312 research outputs found
Interactions between benthic macroinvertebrates and saltmarsh plants : consequences for saltmarsh restoration and the policy of managed realignment on the coast of SE England.
No full textPhDOver the last half century, the saltmarshes of south east England have undergone
an extensive decline, especially the pioneer zone vegetation. These losses have
generally been blamed on coastal squeeze resulting from sea level rising against sea
walls. There is little evidence to support this hypothesis however, and an alternative
hypothesis, based on infaunal invertebrates preventing the establishment of saltmarsh
plants was tested.
In the managed realignment site at Tollesbury, and the other sites examined, the
mudflat fauna was dominated by Nereis (= Hediste) diversicolor and Hydrobia ulvae. In
laboratory experiments N. diversicolor and H. ulvae reduced the production of seedlings
from seeds of Salicornia europaea agg.. Conversely the presence of S. europaea agg.
significantly reduced the normal burrowing activity of N. diversicolor.
Invertebrate exclusion experiments established at five sites in south east
England facilitated colonisation by saltmarsh plants at some sites (Orplands, the Blythe
Estuary, Wallasea Island and Maldon), by excluding large (>3cm) N. diversicolor.
However, at the Tollesbury realignment site, the high rate of sediment deposition and
the relatively long distance to a source of seeds prevented plant colonisation.
This study supports the hypothesis that establishment of saltmarsh vegetation is
prevented by infaunal invertebrates,particularly N.diversicolor, which exclude plants
through bioturbation, herbivory and granivory. These interactions may help explain the
loss of saltmarshes and will reduce the success of future managed realignment schemes
which depend upon the colonisation of new intertidal areas by saltmarsh vegetation.
Further management of realignment sites will be necessary to encourage saltmarsh
development.Ministry of Agriculture, Fisheries and Foo
Mechanisms for accumulation and migration of technetium-99 in saltmarsh sediments
No full textThis thesis describes the development of analytical methods for both the bulk determination of 99Tc, and determination of 99Tc in sequential extracts from sediments. These methods have been used to collect data, which, along with trace and major element data have been used to interpret the mechanisms for 99Tc input, migration and accumulation in saltmarshes. The inventory of 99Tc stored in the Thornflatt Saltmarsh, Esk Estuary has also been determined. The routine determination of 99Tc in bulk samples uses 99mTc as a yield monitor. Samples are ignited stepwise to 550°C and the 99Tc is extracted using 8M nitric acid. Many contaminants are precipitated with Fe(OH)3 and the Tc in the supernant is pre-concentrated and further purified using anion-exchange chromatography. Final separation of Tc from Ru is achieved by extraction of Tc into 5% TnOA in xylene from 2M sulphuric acid. The yield is determined by γ-spectrometric analysis of 99mTc. Determination of 99Tc is made by liquid scintillation counting. Typical recoveries are in the order of 70-95% and the method has a detection limit of 1.7 Bq/kg for a sample size of 10g. Determination of Tc in sequential extracts uses operationally defined procedures to extract: exchangeable Tc, reducible Tc and oxidisable Tc. An initial water wash is used to extract any occluded Tc and a final leach in 8 M nitric acid is used to dissolve any residual Tc. The isolation of 99Tc uses TEVA resin for Extracts 1-4 and the decontamination procedure developed for bulk analysis for Extract 5. 99mTc was used as a yield monitor, and determination of 99Tc is by liquid scintillation counting. Limits of detection were dependent on the amount of 99mTc tracer used but were found to be as low as 2.4 Bq/kg for a sample size of 2g. A study was made of the mechanisms responsible for the accumulation and migration of Tc in estuarine sediments using sediments collected from saltmarshes at Thornflatt, Carlaverock and the Ribble Estuary. 