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Articoli di riviste sul tema "Seagrass meadow"
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Scott, Abigail L., Paul H. York e Michael A. Rasheed. "Spatial and Temporal Patterns in Macroherbivore Grazing in a Multi-Species Tropical Seagrass Meadow of the Great Barrier Reef". Diversity 13, n. 1 (2 gennaio 2021): 12. http://dx.doi.org/10.3390/d13010012.
Testo completoAbstract (sommario):
Macroherbivory is an important process in seagrass meadows worldwide; however, the impact of macroherbivores on seagrasses in the Great Barrier Reef (GBR) has received little attention. We used exclusion cages and seagrass tethering assays to understand how the intensity of macroherbivory varies over space and time in the seagrass meadows around Green Island (Queensland), and what impact this has on overall meadow structure. Rates of macroherbivory were comparatively low, between 0.25–44% of daily seagrass productivity; however, rates were highly variable over a one-year period, and among sites. Loss of seagrass material to macroherbivory was predominantly due to fish; however, urchin herbivory was also taking place. Macroherbivory rates were of insufficient intensity to impact overall meadow structure. No macroherbivory events were identified on video cameras that filmed in the day, indicating that feeding may be occurring infrequently in large shoals, or at night. While relatively low compared to some meadows, seagrass macroherbivory was still an important process at this site. We suggest that in this highly protected area of the GBR, where the ecosystem and food webs remain largely intact, macroherbivory was maintained at a low level and was unlikely to cause the large-scale meadow structuring influence that can be seen in more modified seagrass systems.
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Rattanachot, Ekkalak, Milica Stankovic, Supaphon Aongsara e Anchana Prathep. "Ten years of conservation efforts enhance seagrass cover and carbon storage in Thailand". Botanica Marina 61, n. 5 (25 settembre 2018): 441–51. http://dx.doi.org/10.1515/bot-2017-0110.
Testo completoAbstract (sommario):
Abstract Seagrasses are known as engineering ecosystems that play important roles in coastal environments. Globally, seagrass areas have been declining, and many conservation projects have been carried out to prevent further decline. The goal of this work was to determine how successful conservation efforts have been in a seagrass meadow at Koh Tha Rai in the Nakhon Si Thammarat Province of southern Thailand in terms of meadow extent, coverage and organic carbon storage. A study was conducted in 2017 and compared to a previous study from 2006 to determine the effects of the various conservation efforts devoted to this area. The results show that the total seagrass area increased by 0.7 ha with a rate of increase of approximately 0.06 ha year−1. The total coverage of seagrass increased by approximately 3 times. The organic carbon in existing seagrass meadows (2006) was 53.35 Mg ha−1, while growth was 32.34 Mg ha−1 in the areas of new seagrass. Moreover, the total organic carbon storage in the sediment increased by 26.86 MgC from 2006 to 2017 (from 211.60 MgC to 235.46 MgC). In conclusion, this study demonstrated the importance of successful conservation efforts in terms of increasing seagrass meadow areas, seagrass coverage and carbon storage within the meadow.
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Titioatchasai, Jatdilok, Komwit Surachat, Ekkalak Rattanachot, Piyalap Tuntiprapas e Jaruwan Mayakun. "Assessment of Diversity of Marine Organisms among Natural and Transplanted Seagrass Meadows". Journal of Marine Science and Engineering 11, n. 10 (6 ottobre 2023): 1928. http://dx.doi.org/10.3390/jmse11101928.
Testo completoAbstract (sommario):
Seagrass ecosystems have been declining, and restorations are conducted in many parts of the world to compensate for habitat loss and restore the ecosystem services seagrasses provide. Assessment of transplantation success requires the monitoring of the level of biodiversity between the donor and transplanted sites. In this study, we assessed a seagrass ecosystem after restoration in terms of the diversity of marine organisms using environmental DNA (eDNA) to compare four sites: (1) bare sand, (2) a natural meadow of Cymodocea serrulata, (3) a natural meadow of Halophila ovalis, and (4) a transplanted seagrass meadow. The results showed the presence of 3 domains, 34 phyla, 59 classes, 92 orders, 155 families, 156 genera, and 121 species. Proteobacteria, Actinobacteria, Cyanobacteria, and Bacteroidetes were the dominant bacterial phyla. Among eukaryotes, Phragmoplastophyta/Charophyta (epiphytes), Ascomycota (fungi), Cnidaria (jelly fish), and Arthropoda (Crabs and bivalves) were the dominant phyla. Dugong tails and commercial species (sea cucumber, dog conch, and swimming crab) have been observed in both the natural and transplanted meadows. Relative abundance among the four sites was significantly different. There were no differences in species richness and evenness between the four sites and no differences in species richness and evenness between the natural meadows and the transplanted seagrass meadow. It is possible that transplanted seagrass meadow can be successfully restored and established and can provide habitat for fauna and microbes. Additionally, fauna are not limited in their capacity to move between the natural and transplanted habitats. This study provides an assessment of biodiversity of restored seagrass patches and a better understanding of a seagrass ecosystem after restoration. However, to assess seagrass ecosystem services after restoration and the success of restoration actions, long-term monitoring of marine organism diversity and additional assessments are needed.
