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H L Rees - One of the best experts on this subject based on the ideXlab platform.
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the effects of marine gravel extraction on the macrobenthos results 2 years post dredging
Marine Pollution Bulletin, 1996Co-Authors: Andrew Kenny, H L ReesAbstract:Abstract An offshore experimental dredging study was initiated off North Norfolk (UK) in 1992 to investigate the impacts of marine gravel extraction on the macrofauna. A dredged ‘treatment’ and a non-dredged ‘reference’ site were selected to evaluate the initial impacts and subsequent processes of recolonization. A survey of the benthos was conducted prior to the removal of 50 000 t of marine aggregate from the treatment site. Thereafter annual monitoring surveys were conducted commencing immediately after the dredging episode. Results indicated that whilst the dominant species recolonized quickly following dredging many rarer species did not. Evidence from sidescan sonar records and underwater cameras indicated a considerable amount of sediment transport during the first two winters following dredging and the once well-defined dredge tracks have now become infilled with sand and gravel. The substantially reduced biomass at the treatment site some 24 months after dredging is thought to be due to a local increase in sediment disturbance caused by tide and wave action over the winter period. Finally, the biological findings of this study are discussed in relation to their wider environmental significance.
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the effects of marine gravel extraction on the macrobenthos early post dredging recolonization
Marine Pollution Bulletin, 1994Co-Authors: Andrew Kenny, H L ReesAbstract:Abstract A small area of sea bed off the English east coast was experimentally dredged by a commercial suction-trailer Dredger. Some 50 000 t of mixed aggregate were removed, representing about 70% of the sea bed area down to an average depth of 0.3 m. Results from benthic surveys undertaken at the experimental site and at a nearby reference site, indicate that significant reductions had occurred in the variety, abundance and biomass of benthic organisms as a consequence of dredging. Subsequent recolonization of dunuded substrates by the dominant taxa proceeded relatively rapidly, although the dredged site had clearly not fully recovered some 7 months later. Differences in the recruitment success of the dominant taxa, notably Dendrodoa grossularia and Balanus crenatus, between the reference and treatment sites pre- and post-dredging were observed. Possible explanations for these differences in relation to the observed physical alterations to the sea bed are discussed.
Andrew Kenny - One of the best experts on this subject based on the ideXlab platform.
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the effects of marine gravel extraction on the macrobenthos results 2 years post dredging
Marine Pollution Bulletin, 1996Co-Authors: Andrew Kenny, H L ReesAbstract:Abstract An offshore experimental dredging study was initiated off North Norfolk (UK) in 1992 to investigate the impacts of marine gravel extraction on the macrofauna. A dredged ‘treatment’ and a non-dredged ‘reference’ site were selected to evaluate the initial impacts and subsequent processes of recolonization. A survey of the benthos was conducted prior to the removal of 50 000 t of marine aggregate from the treatment site. Thereafter annual monitoring surveys were conducted commencing immediately after the dredging episode. Results indicated that whilst the dominant species recolonized quickly following dredging many rarer species did not. Evidence from sidescan sonar records and underwater cameras indicated a considerable amount of sediment transport during the first two winters following dredging and the once well-defined dredge tracks have now become infilled with sand and gravel. The substantially reduced biomass at the treatment site some 24 months after dredging is thought to be due to a local increase in sediment disturbance caused by tide and wave action over the winter period. Finally, the biological findings of this study are discussed in relation to their wider environmental significance.
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the effects of marine gravel extraction on the macrobenthos early post dredging recolonization
Marine Pollution Bulletin, 1994Co-Authors: Andrew Kenny, H L ReesAbstract:Abstract A small area of sea bed off the English east coast was experimentally dredged by a commercial suction-trailer Dredger. Some 50 000 t of mixed aggregate were removed, representing about 70% of the sea bed area down to an average depth of 0.3 m. Results from benthic surveys undertaken at the experimental site and at a nearby reference site, indicate that significant reductions had occurred in the variety, abundance and biomass of benthic organisms as a consequence of dredging. Subsequent recolonization of dunuded substrates by the dominant taxa proceeded relatively rapidly, although the dredged site had clearly not fully recovered some 7 months later. Differences in the recruitment success of the dominant taxa, notably Dendrodoa grossularia and Balanus crenatus, between the reference and treatment sites pre- and post-dredging were observed. Possible explanations for these differences in relation to the observed physical alterations to the sea bed are discussed.
