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James T. Morris

Bio: James T. Morris is an academic researcher from University of South Carolina. The author has contributed to research in topics: Salt marsh & Spartina alterniflora. The author has an hindex of 50, co-authored 125 publications receiving 8911 citations. Previous affiliations of James T. Morris include Marine Biological Laboratory & Bristol Royal Infirmary.


Papers
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Journal ArticleDOI
01 Oct 2002-Ecology
TL;DR: In this paper, the authors show that the long-term stability of salt marsh ecosystems is explained by interactions among sea level, land elevation, primary production, and sediment accretion that regulate the elevation of the sediment surface toward an equilibrium with mean sea level.
Abstract: Salt marsh ecosystems are maintained by the dominant macrophytes that regulate the elevation of their habitat within a narrow portion of the intertidal zone by accumulating organic matter and trapping inorganic sediment. The long-term stability of these ecosystems is explained by interactions among sea level, land elevation, primary production, and sediment accretion that regulate the elevation of the sediment surface toward an equilibrium with mean sea level. We show here in a salt marsh that this equilibrium is adjusted upward by increased production of the salt marsh macrophyte Spartina alterniflora and downward by an increasing rate of relative sea-level rise (RSLR). Adjustments in marsh surface elevation are slow in comparison to interannual anomalies and long-period cycles of sea level, and this lag in sediment elevation results in significant variation in annual primary productivity. We describe a theoretical model that predicts that the system will be stable against changes in relative mean sea level when surface elevation is greater than what is optimal for primary production. When surface elevation is less than optimal, the system will be unstable. The model predicts that there is an optimal rate of RSLR at which the equilibrium elevation and depth of tidal flooding will be optimal for plant growth. However, the optimal rate of RSLR also represents an upper limit because at higher rates of RSLR the plant community cannot sustain an elevation that is within its range of tol- erance. For estuaries with high sediment loading, such as those on the southeast coast of the United States, the limiting rate of RSLR was predicted to be at most 1.2 cm/yr, which is 3.5 times greater than the current, long-term rate of RSLR.

1,544 citations

Journal ArticleDOI
TL;DR: Kirwan et al. as discussed by the authors used simulations from five numerical models to quantify the conditions under which ecogeomorphic feedbacks allow coastal wetlands to adapt to projected changes in sea level, finding that nonlinear feedbacks among inundation, plant growth, organic matter accretion, and sediment deposition, allow marshes to survive conservative projections of sea level rise where suspended sediment concentrations are greater than ∼20 mg/L.
Abstract: [1] Assumptions of a static landscape inspire predictions that about half of the world’s coastal wetlands will submerge during this century in response to sea‐level acceleration. In contrast, we use simulations from five numerical models to quantify the conditions under which ecogeomorphic feedbacks allow coastal wetlands to adapt to projected changes in sea level. In contrast to previous sea‐level assessments, we find that non‐linear feedbacks among inundation, plant growth, organic matter accretion, and sediment deposition, allow marshes to survive conservative projections of sea‐ level rise where suspended sediment concentrations are greater than ∼20 mg/L. Under scenarios of more rapid sea‐level rise (e.g., those that include ice sheet melting), marsheswill likelysubmerge neartheend ofthe 21stcentury. Our results emphasize that in areas of rapid geomorphic change, predicting the response of ecosystems to climate change requires consideration of the ability of biological processestomodifytheirphysicalenvironment.Citation: Kirwan, M. L., G. R. Guntenspergen, A. D’Alpaos, J. T. Morris, S. M. Mudd, and S. Temmerman (2010), Limits on the adaptability of coastal marshes to rising sea level, Geophys. Res. Lett., 37, L23401,

697 citations

Journal ArticleDOI
24 Jan 2003-Science
TL;DR: Although the plant community in a pristine salt marsh was found to be limited primarily by nitrogen availability, the bacterial community in the soil was limited by phosphorus, indicating that individual trophic groups may respond differently to nitrogen and phosphorus loading.
Abstract: Primary production in coastal wetlands is conventionally thought to be limited by nitrogen. Although the plant community in a pristine salt marsh was found to be limited primarily by nitrogen availability, the bacterial community in the soil was limited by phosphorus. Hence, in coastal wetlands, and possibly in many ecosystems, individual trophic groups may respond differently to nitrogen and phosphorus loading. Phosphorus limitation of the growth of nitrogen-transforming bacteria will affect carbon fixation, storage, and release mediated by plants, a result that has important implications for ecosystem management.

380 citations

Journal ArticleDOI
TL;DR: In this paper, the authors use a biocomplexity framework to provide a perspective of the consequences of climate change for coastal wetland ecogeomorphology, focusing on three dimensions of change: sea level rise, changes in storm frequency and intensity, and changes in freshwater, sediment, and nutrient inputs.
Abstract: Climate impacts on coastal and estuarine systems take many forms and are dependent on the local conditions, including those set by humans. We use a biocomplexity framework to provide a perspective of the consequences of climate change for coastal wetland ecogeomorphology. We concentrate on three dimensions of climate change affects on ecogeomorphology: sea level rise, changes in storm frequency and intensity, and changes in freshwater, sediment, and nutrient inputs. While sea level rise, storms, sedimentation, and changing freshwater input can directly impact coastal and estuarine wetlands, biological processes can modify these physical impacts. Geomorphological changes to coastal and estuarine ecosystems can induce complex outcomes for the biota that are not themselves intuitively obvious because they are mediated by networks of biological interactions. Human impacts on wetlands occur at all scales. At the global scale, humans are altering climate at rapid rates compared to the historical and recent geological record. Climate change can disrupt ecological systems if it occurs at characteristic time scales shorter than ecological system response and causes alterations in ecological function that foster changes in structure or alter functional interactions. Many coastal wetlands can adjust to predicted climate change, but human impacts, in combination with climate change, will significantly affect coastal wetland ecosystems. Management for climate change must strike a balance between that which allows pulsing of materials and energy to the ecosystems and promotes ecosystem goods and services, while protecting human structures and activities. Science-based management depends on a multi-scale understanding of these biocomplex wetland systems. Causation is often associated with multiple factors, considerable variability, feedbacks, and interferences. The impacts of climate change can be detected through monitoring and assessment of historical or geological records. Attribution can be inferred through these in conjunction with experimentation and modeling. A significant challenge to allow wise management of coastal wetlands is to develop observing systems that act at appropriate scales to detect global climate change and its effects in the context of the various local and smaller scale effects.