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Hendriks, I. E., Y. S. Olsen, L. Ramajo, L. Basso, A. Steckbauer, T. S. Moore, J. Howard e C. M. Duarte. "Photosynthetic activity buffers ocean acidification in seagrass meadows". Biogeosciences 11, n. 2 (28 gennaio 2014): 333–46. http://dx.doi.org/10.5194/bg-11-333-2014.
Testo completoAbstract (sommario):
Abstract. Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5–12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr)) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean, max and range pHNBS and max and range ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced max and min ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. Max and range ΩAr within the meadow showed a positive trend with the calcium carbonate load of the leaves, pointing to a possible link between structural parameters, ΩAr and carbonate deposition. Calcifying organisms, e.g. epiphytes with carbonate skeletons, may benefit from the modification of the carbonate system by the meadow. There is, however, concern for the ability of seagrasses to provide modifications of similar importance in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, on which LAI is based. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.
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Hendriks, I. E., Y. S. Olsen, L. Ramajo, L. Basso, A. Steckbauer, T. S. Moore, J. Howard e C. M. Duarte. "Photosynthetic activity buffers ocean acidification in seagrass meadows". Biogeosciences Discussions 10, n. 7 (22 luglio 2013): 12313–46. http://dx.doi.org/10.5194/bgd-10-12313-2013.
Testo completoAbstract (sommario):
Abstract. Macrophytes growing in shallow coastal zones characterized by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH ranges is in shallow (5–12 m) seagrass (Posidonia oceanica) meadows from 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean and max pHNBS and max ΩAr. Oxygen production positively influenced the range and maximum pHNBS and the range of ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. ΩAr was positively correlated with the calcium carbonate load of the leaves, demonstrating a direct link between structural parameters, ΩAr and carbonate deposition. There was a direct relationship between ΩAr, influenced directly by meadow LAI, and CaCO3 content of the leaves. Therefore, calcifying organisms, e.g. epiphytes with carbonate skeletons, might benefit from the modification of the carbonate system by the meadow. The meadow might be capable of providing refugia for calcifiers by increasing pH and ΩAr through metabolic activity. There is, however, concern for the ability of seagrasses to provide this refugia function in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, both strongly linked to LAI. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.
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Leemans, Luuk, Isis Martínez, Tjisse van der Heide, Marieke M. van Katwijk e Brigitta I. van Tussenbroek. "A Mutualism Between Unattached Coralline Algae and Seagrasses Prevents Overgrazing by Sea Turtles". Ecosystems 23, n. 8 (18 febbraio 2020): 1631–42. http://dx.doi.org/10.1007/s10021-020-00492-w.
Testo completoAbstract (sommario):
AbstractSeagrass meadows are threatened biodiversity hot spots that provide essential ecosystem services. Green sea turtles may overgraze meadows, further enhancing seagrass decline. However, we observed an unexpected, remarkable recovery of seagrasses in a previously overgrazed meadow with abundant unattached branched coralline algae, suggesting that turtle grazing had ceased. We hypothesize that this recovery is due to an effective grazing-protection mutualism, in which the spiny coralline algae structures protect the seagrass meadows from overgrazing, while the seagrasses protect the algae from removal by currents and waves. Removing coralline algae from recovered seagrass plots allowed the turtles to resume grazing, while addition of coralline algae to grazed plots caused cessation of grazing. Coralline algae that were placed on bare sand were quickly displaced by wave action, whereas those placed in grazed or ungrazed seagrass remained. Our experiments demonstrate a grazing-protection mutualism, which likely explains the witnessed recovery of an overgrazed seagrass meadow. To our knowledge, this is the first account of a plant–plant grazing-protection mutualism in an aquatic environment. Our findings show that grazing-protection mutualisms can be vital for the maintenance and recovery of ecosystems shaped by habitat-structuring foundation species, and highlight the importance of mutualisms in coastal ecosystems. As seagrasses, sea turtles and coralline algae share habitats along tropical shores worldwide, the mutualism may be a global phenomenon. Overgrazing is expected to increase, and this mutualism adds a new perspective to the conservation and restoration of these valuable ecosystems.
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Bongolan, V. P., G. M. Torres e J. E. Branzuela. "MODELLING, SIMULATION AND VISUALIZATION OF A MULTISPECIFIC PHILIPPINE SEAGRASS MEADOW". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W19 (23 dicembre 2019): 77–82. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w19-77-2019.
Testo completoAbstract (sommario):
Abstract. Seagrass meadows are constantly under threat from natural and man-made stresses due to its shallow existence in the coastal environment. Restoration and preservation of seagrasses by means of rehabilitation or transplanting strategies is possible, but the studies have been limited. An agent-based model of a mixed Philippine seagrass meadow is presented. Three species were used for testing: Enhalus acoroides, Thalassia hemprichii, and Cymodocea rotundata. The model features parameter-based clonal growth of seagrass species, recruitment of new seagrass apices through basic flowering/seeding, and a crowding logic for multiple coexisting species in a single meadow. Seagrass clonal growth is modeled using a modified Diffusion-Limited Aggregation (DLA) model. Each species has a preconfigured set of parameters for clonal growth including rhizome elongation, branching rate, vertical elongation rate, rhizome branching angle and shoot age. Seed recruitment is applied through occasional flowering/seeding events configurable per species. We developed a simple three-species competition model which controls the growth and direct competition effects based on a configurable population size and comparison radius. Upon further calibration and validation, the model would enable more accurate long-term predictions for different rehabilitation and transplanting strategies of mixed seagrass meadows. Further improvements can also be implemented, particularly taking into account the environmental variables within the meadows such as light attenuation and salinity, among other factors.
