Influence of multiple stressors on the auto-remediation processes occurring in salt marshes     

Sousa AI  Lillebø AI  Pardal MA  Caçador I 《Marine pollution bulletin》2011,62(7):1584-1587

Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni - micronutrients, and Cd - class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health.  相似文献   

Seasonal nitrogen and phosphorus dynamics during benthic clam and suspended mussel cultivation   总被引：1，自引：0，他引：1  

Nizzoli D  Welsh DT  Viaroli P 《Marine pollution bulletin》2011,62(6):1276-1287

Effects of suspended mussel and infaunal clam cultivation on sediment characteristics, and benthic organic and inorganic nitrogen and phosphorus fluxes were compared in a shallow coastal lagoon. The two species had different impacts on sediment features, but both created “hotspots” of nutrient fluxes with annual N and P regeneration rates being 4.9 and 13.5 (mussel) and 4.5 and 14.9 (clams) fold greater than those of unfarmed control sediments. Mussel farming also caused considerable nutrient regeneration within the water column with the mussel ropes contributing ∼25% of total inorganic N and P production and at times dominating the sediments (e.g. 95% of SRP production in summer and 45% of DIN production in winter). Such nutrient regeneration rates seriously question the proposal that suspension-feeding bivalves act as a eutrophication buffer, especially during summer when nutrient regeneration rates are maximal, but other nutrient sources (freshwater run-off and unfarmed sediments) are at their lowest.  相似文献   

Effect of eutrophication on molluscan community composition in the Lake Dianchi (China, Yunnan)   总被引：4，自引：0，他引：4  

Li-Na Du  Yuan Li  Xiao-Yong Chen  Jun-Xing Yang 《Limnologica》2011,41(3):213-219

In this paper, three historical biodiversity datasets (from 1940s, 1980–1999 and 2000–2004) and results from the recent inventory are used to trace the long-term changes of the mollusks in the eutrophic Lake Dianchi. Comparison of the obtained results with those of earlier investigations performed during the period of 1940s and 1980–1999 as well as 2000–2004 showed that changes have occurred in the interval. There were 31 species and 2 sub-species recorded prior to the 1940s, but the species richness decreased from a high level of 83 species and 7 sub-species to 16 species and one sub-species from 1990s to the early of 21st century in lake body. Species from the genera of Kunmingia, Fenouilia, Paraprygula, Erhaia, Assiminea, Galba, Rhombuniopsis, Unionea and Aforpareysia were not found in Dianchi basin after 2000. The species from the genera Lithoglyphopsis, Tricula, Bithynia, Semisulcospira and Corbicula were only found in the springs and upstream rivers. Anoxia and the changing of substrates and fish species composition could explain why molluscan community composition changed in eutrophic Lake Dianchi. Additionally, the different sampling methods and ignore of the specific groups in earlier studies are cause for Sphaerium and Pisidium first found in our study. This study is first time to enlarge the investigation region to the Dianchi basin. Although some endemic species disappeared in the lake body, they still distribute in the springs and upstream rivers. The springs and upstream rivers are important refuges for mollusks.  相似文献   

Mussel farming as a nutrient reduction measure in the Baltic Sea: consideration of nutrient biogeochemical cycles   总被引：1，自引：0，他引：1  

Stadmark J  Conley DJ 《Marine pollution bulletin》2011,62(7):1385-1388

Nutrient loads from the land to the sea must be reduced to combat coastal eutrophication. It has been suggested that further mitigation efforts are needed in the brackish Baltic Sea to decrease nutrients, especially in eutrophic coastal areas. Mussel farming is a potential measure to remove nutrients directly from the sea. Mussels consume phytoplankton containing nitrogen (N) and phosphorus (P); when the mussels are harvested these nutrients are removed from the aquatic system. However, sedimentation of organic material in faeces and pseudo-faeces below a mussel farm consumes oxygen and can lead to hypoxic or even anoxic sediments causing an increased sediment release of ammonium and phosphate. Moreover, N losses from denitrification can be reduced due to low oxygen and reduced numbers of bioturbating organisms. To reveal if mussel farming is a cost-effective mitigation measure in the Baltic Sea the potential for enhanced sediment nutrient release must be assessed.  相似文献   

Paleolimnological evidence of mining and demographic impacts on Lac Dauriat, Schefferville (subarctic Québec, Canada)     

Laurence Laperrière  Marie-Andrée Fallu  Sonja Hausmann  Reinhard Pienitz  Derek Muir 《Journal of Paleolimnology》2008,40(1):309-324

Qualitative and quantitative analysis of fossil diatoms and geochemical signals preserved in the sediments of Lac Dauriat (subarctic Quebec) were performed to evaluate the impacts of nearby mining activity and the expansion of the town of Schefferville on the water quality of the lake, and to reconstruct the changes of its trophic status. The presence of taxa typical of nutrient-enriched environments (e.g., Cyclostephanos invisitatus, Nitzschia gracilis, Nitzschia perminuta) and the low percentages of chrysophytes were indicative of the advanced state of eutrophication of the lake during the peak of mining activity, and were evidence of the negative impacts of municipal waste on the water quality of Lac Dauriat. Sedimentary analysis of metals, notably lead, mercury, cadmium, bismuth, cobalt, copper and zinc, showed maximum concentrations between 1940 and 1960 with mining era to pre-development enrichment factors ranging from 4.5 to 7.9. The changes seen in recent sediments reflected 3 distinct stages in the recent history of this ecosystem: (a) the non-perturbed, pre-mining (1882–1939), (b) the perturbed, mining period (1939–1977) with accelerated eutrophication, and (c) the post-mining period (1977–1999) with indications of natural recovery of the system after the installation of a water treatment plant in 1975, the closing of the mine in 1983, and the subsequent exodus of the town’s population. Despite the trajectory towards a return to the lake’s natural conditions, water resource managers and (paleo-)limnologists should be alarmed that the impacts of past human disturbance are still in evidence more than 20 years after the closure of the mines, and that Lac Dauriat has yet to reach its natural state of the period preceding extreme anthropogenic impact.  相似文献   

