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  • 1
    Language: English
    In: The Science of the Total Environment, April 15, 2013, Vol.450-451, p.92(16)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.scitotenv.2013.01.096 Byline: David Kaiser, Daniela Unger, Guanglong Qiu, Haolang Zhou, Huayang Gan Keywords: Macro-tides; Anthropogenic impact; Long-term trend; Flushing; Nutrient pollution; River export Abstract: Global understanding of land-ocean nutrient fluxes increasingly recognizes the disproportionate importance of small rivers. We studied nutrient fluxes from a small catchment in fast developing southern China to uncover effects of land-use. Water was sampled in the macro-tidal estuary of Nanliu River and adjacent Lianzhou Bay in spring and summer of investigate spatial and temporal variations of dissolved nutrients. High riverine concentrations of nitrate (NO.sub.3; up to 220[mu]M) and phosphate (PO.sub.4; up to 3.7[mu]M) mainly originated from agricultural fertilizer input. Riverine dissolved silica (Si; up to 47[mu]M) increased in the oligosaline part of the estuary through human disturbance of bottom sediments. Dissolved organic nitrogen (DON; up to 194[mu]M) and ammonium (NH.sub.4; up to 40[mu]M) concentrations increased within the estuary due to inputs from livestock and mussel beds, respectively. Aquaculture ponds contained high concentrations of NH.sub.4 (up to 355[mu]M) and DON (up to 151[mu]M) but are not an important source to the estuary due to rare wastewater discharge and low absolute nutrient amounts relative to river export. Nutrient concentrations in Lianzhou Bay were low because tidal currents disperse land-derived nutrients offshore into the adjacent Beibu Gulf. A high proportion of regenerated nitrogen in the bay suggests that primary production is sustained by rapid in situ nutrient cycling between primary producers and benthic consumers. High nutrient export makes the Nanliu River an important nutrient source for the north-western South China Sea, despite its proportionately small size. Macro-tide induced short-term concentration changes exceed variability on seasonal and sub-seasonal scales. All nutrients vary inter-annually and between seasons, depending on precipitation-driven river runoff. Total nutrient export to Beibu Gulf coastal waters is stronger during the high discharge period in summer and autumn. In recent years changing nitrogen to phosphorus ratios have alleviated phosphorus limitation in Lianzhou Bay, permitting increased primary productivity. Article History: Received 12 November 2012; Revised 28 January 2013; Accepted 28 January 2013
    Keywords: Ponds ; Rivers ; Fertilizers ; Rain ; Livestock ; Tidal Currents ; Phosphates ; Estuaries
    ISSN: 0048-9697
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, Feb 1, 2013, Vol.371, p.119(17)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2012.12.024 Byline: Lina P. Mergulhao, M.V.S. Guptha, Daniela Unger, V.S.N. Murty Keywords: Coccolithophores; Bay of Bengal; Sediment traps; Upwelling; Monsoon; Dissolution Abstract: A study on coccolithophores from the sediment trap samples, collected over a period of one year (January 1992-December 1992) from three trap locations in the Bay of Bengal (BOB) were used to understand their production and export processes in relation to diverse oceanographic regimes associated with the reversing monsoons. A total of 25 species of coccolithophores were identified, which include some of the ecologically important species: viz: Gephyrocapsa oceanica, Umbilicosphaera sibogae, Florisphaera profunda, Umbellosphaera irregularis, Emiliania huxleyi, Oolithotus antillarum, U. tenuis, Helicosphaera carteri and Calcidiscus leptoporus. The total coccolithophore fluxes increased from the northern to southern Bay of Bengal where G. oceanica, U. sibogae and E. huxleyi were dominant species displaying seasonality with peak fluxes occurring during southwest (SW) and northeast (NE) monsoons reflecting their affinity for nutrient-rich waters brought in by river plumes, divergences and cyclonic eddies. U. irregularis, an indicator of oligotrophic/warm water, recorded peak abundance fluxes only during the spring intermonsoon period at all trap locations thus inferring its preference for oligotrophic conditions caused by increased Sea Surface Temperature (SST), stratification and lack of nutrient supply due to weak wind velocities. The deep dwelling species, F. profunda recorded high fluxes during the fall intermonsoon (October/November) in the northern and southern traps during the spring intermonsoon. The peak fluxes observed during the spring intermonsoon (April/May) in the central and southern traps indicated the prevalence of a deep nutricline when oligotrophic conditions prevailed at the surface. The interannual variability of coccolithophore assemblages between the years 1992 and 1994 may be attributed to the prevalence of ENSO (El Nino-Southern Oscillation) and negative IOD (Indian Ocean Dipole) during 1992 and moderate ENSO and positive IOD with different ocean dynamics in 1994. Interestingly, dissolution was encountered as evidenced by the presence of corroded coccoliths. Similarly, mechanical breakage of coccoliths was also observed. It is believed that the biologically mediated processes were the main factors responsible for both the dissolution and mechanical breakage of coccoliths. Article History: Received 22 August 2012; Revised 5 December 2012; Accepted 18 December 2012
    Keywords: Sediments (Geology) ; El Nino ; Coccoliths
    ISSN: 0031-0182
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Marine Ecology Progress Series, 2013, Vol.478, pp.71-86
    Description: ABSTRACT: Despite the enormous growth in aquaculture in recent years, little is known of the impact of effluents from large-scale pond agglomerations on tropical coastal ecosystems. The aim of the present study was to evaluate the dispersal and ecological impact of effluents...