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Ivajnšič, Danijel, Martina Orlando-Bonaca, Daša Donša, Veno Jaša Grujić, Domen Trkov, Borut Mavrič e Lovrenc Lipej. "Evaluating Seagrass Meadow Dynamics by Integrating Field-Based and Remote Sensing Techniques". Plants 11, n. 9 (28 aprile 2022): 1196. http://dx.doi.org/10.3390/plants11091196.
Testo completoAbstract (sommario):
Marine phanerogams are considered biological sentinels or indicators since any modification in seagrass meadow distribution and coverage signals negative changes in the marine environment. In recent decades, seagrass meadows have undergone global losses at accelerating rates, and almost one-third of their coverage has disappeared globally. This study focused on the dynamics of seagrass meadows in the northern Adriatic Sea, which is one of the most anthropogenically affected areas in the Mediterranean Sea. Seagrass distribution data and remote sensing products were utilized to identify the stable and dynamic parts of the seagrass ecosystem. Different seagrass species could not be distinguished with the Sentinel-2 (BOA) satellite image. However, results revealed a generally stable seagrass meadow (283.5 Ha) but, on the other hand, a stochastic behavior in seagrass meadow retraction (90.8 Ha) linked to local environmental processes associated with anthropogenic activities or climate change. If systemized, this proposed approach to monitoring seagrass meadow dynamics could be developed as a spatial decision support system for the entire Mediterranean basin. Such a tool could serve as a key element for decision makers in marine protected areas and would potentially support more effective conservation and management actions in these highly productive and important environments.
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Digdo, A. A., E. Astari, B. R. Arinda e J. Arendege. "Humans and seagrass: a complex and intertwining links - an illustration from North Sulawesi, Indonesia". IOP Conference Series: Earth and Environmental Science 1220, n. 1 (1 luglio 2023): 012027. http://dx.doi.org/10.1088/1755-1315/1220/1/012027.
Testo completoAbstract (sommario):
Abstract Interactions between humans and seagrasses in a rural area in North Sulawesi (North Minahasa) were determined by applying the ecosystem goods and services concept and related social-ecological system. The main role in the villages is small-scale fishermen and the general public. By conducting interviews, questionnaires, focus group discussions, community immersion, and field surveys, we discovered complex social-ecological ties that are essential for local society and the ecosystem. Nursery ground and habitat for fish and invertebrates, traditional medicine, indicative for Ramadan season-opening, and sites for bait collection were within the significant seagrass meadow ecosystem services for the local coastal people. We identified 183 traditional fish names that are associated with seagrass. Gleaning (banyare) and trapping fisheries (“soma”, “sero” and “bubu”) in the areas captured seagrass-associated fishes (Siganidae) that contribute a major livelihood source for the fishermen. The seagrass meadow overlaps with species habitats, for instance, dugongs and sea turtles. Out of 90 fishing grounds, 13 overlapped with seagrass beds, which also have dugong feeding trails. Most of the seagrass beds are open and free for all areas, except around LMMAs managed by villages, which likely create positive effects on seagrass meadows.
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Strydom, Simone, Roisin McCallum, Anna Lafratta, Chanelle L. Webster, Caitlyn M. O'Dea, Nicole E. Said, Natasha Dunham et al. "Global dataset on seagrass meadow structure, biomass and production". Earth System Science Data 15, n. 1 (1 febbraio 2023): 511–19. http://dx.doi.org/10.5194/essd-15-511-2023.
Testo completoAbstract (sommario):
Abstract. Seagrass meadows provide valuable socio-ecological ecosystem services, including a key role in climate change mitigation and adaption. Understanding the natural history of seagrass meadows across environmental gradients is crucial to deciphering the role of seagrasses in the global ocean. In this data collation, spatial and temporal patterns in seagrass meadow structure, biomass and production data are presented as a function of biotic and abiotic habitat characteristics. The biological traits compiled include measures of meadow structure (e.g. percent cover and shoot density), biomass (e.g. above-ground biomass) and production (e.g. shoot production). Categorical factors include bioregion, geotype (coastal or estuarine), genera and year of sampling. This dataset contains data extracted from peer-reviewed publications published between 1975 and 2020 based on a Web of Science search and includes 11 data variables across 12 seagrass genera. The dataset excludes data from mesocosm and field experiments, contains 14 271 data points extracted from 390 publications and is publicly available on the PANGAEA® data repository (https://doi.org/10.1594/PANGAEA.929968; Strydom et al., 2021). The top five most studied genera are Zostera, Thalassia, Cymodocea, Halodule and Halophila (84 % of data), and the least studied genera are Phyllospadix, Amphibolis and Thalassodendron (2.3 % of data). The data hotspot bioregion is the Tropical Indo-Pacific (25 % of data) followed by the Tropical Atlantic (21 %), whereas data for the other four bioregions are evenly spread (ranging between 13 and 15 % of total data within each bioregion). From the data compiled, 57 % related to seagrass biomass and 33 % to seagrass structure, while the least number of data were related to seagrass production (11 % of data). This data collation can inform several research fields beyond seagrass ecology, such as the development of nature-based solutions for climate change mitigation, which include readership interested in blue carbon, engineering, fisheries, global change, conservation and policy.