Gilbert C Sigua - One of the best experts on this subject based on the ideXlab platform.
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recycling biosolids and lake dredged materials to pasture based animal agriculture alternative nutrient sources for forage productivity and sustainability a review
Agronomy for Sustainable Development, 2009Co-Authors: Gilbert C SiguaAbstract:Domestic sewage sludge or biosolids and lake-dredged materials are examples of materials that can be used to cut fertilizer costs in pasture-based animal agriculture. Sustainable biosolids and lake-dredged materials management is based upon controlling and influencing the quantity, quality and characteristics of these materials in such a way that negative impacts to the environment are avoided and beneficial uses are optimized. This article examines the following two key questions. Is the use of these materials in an agricultural setting harmless and sensible? Is the use of biosolids secure in all climates, in all soils and is it sustainable over the long term? Recycling biosolids and lake-dredged materials to pasture-based animal production is quite productive as alternative nutrient sources for forage production. Perennial grass can be a good choice for repeated applications of biosolids and lake-dredged materials. Although biosolids and lake-dredged materials supply some essential plant nutrients and provide soil property-enhancing organic matter, land-application programs still generate some concerns because of possible health and environmental risks involved. Repeated applications of biosolids and lake-dredged materials indicate no harmful effects on soil quality and forage quality. Beneficial uses of biosolids and lake-dredged materials are both economical and environmental. The concentrations of soil nitrogen and phosphorus following repeated application of biosolids were far below the contamination risk in the environment. The residual effect of biosolids over the long term can be especially significant in many forage-based pastures where only 50% of the million hectares of pastures are given inorganic nitrogen yearly. Long-term studies have demonstrated the favorable and beneficial effects of added lake-dredged materials on the early establishment of bahiagrass in sandy pasture fields. Often these materials can be obtained at little or no cost to the farmers or landowners. Lake-dredged materials can be used as soil amendments (lime and fertilizer) for early establishment of bahiagrass in beef cattle pastures. Bahiagrass in plots that were treated with biosolids and lake-dredge materials had significantly higher forage yield and crude protein content when compared with those bahiagrass in the control plots or untreated plants.
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land application of lake dredged materials for bahiagrass establishment in the subtropical beef pasture
Journal of Soils and Sediments, 2003Co-Authors: Gilbert C Sigua, Mike L Holtkamp, John M Linton, S W ColemanAbstract:The continued need to dredge lakes, rivers, and canals in Florida, both for maintenance and environmental improvement, will produce millions of cubic meters of dredged materials. Productive disposal options of lake-dredged materials (LDM) may provide substantial and intangible benefits that will enhance the environment, community, and society. The objective of this study was to assess lake-dredged materials from Lake Panasoffkee as soil amendment for early establishment of bahiagrass (BG,Paspalum notatum Flugge) in subtropical beef cattle pasture at Sumter County, Florida. Results and Discussion. This study encompassed two phases: Phase 1 comprised of five small observation plots (0.3 x 0.3 m); Phase 2 consisted of five larger test plots (30.5 x 30.5 m). Each of the plots in Phase 1 and Phase 2 had a different ratio LDM to natural soil (NS): Plot 1 (0% LDM + 100% NS); Plot 2 (25% LDM + 75% NS); Plot 3 (50% LDM + 50% NS); Plot 4 (75% LDM + 25% NS); and Plot 5 (100% LDM + 0% NS). Each plot was seeded with BG and early growth and yield establishment were monitored for 16 weeks. Results disclosed significantly taller (p ≤ 0.001) plants and higher biomass production (p ≤ 0.001) of BG from plots amended with 75% LDM than those of BG planted on plots with 0% LDM. Results suggest that LDM can serve as source of lime and fertilizer to establish BG beef pasture fields. Sediments with high CaCO3 improved the physical and chemical conditions of subtropical beef pastures. Lake-dredged materials could be removed from the spoil containment areas, trucked to other locations, and incorporated into existing fields for agricultural uses. There is still much to be learned, but it is certain that Lake Panasoffkee sediments should be regarded as a resource, with no observed harmful ecological effects. The agricultural or livestock industry could utilize these LDM to produce forages. LDM should be regarded as a beneficial resource, as a part of the ecological system. This study has been continued for several years to explore and assess the long term efficacy of LDM on productivity and quality of BG beyond its early establishment stage.
