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Long-term effects of mercury in a salt marsh: Hysteresis in the distribution of vegetation following recovery from contamination

Válega, M.; Lillebø, A. I.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
66.4%
During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh.; http://www.sciencedirect.com/science/article/B6V74-4R8M09D-2/1/1da80b1f6cad6e36f85e4a8c58552055

Heavy metal accumulation in Halimione portulacoides: Intra- and extra-cellular metal binding sites

Sousa, Ana I.; Caçador, Isabel; Lillebø, Ana I.; Pardal, Miguel A.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
56.21%
Salt marsh plants can sequestrate and inherently tolerate high metal concentrations found in salt marsh sediments. This work intended to understand the Halimione portulacoides (L.) Aellen strategies to prevent metal toxicity, by investigating the metal location in different plant organs and in the cell. A sequential extraction was performed on leaves, stems and roots of H. portulacoides in order to determine and compare the metal (Zn, Pb, Co, Cd, Ni and Cu) concentration in several fractions of the plant material (ethanolic, aqueous, proteic, pectic, polissacaridic, lenhinic and cellulosic). This study shows that all plant organs of H. portulacoides mostly retain metals in the cell wall (65% is the average for all studied metals stored in the root cell wall, 55% in the stems and 53% in the leaves), and the metal content in the intracellular compartment is much lower (21% in roots, 25% in stems and 32% in leaves). High levels of heavy metal in the sedimentary environment do not cause toxicity to H. portulacoides, because H. portulacoides immobilizes them in different cell compartments (cell wall + proteic fraction + intracellular) outside key metabolic sites.; http://www.sciencedirect.com/science/article/B6V74-4PJ6BH4-1/1/6c9b1b476e86f320046384f6c3e90548

Carbon budget in a temperate estuary salt marsh. Influence of temperature increase in carbon sequestration

Couto, Thiago Drumond Teixeira Correia
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
56.67%
Devido ao aumento do uso de combustíveis fósseis pelo homem desde que começou a atividade industrial, o mundo tem sofrido com o aumento do CO2 atmosférico e com o aumento da temperatura. Zonas húmidas costeiras, como os sapais são excelentes acumuladores de carbono, pois retiram CO2 da atmosfera, que se acumula nos tecidos das plantas. Modelos ecológicos têm sido utilizados para tentar entender quais os resultados de impactos antropogénicos numa escala global. O aquecimento global pode ameaçar áreas de sapal nomeadamente, por exemplo, através do aumento do nível do mar. O presente trabalho, realizado no sapal do estuário do rio Mondego, localizado na costa Atlântica de Portugal, teve os seguintes objetivos principais: 1. Comparar mudanças sazonais e funções associadas aos diferentes mecanismos fotossintéticos de três espécies de plantas de sapal (Scirpus maritimus, Spartina maritima and Zostera noltii) no estuário do Mondego e avaliar as implicações na sua capacidade de acumular carbono. 2. Com recurso à análise dos isótopos estáveis de carbono, avaliar as concentrações de carbono no sedimento, assim como em folhas, caules e raízes de três espécies de plantas de sapal do estuário do Mondego, considerando suas diferenças metabólicas...

Impact of seasonal fluctuations on the Sediment-Mercury, its accumulation and partitioning in Halimione portulacoides and Juncus maritimus collected from Ria de Aveiro Coastal Lagoon (Portugal)