Tesi sul tema "Seagrass meadow"
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Vivoni-Gallart, Enrique Rafael 1975. "Turbulence structure of a model seagrass meadow". Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/35483.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (p. 235-239).
A laboratory study of the hydrodynamics of a seagrass meadow was conducted to investigate the effect of water depth and velocity variations during a tidal cycle on the mean and turbulent velocity fields in and above the vegetation layer. The principal goal was to characterize the turbulence structure of a depth-limited canopy, a gap that presently exists in the knowledge concerning the interaction of a unidirectional flow with an assemblage of plants. The experiments were carried out in an open channel flume with a model seagrass canopy. Proper modeling of the system for both the geometric and dynamic behavior of natural Zostera marina communities allows the results to be extrapolated to the conditions in a coastal, tidal meadow. The results also serve as an important comparative case to the characterization of turbulence within atmospheric plant canopies. The laboratory study included the measurement of the mean and turbulent velocity fields with the use of an acoustic Doppler velocimeter and a laser Doppler velocimeter. Standard turbulence parameters were evaluated including the velocity moments, the turbulence spectra. the turbulent kinetic energy budget and the quadrant distribution of the Reynolds stress. Each of these provided a means of describing the effect of submergence depth and the degree of canopy waving (monami) on the transport of momentum and mass between the canopy and its surrounding fluid environment. In addition. surface slope measurements were made with surface displacement gauges. the plant motion was quantified using video and camera images. and the canopy morphology was recorded from measurements taken from a random sampling of the model plants. The investigation showed a clear link between the shear generated eddies arising at the interface of the canopy and the surface layer and the vertical exchange of momentum. the plant motion characteristics and the turbulence time and length scales. The turbulence field within the seagrass meadow was composed of a shear-generated turbulence zone near the canopy height and a wake-generated zone near the bed In addition. a mean flow due to the pressure gradient from the water surface slope created a region of secondary maxima in the mean velocity profile near the bed. The parameter determining the seagrass turbulence structure was found to be the characteristic depth (H' h). defined such that the effective canopy height. reflects the plant deflection. Across the range of values considered for H/h. the flow characteristics showed a clear transition from a confined to an unbounded canopy flow. This transition was observed in all the principal turbulence parameters. From this analysis. a critical surface layer depth governing the transition between the two extreme canopy flow conditions was identified as half the effective canopy height. H'h = 1.50.
by Ernique Rafael Vivoni Gallart.
S.M.
2
Bouvais, Pierre. "Influence of increased sediment exposure on suspension-feeder assemblages in a temperate seagrass meadow". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2016. https://ro.ecu.edu.au/theses/1814.
Testo completoAbstract (sommario):
The impact of increased sediment exposure on coastal marine ecosystems is one of the most important contemporary environmental issues. Sediment exposure is defined as the concentrations of sediment particles suspended in the water column and the amount of sediment depositing on the seabed. In addition to natural events, such as land erosion, rainfall, and tidal currents, anthropogenic activities such as land use, road building, logging, mining, port maintenance and dredging, contribute to the discharge of a great amount of sediment in the water column. As sessile suspension-feeder assemblages play a critical role in marine ecosystems through their active transfers of organic and inorganic between the water column and the seabed (i.e. benthic-pelagic coupling), increased sediment exposure generated by anthropogenic activities may negatively impact these organisms. This study set out to evaluate the influence of increased sediment exposure on suspension-feeder assemblages in a temperate seagrass habitat. Most of the research was conducted within Posidonia sinuosa meadows near Woodman Point (32◦7’S, 115◦44’E), south of Fremantle, Western Australia. At this location, persistent sediment plumes from a cement manufacturer’s wash plant provided an opportunity to study the mechanisms through which increased sediment exposure can affect suspension feeder assemblages. This study was examining: the relationship between sediment exposure and suspension feeder assemblage composition; the influence of increased sediment exposure on the contribution of potential food sources to suspension feeder diets; and the influence of sediment exposure on suspension-feeding mechanisms (filtration and retention rates) and strategies (food particle selection).
The descriptive work, presented in Chapter 1, revealed a strong gradient in sediment exposure with decreasing sediment deposition with distance from the wash plant. There was little dissimilarity, in term of species diversity and biomass, among suspension-feeder assemblages under high sediment exposure and those experiencing natural sedimentation regimes. These findings indicated that the suspension-feeder assemblages at the study site were resistant to high sediment exposure and that some species could potentially display compensatory mechanisms. Thus, the degree to which increased sediment exposure influences suspension feeders was more likely to be species specific and depend on the resilience of their feeding mechanisms and strategies. Those findings underlined the need to test the causal parameters underlying responses to suspension-feeding activity and selectivity due to increased sediment exposure.