    ISSN: 01718630
    E-ISSN: 16161599
    Source: JSTOR Sustainability
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  • 4
    Language: English
    In: Science of the total environment, 2013, Vol.450, pp.92-107
    Description: Global understanding of land–ocean nutrient fluxes increasingly recognizes the disproportionate importance of small rivers. We studied nutrient fluxes from a small catchment in fast developing southern China to uncover effects of land-use. Water was sampled in the macro-tidal estuary of Nanliu River and adjacent Lianzhou Bay in spring and summer of investigate spatial and temporal variations of dissolved nutrients. High riverine concentrations of nitrate (NO₃; up to 220μM) and phosphate (PO₄; up to 3.7μM) mainly originated from agricultural fertilizer input. Riverine dissolved silica (Si; up to 47μM) increased in the oligosaline part of the estuary through human disturbance of bottom sediments. Dissolved organic nitrogen (DON; up to 194μM) and ammonium (NH₄; up to 40μM) concentrations increased within the estuary due to inputs from livestock and mussel beds, respectively. Aquaculture ponds contained high concentrations of NH₄ (up to 355μM) and DON (up to 151μM) but are not an important source to the estuary due to rare wastewater discharge and low absolute nutrient amounts relative to river export. Nutrient concentrations in Lianzhou Bay were low because tidal currents disperse land-derived nutrients offshore into the adjacent Beibu Gulf. A high proportion of regenerated nitrogen in the bay suggests that primary production is sustained by rapid in situ nutrient cycling between primary producers and benthic consumers. High nutrient export makes the Nanliu River an important nutrient source for the north-western South China Sea, despite its proportionately small size. Macro-tide induced short-term concentration changes exceed variability on seasonal and sub-seasonal scales. All nutrients vary inter-annually and between seasons, depending on precipitation-driven river runoff. Total nutrient export to Beibu Gulf coastal waters is stronger during the high discharge period in summer and autumn. In recent years changing nitrogen to phosphorus ratios have alleviated phosphorus limitation in Lianzhou Bay, permitting increased primary productivity. ; p. 92-107.
