems present, but recent changes in climate have produced an enhanced salinization of the aquatic environments located there
In the particular instance of zooplankton, investigations in semi-arid and arid regions of the world have far been limited (Shiel et al 2006); though in the last decade the studies performed in China (Wen et al 2005), in Australia (Timms 2009), in Chile (De los Rıos 2005; De los Rıos and Contreras 2005; De los Rıos Escalante and Gajardo 2010), and in the pampean region of Argentina (Echaniz et al 2006; Vignatti et al 2007; Battauz et al 2013) can be mentioned, among others
The number of species registered in the Llancanelo Lake in this work coincides with previous findings from shallow lakes of the Puna region of this country (Locascio de Mitrovich et al 2005) and from the saline lakes of Chile (De los Rıos and Contreras 2005)

Summary

Introduction

Climatic conditions exert a great control on the aquatic systems present, but recent changes in climate have produced an enhanced salinization of the aquatic environments located there. In Argentina, these effects would be even more pronounced in those systems lying within the so-called arid diagonal (Bruniard 1982)—it being surrounded by contrasting climatic and phytogeographic regions both to the south and to the north In this arid zone, rainfall is usually low and global warming has recently led to a consequent decrease in snowfall and a gradual decline in the glaciers constituting the main source of water for the aquatic environments. Rainfall is usually low and global warming has recently led to a consequent decrease in snowfall and a gradual decline in the glaciers constituting the main source of water for the aquatic environments In recent decades, these wetlands have been retracting, partly because of that decline in snowfall and as a result of the variation in precipitation in general owing to the interannual or periodical fluctuations caused by the El-Nino-SouthernOscillation (ENSO) phenomenon (Isla et al 2005). Other relevant impacts on the area have been the diversion of water for irrigation, the exploitation of oil reserves around the lake, fishing, and the introduction of exotic species that undermine the continuity of sustainability in the diagonal (Ramsar 2002)

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