Gail L. Chmura

Gail L. Chmura
McGill University | McGill · Department of Geography

Ph.D. Louisiana State University

About

122
Publications
38,099
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8,319
Citations
Citations since 2017
38 Research Items
5189 Citations
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201720182019202020212022202302004006008001,000
201720182019202020212022202302004006008001,000
Additional affiliations
April 1990 - present
McGill University
Position
  • Professor (Associate)

Publications

Publications (122)
Article
Accumulation of belowground plant material (live roots, rhizomes, and dead material) is critical to vertical accretion of tidal salt marsh soils and their ability to maintain elevation with respect to sea-level rise. Many studies utilize a single, global relationship between soil organic carbon and belowground volume, which does not include the por...
Article
Much uncertainty exists about the vulnerability of valuable tidal marsh ecosystems to relative sea level rise. Previous assessments of resilience to sea level rise, to which marshes can adjust by sediment accretion and elevation gain, revealed contrasting results, depending on contemporary or Holocene geological data. By analyzing globally distribu...
Article
Postglacial isostatic uplift causes rapid land emergence and drives wetland development on Canada's James Bay providing a modern field laboratory to test models of wetland succession. In this study, we reconstruct wetland development in four Holocene sediment/peat records ranging in age from 6500 to 250 years based on a suite of palynomorph (pollen...
Article
Salt marshes have the ability to store large amounts of ‘blue carbon’, potentially mitigating some of the effects of climate change. Salt marsh carbon storage may be partially offset by emissions of CH4, a highly potent greenhouse gas (GHG). Sea level rise and invasive vegetation may cause shifts between different elevation and vegetation zones in...
Article
Climate warming is likely to cause differential shifts in the phenology of pollinators and nectar sources. Detection of these shifts requires careful observation of emergence and peak populations of both the animals and plants involved. On salt marshes of Canada's Chaleur Bay, the potential for asynchronous appearance of the adults of the endangere...
Article
Full-text available
Plain Language Summary We collected soils from tidal marshes on the Kilbella and Wannock Rivers on the central coast of British Columbia, Canada, a region where tidal marsh studies are rare. We measured the bulk density (mass/volume) %carbon (C) and determined the %sand, silt, and clay of the soil. Multiplying the bulk density by the %C provided so...
Article
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The determination of rates and stocks of carbon storage in salt marshes, as well as their protection, require that we know where they and their boundaries are. Marsh boundaries are conventionally mapped through recognition of plant communities using aerial photography or satellite imagery. We examined the possibility of substituting the use of 1 m...
Article
Full-text available
Alongside the steep reductions needed in fossil fuel emissions, natural climate solutions (NCS) represent readily deployable options that can contribute to Canada’s goals for emission reductions. We estimate the mitigation potential of 24 NCS related to the protection, management, and restoration of natural systems that can also deliver numerous co...
Chapter
Salt marshes are highly dynamic and important ecosystems that dampen impacts of coastal storms and are an integral part of tidal wetland systems, which sequester half of all global marine carbon. They are now being threatened due to sea-level rise, decreased sediment influx, and human encroachment. This book provides a comprehensive review of the l...
Preprint
Full-text available
The vulnerability of the world’s tidal marshes to sea-level rise threatens their substantial contribution to fisheries, coastal protection, biodiversity conservation and carbon sequestration. Feedbacks between relative sea-level rise (RSLR) and the rate of mineral and organic sediment accumulation in tidal wetlands, and hence elevation gain, have b...
Article
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Our study of a St. Lawrence Estuary marsh reveals that, compared to native Spartina patens‐dominated vegetation, invasive Phragmites australis makes a greater contribution to soil volume and carbon stock (referred to as blue carbon). Phragmites' contributions to soil volume enhance marsh sustainability in face of sea level rise, and its greater con...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
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The term Blue Carbon (BC) was first coined a decade ago to describe the disproportionately large contribution of coastal vegetated ecosystems to global carbon sequestration. The role of BC in climate change mitigation and adaptation has now reached international prominence. To help prioritise future research, we assembled leading experts in the fie...
Article
Our study examined the relationship of microphytobenthos to greenhouse gas fluxes from sediments of a subtropical mangrove forest and adjacent mudflat in the Jiulong River Estuary, South China. The relationship between chlorophyll a concentration at the sediment surface and diatom density confirmed that these microalgae were the important component...
Article
Full-text available
Salt marshes are highly effective carbon (C) sinks and bury more C per square meter annually than any other ecosystem. Reclamation and anthropogenic impacts, however, have resulted in extensive losses of salt marshes. Carbon credits can be generated and sold by restoring marshes, but only if C sequestration and net reductions in greenhouse gases (G...