    Keywords: Fertilizers ; Watersheds ; Trophic Relationships ; Spring ; Nitrogen ; Biogeochemical Cycles ; Estuaries ; Autumn ; Silica ; Sediments ; Dissolved Organic Nitrogen ; Nutrient Transport ; Seasonal Variation ; Mussels ; Nitrates ; Phosphorus ; Primary Productivity ; Humans ; Phosphates ; Rivers ; Nutrient Content ; Livestock ; Tides ; Nutrients ; Ponds ; Runoff ; Summer ; Coastal Water
    ISSN: 0048-9697
    Source: AGRIS (Food and Agriculture Organization of the United Nations)
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  • 5
    Language: English
    In: Science of the Total Environment, 15 April 2013, Vol.450-451, pp.92-107
    Description: Global understanding of land–ocean nutrient fluxes increasingly recognizes the disproportionate importance of small rivers. We studied nutrient fluxes from a small catchment in fast developing southern China to uncover effects of land-use. Water was sampled in the macro-tidal estuary of Nanliu River and adjacent Lianzhou Bay in spring and summer of investigate spatial and temporal variations of dissolved nutrients. High riverine concentrations of nitrate (NO ; up to 220 μM) and phosphate (PO ; up to 3.7 μM) mainly originated from agricultural fertilizer input. Riverine dissolved silica (Si; up to 47 μM) increased in the oligosaline part of the estuary through human disturbance of bottom sediments. Dissolved organic nitrogen (DON; up to 194 μM) and ammonium (NH ; up to 40 μM) concentrations increased within the estuary due to inputs from livestock and mussel beds, respectively. Aquaculture ponds contained high concentrations of NH (up to 355 μM) and DON (up to 151 μM) but are not an important source to the estuary due to rare wastewater discharge and low absolute nutrient amounts relative to river export. Nutrient concentrations in Lianzhou Bay were low because tidal currents disperse land-derived nutrients offshore into the adjacent Beibu Gulf. A high proportion of regenerated nitrogen in the bay suggests that primary production is sustained by rapid in situ nutrient cycling between primary producers and benthic consumers. High nutrient export makes the Nanliu River an important nutrient source for the north-western South China Sea, despite its proportionately small size. Macro-tide induced short-term concentration changes exceed variability on seasonal and sub-seasonal scales. All nutrients vary inter-annually and between seasons, depending on precipitation-driven river runoff. Total nutrient export to Beibu Gulf coastal waters is stronger during the high discharge period in summer and autumn. In recent years changing nitrogen to phosphorus ratios have alleviated phosphorus limitation in Lianzhou Bay, permitting increased primary productivity. ► Small catchments supply high proportion of nutrients to north western South China Sea. ► Hinterland and offshore sources, not intensive aquaculture, dominate nitrogen input. ► Marcotides prevent near-shore eutrophication by dispersing human nutrient inputs. ► Long-term changes in nutrient delivery increased coastal productivity.
    Keywords: Macro-Tides ; Anthropogenic Impact ; Long-Term Trend ; Flushing ; Nutrient Pollution ; River Export ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 6
    Language: English
    In: Palaeogeography, Palaeoclimatology, Palaeoecology, 01 February 2013, Vol.371, pp.119-135
    Description: A study on coccolithophores from the sediment trap samples, collected over a period of one year (January 1992–December 1992) from three trap locations in the Bay of Bengal (BOB) were used to understand their production and export processes in relation to diverse oceanographic regimes associated with the reversing monsoons. A total of 25 species of coccolithophores were identified, which include some of the ecologically important species: viz: , , , , , , , and . The total coccolithophore fluxes increased from the northern to southern Bay of Bengal where , and were dominant species displaying seasonality with peak fluxes occurring during southwest (SW) and northeast (NE) monsoons reflecting their affinity for nutrient-rich waters brought in by river plumes, divergences and cyclonic eddies. , an indicator of oligotrophic/warm water, recorded peak abundance fluxes only during the spring intermonsoon period at all trap locations thus inferring its preference for oligotrophic conditions caused by increased Sea Surface Temperature (SST), stratification and lack of nutrient supply due to weak wind velocities. The deep dwelling species, recorded high fluxes during the fall intermonsoon (October/November) in the northern and southern traps during the spring intermonsoon. The peak fluxes observed during the spring intermonsoon (April/May) in the central and southern traps indicated the prevalence of a deep nutricline when oligotrophic conditions prevailed at the surface. The interannual variability of coccolithophore assemblages between the years 1992 and 1994 may be attributed to the prevalence of ENSO (El Nino–Southern Oscillation) and negative IOD (Indian Ocean Dipole) during 1992 and moderate ENSO and positive IOD with different ocean dynamics in 1994. Interestingly, dissolution was encountered as evidenced by the presence of corroded coccoliths. Similarly, mechanical breakage of coccoliths was also observed. It is believed that the biologically mediated processes were the main factors responsible for both the dissolution and mechanical breakage of coccoliths. ► Coccolithophores in the sediment traps from the Bay of Bengal were investigated. , and were dominant species displaying seasonality. ► recorded high fluxes during the fall and spring intermonsoons. ► The interannual variability attributed to different ocean dynamics in 1992 and 1994. ► Mechanical breakage and dissolution of coccoliths resulted by biological processes.
    Keywords: Coccolithophores ; Bay of Bengal ; Sediment Traps ; Upwelling ; Monsoon ; Dissolution ; Geology
    ISSN: 0031-0182
    E-ISSN: 1872-616X
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  • 7
    Language: English
    In: Marine Pollution Bulletin, 15 August 2014, Vol.85(1), pp.190-203
    Description: The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ N in seagrass leaves and epiphytes (6–9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.