Results presented in Chapter 2 indicated that the three most conspicuous suspension feeder in term of biomass and abundances presented distinct isotopic signatures, implying dissimilarities in their diets. Differences in δ13C and δ15N can be explained by consumption of different types of picoplanktonic particles and the degree to which sedimentary organic matter contributed to their diets. Increased sediment exposure had no influence on the natural diets of the ascidian Herdmania momus and the bivalve Pinna bicolor. For the sponge Tethya sp, the contribution of sedimentary organic matter to its diet increased at sites with high sediment exposure, suggesting a potential benefit to its diet. Overall, the influence of sediment exposure on suspension feeder diets was species specific and dependent on the nature (e.g. organically rich versus organically depleted) and concentrations of the sediment.
In Chapter 3 data are presented to show that feeding mechanisms and strategies of three species of suspension feeders best representing the benthic assemblages were influenced by sediment exposure. Under high sediment exposure, the ascidian Herdmania momus had lower pumping rates, but maintained a relatively constant food retention rate, and optimised its food intake by expanding its food sources from mainly cyanobacteria (Synechococcus) to a wider range of food sources. The bivalve Pinna bicolor also had lower filtration activity with high sediment exposure, again, maintaining relatively constant total retention rates and displaying a change in particle selection from bacteria and Synechococcus to larger picoeukaryotic cells of higher carbon content. The sponge Tethya sp. appeared to benefit from elevated sediment concentrations, as filtration and retention rates increased, potentially related to a lack of food selectivity.
In Chapter 4, a short-term laboratory experiment was combined with a field transplant experiment to investigate the response of suspension feeders to increased sediment exposure. Under elevated sediment exposure, Herdmania momus and Pinna bicolor modulated their particle selection to optimise food intake, while the non-selective suspension feeder Tethya sp increased its particle retention rate and efficiency. Both the laboratory and transplant experiment findings corroborated observations made in Chapters 1 and 2; compensatory adaptations associated with the feeding activity, such as the modulation of pumping rates and the optimisation of food intake by particle selection, help to explain the potential resistance of suspension feeder community structure to high sediment exposure. A major outcome of this research is that it informs shallow coastal ecosystems stakeholders of the possible consequences of anthropogenic activities that increase sediment exposure, particularly those in the order of TSS at 40 mg·l-1 and deposition rates in the order of 10 g·cm- 2·month-1. Despite this magnitude of sediment exposure had little influence on suspension feeder assemblage composition, the effects on the suspension-feeding function, including the increase of the filtration activity and transfers of carbon to the benthos, potentially influence benthicpelagic coupling and other ecosystem-scale processes. Given the variation in sensitivity to sediment exposure among suspension feeder species, meaningful criteria to limit the effects of anthropogenic sediment loading on shallow coastal ecosystems should take into account the whole species assemblage present at any given site.
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Jamaludin, Mohammad Rozaimi. "Carbon storage and preservation in seagrass meadows". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2015. https://ro.ecu.edu.au/theses/1683.
Testo completoAbstract (sommario):
Seagrass meadows are important ‘Blue Carbon’ sinks but many questions remain unaddressed in regards to the organic carbon (OC) sequestration capacity and processes leading to retention and persistence of OC in seagrass sediments. The research summarised in this dissertation examined 37 sediment cores from twelve Australian seagrass meadows (Posidonia australis and Halophila ovalis) in order to improve our understanding of OC storage and preservation in seagrass sediments. The research: quantified the OC storage in seagrass meadows and the reduction in stores after ecosystem degradation; the rates of OC accumulation; the roles of species composition and the depositional nature of the habitat as factors affecting OC storage; and, characterised the sedimentary organic matter (OM) accumulated over millennia using techniques not previously applied to seagrass sediments.
In Oyster Harbour, Western Australia, P. australis had been present over the past 6000 years, as evidenced from radiocarbon analysis of sedimentary matter. Both seagrass- and nonseagrass-derived OM contributed to high sedimentary organic stores (10.79-11.42 kg OC m- 2; 150 cm sediment depth). The persistence of sedimentary OM over millennial scales indicated that the carbon was well-preserved, thus showing a link between carbon storage and its preservation. By quantifying accumulation rates, and using historical accounts of the highest areal cover (6.1 to 6.7 km2) and recent losses in cover (by 2.8-3.1 km2) due to eutrophication, it was estimated that up to 11.17 Gg OC has been lost from shallow sediments (50 cm depth) following seagrass loss. This carbon was potentially remineralisable and may, therefore, have been liberated back to the atmospheric CO2 pool.
Nine Posidonia australis meadows were then investigated for the effect of the depositional environment on sedimentary OC stores. Based on hydrodynamic differences of meadows categorised as More Sheltered, Less Sheltered, and Exposed, the More Sheltered sites had OC stores 6-fold higher (4.57 ± 0.16 to 13.51 ± 0.53 kg OC m-2; 140 cm sediment depth) compared to Exposed meadows (2.24 ± 0.31 to 3.77 ± 0.85 kg OC m-2). The OC stores of Less Sheltered meadows were not significantly different to either of the other two categories. It was concluded that the depositional nature of a seagrass habitat can affect the OC stores, though the affects may be influenced by other site-specific characteristics.