L J Seiderer - One of the best experts on this subject based on the ideXlab platform.
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impacts of aggregate dredging on sediment composition and associated benthic fauna at an offshore dredge site in the southern north sea
Marine Environmental Research, 2005Co-Authors: J E Robinson, R C Newell, L J Seiderer, N M SimpsonAbstract:Dredging and associated screening at a dredge site in the southern North Sea (Area 408) is associated with areas of well-sorted fine sand that extend for up to 3 km to the south-east of the dredged area and overlay sediments with a more variable particle size composition. This well-sorted fine sand may reflect deposition and transport of material mobilised by the dredging and screening processes at the dredge site. Multivariate analysis of the benthic community structure suggests that marine aggregate dredging, at the level of intensity employed in the study area prior to sample collection, has had a limited impact on benthic community composition compared with that reported from studies elsewhere. This is ascribed to the likely rapid rates of recolonisation by the mobile opportunistic polychaetes and crustaceans that dominate the macrofauna of the sandy gravel deposits at this particular dredge site. Analysis of variance showed, however, that significant differences existed between the sample treatments in terms of species evenness (Pielou's J). Dredged samples were found to have the lowest mean species evenness (0.71) when compared to controls (0.77). The present study highlights the inherent difficulties in the application of general impact/recovery predictions to dredged sites with varying environmental characteristics.
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impacts of marine aggregate dredging on benthic macrofauna off the south coast of the united kingdom
Journal of Coastal Research, 2004Co-Authors: R C Newell, L J Seiderer, N M Simpson, J E RobinsonAbstract:Abstract A survey of benthic macrofauna in the vicinity of a coastal marine aggregate dredging site off the south coast of UK was carried out in 1999. The object of the survey was to determine impact of marine aggregate dredging on community composition, the extent of impact outside the boundaries of the dredge site, and the rate of recolonization and recovery of the fauna following cessation of dredging. Part of the site was intensively dredged by vessels at anchor whilst other parts were less intensively exploited by trailer Dredger. The impact of dredging within the intensively exploited anchor dredge site was limited to the dredged area. Impacts included a suppression of species variety, population density and biomass, as well as differences in species composition compared with the surrounding deposits. In contrast, trailer dredging had no impact on community composition of macrofauna within the dredge site. No suppression of benthic community structure was recorded beyond 100 m from the dredge site. ...
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organic enrichment associated with outwash from marine aggregates dredging a probable explanation for surface sheens and enhanced benthic production in the vicinity of dredging operations
Marine Pollution Bulletin, 1999Co-Authors: R C Newell, D R Hitchcock, L J SeidererAbstract:Abstract Most recent studies of dispersion of sediment plumes generated by marine aggregates dredging, including those reported here, suggest that the zone of settlement of fine material temporarily suspended by the dredging and screening process is smaller than estimates based on Gaussian diffusion models. There is, however, often a relatively larger zone of visible impact which can extend for several kilometres downstream from a Dredger during normal loading operations. This paper presents evidence which suggests that the “far field” visibility of the dispersing plume is associated with organic enrichment derived from fragmented marine benthos discharged with the outwash water. The values which we have recorded for unexploited deposits off Southwold, Suffolk are as high as 1.454 g/l AFDW(ash-free dry weight) of which 0.007 g/l (0.48%) comprises lipids. Such material appears to be of sufficient concentration to match the likely removal of benthos from the sediments by the dredgehead. Even allowing for the dispersion which must occur downstream from the Dredger, it seems likely that the organic enrichment derived from fragmented invertebrates in the Dredger outwash may account for the enhanced species diversity and population density of benthic invertebrates recorded by others beyond the boundaries of dredged areas.