    Keywords: Mixed Seagrass Meadows ; Pond Aquaculture ; Eutrophication ; Epiphytes ; Nitrogen and Sulphur Stable Isotopes ; Biodiversity ; Environmental Sciences ; Oceanography
    ISSN: 0025-326X
    E-ISSN: 1879-3363
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  • 8
    Language: English
    In: Continental Shelf Research, April 1, 2013, Vol.57, p.44(15)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.csr.2012.02.014 Byline: Daniela Unger (a), Lucia S. Herbeck (a), Min Li (a), Hongyan Bao (b), Ying Wu (b), Jing Zhang (b), Tim Jennerjahn (a) Keywords: Suspended particulate matter; Amino acids; Hexosamines; Mangrove; Stable carbon isotopes; Wenchang/Wenjiao Estuary Abstract: The small tropical Wenchang and Wenjiao Rivers on the island of Hainan, tropical China, are affected by effluents from municipal sewage, aquaculture and agriculture, and by contrasting hydrological regimes related to monsoon and tropical storms. In order to obtain information on the sources, transformation and fate of organic matter (OM) we investigated the amount and composition of amino acids and hexosamines as well as the carbon isotope composition in suspended particulate matter (SPM) from the Wenchang/Wenjiao Estuary. SPM was collected along the salinity gradient starting from the river sites, along the lagoon-shaped Bamen Bay to coastal waters during four sampling campaigns between 2006 and 2009. SPM concentrations ranged between 4.7 and 58.2mgL.sup.-1. Apart from highest values after heavy rain events in spring and summer, SPM showed little seasonal variation, but increased with salinity. From SPM POC% (1.2-20.9%), C/N (4.9-16.5) and [delta].sup.13C.sub.org (-31.5 to -19.5a[degrees]), the molar composition and content of amino acids and hexosamines (8.2-156.2mgg.sup.-1 dry weight) and by comparison with sediments, mangroves, soils and plants we are able to show that soil-derived material, freshwater and marine plankton were the major sources of suspended OM. High POC and amino acid contents were related to primary production sustained by dissolved nutrients to a large extent stemming from municipal and aquaculture effluents. Factor analysis showed that the suite of biogeochemical parameters measured clearly depict the terrestrial vs. marine origin and the freshness/reactivity of OM. The four groups of samples resulting from cluster analysis were basically related to varying hydrological regimes. With respect to the sources, degradation and fate of particulate OM the major factors were: (i) the year round input of labile, amino acid rich riverine OM matter at the freshwater dominated sites, (ii) high input of degraded soil OM after heavy rains with dispersal throughout the estuary and export to the adjacent coastal area, (iii) significant production of labile marine OM especially during summer inside the bay and the (iv) dominance of refractory marine OM during winter and spring season and in the offshore region. While a major part of the fresh OM fuelled by anthropogenic nutrients appears to be stored or recycled inside the bay, periodic torrential rainfalls can lead to a pulsed export of this OM to the coastal area where it may adversely affect seagrass meadows and coral reefs. Author Affiliation: (a) Leibniz-Zentrum fur Marine Tropenokologie GmbH (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany (b) State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 Zhongshan Road North, Shanghai 200062, PR China Article History: Received 2 May 2011; Revised 2 December 2011; Accepted 23 February 2012
    Keywords: Reefs -- Analysis ; Rivers -- Analysis ; Amino Acids -- Analysis ; Storms -- Analysis ; Estuaries -- Analysis ; Hydrology -- Analysis ; Air Pollution -- Analysis
    ISSN: 0278-4343
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Continental Shelf Research, July 1, 2014, Vol.82, p.99(20)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.csr.2014.04.006 Byline: David Kaiser, Daniela Unger, Guanglong Qiu Abstract: Estuarine particle fluxes are an integral part of land-ocean-connectivity and influence coastal environmental conditions. In areas with strong anthropogenic impact they may contribute to coastal eutrophication. To investigate the particulate biogeochemistry of a human affected estuary, we sampled suspended, sedimentary and plant particulate matter along the land-ocean continuum from Nanliu River to Lianzhou Bay in southern China. Riverine particle fluxes exceed inputs from land based pond aquaculture. Elemental (C/N) and isotopic composition of particulate organic carbon ([delta].sup.13C) and total nitrogen ([delta].sup.15N) showed that suspended and sedimentary organic matter (OM) mainly