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Effects of Substrate Salinity on Early Seedling survival and Growth of Scirpus robustus Pursh and Spartina alterniflora Loisel
Citation:
Lewis, M A. AND D. E. Weber. Effects of Substrate Salinity on Early Seedling survival and Growth of Scirpus robustus Pursh and Spartina alterniflora Loisel. Ecotoxicology 11(1):19-26, (2002).
Impact/Purpose:
The objective of this study was to determine the toxicity of NaCl-amended sediments on early seedling survival and dry-weight biomass of Spartina alterniflora Loisel and Scirpus robustus Pursh
Description:
Rooted aquatic plants are being used increasingly as test species in estuarine sediment toxicity evaluations. Effects of naturally occurring substrate constituents on most potential test species however, are not well understood even though their effects could impact the data interpretation of these sediment phytotoxicity tests. The objective of this study was to determine the effect of substrate pore water salinity (NaCl) on early seedling survival and growth of the emergent macrophytes, Scirpus robustus Pursh and Spartina alterniflora Loisel. Results of these four 21 d and 28 d toxicity tests, conducted in an artificial sediment (5% organic matter), indicated interspecific differences in NaCl sensitivity when based on changes in shoot and root biomass. Concentrations greater than 10 g NaCl/R and 18 g NaCl/R and reduced biomass of S. robustus and S. alterniflora (P<0.05), respectively, when compared to plants grown in sediment containing no pore water salinity. In contrast to the reductions in biomass, seedling survival was relatively unaffected at the maximum average test concentrations of 20 g NaCl/R (S. robustus) and 23 g NaCl/R (S. alterniflora). Results of these seedling tests indicate that substrate salinity is an important consideration in the selection of test species for phytotoxicity tests. It is important to ensure that the salinity of estuarine sediments used in plant bioassays does not have an impact on the test species particularly if determination of chronic toxicity attributable to anthropogenic contamination is the objective.