R C Newell - One of the best experts on this subject based on the ideXlab platform.
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impacts of aggregate dredging on sediment composition and associated benthic fauna at an offshore dredge site in the southern north sea
Marine Environmental Research, 2005Co-Authors: J E Robinson, R C Newell, L J Seiderer, N M SimpsonAbstract:Dredging and associated screening at a dredge site in the southern North Sea (Area 408) is associated with areas of well-sorted fine sand that extend for up to 3 km to the south-east of the dredged area and overlay sediments with a more variable particle size composition. This well-sorted fine sand may reflect deposition and transport of material mobilised by the dredging and screening processes at the dredge site. Multivariate analysis of the benthic community structure suggests that marine aggregate dredging, at the level of intensity employed in the study area prior to sample collection, has had a limited impact on benthic community composition compared with that reported from studies elsewhere. This is ascribed to the likely rapid rates of recolonisation by the mobile opportunistic polychaetes and crustaceans that dominate the macrofauna of the sandy gravel deposits at this particular dredge site. Analysis of variance showed, however, that significant differences existed between the sample treatments in terms of species evenness (Pielou's J). Dredged samples were found to have the lowest mean species evenness (0.71) when compared to controls (0.77). The present study highlights the inherent difficulties in the application of general impact/recovery predictions to dredged sites with varying environmental characteristics.
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impacts of marine aggregate dredging on benthic macrofauna off the south coast of the united kingdom
Journal of Coastal Research, 2004Co-Authors: R C Newell, L J Seiderer, N M Simpson, J E RobinsonAbstract:Abstract A survey of benthic macrofauna in the vicinity of a coastal marine aggregate dredging site off the south coast of UK was carried out in 1999. The object of the survey was to determine impact of marine aggregate dredging on community composition, the extent of impact outside the boundaries of the dredge site, and the rate of recolonization and recovery of the fauna following cessation of dredging. Part of the site was intensively dredged by vessels at anchor whilst other parts were less intensively exploited by trailer Dredger. The impact of dredging within the intensively exploited anchor dredge site was limited to the dredged area. Impacts included a suppression of species variety, population density and biomass, as well as differences in species composition compared with the surrounding deposits. In contrast, trailer dredging had no impact on community composition of macrofauna within the dredge site. No suppression of benthic community structure was recorded beyond 100 m from the dredge site. ...
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organic enrichment associated with outwash from marine aggregates dredging a probable explanation for surface sheens and enhanced benthic production in the vicinity of dredging operations
Marine Pollution Bulletin, 1999Co-Authors: R C Newell, D R Hitchcock, L J SeidererAbstract:Abstract Most recent studies of dispersion of sediment plumes generated by marine aggregates dredging, including those reported here, suggest that the zone of settlement of fine material temporarily suspended by the dredging and screening process is smaller than estimates based on Gaussian diffusion models. There is, however, often a relatively larger zone of visible impact which can extend for several kilometres downstream from a Dredger during normal loading operations. This paper presents evidence which suggests that the “far field” visibility of the dispersing plume is associated with organic enrichment derived from fragmented marine benthos discharged with the outwash water. The values which we have recorded for unexploited deposits off Southwold, Suffolk are as high as 1.454 g/l AFDW(ash-free dry weight) of which 0.007 g/l (0.48%) comprises lipids. Such material appears to be of sufficient concentration to match the likely removal of benthos from the sediments by the dredgehead. Even allowing for the dispersion which must occur downstream from the Dredger, it seems likely that the organic enrichment derived from fragmented invertebrates in the Dredger outwash may account for the enhanced species diversity and population density of benthic invertebrates recorded by others beyond the boundaries of dredged areas.
