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RELEVANCE OF ROOTED VASCULAR PLANTS AS INDICATORS OF ESTUARINE SEDIMENT QUALITY
Lewis, M A., D. E. Weber, R S. Stanley, AND J C. Moore. RELEVANCE OF ROOTED VASCULAR PLANTS AS INDICATORS OF ESTUARINE SEDIMENT QUALITY. ARCHIVES OF CONTAMINATION AND TOXICOLOGY 40(1):25-34, (2001).
Toxicity assessments and numerical quality assessment guidelines for estuarine sediments are rarely based on information for aquatic plants. The effect of this lack of information on contaminated sediment evaluations is largely unknown. For this reason, the toxicities of whole sediments collected from 15 sites in three urbanized Florida bayou-estuaries were determined for the benthic invertebrates, Mysidopsis bahia, and Ampelisca abdita and Scirpus robustus Pursh (saltmarsh bulrush) and Spartina alterniflora Loisel (cordgrass). The results of the bioassays, conducted for 7 to 28 days, were compared for interspecific differences and to effects-based, sediment quality assessment guidelines. A variety of inorganic and organic analytes were detected in the estuarine sediments and concentrations of as many as seven analytes exceeded the sediment guidelines at 14 of the 15 sampling locations. Toxicity occurred at 2 of the 15 sampling stations based on invertebrate survival. Twelve of the 15 sediments had either a significant stimulatory or inhibitory effect on plant biomass relative to a reference sediment (P<0.05) The phytoresponse was specific to the location, test species and plant tissue. There was no consistent trend between the sensitivities of the plant and invertebrates exposed to the sediments collected from the same sites. Of the 12 sediments that significantly affected plant dry weight, 10 were not acutely toxic to the invertebrates. Consequently, the plant test species provided information that would have been missing if only animal test species were used. For this reason, the phytotoxicity data base needs to be increased for contaminated sediments to further evaluate these interspecific sensitivities, and to provide perspective on the environmental relevancy of current contaminated sediment evaluations and sediment quality assessment guidelines for which this information is usually missing. However, additional test method development and validation will be needed to support this effort by identifying sensitive plant test species, and response parameters and non-contaminant sediment factors that influence plant growth.