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One of the most recognised values of tidal salt marshes is the ecosystem service they provide as natural sinks for contaminants such as metals. This study examines net accumulation of metals (As, Cr, Cu, Hg, Ni, Pb, Zn and V) over a 5-yr period, from 1997 to 2002, in surface sediments of salt marshes in the Bay of Fundy, Canada. Metal accumulation has been measured in seven sites that extend from outer to inner Bay and in low and high marsh areas within each site. Overall, sediment metal concentrations are at or near their natural levels. Concentrations of metals show variability among marshes but are not significantly different between low and high marsh. Concentrations of As, Hg, Pb and V appear to be influenced by anthropogenic inputs. Calculated sediment loading rates for these metals generally showed gradients of increased loading from outer to inner Bay. Variability in sediment deposition rate is the driving force behind this spatial pattern. Results of this study suggest that the value of salt marshes as a sink for metals may be enhanced by high sedimentation rates.

There is a growing interest to restore Bay of Fundy salt marshes diked for agriculture. Marshes recovering for several decades from storm-breached dikes can serve as analogues for restored marshes. In this study I examine factors driving sub-surface hydrology and vegetation at recovering and reference Bay of Fundy salt marshes. In Fundy marshes, groundwater at channel edges is insensitive to tidal flooding (<10 cm change in depth) and deep draw-downs (40-100 cm) occur. Sub-surface hydrology here differs from organogenic, microtidal marshes due to low saturated hydraulic conductivity, infrequent flooding of marsh interiors, and larger hydraulic gradients imposed at channel edges. By calculating marsh elevation at dike-breach and considering Spartina alterniflora's vertical range, it is apparent that salt marsh vegetation could establish when dikes breached. Multivariate analysis indicates that reference and restored/recovering sites should have similar sizes and tidal ranges. These criteria introduce problems as Fundy dikelands are more extensive than marshes not targeted for agriculture and tidal range increases exponentially up-Bay.

This study examines carbon flow in the Dipper Harbour salt marsh, a macrotidal system located on the north-west coast of the Bay of Fundy, New Brunswick. The vegetated marsh surface is composed of three major zones; the Spartina alterniflora-dominated low marsh, the Plantago maritima-dominated Middle marsh, and the Spartina patens-dominated high marsh. The total net primary production (NPP) of these dominant macrophytes is 860, 300 and 650 g C m$ sp{-2}$ yr$ sp{-1}$ respectively. In all plant zones, 66% of the NPP occurs in the belowground fraction. / Empirical measurements of organic matter burial indicate that the marsh sediment acts as a carbon sink, accumulating between 75 and 105 g C m$ sp{-2}$ yr$ sp{-1}$. The tidal export of aboveground plant biomass in the form of particulate organic matter accounts for a net loss of carbon ranging from 65 to 170 g C m$ sp{-2}$ yr$ sp{-1}$. An experiment examining the exchange of dissolved organic carbon (DOC) suggest a net annual export of roughly 500 g C m$ sp{-2}$ yr$ sp{-1}$. The forementioned fluxes are combined with estimates of surface gas exchange and algal productivity in order to construct a carbon budget. The budget predicts a DOC export term of 365 g C m$ sp{-2}$ yr$ sp{-1}$, which is of the same order of magnitude as that obtained from the empirical DOC data. / The results of this study show that the Plantago zone plays a significant role in the circulation of carbon in the Dipper Harbour salt marsh. This suggests that the patterns of carbon circulation in northern marshes may differ considerably from those in marshes further south where no distinct Plantago zone has been reported.

A combination of DGPS/GIS mapping, invertebrate surveys and environmental monitoring over one year (July 2004--July 2005) were used to examine the recovery of permanent tidal pools on a salt marsh in the lower Bay of Fundy which underwent an unmanaged restoration after breach of the dyke over 50 years ago. The results are compared to those of a nearby relatively undisturbed reference marsh. / Pools were found to represent a substantial portion of the marsh habitat, comprising 13% of the total marsh area in the recovering marsh and 4.8% in the natural marsh. Observations indicate ice may be an important mechanism of pool formation and growth in these marshes. Water temperature in the pools ranged from freezing (-2°C) to a maximum of 36°C with ice covering pools for up to one month in the winter. Salinity of the pools ranged from near freshwater (4) to hypersaline (41). Environmental variability was mainly driven by climatic conditions with increased tidal flooding of pools at low elevations tending to make the conditions more stable. / A total of 42 macroinvertebrate taxa were identified in pools of the two marshes, with species richness (S) of individual pools ranging from 13 to 23. An estimated 50 years since dyke failure, the invertebrate fauna of pools in the recovering marsh is indistinguishable from that of the reference marsh. No significant differences in macroinvertebrate communities were detected between sampling dates, pool size or pool depth. Non metric multidimentional scaling and hierarchical cluster analysis supported separating the pool invertebrate communities of this study into those occurring in regularly flooded pools, and those occurring in irregularly flooded pools. Average production of pool macroinvertebrates ranged from 1.79 to 4.03 g dry wt m-2, depending on the amount of vegetative cover in the pools. The pools are characterized by low equitability in species abundance and biomass. The numerically dominant organisms of the pools were mites (Acarina), the gastropod Hydrobia tottentei, Tubificidae oligochaetes, and Chironomus sp. larvae as well as copepods and ostracods.

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Saltwater marshes in the Bay of Fundy act as greenhouse gases sinks and reservoirs by fixing atmospheric carbon dioxide and storing it in carbon rich deposits. There are approximately 3,131.5 hectares of saltwater marsh in the Bay of Fundy, of which 958 ha are currently owned by the government or conservation organizations and 2,173.5 ha are owned by private landowners. A multiple bounded discrete choice contingent valuation survey was conducted to estimate landowners' willingness to accept compensation for selling their saltwater marshes to a conservation program. A multiple bounded model developed by Gregory Poe and Michael Welsh (1995) was used to analyze the responses. Mean willingness to accept compensation for one hectare of saltwater marsh was estimated to be $1,004.22, and aggregate willingness to accept compensation for the total of 2,173.5 ha of saltwater marsh owned by private landowners was approximately $2,180,000. Using these estimates and the rate of carbon dioxide-equivalent absorption of saltwater marshes, the opportunity cost of one tonne of carbon dioxide-equivalent sequestered by saltwater marshes in the Bay of Fundy was calculated to range between $16.70 and $19.95. Decision-makers can use this result for policy purposes concerning the achievement by Canada of its greenhouse gases emission reduction commitment under the Kyoto Protocol (1997).

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