Article
Efforts to address anthropogenic global climate change (AGCC) require public understanding of Earth and climate science. To meet this need, educational reforms and prominent scientists have called for instructional approaches that teach students how climate scientists examine AGCC. Yet, only a few educational studies have reported clear empirical r...
Article
The data presented here includes a table of soils measurements taken at high resolution depth intervals (5 cm) for three salt marshes, two along the New Brunswick coast of Canada and one on the southern coast of Maine, USA. The data includes a table which includes the bulk density, percent organic matter, percent organic carbon, carbon stock, and r...
Article
Full-text available
The Second Warning to Humanity provides a clarion call for wetland researchers and practitioners given the loss and degradation of wetlands, the declining availability of fresh water, and the likely consequences of climate change. A coordinated response and approach to policies has the potential to prevent further degradation and support resilient...
Article
We measured total carbon stocks of three marshes: Two formed in association with a developing spit along the Gulf of St. Lawrence coast of New Brunswick, Canada, and another with a lagoon on the coast of Maine, USA. Overall, 46 cores and 157 depth recordings were collected to determine depth of the marsh deposits. Total marsh soil volume was estima...
Article
Full-text available
Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over the global carbon cycle and at the same time gain elevation to keep pace with sea-level rise (SLR). The present study assessed the effects of temperatu...
Article
Full-text available
Part 1 of this review synthesizes recent research on status and climate vulnerability of freshwater and saltwater wetlands, and their contribution to addressing climate change (carbon cycle, adaptation, resilience). Peatlands and vegetated coastal wetlands are among the most carbon rich sinks on the planet sequestering approximately as much carbon...
Article
Full-text available
The supply of nitrogen to ecosystems has surpassed the Earth's Planetary Boundary and its input to the marine environment has caused estuarine waters to become eutrophic. Excessive supply of nitrogen to salt marshes has been associated with shifts in species' distribution and production, as well as marsh degradation and loss. Our study of salt mars...
Article
Full-text available
Salt marshes are highly effective carbon (C) sinks and have higher rates of soil C burial (per square meter) than terrestrial ecosystems. Marsh reclamation and anthropogenic impacts, however, have resulted in extensive losses of salt marshes. Restoration of marshes drained and “reclaimed” for agriculture (referred to in Canada as dykelands) and deg...
Data
Measurements of carbon density. (XLSX)
Article
Full-text available
An increase in greenhouse gas emissions has led to a rise in average global air and ocean temperatures. Increased sea surface temperatures can cause changes in species’ distributions, particularly those species close to their thermal tolerance limits. We use a bioclimate envelope approach to assess potential shifts in the range of marine macroalgae...
Article
Full-text available
Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over the global carbon cycle and at the same time gain elevation to keep pace with sea-level rise (SLR). The present study provides the first global-scale f...
Poster
Full-text available
Efforts to address climate change require public understanding of Earth and climate science. To meet this need, educators require instructional approaches and scientific technologies that overcome cultural barriers to impart conceptual understanding of the work of climate scientists. We compared student inquiry learning with now ubiquitous climate...
Article
Full-text available
We examined organic-walled dinoflagellate cysts from one ²¹⁰Pb-dated sediment core and 39 surface sediment samples from the northern Gulf of Mexico to determine the relationship between nutrient enrichment and cyst assemblages in this region characterized by oxygen deficiency. The core spans from 1962 to 1997 and its sampling location is directly i...
Article
Major changes in both pollen and dinocyst assemblages are recorded during the Younger Dryas in Bay of Islands and are associated with large drops in air and sea surface temperatures, and sea surface salinity. The changes in vegetation are similar with those observed at other sites in Newfoundland. Dinoflagellate cyst assemblages also show similar s...
Article
We analyzed surface sediments from 23 northeast USA estuaries, from Maine to Delaware, and nine estuaries from Prince Edward Island (PEI, Canada), to determine how dinoflagellate cyst assemblages varied with nutrient loading. Overall the abundance of cysts of heterotrophic dinoflagellates correlates with modeled nitrogen loading, but there were als...
Conference Paper
Full-text available
The geoscience community must consider the value of differing educational pedagogy if they hope to foster a citizenry capable of engaging with policies addressing climate change. We compared inquiry methods in which students use widely available climate education tools to those in which students run a computational global climate model from the Nat...
Article
Full-text available
Mangrove forests have the potential to export carbon to adjacent ecosystems but whether mangrove-derived organic carbon (OC) would enhance the soil OC storage in seagrass meadows adjacent to mangroves is unclear. In this study we examine the potential for the contribution of mangrove OC to seagrass soils on the coast of North Sulawesi, Indonesia. W...
