Effects of Salinity on Growth of Several Aquatic Macrophytes

Abstract

PURPOSE: The research reported herein investigated the effects of a range of lime (as calcium hydroxide; Ca(OH) 2) dosage levels on the growth of Sago pondweed in outdoor experimental mesocosms. BACKGROUND: Lime (CaCO 3 and Ca(OH) 2) application has been used primarily as a lake rehabilitation technique for limiting algal growth by controlling phosphorus availability in the water column and its release from the sediment (Prepas et al. 1990). At supersaturated concentrations, calcium co-precipitates with phosphorus and settles from the water column. As a deposited layer on the sediment, it can adsorb additional phosphorus (at pH > 8), preventing it from diffusing into the water column for algal uptake. More recently, researchers have found that lime additions can suppress submersed macrophyte growth as well (Babin et al. 1992, Chambers et al. 2001, Prepas et al. 2001). However, the mode of growth suppression, dosage levels, and exposure time requirements are not entirely known. Since lime application drives the pH upward, it may stress macrophyte metabolic activities by inducing inorganic carbon limitation for photosynthesis in hardwater systems. Lime additions to aquatic systems at varying concentrations have not resulted in clear macrophyte community responses. For instance, single dosages of lime at modest concentration levels (<110 mg Ca L-) to hardwater lakes were accompanied by control of macrophyte biomass (species) for over a year (Reedyk et al. 2001). However, Chambers et al. (2001) indicated that exposure time, in addition to concentration, might be important in the control of macrophytes in aquatic systems located in the Canadian Great Plains. These findings suggest that lime application may be a very promising technique for integrated control of both macrophyte and algal production in eutrophic hardwater systems. More information is needed regarding the mode of action, dosage requirements, and impacts on different aquatic macrophyte species in order to develop sound integrated management and control strategies using lime.

Nutrient removal by floating aquatic macrophytes cultured in anaerobically digested flushed dairy manure wastewater

“…These symptoms are similar to those described by Haller et al (1974) in a study conducted on the effect of salinity on growth of aquatic macrophytes. Haller et al (1974) reported toxic effects in water lettuce and water hyacinth when these plants were exposed to diluted seawater with salt concentrations of 1660 and 2500 mg/kg, respectively.…”

“…These symptoms are similar to those described by Haller et al (1974) in a study conducted on the effect of salinity on growth of aquatic macrophytes. Haller et al (1974) reported toxic effects in water lettuce and water hyacinth when these plants were exposed to diluted seawater with salt concentrations of 1660 and 2500 mg/kg, respectively. Since a common measure of salinity is EC, an EC level was estimated for these figures using a conversion factor of 1000 mg/kg = 1616 S/cm, calculated from values given by Haller et al (1974).…”

“…Haller et al (1974) reported toxic effects in water lettuce and water hyacinth when these plants were exposed to diluted seawater with salt concentrations of 1660 and 2500 mg/kg, respectively. Since a common measure of salinity is EC, an EC level was estimated for these figures using a conversion factor of 1000 mg/kg = 1616 S/cm, calculated from values given by Haller et al (1974). The calculations give a conductivity of 2683 S/cm as a toxic level for water lettuce and 4040 S/cm for water hyacinth.…”

Unexpected resurgence of a large submersed plant bed in Chesapeake Bay: Analysis of time series data

“…From 2007 to 2009, biweekly to monthly water quality data were available for several additional locations around Susquehanna Flats, including inside the SAV bed and down-bay from the SAV bed. Salinity was not included in this analysis because values in and around the plant bed were generally , 1.0, well within the tolerance range of the dominant submersed plant species populating the study site (Haller et al 1974). Susquehanna River flow rates were measured at gauging stations located at Conowingo Dam (1968 to present) and at Harrisburg, Pennsylvania (1890 to present).…”

A Conceptual Model of the Aquatic Food Web of the Upper San Francisco Estuary

“…Other species may be more readily constrained by salinity. The aquatic plants E. densa and E. crassipes are limited to the mostly freshwater region east of Browns Island (Haller et al 1974;Hauenstein and Ramirez 1986). …”