The effect of species composition on OC stores and accumulation rates was subsequently investigated by comparing the stores in estuarine P. australis and H. ovalis meadows. Comparisons were based on stratigraphic- (OC stores over a set depth) and temporal-based (i.e. accumulation over a set period of time, and as accumulation rates) measures. Organic carbon stores were between 2- (P. australis: 10.81 ± 2.06 kg OC m-2, H. ovalis: 5.17 ± 2.16 kg OC m-2; 150 cm depth) and 11-fold (P. australis: 10.87 ± 2.86 kg OC m-2, H. ovalis: 0.97 ± 0.47 kg OC m-2; 2500 yr accumulation) different between meadows of the two species. While the OC stores were different between species, it was also apparent that environmental factors also contributed to the variability, with some H. ovalis meadows having stores comparable to some P. australis meadows. Thus, both the species and environmental factors needs to be considered for robust predictions of OC storage in seagrass meadows.
The final study reported here investigated the preservation of sedimentary OC in the P. australis meadow of Oyster Harbour. A range of biogeochemical variables (age, sediment grain size, anoxia, OM and OC contents, and _13C values) were characterised at increasing depth within a sediment core. Solid-state 13C nuclear magnetic resonance was applied to a seagrass core for the first time to characterise the biochemical constituents of the sedimentary OM. There was a 76-80% contribution of seagrass-derived organics (lignin, carbohydrate, and a black-carbon-like OM) into the sediment. The proportion of black-carbon-like material increased with age/depth, indicating that it underwent selective preservation. Carbohydrates decreased with depth/age and lignin showed no changes, indicating that they have undergone non-selective preservation. There was remarkable consistency in the biochemical makeup of the OM with depth, which accumulated over the past 1900 years, indicating a very high preservation potential within seagrass sediments.
Cumulatively, the research presented in this dissertation has highlighted the variability of OC stores in seagrass meadows and how OC may be preserved. The research has indicated that any attempts to estimate regional or global carbon stores must take into account both the species of seagrass that dominate the meadows and the type of depositional environment that the meadows occur in. It is also clear that Posidonia meadows in south-western Australia have the potential to store very large amount of Blue Carbon, comparable in some instances to the highest stores recorded globally, and to preserve these stores over millennia. Modelling future Blue Carbon stores requires an understanding of the fate of the stored carbon following disturbance. It is clear that this carbon can be lost from the meadow, but much of it appears to be in highly recalcitrant forms and it is unclear whether this material is available for subsequent re-mineralisation.
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Samsonova, Maria. "Tropicalisation of temperate seagrass meadows in Western Australia: Predicting the impact of tropical herbivorous fishes on temperate seagrass meadows". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2294.
Testo completoAbstract (sommario):
Rising sea temperatures through climate change produce shifts in the distribution of tropical species to temperate regions, a process termed “tropicalisation”. The poleward expansion of tropical herbivores into temperate seagrass meadows is predicted to increase grazing pressure and alter ecosystem services and processes in these seagrass systems. This study attempted to examine the effects of tropicalisation on temperate seagrass meadows along the western coast of Australia, where the increasing abundance of tropical consumers such as the herbivorous Siganus fuscescens has already been documented. Through the assessment of fish assemblages in seagrass meadows and the grazing levels on seagrass in 2001 and 2016/17, as well as in situ and mesocosm feeding preference experiments, this study attempted to estimate the grazing rates and impact that the growing abundance of S. fuscescens may have in temperate seagrass meadows.
Shifts in the grazing rates on seagrass between 2001 and 2016/17 were inconsistent, varying between seagrass species and location. Based on observational data on the bites on seagrass leaves, rates of consumption increased for Posidonia sinuosa while no similar pattern was found for Posidonia australis. This was despite an apparent greater consumption on P. australis compared to P. sinuosa in 2001, and the minimal amount of grazing on tethered seagrass. The higher observed level of P. sinuosa consumption in 2016/17 is likely explained by the changed herbivorous fish species composition, even though no fish were clearly observed feeding on seagrass in the current study. The tropical herbivore S. fuscescens was more abundant in 2016/17 that 2001, although abundances were patchy and no fish was observed feeding on seagrass. The higher level of P. sinuosa consumption in 2016/17, compared to 2001, supports the prediction that with increasing abundances in temperate seagrass ecosystems, tropical herbivores will enhance the consumption of seagrass. However, seagrass consumption is likely to be strongly influenced by the availability of macroalgae which were shown as the preferred food sources.
Feeding trials in mesocosms were compromised by the large number of deaths and the limited grazing on natural food sources by S. fuscescens, suggesting that the population in the Perth region is susceptible to adverse handling and husbandry effects. To maximise the survival rate of captured fish, the fishing and handling procedures were altered to adapt to the ongoing observations in the response of fish to handling in the field or in the mesocosm facilities. Lesson learned from the capture, handling and husbandry of S. fuscescens in feeding trials in the current study will hopefully provide greater success for feeding preference experiments in the future. The sampling program initiated in 2001 and repeated in 2016/17 provides base-line data and the opportunity to monitor and track the shift in abundances of tropical herbivores and resultant increases in grazing rates to test the above predictions. The consequences of tropicalisation will depend on the variety of abiotic and biotic factors, including the fish assemblages in the area, the abundance of tropical species, the availability of food, and the feeding preferences that invading species will develop in response to the changed environmental conditions.
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Bourque, Amanda. "Ecosystem structure in disturbed and restored subtropical seagrass meadows". FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/792.