317 citations

Journal ArticleDOI
TL;DR: In this article, an analytical and numerical model of salt marsh sedimentation is presented to examine the bias introduced by organic processes into proxy records of sedimentation, namely 137Cs and 210Pb.
Abstract: Salt marshes accrete both organic and inorganic sediments. Here we present analytical and numerical models of salt marsh sedimentation that, in addition to capturing inorganic processes, explicitly account for above- and belowground organic processes including root growth and decay of organic carbon. The analytical model is used to examine the bias introduced by organic processes into proxy records of sedimentation, namely 137Cs and 210Pb. We find that accretion rates estimated using 210Pb will be less than accretion rates estimated using the 137Cs peak in steadily accreting marshes if (1) carbon decay is significant and (2) data for 210Pb extend below the 137Cs peak. The numerical model expands upon the analytical model by including belowground processes such as compaction and root growth, and by explicitly tracking the evolution of aboveground biomass and its effect on sedimentation rates. Using the numerical model we explore how marsh stratigraphy responds to sediment supply and the rate of sea-level rise. It is calibrated and tested using an extensive data set of both marsh stratigraphy and measurements of vegetation dynamics in a Spartina alterniflora marsh in South Carolina, USA. We find that carbon accumulation in marshes is nonlinearly related to both the supply of inorganic sediment and the rate of sea-level rise; carbon accumulation increases with sea-level rise until sea-level rise reaches a critical rate that drowns the marsh vegetation and halts carbon accumulation. The model predicts that changes in carbon storage resulting from changing sediment supply or sea-level rise are strongly dependent on the background sediment supply: if inorganic sediment supply is reduced in an already sediment poor marsh the storage of organic carbon will increase to a far greater extent than in a sediment-rich marsh, provided that the rate of sea-level rise does not exceed a threshold. These results imply that altering sediment supply to estuaries (e.g., by damming upstream rivers or altering littoral sediment transport) could lead to significant changes in the carbon budgets of coastal salt marshes.

285 citations


Cited by
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Journal Article
TL;DR: This book by a teacher of statistics (as well as a consultant for "experimenters") is a comprehensive study of the philosophical background for the statistical design of experiment.
Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

13,333 citations

Journal ArticleDOI
TL;DR: These mutants—the ‘Keio collection’—provide a new resource not only for systematic analyses of unknown gene functions and gene regulatory networks but also for genome‐wide testing of mutational effects in a common strain background, E. coli K‐12 BW25113.
Abstract: We have systematically made a set of precisely defined, single-gene deletions of all nonessential genes in Escherichia coli K-12. Open-reading frame coding regions were replaced with a kanamycin cassette flanked by FLP recognition target sites by using a one-step method for inactivation of chromosomal genes and primers designed to create in-frame deletions upon excision of the resistance cassette. Of 4288 genes targeted, mutants were obtained for 3985. To alleviate problems encountered in high-throughput studies, two independent mutants were saved for every deleted gene. These mutants-the 'Keio collection'-provide a new resource not only for systematic analyses of unknown gene functions and gene regulatory networks but also for genome-wide testing of mutational effects in a common strain background, E. coli K-12 BW25113. We were unable to disrupt 303 genes, including 37 of unknown function, which are candidates for essential genes. Distribution is being handled via GenoBase (http://ecoli.aist-nara.ac.jp/).

7,428 citations

01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

5,548 citations

Journal ArticleDOI
TL;DR: This review of 68 studies compares the methodologies used for the identification and quantification of microplastics from the marine environment and suggests standardized sampling procedures which allow the spatiotemporal comparison ofmicroplastic abundance across marine environments.
Abstract: This review of 68 studies compares the methodologies used for the identification and quantification of microplastics from the marine environment. Three main sampling strategies were identified: selective, volume-reduced, and bulk sampling. Most sediment samples came from sandy beaches at the high tide line, and most seawater samples were taken at the sea surface using neuston nets. Four steps were distinguished during sample processing: density separation, filtration, sieving, and visual sorting of microplastics. Visual sorting was one of the most commonly used methods for the identification of microplastics (using type, shape, degradation stage, and color as criteria). Chemical and physical characteristics (e.g., specific density) were also used. The most reliable method to identify the chemical composition of microplastics is by infrared spectroscopy. Most studies reported that plastic fragments were polyethylene and polypropylene polymers. Units commonly used for abundance estimates are “items per m2” ...

3,119 citations

Book
01 Sep 2011
TL;DR: In this paper, the Ecosystem Concept is used to describe the Earth's Climate System and Geology and Soils, and the ecosystem concept is used for managing and sustaining ecosystems.
Abstract: I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

3,086 citations