99Tc was present at determinable activities in all the sediment cores taken from these sites. Good correlations between Tc and CaO as well as CO3 concentrations and poor correlation between Tc and radionuclides adsorbed to inorganic detritus infer a direct input of 99Tc to marsh sediments. Determination of 99Tc in biota living on the marsh also showed that this was not a significant pathway for input of Tc to the sediments. Sequential extraction data imply sorption to an organic fraction of the sediment. Stable element and sequential extraction data indicates that Tc is readily oxidised and remobilised before reprecipitation where redox conditions are favourable. Data indicate a reduction potential between those of the MnIV to MnII reaction and the FeIII to FeII reaction is necessary for re-accumulation to occur, as suggested by published thermodynamic data. Data collected from reducing sediments imply that similar mechanisms are responsible for the accumulation of Mn (e.g. reduction by sulphate reducing bacteria) and the accumulation of Tc. The inventory of 99Tc held within the Thornflatt saltmarsh is proportionally less than that of 137Cs or 241Am when compared to discharges from Sellafield. However a higher proportion of 99Tc is transferred from Seliafield and incorporated into saltmarsh sediments than is suggested by previously published standard distribution coefficient data. Saltmarsh sediments are therefore a more important sink of 99Tc than extrapolations made from inventories of other radionuclides would suggest
Saltmarsh Halophytes in Mannar Landscape, Sri Lanka
No full textAbstract: The coastal ecosystem diversity in Sri Lanka is a combination of several ecosystems which are estuaries, lagoons, beaches, rocky shores, sand dunes, salt marshes and mangroves. Saltmarsh vegetation is mainly found in Northwestern and Southeastern regions in Sri Lanka. This ecosystem in the Northern region of Sri Lanka have not received any attention from ecologists for a long period of time. This review studying the saltmarsh vegetation, mainly halophyte species in Mannar landscape, Sri Lanka. The unique features of salt marsh vegetation, previous and current classifications of Sri Lankan saltmarsh vegetation and the physical morphological characteristics of saltmarsh halophytes in Mannar with the observations are focusing to communicating by this paper.
The saltmarsh halophytes are unique vegetation including a conservational importance, the coastal studies are currently discussed as the issues of sea level rising with the global warming. Sri Lankan saltmarsh halophytes, Sesuvium portulacastrum, Salicornia branchiata, Suaeda maritima, Suaeda monoica, Suaeda vermiculata, Tecticornia indica (Halosarcia indica) and Cressa cretica are assessed unique physical characteristics, qualitative morphological features such as colour variations of plants with their age and other environmental factors.
Since this coastal wetland has numerous ecological, economical and other variety of values, conserving these habitats are very important. Saltmarsh halophytes consist with important physical and chemical properties are also adding a greater importance to the coastal wetlands. Since restoring or rehabilitation of a coastal habitat is a costly and time-taking process compare to the terrestrial habitats the scope of this review is highlighting the uniqueness and conserving importance to the society.
Keywords: Coastal ecosystem, Conservation, Halophytes, Saltmarsh vegetation, Species, Morphological characteristics.
Title: Saltmarsh Halophytes in Mannar Landscape, Sri Lanka
Author: G. Madushika M. Kumari, K.B Ranawana, Sanjeewa Jayaratne
International Journal of Novel Research in Life Sciences
ISSN 2394-966X
Vol. 9, Issue 6, November 2022 - December 2022
Page No: 1-14
Novelty Journals
Website: www.noveltyjournals.com
Published Date: 02-November-2022
DOI: https://doi.org/10.5281/zenodo.7274161
Paper Download Link (Source)
https://www.noveltyjournals.com/upload/paper/Saltmarsh%20Halophytes-02112022-6.pdfInternational Journal of Novel Research in Life Sciences, ISSN 2394-966X, Novelty Journals, Website: www.noveltyjournals.co
Saltmarshes on the fringe : restoring the degraded shoreline of the Eden Estuary, Scotland
No full textSaltmarshes are highly valued habitats but the majority of the Eden Estuary’s saltmarsh was buried under sea defences and ad hoc rubbish dumps during the last century. Without saltmarsh, the degraded shoreline may be even more vulnerable to rising sea levels and increased wave and tidal energy. This study investigated planting native saltmarsh species, common in the estuaries of Eastern Scotland, to restore saltmarsh development and sedimentation to the Eden Estuary’s shoreline.
The survival and growth of the sedge Bolboschoenus maritimus (Sea Club-rush) and the grasses Phragmites australis (Common Reed) and Puccinellia maritima (Common Saltmarsh Grass) were compared in planting trials. These were seeded or transplanted onto unvegetated upper mudflats in front of eroded P. maritima saltmarsh and a disused rubbish dump. The longer term sustainability of this practice was assessed by comparing sediment deposition and surface elevation in the transplant sites, natural saltmarsh and upper unvegetated mudflats.