Testo completoAbstract (sommario):
Shallow seagrass ecosystems frequently experience physical disturbance from vessel groundings. Specific restoration methods that modify physical, chemical, and biological aspects of disturbances are used to accelerate recovery. This study evaluated loss and recovery of ecosystem structure in disturbed seagrass meadows through plant and soil properties used as proxies for primary and secondary production, habitat quality, benthic metabolism, remineralization, and nutrient storage and exchange. The efficacy of common seagrass restoration techniques in accelerating recovery was also assessed.
Beyond removal of macrophyte biomass, disturbance to seagrass sediments resulted in loss of organic matter and stored nutrients, and altered microbial and infaunal communities. Evidence of the effectiveness of restoration actions was variable. Fill placement prevented additional erosion, but the resulting sediment matrix had different physical properties, low organic matter content and nutrient pools, reduced benthic metabolism, and less primary and secondary production relative to the undisturbed ecosystem. Fertilization was effective in increasing nitrogen and phosphorus availability in the sediments, but concurrent enhancement of seagrass production was not detected. Seagrass herbivores removed substantial seagrass biomass via direct grazing, suggesting that leaf loss to seagrass herbivores is a spatially variable but critically important determinant of seagrass transplanting success.
Convergence of plant and sediment response variables with levels in undisturbed seagrass meadows was not detected via natural recovery of disturbed sites, or through filling and fertilizing restoration sites. However, several indicators of ecosystem development related to primary production and nutrient accumulation suggest that early stages of ecosystem development have begun at these sites. This research suggests that vessel grounding disturbances in seagrass ecosystems create more complex and persistent resource losses than previously understood by resource managers. While the mechanics of implementing common seagrass restoration actions have been successfully developed by the restoration community, expectations of consistent or rapid recovery trajectories following restoration remain elusive.
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Gustafson, Johan Albin. "Value of Small Seagrass Patches as Tidal Flow-Refuges". Thesis, Griffith University, 2012. http://hdl.handle.net/10072/367575.
Testo completoAbstract (sommario):
One central challenge in the study of seagrass meadows is explaining the abundance and diversity of nekton associated with these productive habitats. While many models have been proposed to explain fish use of seagrass habitats, mainly focusing on their nursery and predator-avoidance values based on the complex habitat structure, most empirical studies were conducted on relatively large patches using catch data collected from invasive capture methods. Seagrass meadows on peri-urban coasts, however, continually being threatened and fragmented, while invasive surveying techniques could bias fish abundance data. This thesis aims to determine if small remnant Zostera capricorni patches in a peri-urban estuary provide small mobile fish with a flow-refuge within a strong tidal flow environment, using non-invasive video surveying techniques to monitor fish abundance and behaviour.
The hydrodynamic characteristics of three small patches of Z. capricorni were measured using in situ deployment of Acoustic Doppler Current Profilers (ADCP) at the front and rear of the patches during tidal current flow between 20 and 30 cm/s. Seagrass canopies of densities and morphologies covered by these patches significantly baffled the free-stream flow (X), creating a near-zero, turbulent free, within-canopy hydraulic environment 0.25m from the canopy’s leading edge. Flows were deflected over the canopy surface causing the leaves to bend, compressing the canopy and thereby reducing the vertical flux under high flows. While lower flows were still significantly reduced, a small vertical flux occurred, with large turbulent eddies generating from the canopy friction. The hydraulic environment behind the patch was significantly different to that at the patch’s front – characterised by near zero flows and turbulent fluctuations (at 0m), and flow velocities increasing with downstream distance. This effect was noticeable due to the velocity above the canopy being significantly reduced from flows above the canopy (fast). This difference diminished with downstream distance, gradually resembling the front profile. The rear environment close to the patch edge matched those of other flow-refuges.Thesis (Masters)
Master of Philosophy (MPhil)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text
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Dahl, Martin. "Natural and human-induced carbon storage variability in seagrass meadows". Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-148400.
Testo completoAbstract (sommario):
Seagrasses are considered highly important CO2 sinks, with the capacity to store substantial quantities of organic carbon in the living biomass and sediments, and thereby acting as a buffer against climate change. In this thesis, I have studied carbon storage variability in temperate and tropical seagrass habitats and identified factors influencing this variation. In addition, as seagrass areas are decreasing worldwide, I have assessed effects of different anthropogenic disturbances on carbon sequestration processes. The result from this thesis showed that there was a large variation in carbon storage within and among temperate, tropical and subtropical regions. The highest organic carbon stocks were found in temperate Zostera marina meadows, which also showed a larger carbon storage variability than the subtropical and tropical seagrass habitats. The tropical and subtropical seagrass meadows had inorganic carbon pools exceeding the organic carbon accumulation, which could potentially weakens the carbon sink function. The variability in organic carbon stocks was generally strongly related to the sediment characteristics of the seagrass habitats. In Z. marina meadows, the strength of the carbon sink function was mainly driven by the settings of the local environment, which in turn indicates that depositional areas will likely have higher organic carbon stocks than more exposed meadows, while in the tropics seagrass biomass was also influencing sedimentary carbon levels. Furthermore, locations with large areas of seagrass were associated with higher carbon storage in tropical and subtropical regions, which could be related to increased accumulation of both autochthonous and allochthonous carbon. In an in situ experiment, impacts on carbon sequestration processes from two types of disturbances (with two levels of intensity) were tested by simulating reduced water quality (by shading) and high grazing pressure (through removal of shoot biomass). At high disturbance intensity, reductions in the net community production and seagrass biomass carbon were observed, which negatively affected carbon sequestration and could impact the sedimentary organic carbon stocks over time. In the treatments with simulated grazing, erosion was also seen, likely due to an increase in near-bed hydrodynamics. When experimentally testing effects of increased current flow on organic carbon suspension in Z. marina sediment, a ten-fold release of organic carbon with higher current flow velocities was measured, which resulted in an increase in the proportion of suspended organic carbon by three times in relation to other sediment particles. Therefore, periods with enhanced hydrodynamic activity could result in a removal of organic carbon and thereby likely reduce the seagrass meadows’ capacity to store carbon. The findings of this thesis add to the emerging picture that there is a large natural variability in seagrasses’ capacity to store carbon, and highlight how human-induced disturbances could negatively affect the carbon sink function in seagrass meadows.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.