derive from freshwater and marine phytoplankton, with minor contributions from terrestrial and aquaculture derived particles. Amino acid composition indicates subseasonal variability of production and freshness of phytoplankton OM. Strongest compositional changes of suspended particles are associated with storm-related extreme precipitation events, which introduce soil derived OM. High concentrations of chlorophyll a reflect eutrophic conditions in riverine and coastal waters. Human impact results in high [delta].sup.15N signals in suspended, sedimentary and plant particulate matter. Using these in a comparison with two little affected sites shows that anthropogenic influence disperses from the Nanliu River to remote estuaries and mangrove areas. Our results suggest that autochthonous production binds anthropogenic nutrients in particles that are transported along the coast. Author Affiliation: (a) Wetland Dynamics Group, Biogeochemistry & Geology Department, Leibniz Center for Tropical Marine Ecology, D-28359 Bremen, Fahrenheitstr. 6-8, Germany (b) Guangxi Mangrove Research Center, Guangxi Marine Environment & Coastal Wetland Research Center, Beihai 536000, 92 Chang Qing Dong Lu, Guangxi, China (c) State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing 100085, 18 Shuangqing Lu, Haidian District, China Article History: Received 6 July 2013; Revised 2 April 2014; Accepted 7 April 2014
    Keywords: Chlorophyll -- Analysis ; Biogeochemistry -- Analysis ; Rain -- Analysis ; Estuaries -- Analysis ; Eutrophication -- Analysis ; Air Pollution -- Analysis
    ISSN: 0278-4343
    Source: Cengage Learning, Inc.
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  • 10
    Language: English
    In: Continental Shelf Research, April 1, 2013, Vol.57, p.92(13)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.csr.2012.05.006 Byline: Lucia S. Herbeck (a), Daniela Unger (a), Ying Wu (b), Tim C. Jennerjahn (a) Keywords: Aquaculture; Shrimp and fish ponds; Nutrient export; Back-reef area; Eutrophication; Hainan Abstract: Global aquaculture has grown at a rate of 8.7% per year since 1970. Particularly along the coasts of tropical Asia, aquaculture ponds have expanded rapidly at the expense of natural wetlands. The objectives of this study were (i) to characterize the extent and production process of brackish-water pond aquaculture at the NE coast of Hainan, tropical China, (ii) to quantify effluent and organic carbon, nitrogen and phosphorus export from shrimp and fish ponds and (iii) to trace their effect on the water quality in adjacent estuarine and nearshore coastal waters harboring seagrass meadows and coral reefs. During two expeditions in 2008 and 2009, we determined dissolved inorganic nutrients, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), chlorophyll a (chl a) and particulate organic matter (POM) in aquaculture ponds, drainage channels and coastal waters in three areas varying in extent of aquaculture ponds. From the analysis of satellite images we calculated a total of 39.6kmA[sup.2] covered by shrimp and fish ponds in the study area. According to pond owners, there is no standardized production pattern for feeding management and water exchange. Nutrient and suspended matter concentrations were high in aquaculture ponds and drainage channels, but varied considerably. The calculated annual export of total dissolved nitrogen (TDN) and particulate nitrogen (PN) from pond aquaculture into coastal waters was 612 and 680tyr.sup.-1, respectively. High concentrations of dissolved inorganic nitrogen (DIN), phosphate and chl a at the majority of the coastal stations point at eutrophication of coastal waters, especially close to shore. Coastal eutrophication driven by the introduction of untreated aquaculture effluents may be especially harmful in back-reef areas, where estuarine retention and mixing with open ocean water is restricted thus threatening seagrasses and corals. Author Affiliation: (a) Leibniz-Zentrum fur Marine Tropenokologie (ZMT) GmbH, Fahrenheitstr. 6, 28359 Bremen, Germany (b) State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 North Zhongshan Road, 200062 Shanghai, PR China Article History: Received 21 September 2011; Revised 28 March 2012; Accepted 8 May 2012
    Keywords: Ponds -- Analysis ; Chlorophyll -- Analysis ; Coral Reefs -- Analysis ; Corals -- Analysis ; Seafood Industry -- International Trade ; Seafood Industry -- Analysis ; Air Pollution -- Analysis ; Phosphates -- International Trade ; Phosphates -- Analysis ; Estuaries -- Analysis ; Eutrophication -- Analysis
    ISSN: 0278-4343
    Source: Cengage Learning, Inc.
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