Data
Appendix S2. Supporting tables and figures. Table S1. Taxonomic citation of dinoflagellate cysts identified in this study. Figure S1 Total cyst concentrations. Figure S2. Maps showing the abundance of Spiniferites cf. delicatus, Islandinium? cezare, Selenopemphix quanta, and Dubridinium spp. Figure S3. Maps showing the abundance of Operculodini...
Article
We show the first conclusive evidence that Melitasphaeridium choanophorum, a dinoflagellate cyst species until recently considered extinct, is still living in the northern Gulf of Mexico. This suggests the Gulf of Mexico may have acted as a refugium for some warm-water dinoflagellates during past glaciations. Melitasphaeridium choanophorum can be c...
Article
Full-text available
Few biogeographic studies of dinoflagellate cysts include the near-shore estuarine environment. We determine the effect of estuary type, biogeography, and water quality on the spatial distribution of organic-walled dinoflagellate cysts from the Northeast USA (Maine to Delaware) and Canada (Prince Edward Island). A total of 69 surface sediment sampl...
Article
Full-text available
We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly C...
Data
Gas flux and environmental data by sample event. (DOCX)
Poster
Full-text available
Research into perceptions of anthropogenic climate change demonstrates that providing the public with increasing amounts of scientific evidence has failed to significantly alter public opinion or knowledge of this complex issue due to differing views of the human relationship to the natural world and the work of climate scientists. Our research ide...
Article
Hydrology is a major driver of salt marsh functions and the ecological services they support. Sediment saturation, and thus subsurface hydrology, affects salt marsh vegetation productivity, zonation, and survival. Subsurface hydrology influences rates of subsidence; concentrations of nutrients, organic matter, and oxygen; fluxes of the greenhouse g...
Data
Full-text available
Sea level rise and accompanying coastal squeeze will drive changes in marsh spatial configuration and connec-tivity affecting how fishes utilize the marsh. We investigate how sea level rise and coastal squeeze affect the spatial distribution, configuration, and connectivity within tidal marshes in a landscape context. Using spatial analyses, we com...
Article
Full-text available
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 y...
Article
Full-text available
Khan, A. H., Levac, E., and Chmura, G. L. 2013. Future sea surface temperatures in Large Marine Ecosystems of the Northwest Atlantic. - ICES Journal of Marine Science, 70: 915-921.We analysed projections of future sea surface temperatures (SSTs) for six Large Marine Ecosystems (LMEs) of the Northwest Atlantic: the West Greenland Shelf, the Newfound...
Data
Full-text available
ISSN 0749-0208. As sea level rise accelerates and land development intensifies along coastlines, tidal wetlands will become increasingly threatened by coastal squeeze. Barriers that protect inland areas from rising sea level prevent or reduce tidal flows, and impermeable surfaces prevent wetland migration to the adjacent uplands. As vegetation succ...
Article
Full-text available
Pollen extracted from ocean and wetland sediments cored from the eastern Canadian Margin, James Bay region, and Atlantic provinces of Canada have been radiocarbon dated and results are reported here. Pollen dates from ocean sediments were compared with marine carbonate (mollusk shells or foraminifera) dates from the same core levels, dates for whic...
Article
Full-text available
Boreal peatlands are a major global C sink, thus having important feedbacks to climate. A decreased concentration in atmospheric CO<sub>2</sub> 7000–10 000 yr ago has been linked to variations in peatland C accumulation rates attributed to a warm climate and increased productivity. Yet, this period also corresponds to early stages of peatland devel...
Article
Differentiation of boreal wetlands in the palaeo record is required for studies of isostacy and sea level change, landscape change, and climate dynamics. To develop palynomorph signatures and calibrate soil C–N ratios for boreal wetlands we sampled low and high elevation tidal marshes, fens and bogs along eastern James Bay, Canada. A discriminant a...
Chapter
Full-text available
Some would maintain that conservation and restoration activities are justified on ethical grounds alone (see review by Brennan and Lo 2008). However, demonstration of the economic benefit of ecosystems can help drive social and governmental support for conservation; and restoration and economic limitations could force choices among restoration acti...
Article
Full-text available
Recent research has highlighted the valuable role that coastal and marine ecosystems play in sequestering carbon dioxide (CO2). The carbon (C) sequestered in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds, and salt marshes, has been termed "blue carbon". Although their global area is one to two orders of magnitude smalle...
Article
Full-text available
Boreal peatlands are a major global C sink, thus having important feedbacks to climate. A decreased concentration in atmospheric CO2 7000-10 000 yr ago has been linked to variations in peatland C accumulation rates attributed to a warm climate and increased productivity. Yet, this period also corresponds to early stages of peatland development (as...
Article
Full-text available
Conversion of wetlands by drainage for agriculture or other anthropogenic activities could have a negative or positive feedback to global warming (GWF). We suggest that a major predictor of the GWF is salinity of the wetland soil (a proxy for available sulfate), a factor often ignored in other studies. We assess the radiative balance of two norther...
