Effect of salinity on four freshwater macrophytes

James, Kimberley; Hart, BT

doi:10.1071/mf9930769

Cited by 39 publications

(26 citation statements)

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“…The sub-lethal responses to salinity are often characterized by reductions in plant biomass, height, flowering, shoot numbers, leaf proliferation, and leaf size. These effects may be apparent at salinities as low as 1000 mg l 1 (James and Hart, 1993). Leaf production is often slowed, and in some cases premature leaf senescence is induced (e.g.…”

Section: Available Australian Salinity Tolerance Data Knowledge Gapsmentioning

confidence: 97%

A review of groundwater–surface water interactions in arid/semi‐arid wetlands and the consequences of salinity for wetland ecology

2008

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In arid/semi-arid environments, where rainfall is seasonal, highly variable and significantly less than the evaporation rate, groundwater discharge can be a major component of the water and salt balance of a wetland, and hence a major determinant of wetland ecology. Under natural conditions, wetlands in arid/semi-arid zones occasionally experience periods of higher salinity as a consequence of the high evaporative conditions and the variability of inflows which provide dilution and flushing of the stored salt. However, due to the impacts of human population pressure and the associated changes in land use, surface water regulation, and water resource depletion, wetlands in arid/semi-arid environments are now often experiencing extended periods of high salinity. This article reviews the current knowledge of the role that groundwater-surface water (GW-SW) interactions play in the ecology of arid/semi-arid wetlands. The key findings of the review are as follows:1. GW-SW interactions in wetlands are highly dynamic, both temporally and spatially. Groundwater that is low in salinity has a beneficial impact on wetland ecology which can be diminished in dry periods when groundwater levels, and hence, inflows to wetlands are reduced or even cease. Conversely, if groundwater is saline, and inflows increase due to raised groundwater levels caused by factors such as land use change and river regulation, then this may have a detrimental impact on the ecology of a wetland and its surrounding areas. 2. GW-SW interactions in wetlands are mostly controlled by factors such as differences in head between the wetland surface water and groundwater, the local geomorphology of the wetland (in particular, the texture and chemistry of the wetland bed and banks), and the wetland and groundwater flow geometry. The GW-SW regime can be broadly classified into three types of flow regimes: (i) recharge-wetland loses surface water to the underlying aquifer; (ii) discharge-wetland gains water from the underlying aquifer; or (iii) flow-through-wetland gains water from the groundwater in some locations and loses it in others. However, it is important to note that individual wetlands may temporally change from one type to another depending on how the surface water levels in the wetland and the underlying groundwater levels change over time in response to climate, land use, and management. 3. The salinity in wetlands of arid/semi-arid environments will vary naturally due to high evaporative conditions, sporadic rainfall, groundwater inflows, and freshening after rains or floods. However, wetlands are often at particular risk of secondary salinity because their generally lower elevation in the landscape exposes them to increased saline groundwater inflows caused by rising water tables. Terminal wetlands are potentially at higher risk than flow-through systems as there is no salt removal mechanism. 4. Secondary salinity can impact on wetland biota through changes in both salinity and water regime, which result from the hydrological and hydrogeo...

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Section: Available Australian Salinity Tolerance Data Knowledge Gapsmentioning

confidence: 97%

A review of groundwater–surface water interactions in arid/semi‐arid wetlands and the consequences of salinity for wetland ecology

2008

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“…Thus, in A. germinans, soil salinity affected more the leaf length than the width, and resulted in oblong leaves at low salinity and round leaves at high salinity. Similarly, in Triglochin procera, an aquatic species tolerant to high salinity, salt caused a reduction in both length and width of the leaf, in such a way that its general morphology was altered (James and Hart 1993). Since the cellular expansion is more sensitive to low water potential than the cellular division (Meyer and Boyer 1972), it is possible that at high salinity the reduction in size and the changes in shape of A. germinans leaves are a consequence of limited cellular expansion rather than a decrease in the cellular division process.…”

Section: Individual Leaf Size and Growthmentioning

confidence: 97%

Salinity effect on plant growth and leaf demography of the mangrove, Avicennia germinans L.