Anjum, N. A.; Ahmad, I.; Válega, M.; Pacheco, M.; Figueira, E.; Duarte, A. C.; Pereira, E.
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.41%
The availability of metals to plants is a complex function of numerous environmental factors. Many of these factors are interrelated, and vary seasonally and temporally. The current study intended to understand the influence of seasonal fluctuations and the vegetation of salt marsh plants (SMPs; Halimione portulacoides, Juncus maritimus) on sediment’s mercury (Hg) and its pH and redox potential (Eh), as well as their cumulative effect on the plant’s Hg-accumulation and Hg-partitioning potential. The area selected for the study was Laranjo Basin at Ria de Aveiro lagoon (Portugal) where a known Hg gradient was existed due to chlor-alkali plant discharge. Three sampling sites (L1, L2 and L3) were selected along a transect defined by the distance from the main Hg source. Samples were also collected from the Hg-free site (R). Irrespective of the plant vegetation, Hg in sediments gradually increased with a decreasing distance towards Hg-point source. The sediment colonised by J. maritimus showed more Hg concentration compared with H. portulacoides irrespective of the season. As a whole, J. maritimus accumulated Hg more than H. portulacoides at all the sampling sites, whereas in root, stem and leaf, the concentration was ranked as: L1 > L2 > L3 in both the plant species and was differentially influenced by seasonal changes. Moreover...

Contribution of primary producers to mercury trophic transfer in estuarine ecosystems: possible effects of eutrophication

Coelho, J. P.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.51%
There is an ongoing eutrophication process in the Ria de Aveiro coastal lagoon (Portugal), with progressive replacement of rooted primary producers for macroalgae. Taking advantage of a well-defined environmental contamination gradient, we studied mercury accumulation and distribution in the aboveground and the belowground biomass of several salt marsh plants, including the seagrass species Zostera noltii and the dominant green macroalgal species Enteromorpha sp. The results of these experiments were then placed into the context of the estuarine mercury cycle and transport from the contaminated area. All salt marsh plants accumulated mercury in the root system, with Halimione portulacoides showing the highest levels, with up to 1.3 mg kg−1 observed in the most contaminated area. Belowground/aboveground ratios were generally below 0.4, suggesting that salt marsh plants are efficient immobilizers and retainers of mercury agents. Moreover, due to their sediment accretion capacities, salt marsh plants seem to play an important role in the sequestration of mercury in estuarine sediments. Seagrasses, on the other hand, accumulated considerable amounts of mercury in the aboveground biomass with belowground/aboveground ratios reaching as high as 1.4. These results may be due to their different routes of uptake (roots and foliar uptake) which suggests that seagrass meadows can be an important agent in the export of mercury from contaminated areas...

Influence of multiple stressors on the auto-remediation processes occurring in salt marshes

Sousa, A. I.; Lillebo, A. I.; Pardal, M. A.; Cacador, I.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.28%
Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni – micronutrients, and Cd – class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health.

Long-term effects of mercury in a salt marsh: Hysteresis in the distribution of vegetation following recovery from contamination

Valega, M.; Lillebo, A. I.; Pereira, M. E.; Duarte, A. C.; Pardal, M. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.4%
During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh.

Mercury intracellular partitioning and chelation in a salt marsh plant, Halimione portulacoides (L.) Aellen: strategies underlying tolerance in environmental exposure

Válega, M; Lima, A I G; Figueira, E M A P; Pereira, E; Pardal, M A; Duarte, A C
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.24%
In the presence of metal stress, plants can resort to a series of tolerance mechanisms. Therefore field studies should be undertaken in order to evaluate the real role of these mechanisms in stress coping. The aim of this paper was to clarify the biochemical processes behind mercury tolerance in Halimione portulacoides (L.) Aellen (Caryophyllales: Chenopodiaceae) collected in a mercury contaminated salt marsh. Different fractions of mercury were separated: buffer-soluble (mainly cytosolic) and insoluble mercury (mainly associated with membranes and cell walls). The amounts in each fraction of metal were compared and related to metal distribution within plant organs. Protein-mercury complexes were isolated and analysed for their thiol content in order to assess wether the tolerance of this salt marsh plant was associated with the induction of metal chelation by phytochelatins. Overall, the mercury tolerance strategies of the plant are likely to involve root cell wall immobilization as a major mechanism of metal resistance, rather than metal chelation in the cytosolic fraction. Nevertheless, phytochelatins were demonstrated to chelate mercury under environmental exposure.