Article
We monitored salinity and temperature in pools at different elevations in two marshes on the Bay of Fundy to assess variability in pool environments and how climate change might affect these ecosystems. Water temperatures reached a maximum of 36.1°C, and ice covered pools in the winter. Ice lifting out of ponds in the spring scoured bottoms. Salini...
Article
Full-text available
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...
Article
Tidal salt marshes provide a range of ecosystem services. The most recently recognized is their provision of highly effective sinks for atmospheric carbon dioxide, a characteristic they share with mangroves swamps which largely replace salt marshes in the intertidal zones of tropical regions. Efforts are emerging to use salt marsh preservation or r...
Article
Conversion of wetlands by drainage for agriculture or other anthropogenic activities could have a negative or a positive climate feedback. We suggest that a major predictor of the climate feedback is salinity of the wetland soil, a factor often ignored in other studies. Our study compares flux of the greenhouse gases and sequestration of soil C to...
Article
The shoreline displacement history of the eastern James Bay lowlands in the last 7 ka has been investigated by means of AMS radiocarbon dating of sediments cored from wetlands. We present twelve radiocarbon dates on macrofossils from six sites spread along a gradient of increasing land age and elevation. Palynomorph analysis (pollen, spores, and di...
Article
Full-text available
Reports of shifts in rates of aggradation in a salt marsh deposit at Amherst Point, Nova Scotia have been linked with fluctuations in eustatic sea level, crustal subsidence and, possibly, changes in tidal amplitude. However, evidence for the most recent fluctuation is an artifact of early Acadian land reclamation that occurred in the seventeenth ce...
Article
Full-text available
We assess the status of channel networks and pools of two tidal salt marshes recovering from more than a century of agricultural reclamation on the Bay of Fundy, Canada. A process of largely unmanaged restoration occurred at these sites since abandonment of agricultural activities during the first half of the twentieth century. Each recovering mars...
Article
Production of belowground organic matter is critical to sustainability of salt marshes. It plays a role in vertical soil accretion, a process essential for salt marshes to maintain their relative elevation and persist as sea levels rise. This paper examines belowground production and soil carbon of a high-latitude saltmarsh in the St Lawrence Estua...
Article
Changes in atmospheric mercury deposition are used to evaluate the effectiveness of regulations controlling emissions. This analysis can be complicated by seemingly incongruent data from different model runs, model types, and field measurements. Here we present a case study example that describes how to identify trends in regional scale mercury dep...
Article
Full-text available
Recent archaeological excavations on the heads (i.e., the most elevated and upstream parts) of several large Everglades fixed tree islands may reshape what is understood about the age and formation of these landforms, and about the role of humans in the early Everglades wetland, between 3500 and 1000 B.C. Tree islands are patches of high ground, dr...
Article
Beginning in the 17th century many Bay of Fundy marshes were diked and drained for agricultural use, but storm breaching of dikes and failure of tidal gates has returned tidal flooding to some marshes. We investigated two breached and undiked salt marsh pairs in the Bay of Fundy to assess the potential for recovery of these reclaimed lands and impr...
Article
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...
Article
Full-text available
Abstract Restoration of Fundy salt marshes is sometimes required by federal and provincial agencies as compensation for the unavoidable loss of wetlands. To understand the potential outcomes of restoration, it is useful to examine marshes that have already experienced a period of recovery. By comparing conditions at marshes recovering for different...
Article
Full-text available
Abstract Soil saturation, and thus water table depth, is important to salt marsh vegetation as it drives zonation, pro- ductivity, and survival. In organogenic, microtidal marshes tidal fl ooding is the main driver of water table. What driver(s) account for water table variability in minerogenic, macrotidal salt marshes? We examined sub-surface hyd...
Article
Mercury contamination in Canada's Bay of Fundy is a priority concern because of elevated levels observed in fish, birds and wildlife. Salt marshes constitute an important part of the Bay's coastline and are potential stores of mercury for the region. We measured the amount of mercury accumulated over a 5-yr period from 1997 to 2002 in surface sedim...
Article
Full-text available
Modifications of the hydrology of the Florida Everglades began in the 1880s. Impacts due to changes in the hydrological regime, as well as nutrient enrichment are clear in the northern Everglades. Although these changes were more subtle in the southern Everglades, altered hydroperiods and plant communities are targeted for restoration. Identificati...
Article
Tens of thousands of hectares of salt marsh have formed along eastern Canada's macro-tidal Bay of Fundy. Most of these marshes have been diked and converted to agricultural land since the arrival of Acadian settlers in the 17th century. Although there are currently no controlled salt marsh restoration efforts underway in the Bay of Fundy, there are...