Salinity impacts on river ecosystem processes: a critical mini-review

Abstract

In many dry parts of the world, salinization of water resources threatens freshwater biodiversity and the livelihood of people. However, ecological impact studies remain scarce. Here, we review field-observations of salinity impacts on ecosystem processes such as leaf decomposition, metabolism, biomass production and nutrient cycling, with a special emphasis on dryland ecosystems. In addition, we discuss the potential linkages of these processes to ecosystem service delivery-the benefits that humans derive from ecosystems-as additional nature conservation arguments and the challenges associated with this endeavour.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Keywords: desert rivers; ecosystem functions; freshwater management; salinization.

Figure 1.

(a) Relationship between conductivity and organic matter breakdown rates (R² = 0.43, p < 0.001). Data are combined from four case studies (different symbols) published in three papers [39,41,45], n = 57. Breakdown rates per degree day were standardized relative to the breakdown rate determined at a conductivity of approximately 1700 µS cm⁻¹, which was a level occurring across all studies. (b) Difference in the mean % leaf mass loss relative to a low salinity control level from controlled mesocsom experiments [39,43,44]. Different symbols denote different salt types used to achieve experimental conductivity levels; circle with plus sign, NaCl; filled square, sea salt; times, NaHCO₃.