B. maritimus outperformed P. australis and P. maritima. Springtime, high density planting was successful, whereas seeds, planting in autumn and low density planting failed. Growth in the transplanted B. maritimus sites was relatively slow for the first three years but subsequently overtook growth of the seaward edge of natural B. maritimus marsh. Sediment was not deposited on natural P. maritima and was low on upper unvegetated mudflats and in young transplant sites. Most deposition occurred in four year old sites of B. maritimus. Sediment surface elevation in natural P. maritima remained constant throughout the year, but increased in all the other sites during the summer. The upper mudflat was the only site to erode during winter. A significant, positive association was found between tide height and sediment deposition, while winds from the south-east were associated with significantly more deposition than winds from the south-west.
The direct planting of saltmarsh vegetation has restored a valuable and rapidly disappearing habitat to the degraded shoreline of the Eden Estuary. The low-cost and simplicity of this restoration practice give it great potential as a sustainable coastal management option that should be explored in other Scottish estuaries. This form of restoration could help to increase the resilience and reduce the vulnerability of degraded shorelines to climate change and rising sea levels
The ecological significance of saltmarshes to the Peel-Harvey Estuarine system. In: McComb, A.J., Kobryn, H.T. and Latchford, J.A. (eds) Samphire marshes of the Peel-Harvey estuarine system Western Australia.
No full textThe saltmarshes of the Peel-Harvey system are important to the environmental health of the estuary and to this region of the Swan Coastal Plain. Although there have been few scientific investigations specific to this area, a number of world-wide studies on the ecological characteristics of saltmarshes have indicated they are very important to the environmental health of estuaries and coastal ecosystems (Mann, 1982; Kennish, 1990). Unfortunately, there is a paucity of studies on Australian saltmarsh ecosystems (Fairweather, 1990). However, in a local context there is evidence that saltmarshes in the Peel-Harvey system are critical to the overall ecological health of the Estuary (Table 6.1). For example, over 83 bird species have been observed in the saltmarshes of the estuary (Ninox, 1990) (Plate 6.1) and between 18 and 25 of these species are known to be trans-equatorial migrants (Jaensch et al., 1988; Wilkes, 1990). This provides the basis for listing the whole Peel-Harvey Estuarine area as a RAMSAR bird treaty area as well as for the estuary being listed in the JAMBA and CAMBA treaties.
The area is also significant for other ecological reasons which will be briefly outlined, along with the major ecological points suggested in the previous chapters, and compared with data and literature generated from saltmarsh research elsewhere in the world. In this way it is hoped that a better appreciation of the ecological significance of the saltmarshes in the Peel-Harvey Estuary will be reached
Water regimes and marsh distribution. In: McComb, A.J., Kobryn, H.T. and Latchford, J.A. (eds) Samphire marshes of the Peel-Harvey estuarine system Western Australia.
No full textTide has long been recognised as the most influential factor determining plant zonation and the development of saltmarsh communities, and it is the tide that largely determines the structure and function of saltmarshes (Clarke & Hannon, 1969).
The zonation of species with increasing distance from the water's edge and increasing elevation is initially determined by the frequency of tidal flooding and the tolerance of various species to this (Huiskes, 1990). Tidal range usually sets the upper and lower limits of the marsh. The lower limits are set by depth and duration of flooding, and the consequent mechanical effect of the waves, sediment availability and rate of erosion. The upper limits are influenced mainly by soil water salinity and nutrient availability, both of which are linked to tidal flooding frequency (Mitsch & Gosselink, 1993), tidal water being the main source of soil salt and the major mechanism for nutrient transport (Clarke & Hannon, 1971)
Aspects of the ecology, behaviour and ecosystem effects of the marine polychaete Nereis diversicolor (O.F. Müller, 1776) in the estuaries of south-east England.