Microbe-mediated recovery of salt marshes contaminated with oil hydrocarbons; Mediação microbiana na recuperação de sapais contaminados com hidrocarbonetos

Oliveira, Vanessa Jesus de
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
56.58%
Salt marshes are highly productive intertidal habitats that serve as nursery grounds for many commercially and economically important species. Because of their location and physical and biological characteristics, salt marshes are considered to be particularly vulnerable to anthropogenic inputs of oil hydrocarbons. Sediment contamination with oil is especially dangerous for salt marsh vegetation, since low molecular weight aromatic hydrocarbons can affect plants at all stages of development. However, the use of vegetation for bioremediation (phytoremediation), by removal or sequestration of contaminants, has been intensively studied. Phytoremediation is an efficient, inexpensive and environmental friendly approach for the removal of aromatic hydrocarbons, through direct incorporation by the plant and by the intervention of degrading microbial populations in the rhizosphere (microbe-assisted phytoremediation). Rhizosphere microbial communities are enriched in important catabolic genotypes for degradation of oil hydrocarbons (OH) which may have a potential for detoxification of the sediment surrounding the roots. In addition, since rhizosphere bacterial populations may also internalize into plant tissues (endophytes), rhizocompetent AH degrading populations may be important for in planta AH degradation and detoxification. The present study involved field work and microcosms experiments aiming the characterization of relevant plant-microbe interactions in oilimpacted salt marshes and the understanding of the effect of rhizosphere and endosphere bacteria in the role of salt marsh plants as potential phytoremediation agents. In the field approach...

Response of salt marsh plants to the heavy metals in the Tagus estuary

Silva, Vânia Filipa Nunes da, 1985-
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2010 POR
Relevância na Pesquisa
66.17%
Tese de mestrado. Biologia (Biologia Celular e Biotecnologia). Universidade de Lisboa, Faculdade de Ciências, 2010; Há muito que a orla costeira, com os seus estuários e sapais, atrai a população para as suas margens, devido principalmente à sua localização privilegiada e de grande riqueza biológica. Consequentemente, a acção antropogénica desempenhada sobre estas regiões, que actuam frequentemente como reservatório de poluentes e nutrientes, tem vindo a exercer um impacto negativo sobre todos os ecossistemas costeiros. São vários os tipos de poluentes quer orgânicos quer inorgânicos, associados a estas regiões, como por exemplo, os metais pesados. Estes constituem uma séria problemática resultante, quer da sua elevada toxicidade quer da sua persistência. Contudo, vários estudos têm vindo a demonstrar a importância da vegetação existente nos sapais, como fitoremediadora. As plantas de sapal detêm um papel ecológico fulcral, não só devido à sua elevada produtividade, mas também à sua capacidade depurativa de retenção de metais pesados nos seus tecidos. Uma vez que os sapais são ecossistemas dinâmicos, sujeitos diariamente ao regime das marés e consequentemente a inundações periódicas, os halófitos que os colonizam estão continuamente expostos a poluentes vindos de várias fontes. Um desses poluentes é o metal pesado zinco...

Fitoestabilização de sedimentos contaminados por metais e metalóides

Peres, Sara Isabel de Carvalho
Fonte: ISA/UL Publicador: ISA/UL
Tipo: Dissertação de Mestrado
Publicado em //2014 POR
Relevância na Pesquisa
56.33%
Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia; Wastes of a former steel industry were deposited during 40 years on the left bank of the Coina River, an affluent of the Tagus River, near its estuary, creating a landfill that is connected to the river itself. Tides penetrate and exit the landfill, creating a periodic lagoon that shows resemblances to the salt marshes nearby, being colonized by salt marsh plants. This study aims: a) to evaluate the level of contamination of the lagoon by doing a biogeochemi-cal study, b) to evaluate the level of dispersion of the contaminants through a leaching assay, and c) to evaluate the capacity of Tamarix africana Poiret to be used in the phytostabilization of the contaminated sediment. The sediment is considered contaminated by As, Cd, Cr, Cu, Pb and Zn. It also presents high con-centrations in Fe and Al. The contaminant chemical elements seem to be associated to the sediment phases (adsorbed, co-precipitated etc.), as the concentrations of the elements were very low in pore water and leachates, as well as in the river water. Salt marsh plants are able to uptake contaminants without showing signs of toxicity, being the contaminants mostly retained in the roots. Tamarix africana shows potential to be used for phytostabilization...