Suárez

Medina

2005

Trees

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We assessed the effect of salinity on plant growth and leaf expansion rates, as well as the leaf life span and the dynamics of leaf production and mortality in seedlings of Avicennia germinans L. grown at 0, 170, 430, 680, and 940 mol m −3 NaCl. The relative growth rates (RGR) after 27 weeks reached a maximum (10.4 mg g −1 d −1 ) in 170 mol m −3 NaCl and decreased by 47 and 44% in plants grown at 680 and 940 mol m −3 NaCl. The relative leaf expansion rate (RLER) was maximal at 170 mol m −3 NaCl (120 cm m −2 d −1 ) and decreased by 57 and 52% in plants grown at 680 and 940 mol m −3 NaCl, respectively. In the same manner as RGR and RLER, the leaf production (P) and leaf death (D) decreased in 81 and 67% when salinity increased from 170 to 940 mol m −3 NaCl, respectively. Since the decrease in P with salinity was more pronounced than the decrease in D, the net accumulation of leaves per plant decreased with salinity. Additionally, an evident increase in annual mortality rates (λ) and death probability was observed with salinity. Leaf half-life (t 0.5 ) was 425 days in plants grown at 0 mol m −3 NaCl, and decreased to 75 days at 940 mol m −3 NaCl. Thus, increasing salinity caused an increase in mortality rate whereas production of new leaves and leaf longevity decreased and, finally, the leaf area was reduced.

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“…Physiological mechanisms that mitigate salt stress come at a cost of reduced growth, reproduction, and competitive ability (Munns and Tester 2008). Emergent and submerged freshwater vegetation may exhibit various sub-lethal responses to ionic stress, including a reduction in flowering, height, biomass, leaf proliferation, and size while displaying increased leaf burn, wilting, and chlorosis (James and Hart 1993).…”

Section: Wetland Biotamentioning

confidence: 99%

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

et al. 2015

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Abstract. Salinization, a widespread threat to the structure and ecological functioning of inland and coastal wetlands, is currently occurring at an unprecedented rate and geographic scale. The causes of salinization are diverse and include alterations to freshwater flows, land-clearance, irrigation, disposal of wastewater effluent, sea level rise, storm surges, and applications of de-icing salts. Climate change and anthropogenic modifications to the hydrologic cycle are expected to further increase the extent and severity of wetland salinization. Salinization alters the fundamental physicochemical nature of the soil-water environment, increasing ionic concentrations and altering chemical equilibria and mineral solubility. Increased concentrations of solutes, especially sulfate, alter the biogeochemical cycling of major elements including carbon, nitrogen, phosphorus, sulfur, iron, and silica. The effects of salinization on wetland biogeochemistry typically include decreased inorganic nitrogen removal (with implications for water quality and climate regulation), decreased carbon storage (with implications for climate regulation and wetland accretion), and increased generation of toxic sulfides (with implications for nutrient cycling and the health/functioning of wetland biota). Indeed, increased salt and sulfide concentrations induce physiological stress in wetland biota and ultimately can result in large shifts in wetland communities and their associated ecosystem functions. The productivity and composition of freshwater species assemblages will be highly altered, and there is a high potential for the disruption of existing interspecific interactions. Although there is a wealth of information on how salinization impacts individual ecosystem components, relatively few studies have addressed the complex and often non-linear feedbacks that determine ecosystem-scale responses or considered how wetland salinization will affect landscape-level processes. Although the salinization of wetlands may be unavoidable in many cases, these systems may also prove to be a fertile testing ground for broader ecological theories including (but not limited to): investigations into alternative stable states and tipping points, trophic cascades, disturbance-recovery processes, and the role of historical events and landscape context in driving community response to disturbance.

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Effect of salinity on four freshwater macrophytes

Cited by 39 publications

References 0 publications

A review of groundwater–surface water interactions in arid/semi‐arid wetlands and the consequences of salinity for wetland ecology

A review of groundwater–surface water interactions in arid/semi‐arid wetlands and the consequences of salinity for wetland ecology

Salinity effect on plant growth and leaf demography of the mangrove, Avicennia germinans L.

A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands

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