No full textPhDThe marine infaunal polychaete Nereis diversicolor has been shown to restrict the development of pioneer saltmarsh vegetation in south-east England through bioturbation and herbivory while surface deposit feeding. This can have severe implications for saltmarsh conservation as in the UK the greatest loss of internationally important saltmarsh habitat occurs in these estuaries. This thesis addresses several aspects of the ecology of N. diversicolor as an ecosystem engineer. The main aims were to investigate how it disperses and colonises sediments, what food sources support its often dense populations and whether these are enhanced by nutrient pollution, and what other effects on the habitat and other benthic fauna they may have. A 12 month experiment on the Crouch Estuary demonstrated that N. diversicolor disperse throughout the year, from the water column as late larvae and juveniles, and as adults crawling across the sediment surface. Peak dispersal is during late summer, but was not necessarily density dependant and individuals may disperse several times. There may be population differences in the stages of dispersal as funnel trap data from the Thames estuary indicate that N. diversicolor also disperse as much younger larvae. Multiple stable isotope (δ 13C and δ 15N) analyses were used approach was employed to test the hypothesis that N. diversicolor feeding behaviour was affected by sewage inputs, which would encourage surface deposit feeding on organic detritus, microphytobenthos and benthic macroalgae, rather than suspension feeding on phytoplankton and water column organic matter. At polluted sites N. diversicolor were mainly surface deposit feeders feeding on Ulva sp. and sediment organic matter, and at putative clean sites suspension feeding was more important. Their diet varied spatially as in some locations Spartina anglica detritus was important while in others Nereis was a secondary consumer, feeding on the amphipod Corophium volutator. A seasonal study using stable isotopes revealed differences in feeding behaviour between the Wallasea Island managed realignment site, and in an adjacent natural saltmarsh. At the realignment site benthic algae were the important food source, whereas in the mature marsh Nereis consumed predominantly Spartina anglica detritus, C. volutator, and was suspension feeding on water column organic matter. Preventing Nereis from surface deposit feeding within the recharged sediments in the Wallasea Island managed realignment site resulted in a reduction in sediment water content, increased sediment stability and development of diatomaceous mats. However, the exclusion did not provide refuge for young Nereis and bivalves, or encourage the successful establishment of pioneer marsh species (S. anglica and S. europaea agg.).Natural Environment Research Studentship
(NER/S/A/2006/14028)
CASE
Centre for the Environment, fisheries, Aquaculture Science (CEFAS
Recommendations for the future management and conservation of saltmarshes in the Peel-Harvey estuarine system. In: McComb, A.J., Kobryn, H.T. and Latchford, J.A. (eds) Samphire marshes of the Peel-Harvey estuarine system Western Australia.
No full textEstuarine saltmarshes can stimulate a number of senses. In a visual way, they provide a pleasing vista of procumbent to tall shrubs and trees tinged with colours ranging from red in autumn to succulent green in spring. This view is often enhanced by the sight of hundreds of wading birds feeding and dabbling along the shores and flying low over this interface between land and water. Saltmarshes also provide a contrasting sense when the rich productive smells of the marsh are detected. These smells are composed of decaying sun-baked vegetation mixing with the rotting gases of fetid muddy land. To some, the landscape features and the close proximity of open estuarine waters provides a potentially dollar-rich urban development challenge. With enough fill and re-contouring, these areas could be converted into expensive waterside homes. To all, however, the swarming mosquito hazes can drive us into our homes or cars making us wonder why nature has been so free in creating such a varied environment.