Grazing Scar Characteristics Impact Degree of Fungal Facilitation in Spartina alterniflora Leaves in a South American Salt Marsh

Freitas,Ricardo Franco; Schrack,Elizabeth Carol; Sieg,Robert Drew; Silliman,Brian Reed; Costa,César Serra Bonifácio
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 EN
Relevância na Pesquisa
56.21%
Grazing scars of burrowing crabs and Hemiptera insects were simulated on leaves of the salt marsh grass Spartina alterniflora. Simulations of crab feeding generated two-fold higher fungal (ergosterol) content in leaves in comparison to that generated by insect scar simulations (1.26 ±0.55 and 0.57 ±0.25 µg per cm², respectively). This study provided evidence that herbivory could facilitate microbial infection by fungi in dominant South American salt marsh plants and indicated that specific feeding mechanisms used by different herbivores might differentially impact the strength of this interaction.

Isolation and Characterization of Polycyclic Aromatic Hydrocarbon-Degrading Bacteria Associated with the Rhizosphere of Salt Marsh Plants

Daane, L. L.; Harjono, I.; Zylstra, G. J.; Häggblom, M. M.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /06/2001 EN
Relevância na Pesquisa
66.29%
Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were isolated from contaminated estuarine sediment and salt marsh rhizosphere by enrichment using either naphthalene, phenanthrene, or biphenyl as the sole source of carbon and energy. Pasteurization of samples prior to enrichment resulted in isolation of gram-positive, spore-forming bacteria. The isolates were characterized using a variety of phenotypic, morphologic, and molecular properties. Identification of the isolates based on their fatty acid profiles and partial 16S rRNA gene sequences assigned them to three main bacterial groups: gram-negative pseudomonads; gram-positive, non-spore-forming nocardioforms; and the gram-positive, spore-forming group, Paenibacillus. Genomic digest patterns of all isolates were used to determine unique isolates, and representatives from each bacterial group were chosen for further investigation. Southern hybridization was performed using genes for PAH degradation from Pseudomonas putida NCIB 9816-4, Comamonas testosteroni GZ42, Sphingomonas yanoikuyae B1, and Mycobacterium sp. strain PY01. None of the isolates from the three groups showed homology to the B1 genes, only two nocardioform isolates showed homology to the PY01 genes, and only members of the pseudomonad group showed homology to the NCIB 9816-4 or GZ42 probes. The Paenibacillus isolates showed no homology to any of the tested gene probes...

Does vegetation prevent wave erosion of salt marsh edges?

Feagin, R. A.; Lozada-Bernard, S. M.; Ravens, T. M.; Möller, I.; Yeager, K. M.; Baird, A. H.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
56.37%
This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves.

Crabs Mediate Interactions between Native and Invasive Salt Marsh Plants: A Mesocosm Study

Zhang, Xiao-dong; Jia, Xin; Chen, Yang-yun; Shao, Jun-jiong; Wu, Xin-ru; Shang, Lei; Li, Bo
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/09/2013 EN
Relevância na Pesquisa
56.24%
Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet) and plot-level (density, total above- and belowground biomass), were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former...

The Contribution of Mangrove Expansion to Salt Marsh Loss on the Texas Gulf Coast

