Diatom habitats,species diversity and water-depth inference models across surface-sediment transects in Worth Lake,northwest Ontario,Canada     

Kathleen R. Laird  Melanie V. Kingsbury  Brian F. Cumming 《Journal of Paleolimnology》2010,44(4):1009-1024

We analyzed surface-sediment samples collected along transects from three sub-basins of a relatively large (~115 ha), bathymetrically complex lake, in northwest Ontario, Canada, to assess the reproducibility of diatom species habitats and diversity along a water-depth gradient. Transects displayed different orientations with respect to prevailing wind direction and varied in complexity and degree of slope along the lake bottom. Each transect consisted of three replicate samples at a resolution of ~1 m water depth from ~1 to 30 m for the two deep-basin transects and from ~1 to 18 m in the shallower basin. Distinct diatom assemblages were identified in all transects: (1) a near-shore community composed largely of attached life-forms and some motile benthic taxa, (2) a mid-depth community composed largely of motile life-forms and other benthic taxa that are adapted to lower light conditions (e.g. Staurosirella pinnata), and (3) a deep-water community dominated by planktonic taxa. Species richness was highest in the benthic zones (<9 m), with greatest species evenness in the mid-depth zone (~3–9 m). Species richness and evenness were highly correlated across the three transects (r = 0.89–0.93, p < 0.01). Diatom-inferred depth models were developed from the individual transects to assess reproducibility and applicability for down-core analyses using modern analog (MAT) and weighted-averaging (WA-PLS) approaches. Coefficients of determination (r ²) for these models ranged from 0.80 to 0.98, and RMSEP ranged from 1.2 to 4.2 m. The models developed from the transect with the highest resolution sampling, gentlest non-complex slope and shallowest maximum depth were the strongest ( r_\textMAT² = 0.97 r_{\text{MAT}}^{2} = 0.97 ; r_{\textWA - PLS}² = 0.98 r_{\text{WA - PLS}}^{2} = 0.98 ) and had the lowest RMSEP (MAT = 1.2 m, WA-PLS = 1.3 m). These inference models can be used to infer past fluctuations in the depth of the benthic/planktonic boundary from cores retrieved near this ecotone and provide a sensitive record of the past change in location of the benthic zone. These types of data can be used to assess past variability in droughts and lake levels to better plan for potential future extremes. Such records incorporate more realistic estimates of natural variability than the ~100-year instrumental records currently used by water resource managers.  相似文献   

Estimating restorable wetland water storage at landscape scales   总被引：1，自引：0，他引：1       下载免费PDF全文

Charles Nathan Jones  Grey R. Evenson  Daniel L. McLaughlin  Melanie K. Vanderhoof  Megan W. Lang  Greg W. McCarty  Heather E. Golden  Charles R. Lane  Laurie C. Alexander 《水文研究》2018,32(2):305-313

Globally, hydrologic modifications such as ditching and subsurface drainage have significantly reduced wetland water storage capacity (i.e., volume of surface water a wetland can retain) and consequent wetland functions. While wetland area has been well documented across many landscapes and used to guide restoration efforts, few studies have directly quantified the associated wetland storage capacity. Here, we present a novel raster‐based approach to quantify both contemporary and potential (i.e., restorable) storage capacities of individual depressional basins across landscapes. We demonstrate the utility of this method by applying it to the Delmarva Peninsula, a region punctuated by both depressional wetlands and drainage ditches. Across the entire peninsula, we estimated that restoration (i.e., plugging ditches) could increase storage capacity by 80%. Focusing on an individual watershed, we found that over 59% of restorable storage capacity occurs within 20 m of the drainage network, and that 93% occurs within 1 m elevation of the drainage network. Our demonstration highlights widespread ditching in this landscape, spatial patterns of both contemporary and potential storage capacities, and clear opportunities for hydrologic restoration. In Delmarva and more broadly, our novel approach can inform targeted landscape‐scale conservation and restoration efforts to optimize hydrologically mediated wetland functions.  相似文献   

3D soil hydraulic database of Europe at 250 m resolution          下载免费PDF全文

Brigitta Tóth  Melanie Weynants  László Pásztor  Tomislav Hengl 《水文研究》2017,31(14):2662-2666

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The Stubenberg meteorite—An LL6 chondrite fragmental breccia recovered soon after precise prediction of the strewn field          下载免费PDF全文