Overall, samphire marshes truly embody a large ecotone metaphor. On one side is a unique habitat providing an interface and link between land and water, and on the other side an environment fertile for human cultural conflict. Unfortunately, humans are an ecotone species and are drawn to the fringes of estuaries. To reduce conflict and successfully manage these environments requires an understanding of current land ownership, reserve status of fringing land, international treaty obligations, the planning process and the use of practical management plans and structures. It is also important to recognise the wisdom of using applied management and theoretical research plans to provide answers to management questions. They are most helpful if these plans recognise the uniqueness of most saltmarshes and give the public and estuarine manager the kind of information which allows saltmarshes to be conserved and sustained well into the future. Ultimately, any management plan must provide direction to help prevent the degradation of saltmarsh functions, such as ecologically important biodiversity, productivity and nutrient storage and release functions
Saltmarsh plant responses to eutrophication
No full textAuthor Posting. © Ecological Society of America, 2016. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 26 (2016): 2647–2659, doi:10.1002/eap.1402.In saltmarsh plant communities, bottom-up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting these predictions has been based largely on short-term, plot-level (e.g., 1–300 m2) studies, which may miss landscape-level phenomena that drive ecosystem-level responses. We implemented an ecosystem-scale, nine-year nutrient experiment to examine how saltmarsh plants respond to simulated conditions of coastal eutrophication. Our study differed from previous saltmarsh enrichment studies in that we applied realistic concentrations of nitrate (70–100 μM NO3−), the most common form of coastal nutrient enrichment, via tidal water at the ecosystem scale (~60,000 m2 creeksheds). Our enrichments added a total of 1,700 kg N·creek−1·yr−1, which increased N loading 10-fold vs. reference creeks (low-marsh, 171 g N·m−2·yr−1; high-marsh, 19 g N·m−2·yr−1). Nutrients increased the shoot mass and height of low marsh, tall Spartina alterniflora; however, declines in stem density resulted in no consistent increase in aboveground biomass. High-marsh plants S. patens and stunted S. alterniflora did not respond consistently to enrichment. Nutrient enrichment did not shift community structure, contrary to the prediction of nutrient-driven dominance of S. alterniflora and Distichlis spicata over S. patens. Our mild responses may differ from the results of previous studies for a number of reasons. First, the limited response of the high marsh may be explained by loading rates orders of magnitude lower than previous work. Low loading rates in the high marsh reflect infrequent inundation, arguing that inundation patterns must be considered when predicting responses to estuarine eutrophication. Additionally, we applied nitrate instead of the typically used ammonium, which is energetically favored over nitrate for plant uptake. Thus, the form of nitrogen enrichment used, not just N-load, may be important in predicting plant responses. Overall, our results suggest that when coastal eutrophication is dominated by nitrate and delivered via flooding tidal water, aboveground saltmarsh plant responses may be limited despite moderate-to-high water-column N concentrations. Furthermore, we argue that the methodological limitations of nutrient studies must be considered when using results to inform management decisions about wetlands.National Science Foundation Grant Numbers: DEB 0816963, DEB 0213767, DEB 1354494, OCE 0923689, OCE 0423565, OCE 0924287, OCE 1238212, OCE 1354124;
Northeast Climate Science Center Grant Grant Number: DOI G12AC00001;
Connecticut College through the Jean C. Tempel Professorship in Botan
The role of root decomposition in global mangrove and saltmarsh carbon budgets
No full textThis study aims to determine the drivers of root decomposition and its role in carbon (C) budgets in mangroves and saltmarsh. We review the patterns of root decomposition, and its contribution to C budgets, in mangroves and saltmarsh: the impact of climatic (temperature and precipitation), geographic (latitude), temporal (decay period) and biotic (ecosystem type) drivers using multiple regression models. Best-fit models explain 50% and 48% of the variance in mangrove and saltmarsh root decay rates, respectively. A combination of biotic, climatic, geographic and temporal drivers influences root decay rates. Rainfall and latitude have the strongest influence on root decomposition rates in saltmarsh. For mangroves, forest type is the most important; decomposition is faster in riverine mangroves than other types. Mangrove species Avicennia marina and saltmarsh species Spartina maritima and Phragmites australis have the highest root decomposition rates. Root decomposition rates of mangroves were slightly higher in the Indo-west Pacific region (average 0.16% day− 1) than in the Atlantic-east Pacific region (0.13% day− 1). Mangrove root decomposition rates also show a negative exponential relationship with porewater salinity. In mangroves, global root decomposition rates are 0.15% day− 1 based on the median value of rates in individual studies (and 0.14% day− 1 after adjusting for area of mangroves at different latitudes). In saltmarsh, global root decomposition rates average 0.12% day− 1 (no adjustment for area with latitude necessary). Our global estimate of the amount of root decomposing is 10 Tg C yr− 1 in mangroves (8 Tg C yr− 1 adjusted for area by latitude) and 31 Tg C yr− 1 in saltmarsh. Local root C burial rates reported herein are 51–54 g C m− 2 yr− 1 for mangroves (58–61 Tg C yr− 1 adjusted for area by latitude) and 191 g C m− 2 yr− 1 for saltmarsh. These values account for 24.1–29.1% (mangroves) and 77.9% (saltmarsh) of the reported sediment C accumulation rates in these habitats. Globally, dead root C production is the significant source of stored sediment C in mangroves and saltmarsh.Griffith Sciences, Griffith School of EnvironmentFull Tex
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