Habitat context influences nitrogen removal by restored oyster reefs

Like many ecosystem functions in marine and terrestrial environments, nutrient processing varies dramatically over small spatial scales, making efforts to apply findings within and across ecosystems challenging. In estuaries, information on the influence of habitat context on sediment nutrient cycling is lacking even though this is an important estuarine function with high societal value. We collected triplicate intact sediment cores from restored oyster reefs located in different habitat contexts (adjacent to salt marshes, seagrass beds and mudflats), as well as salt marshes, seagrass beds and mudflats without reefs (controls). Sediment denitrification and fluxes of dissolved inorganic nitrogen were measured under ambient and experimentally elevated water column nitrate levels. Under ambient nitrate, oyster reefs enhanced sediment denitrification by 18-275% over the controls, with highest rates of denitrification in the mudflat context. With experimentally elevated nitrate, the rate of denitrification was higher for oyster reefs compared to the controls in all contexts. This suggests that oyster reefs prime sediments to denitrify nitrate pulses by providing a labile carbon source for denitrifying bacteria. There was a weak positive relationship between oyster density and denitrification under ambient nitrate concentrations and a positive relationship with denitrification that became negative beyond approximate to 2400 individuals m(-2) with elevated nitrate concentrations. The effect of the oyster reef on sediment denitrification was most pronounced in the mudflat context, due to the absence of other structured habitats and higher oyster density, compared to the other two habitat contexts investigated. The consistency of denitrification efficiency across the habitats and lack of difference between habitats with reefs and those without (controls) suggest oyster-mediated denitrification is an effective sink for nitrogen in coastal systems.Synthesis and applications. Our study indicates that oyster-mediated denitrification is dependent on the habitat context of the oyster reef, and variation in oyster density and the relative functional redundancy of oyster reefs where other structured habitats exist (e.g. seagrass and salt marshes) may explain this pattern. Efforts to model and predict ecosystem services provided through oyster reef restoration such as the removal of anthropogenically derived nitrogen should incorporate how habitat context influences ecosystem functions. Our study indicates that oyster-mediated denitrification is dependent on the habitat context of the oyster reef, and variation in oyster density and the relative functional redundancy of oyster reefs where other structured habitats exist (e.g. seagrass and salt marshes) may explain this pattern. Efforts to model and predict ecosystem services provided through oyster reef restoration such as the removal of anthropogenically derived nitrogen should incorporate how habitat context influences ecosystem functions

In search of tools for the use of Country-Image (CI) in the brand

Existing country image (CI) literature tends to focus on consumer behaviour. In contrast, this paper approaches CI from the point of view of the firm. In doing so, it seeks to identify the means by which international companies associate a brand with a specific country of origin in order to build brand values. In particular, it looks at the use of CI cues in brand strategies. The paper is based on exploratory research comprising a case study of two contrasting companies from the cosmetics industry, Natura, a domestic company, and the French-owned L’Occitane, both of which draw on images of Brazil to build their brands. Specific elements of CI used in branding are identified, and the extent to which the use of these differs depending on the origin of the owning company is explored. The cases suggest that CI can be exploited in different contexts. Through analysis of the elements used by both companies to build strong brands associated with the Brazilian CI—Natura Cosméticos and L’Occitane au Brésil—six tools are identified that can be combined by firms to deliver brand values, derived from any country, through the use of CI

Oyster-mediated benthic-pelagic coupling modifies nitrogen pools and processes

Removal of nitrogen through enhanced denitrification has been identified as an ecosystem service provided by oysters. In this study, we assessed the effects of an individual oyster (Crassostrea virginica) on nitrogen dynamics. Fluxes of N-2, O-2, nitrate/nitrite (NOx) and ammonium (NH4+) were measured from continuous-flow microcosms that contained a live oyster, sediment, or a live oyster + sediment. Net N-2 fluxes were indicative of nitrogen fixation in the sediment treatment and denitrification in the oyster and oyster + sediment treatments. Organic matter de position and ammonium production associated with oyster biodeposits and excretion likely decreased N limitation, and thus the demand for fixation of new nitrogen, while increasing nitrification and subsequent denitrification. Oyster-mediated denitrification accounted for 48% of the total inorganic nitrogen efflux in the oyster microcosms and 35% in the oyster + sediment microcosms. Despite high rates of ammonium production, inclusion of the eastern oyster did not increase the pool of bioavailable nitrogen but shifted the microcosms from a nitrogen source to a nitrogen sink

Phytoplankton photopigments as indicators of estuarine and coastal eutrophication

953-964Human development of coastal watersheds has greatly increased nutrient loading and accelerated estuarine and coastal eutrophication. These waters are also affected by climatic perturbations (e.g., droughts, hurricanes, floods), which may be increasing. The ecological effects of these stressors are often most evident at the microbial level, where the bulk of primary production and biogeochemical cycling occurs. Phytoplankton dominate coastal primary production and thus may be indicative of eutrophication and other major perturbations underlying coastal ecosystem change. Using photopigments that are diagnostic for phytoplankton functional groups (chlorophytes, cryptophytes, cyanobacteria, diatoms, and dinoflagellates), we examined the relative responses of these taxonomic groups to nutrient and hydrologic alterations and evaluated their use as indicators of ecological change in the Neuse River Estuary, North Carolina, and Galveston Bay, Texas. Photopigment indicators can be routinely incorporated in water-quality monitoring programs to assess environmental controls on ecosystem structure and function over varying spatial and temporal scaleshttp://gbic.tamug.edu/request.ht

Microbial indicators of aquatic ecosystem change: current applications to eutrophication studies

233-246Human encroachment on aquatic ecosystems is increasing at an unprecedented rate. The impacts of human pollution and habitat alteration are most evident and of greatest concern at the microbial level, where a bulk of production and nutrient cycling takes place. Aquatic ecosystems are additionally affected by natural perturbations, including droughts, storms, and floods, the frequency and extent of which may be increasing. Distinguishing and integrating the impacts of natural and human stressors is essential for understanding environmentally driven change of microbial diversity and function. Microbial bioindicators play a major role in detecting and characterizing these changes. Complementary use of analytical and molecular indicator tools shows great promise in helping us clarify the processes underlying microbial population, community, and ecosystem change in response to environmental perturbations. This is illustrated in phytoplankton (microalgal and cyanobacterial) and bacterial community changes in a range of US estuarine and coastal ecosystems experiencing increasing development in their water- and airsheds as well as climatic changes (e.g., increasing hurricane frequency). Microbial indicators can be adapted to a range of monitoring programs, including ferries, moored instrumentation, and remote sensing, in order to evaluate environmental controls on microbial community structure and function over ecosystem to global scales. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reservedhttp://gbic.tamug.edu/request.ht