Addi Bischoff  Jean‐Alix Barrat  Kerstin Bauer  Christoph Burkhardt  Henner Busemann  Samuel Ebert  Michael Gonsior  Janina Hakenmüller  Jakub Haloda  Dennis Harries  Dieter Heinlein  Harald Hiesinger  Rupert Hochleitner  Viktor Hoffmann  Melanie Kaliwoda  Matthias Laubenstein  Colin Maden  Matthias M. M. Meier  Andreas Morlok  Andreas Pack  Alexander Ruf  Philippe Schmitt‐Kopplin  Maria Schönbächler  Robert C. J. Steele  Pavel Spurný  Karl Wimmer 《Meteoritics & planetary science》2017,52(8):1683-1703

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Application of a mass-balance model to predict PCDD/F turnover in a Baltic coastal estuary     

O. Magnus Karlsson  J. Mikael Malmaeus  Sarah Josefsson  Karin Wiberg  Lars Håkanson 《Estuarine, Coastal and Shelf Science》2010

A dynamical, process-based mass-balance model was applied to quantify the transports of polychlorinated-p-dibenzodioxins and dibenzofurans (PCDD/Fs) to, within and from the Kallrigafjärden Bay, a coastal estuary in the Baltic Sea, and to predict the PCDD/F levels in the water and sediments of the bay. Before the modelling, a one-year sampling programme was implemented in 2007–2008 to measure the flows of PCDD/Fs in tributaries entering the system, the fluxes from the adjacent sea and the levels in water, sediment and fish within the estuary. The collected data set was used as input data to the model and for validation purposes.  相似文献   

The value of marine biodiversity to the leisure and recreation industry and its application to marine spatial planning     

Siân E. Rees  Lynda D. Rodwell  Martin J. Attrill  Melanie C. Austen  Steven C. Mangi 《Marine Policy》2010

The incorporation of the ecosystem approach into marine planning requires that all aspects of value associated with marine biodiversity are incorporated into the decision making process. An ecosystem services approach to valuing marine biodiversity is recognised as a framework by which economic, ecological and social values may be incorporated into the decision making process. There are sectors of the marine leisure and recreation industry (sub-aqua diving, sea angling and wildlife watching), which depend on the presence of natural marine resources in order to carry out their activity. Estimating the value of this direct use can provide an evidence base for the sustainable use of marine biodiversity when set against other competing economic interests in marine spatial planning. In the case study area of Lyme Bay, the marine leisure and recreation industry has been valued using both monetary and non-monetary methods. The results show that the leisure and recreation industry is dependent on the diversity of sites (many of which are currently unmanaged) and that the industry is of economic significance and an area which has recently been closed to trawling activity enables the protection of some of the most valuable sites but has limited benefits for protecting the full resource base upon which this local industry depends.  相似文献   

Community perspectives on integrated coastal management: Voices from the Annapolis Basin area,Nova Scotia,Canada     

Lisette Wilson  Melanie G. Wiber 《Ocean & Coastal Management》2009,52(11):559-567

This paper seeks to address the missing dimension of the place of Maritime communities in Canadian Integrated Coastal Management (ICM). This work is part of a larger network of projects on ICM through the participatory Coastal Community University Research Alliance. The implementation of ICM with full community involvement is a challenge, for example: communities are not unified or homogenous units, power varies among stakeholders, and silo constructs and turf wars discourage involvement of the wider public. In 2007, a survey of nine community-based organizations and associations and a First Nation community, located within the Annapolis Basin and surrounding areas of the Nova Scotia side of the Bay of Fundy was conducted. The purpose of the survey was to better understand how the concept of ICM is conceptualized and acted upon by local communities and to draw upon this to enrich ICM theory.Approximately 30 projects representing community-based ICM initiatives over the last 10 years were identified, including: capacity building, habitat and stock enhancement/ management programs and responses to new policies or legislative interventions. Several enabling and constraining factors for community involvement in ICM were identified. One key finding is a major difference between community and government approaches. Government ICM initiatives have captured some aspects of the environmental and economic management issues, but have generally failed to consider cultural and social components. They have also failed to take into account the interconnections within and between human and ecological systems. Community members report that government is more interested in forming partnerships with the corporate sector than with the people who rely on local resources. From the community perspective, dealing with the resulting power imbalances must involve revisiting the “core values” that underpin regulation and resource exploitation.This study demonstrates that communities are usually the “first responders"” for many ecological problems, and there is a willingness to take responsibility for the management of resources. ICM is already embedded in on-going community projects, networks and forums. These initiatives promote the principles identified in Canada's Oceans Act and Oceans Strategy, but the relevant government agencies have provided little support to them. ICM has the potential to bring together many issues that can be addressed by the multi-stakeholder process, but this needs to be facilitated by on-going government collaborations, contributions and recognition.  相似文献   