Hydropower – A Green Energy? Tropical Reservoirs and Greenhouse Gas Emissions     

Günter Gunkel 《洁净——土壤、空气、水》2009,37(9):726-734

Reservoirs are man‐made lakes that severely impact on river ecosystems, and in addition, the new lake ecosystem can be damaged by several processes. Thus, the benefits of a reservoir, including energy production and flood control, must be measured against their impact on nature. New investigations point out that shallow and tropical reservoirs have high emission rates of the greenhouse gases CO₂ and CH₄. The methane emissions contribute strongly to climate change because CH₄ has a 25 times higher global warming potential than CO₂. The pathways for its production include ebullition, diffuse emission via the water‐air interface, and degassing in turbines and downstream of the reservoir in the spillway and the initial river stretch. Greenhouse gas emissions are promoted by a eutrophic state of the reservoir, and, with higher trophic levels, anaerobic conditions occur with the emission of CH₄. This means that a qualitative and quantitative jump in greenhouse gas emissions takes place. Available data from Petit Saut, French Guinea, provides a first quantification of these pathways. A simple evaluation of the global warming potential of a reservoir can be undertaken using the energy density, the ratio of the reservoir surface and the hydropower capacity; this parameter is mainly determined by the reservoir's morphometry but not by the hydropower capacity. Energy densities of some reservoirs are given and it is clearly seen that some reservoirs have a global warming potential higher than that of coal use for energy production.  相似文献   

Changes in the benthic macroinvertebrate fauna of a large microtidal estuary following extreme modifications aimed at reducing eutrophication   总被引：1，自引：0，他引：1  

M.D. Wildsmith  T.H. Rose  I.C. Potter  R.M. Warwick  K.R. Clarke  F.J. Valesini 《Marine pollution bulletin》2009,58(9):1250-1262

An artificial channel was opened in 1994 between the microtidal Peel–Harvey Estuary and the Indian Ocean to increase tidal exchange and thus ameliorate the problems of eutrophication. Although this greatly reduced macroalgal and cyanobacterial growths and the amount of particulate organic matter, our data indicate that, contrary to managerial expectations, the benthic environment has deteriorated. Thus, although macroinvertebrate density has declined as predicted, taxonomic distinctness (Δ^*) has also declined and species composition has become more variable. Macroinvertebrate composition has also changed markedly at the species, family and even phylum levels. The Crustacea, the most sensitive of the major macrobenthic taxa to environmental stress, has become proportionally less abundant and speciose, whereas the Polychaeta, the least sensitive, was unique in showing the reverse trend. The benthos of the Peel–Harvey Estuary is thus apparently more stressed than previously, probably due to the multiple effects of a great increase in system use.  相似文献   

Nitrogen stable isotope ratio in the manila clam, Ruditapes philippinarum, reflects eutrophication levels in tidal flats     

Satoshi Watanabe  Masashi Kodama 《Marine pollution bulletin》2009,58(10):1447-680

Understanding the effects of anthropogenic eutrophication on coastal fisheries may help in the enhancement of fishery production by effective utilization of sewage effluents, as well as in the consequent reduction of eutrophication. In this study, it was revealed that the nitrogen stable isotope ratio (δ¹⁵N) in the soft tissues of the manila clam, Ruditapes philippinarum, can be used as an indicator of anthropogenic eutrophication levels in tidal flat environments by investigation of δ¹⁵N in dissolved inorganic nitrogen (DIN), particulate organic matter (POM), sedimentary organic matter (SOM) and soft tissues of the clam in five tidal flats in Japan with different levels of DIN concentration. In addition, it was found that the acid insoluble fraction of the shell organic matrix, conchiolin, can be used as a proxy for the soft tissues in δ¹⁵N analyses. This will contribute in easier storage handling and the expansion of chances for sample acquisition.  相似文献   

Experimental and geochemical evidence for Δ7/Δ5 sterol ratios as indicators of trophic status in Lake Fuxian,a great lake in Yunnan Province,SW China     

《Limnologica》2016

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Spatial distribution and abundance of Unionidae mussels in a eutrophic floodplain lake     

《Limnologica》2016

Although Unionidae mussels produce large biomass and reach high density in freshwater habitats, little is known about their ecology. We studied the distribution of 5 species of freshwater unionids in a eutrophic floodplain lake, on transects, along the lake shore and across the depth gradient. The clam distribution within the water body was not random: all species form a crowded zone along the lake shore, showing the highest density at ca. 0.5 m depth. The distribution of the most numerous species changed along the shore in Anodonta anatina and Unio pictorum but not in A. cygnea, whose numbers remained constant. The population numbers of the most numerous species showed a positive correlation with silt layer thickness. The generalized model of all the analyzed factors influencing the unionids’ distribution confirmed this relation and indicated a trade-off between water depth and distance from bank, which might be responsible for the occurrence of the zone at some optimum depth. Unionids have an important influence on freshwater ecosystem functions, thus their zonation implies that their functions are also spatially structured.  相似文献