Armitage, Anna R.; Highfield, Wesley E.; Brody, Samuel D.; Louchouarn, Patrick
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/05/2015 EN
Relevância na Pesquisa
56.43%
Landscape-level shifts in plant species distribution and abundance can fundamentally change the ecology of an ecosystem. Such shifts are occurring within mangrove-marsh ecotones, where over the last few decades, relatively mild winters have led to mangrove expansion into areas previously occupied by salt marsh plants. On the Texas (USA) coast of the western Gulf of Mexico, most cases of mangrove expansion have been documented within specific bays or watersheds. Based on this body of relatively small-scale work and broader global patterns of mangrove expansion, we hypothesized that there has been a recent regional-level displacement of salt marshes by mangroves. We classified Landsat-5 Thematic Mapper images using artificial neural networks to quantify black mangrove (Avicennia germinans) expansion and salt marsh (Spartina alterniflora and other grass and forb species) loss over 20 years across the entire Texas coast. Between 1990 and 2010, mangrove area grew by 16.1 km2, a 74% increase. Concurrently, salt marsh area decreased by 77.8 km2, a 24% net loss. Only 6% of that loss was attributable to mangrove expansion; most salt marsh was lost due to conversion to tidal flats or water, likely a result of relative sea level rise. Our research confirmed that mangroves are expanding and...

The role of denitrification in the nitrogen cycle of New England salt marshes

Hamersley, Michael Robert
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 165 leaves; 10435902 bytes; 10435660 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
56.31%
I used direct measurements of nitrogen gas (N₂ fluxes and a ¹⁵N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is a major sink for groundwater nitrate of terrestrial origin. I studied creekbottom denitrification by direct measurements of N₂ fluxes in closed chambers against a low-N₂ background. I undertook experiments and simulation modeling of sediment N₂ fluxes in closed chambers to optimize the key experimental parameters of this approach. Denitrification in these sediments was driven by the degradation of labile organic matter pools which are depleted during long incubations. Sediment thickness was the most important parameter controlling the required incubation time. Errors of up to 13% with gas headspaces and 80% with water headspaces resulted from headspace N2 accumulation and the resulting collapse of the sediment-water diffusion gradient. These errors could be eliminated by using headspaces of sufficient thickness. Headspace flushing to reduce ammonium accumulation did not affect denitrification rates, but caused transient disturbance of N₂ flux rates. Direct measurements of 0₂, C0₂, N₂, and inorganic N fluxes from the sediments of a salt marsh tidal creek were made in order to examine the interaction of denitrification with the carbon...

Short- and long-term vegetative propagation of two spartina species on a salt marsh in southern Brazil

Marangoni, Juliano C??sar; Costa, C??sar Serra Bonif??cio
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
76.29%
Spartina alterniflora and Spartina densiflora are native salt marsh plants from the Atlantic coast; their habitats in Patos Lagoon estuary (southern Brazil) are characterized by a microtidal regime (<0.5 m) and, during El Ni??o events, high estuarine water levels and prolonged flooding due to elevated freshwater discharge from a 200,000-km2 watershed. During and between El Ni??o events, the vegetative propagation of these two Spartina species in the largest estuary of southern Brazil (Patos Lagoon) was evaluated by monitoring transplanted plants for 10 years (short-term study) and interpreting aerial photos of natural stands for 56 years (long-term study). During the short-term study, S. alterniflora quickly occupied mud flats (up to 208 cm year???1) by elongation of rhizomes, whereas S. densiflora showed a modest lateral spread (up to 13 cm year???1) and generated dense circular-shaped stands. However, moderate and strong El Ni??o events can promote excessive flooding and positive anomalies in the estuarine water level that reduce the lateral spread and competitive ability of S. densiflora. During the long-term study, natural stands of S. alterniflora and S. densiflora had steady lateral spread rates of 152 and 5.2 cm year???1, respectively...

Salt Marsh as a Coastal Filter for the Oceans: Changes in Function with Experimental Increases in Nitrogen Loading and Sea-Level Rise

Nelson, Joanna L.; Zavaleta, Erika S.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/08/2012 EN
Relevância na Pesquisa
56.56%
Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH4NO3)-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments...

Tide marsh ecology and wildlife: salt marsh plants and future coastal salt marshes in relation to animals

Daiber, Franklin C.
Fonte: Newark, Del. : College of Marine Studies and and Department of Biological Studies Publicador: Newark, Del. : College of Marine Studies and and Department of Biological Studies
Tipo: Livro
Relevância na Pesquisa
66.42%