We measured the amount of arsenic, chromium, copper, lead, nickel, vanadium, and zinc accumulated over a five-year period from 1997 to 2002 in surface sediments of seven salt marshes along the New ...Brunswick coast of the Bay of Fundy, Canada. Study sites extended from outer to inner Bay, spanning a gradient in tidal range (6-12 m) and mean sediment deposition rate (0.27- 1.76 cm yr super(-1)). In each study site, metal concentrations were measured in low and high marsh areas. Concentrations of chromium, nickel, and zinc appear to be within their natural range, while arsenic, lead, and vanadium are enriched in some sites. Calculated sediment metal loadings rates showed variability among marsh sites that closely followed sediment deposition patterns, suggesting sediment deposition rate is the driving factor of short- term metal accumulation in Fundy marshes. The value of salt marshes as a sink for metals may be enhanced by high sedimentation rates.
The white-footed mouse (Peromyscus leucopus) is an important reservoir host for Borrelia burgdorferi, the pathogen responsible for Lyme disease, and its distribution is expanding northward. We used ...an Ecological Niche Factor Analysis to identify the climatic factors associated with the distribution shift of the white-footed mouse over the last 30 years at the northern edge of its range, and modeled its current and potential future (2050) distributions using the platform BIOMOD. A mild and shorter winter is favouring the northern expansion of the white-footed mouse in Quebec. With more favorable winter conditions projected by 2050, the distribution range of the white-footed mouse is expected to expand further northward by 3 degree latitude. We also show that today in southern Quebec, the occurrence of B. burgdorferi is associated with high probability of presence of the white-footed mouse. Changes in the distribution of the white-footed mouse will likely alter the geographical range of B. burgdorferi and impact the public health in northern regions that have yet to be exposed to Lyme disease.
Tidal Marsh Restoration Roman, Charles T; Burdick, David M; Falk, Donald A
2012, 2014, 2012-08-07
eBook
Many coastal tidal marshes have been significantly degraded by roadways and other projects that restrict tidal flows, limiting their ability to provide vital ecosystem services including support of ...fish and wildlife populations, flood protection, water quality maintenance, and open space.Tidal Marsh Restoration provides the scientific foundation and practical guidance necessary for coastal zone stewards to initiate salt marsh tidal restoration programs. The book compiles, synthesizes, and interprets the current state of knowledge on the science and practice of salt marsh restoration, bringing together leaders across a range of disciplines in the sciences (hydrology, soils, vegetation, zoology), engineering (hydraulics, modeling), and public policy, with coastal managers who offer an abundance of practical insight and guidance on the development of programs.The work presents in-depth information from New England and Atlantic Canada, where the practice of restoring tidal flow to salt marshes has been ongoing for decades, and shows how that experience can inform restoration efforts around the world. Students and researchers involved in restoration science will find the technical syntheses, presentation of new concepts, and identification of research needs to be especially useful as they formulate research and monitoring questions, and interpret research findings.Tidal Marsh Restoration is an essential work for managers, planners, regulators, environmental and engineering consultants, and others engaged in planning, designing, and implementing projects or programs aimed at restoring tidal flow to tide-restricted or diked salt marshes.
We examined the distribution of vegetation and pollen in surface soils of three salt marshes on the outer Bay of Fundy to assess the value of pollen in paleoenvironmental reconstructions. We examined ...the relationship of pollen to vegetation using linear regression at two scales: vegetation zones dominated by graminoids and forb patches within these zones. Of the dominant graminoids, only pollen of Cyperaceae was a dependable indicator of source vegetation. In contrast, at least seven common forbs were significantly represented by their pollen at one or both scales. Because forbs are more abundant in northern marshes, increases in forb pollen abundance in buried sediments of southern marshes could signal colder climate regimes. Other studies have shown Plantago maritima L. and Ligusticum scoti cum L. to be associated with distinct ranges in elevation, and Triglochin maritima L. with soil anoxia. Thus, shifts in forb pollen abundance may indicate changes in tidal flooding frequency and sea levels.Key words: Potentilla anserina, Glaux maritima, Spergularia canadensis, wetland, palynology.
A 4.3 m vibracore, retrieved from a Bay of Fundy saltmarsh, was analysed for total extracted S, Fe, Mn, Pb, Zn, Cu and Organic C. Macrofossils were also identified in several key samples from the ...core. Results showed stable concentrations of all elements except for surficial enrichment of Zn, Cu and Pb and four down-core maxima in Fe, S and Mn concentrations. There was an anomalous elevation of Zn, Pb and Cu concentrations coinciding with the second down-core peak of Fe, S and Mn. Macrofossil analysis revealed a transition from fresh- or brackish water species to Spartina alterniflora and later to Spartina patens. The earliest saltmarsh sediments, located at 334 cm, were radiocarbon dated at 2560$\plus or minus sign$60 yr BP. Both paleoenvironmental and more recent historical interpretations were made from the data. The simultaneous presence of S. alterniflora rhizomes and a rise in Fe and S concentration suggests a low marsh environment existed at a depth of 224-237 cm. The two uppermost concentration maxima are most likely the result of the presence of a redox boundary within the sediment matrix and, therefore, an active site of geochemical processes. Zinc, Cu and Pb concentrations showed an increase above background levels from 30 cm upwards. The positive correlation between the macrofossil and chemical data, combined with the discovery of surficial contamination at a relatively pristine site, clearly demonstrates the usefulness of chemical analysis as a method for paleoenvironmental reconstruction and determination of anthropogenic influences.
A comparison of pollen concentrations on a velocity profile within a cross-section of the Mississippi River at St. Francisville, Louisiana is used to examine processes of pollen suspension and ...transport. The profile consists of five verticals sampled at six different depths paired with current velocity measurements, as well as surface samples. Our results show no significant correlation between pollen load and velocity. Application of sediment mechanics to pollen grain transport demonstrates that such relationships should not be expected in a river. Due to the negligible terminal fall velocities of pollen grains, one should expect a nearly uniform distribution of pollen load with river depth. Differential deposition of pollen grains due to spatial heterogeneity in a fluvial environment is also an unlikely phenomenon. In the Mississippi we find that other mechanisms, such as pollen rain and resuspension of grains from the bed, are more likely to control the spatial distribution of pollen.
In this study we examine the nature of microforaminifera test linings found in palynological preparations and demonstrate the potential of these palynomorphs for paleoenvironmental interpretation. ...Sediment samples from four marsh salinity zones of the Barataria Basin, Mississippi Delta, were processed by conventional palynological techniques which included HC1 and acetolysis treatments. Taxonomic identification was not attempted, but it is assumed that Rotalidae forams, Miliammina fusca and Ammonia beccari, are important constituents of the test lining assemblages. Multi-chambered forms were classed by morphotype, size, number of chambers, spacing of chambers, and condition. The absence of a relationship between size and chamber number within each morphotype implies the presence of multiple species populations. There is also no relationship between foram concentration and salinity. Using stepwise discriminant analysis, six classes were selected which enable successful discrimination among the four salinity zones.
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