Spatial and seasonal variations of sulphate,dissolved organic carbon,and nutrients in deep pore waters of intertidal flat sediments     

Melanie Beck  Olaf Dellwig  Gerd Liebezeit  Bernhard Schnetger  Hans-Jürgen Brumsack 《Estuarine, Coastal and Shelf Science》2008

Spatial and seasonal variations of sulphate, dissolved organic carbon (DOC), nutrients and metabolic products were determined down to 5 m sediment depth in pore waters of intertidal flats located in NW Germany. The impact of sediment permeability, pore water flow, and organic matter supply on deep pore water biogeochemistry was evaluated. Low sediment permeability leads to an enrichment of remineralisation products in pore waters of clay-rich sediments. In permeable sandy sediments pore water biogeochemistry differs depending on whether tidal flat margins or central parts of the tidal flat are studied. Pore water flow in tidal flat margins increases organic matter input. Substrate availability and enhanced temperatures in summer stimulate sulphate reducers down to 3.5 m sediment depth. Sulphate, DOC, and nutrient concentrations exhibit seasonal variations in deep permeable sediments of the tidal flat margin. In contrast, seasonal variations are small in deep pore waters of central parts of the sand flat. This study shows for the first time that seasonal variations in pore water chemistry are not limited to surface sediments, but may be observed down to some metres depth in permeable tidal flat margin sediments. In such systems more organic matter seems to be remineralised than deduced from surface sediment studies.  相似文献   

Using stable isotopes to estimate young water fractions in a heavily regulated,tropical lowland river basin     

Anh Duc Trinh  Thu Nga Do  Virginia N. Panizzo  Suzanne McGowan  Melanie J. Leng 《水文研究》2020,34(22):4239-4250

The young water fraction of streamflow (Fyw), an important hydrological variable, has been calculated for the first time, for a monsoon-fed coastal catchment in northern Vietnam. Oxygen stable isotopes (δ¹⁸O) from six river sites in the Day River Basin (DRB) were analysed monthly, between January 2015 and December 2018. River δ¹⁸O signatures showed sine wave variability, reflecting the amount effect and tropical (dry-rainy) seasonality of the region. The δ¹⁸O composition of precipitation ranged from −12.67 to +1.68‰, with a mean value of −5.14‰, and in-streamflow signatures ranged from −11.63 to −1.37‰ with a mean of −5.02‰. Fractions of young water (Fyw) were calculated from the unweighted and flow-weighted δ¹⁸O composition of samples. Unweighted Fyw ranged between 29 ± 8% and 82 ± 21% with a mean value of 51 ± 19%, and was not significantly different from flow-weighted Fyw (range between 33 ± 25% and 92 ± 73%, mean 52 ± 36%). Both unweighted and flow-weighted Fyw were highest in the middle of stream and lowest in downstream sites, capturing the impacts of landuse changes, hydrology and human activities in the catchment. Our calculations imply that more than a half of rainwater reaches the DRB river mainstream within the first 3 months. The Fyw is much higher than the global average (of one-third) and insensitive to discharge due to the combination of a humid catchment with high rainfall, low storage capacity, flat landscape and an intensive drainage system in the DRB. Also the low discharge sensitivity of Fyw in the DRB implies that the regional hydrology is severely altered by humans.  相似文献   

Late Quaternary vegetation dynamics in a biodiversity hotspot, the Uluguru Mountains of Tanzania     

Jemma Finch  Melanie J. Leng  Rob Marchant 《Quaternary Research》2009,72(1):111-122

Late Quaternary vegetation history and environmental changes in a biodiverse tropical ecosystem are inferred from pollen, charcoal and carbon isotope evidence derived from a ∼ 48,000-yr sedimentary record from the Uluguru Mountains, a component of the Eastern Arc Mountains of Kenya and Tanzania. Results indicate that Eastern Arc forest composition has remained relatively stable during the past ∼ 48,000 yr. Long-term environmental stability of the Eastern Arc forests has been proposed as a mechanism for the accumulation and persistence of species during glacial periods, thus resulting in the diverse forests observed today. The pollen and isotope data presented here indicate some marked changes in abundance but no significant loss in moist forest taxa through the last glacial maximum, thereby providing support for the long-term environmental stability of the Eastern Arc. Anthropogenic activities, including burning and forest clearance, were found to play a moderate role in shaping the mosaic of forest patches and high-altitude grasslands that characterise the site today; however, this influence was tempered by the inaccessibility of the mountain.  相似文献