You are here:
DREDGING IMPACT ON AN URBANIZED FLORIDA BAYOU: EFFECTS ON BENTHOS AND ALGAL-PERIPHYTON.
Citation:
Lewis, M A., D. E. Weber, R S. Stanley, AND J C. Moore. DREDGING IMPACT ON AN URBANIZED FLORIDA BAYOU: EFFECTS ON BENTHOS AND ALGAL-PERIPHYTON. ENVIRONMENTAL POLLUTION 115(2):161-171, (2001).
Description:
Environmental effects of dredging events have been uncommonly reported for shallow, residential estuaries characteristic of the Gulf of Mexico region. The objective of this study was to determine the impact of hydraulic dredging on an urbanized estuary. Physicochemical quality, benthic community composition, whole sediment toxicity, periphytic algal community composition and tissue quality were determined prior to and after dredging. The effects on surface water pH, dissolved oxygen, and temperature were negligible but photosynthetically active radiation was decreased at several stations.Dredging significantly reduced benthic diversity and density (P<0.05). However, the sediments were not acutely toxic to the epibenthic, Americamysis bahia (formerly Mysidopsis bahia); survival averaged 93% (post-dredging) relative to 98% (pre-dredging). There were several taxonomic structural changes in the diatom-dominated, periphyton community after dredging but post-dredging changes in mean density and three diversity indices were not significant (P>0.05). Eight months after dredging, trace metal bioresidues were reduced from an average of 4 to 65% but the only statistcally significant reduction was for mercury (P<0.05). It was concluded that the environmental impact of small-scale dredging events in urbanized near-coastal areas are likely to be localized and of short-term environmental consequence. The choice of the biota and response parameters are important considerations in the outcome of environmental assessment for dredging events.