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Connolly, Roderick Martin. "The role of shallow seagrass meadows as habitat for fish /". Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phc7524.pdf.
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Nobrega, Gabriel Nuto. "Subaqueous soils of the Brazilian seagrass meadows: biogeochemistry, genesis, and classification". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-26102017-143348/.
Testo completoAbstract (sommario):
Seagrass meadows, or submerged aquatic vegetation, constitute an ecosystem with great importance to the coastal zone, and may be characterized as the most productive ecosystem on Earth. In addition to the provision of habitat for a wide variety of species, protection of the coastal zone and production of organic matter base for the marine trophic web, these environments have been recognized for their great capacity to store organic carbon in their soils and are, therefore, a priority area for the mitigation of increased carbon in the atmosphere. In spite of the great importance of these areas, there is little information about the soils of these ecosystems, mainly using an approach based on the genesis of its soils. Thus, this thesis covers 4 chapters aiming to: (i) evaluate changes in the characteristics of seagrass meadows publications in the last 50 years, identify knowledge gaps and priorities for future studies; (ii) to discuss the paradoxical lack of information on Brazilian seagrass meadows soils, stimulate studies to understand their characteristics and contribute to the correct inclusion of seagrass meadows soils in the Brazilian System for Soil Classification; (iii) characterize and investigate soils of seagrass meadows along the Brazilian coast, in order to understand the pedogenetic processes within these soils; and (iv) identify variations in the biogeochemical processes related to the dynamics of Fe, Mn and S along the Brazilian coast, aiming to provide an improved basis for the understanding of this ecosystem and subsidies for the use and protection policies of these coastal areas.As pradarias marinhas (seagrasses), ou vegetação aquática submersa, constituem um ecossistema de grande importância para a zona costeira, caracterizando-se como o ecossistema mais produtivo da Terra. Além de fornecer habitat para uma grande variedade de espécies, favorecer a estabilidade costeira e produzir matéria orgânica base para a teia trófica marinha, estes ambientes têm sido reconhecidos pela grande capacidade de armazenar carbono orgânico em seus solos e são, portanto, prioritários para as medidas de mitigação do aumento de carbono na atmosfera. Apesar da grande importância desse ecossitema, há pouca informação a respeito dos solos onde estes ecossistemas estão inseridos, principalmente utilizando uma abordagem baseada na gênese dos solos. Esta tese contempla 4 capítulos cujos objetivos visam avaliar as mudanças nas características das publicações sobre pradarias marinhas nos últimos 50 anos, identificando lacunas de conhecimentos e prioridades para estudos futuros; discutir a paradoxal ausência de informação sobre os solos das pradarias marinhas do Brasil, estimulando estudos para o entendimento de suas características e contribuindo para a correta inclusão de solos de pradarias marinhas no Sistema Brasileiro de Classificação de solos; caracterizar e investigar os solos das pradarias marinhas ao longo da costa brasileira, com vistas a entender os processos pedogenéticos atuantes nestes solos; e Identificar variações nos processos biogeoquímicos relacionados à dinâmica de Fe, Mn e S ao longo da costa brasileira, com a finalidade de fornecer base para o entendimento deste ecossistema e subsídios para as políticas de proteção e de uso destas áreas costeiras.
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Davis, Braxton C. "Determining interspecific interactions between the dominant macrophytes of tropical, atlantic seagrass meadows". FIU Digital Commons, 1998. http://digitalcommons.fiu.edu/etd/2743.
Testo completoAbstract (sommario):
Though often suggested in seagrass literature, interactions between abundant rhizophytic macroalgae and coexisting tropical seagrasses have not been directly examined. Based on a competitive interaction hypothesis, I first tested for negative correlations between species densities over large and small spatial scales. After finding negative correlations, I tested experimentally for a competitive interaction by manipulating the relative densities of the locally dominant seagrass and a representative macroalga. Based on significant growth responses to density manipulations, I demonstrated that these species are likely competing for some limiting resource, possibly nitrogen. This study contributes to a better understanding of processes that dictate community composition in these systems.
Libri sul tema "Seagrass meadow"
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Webber, Herbert H. Remote sensing inventory of the seagrass meadow of the Padilla Bay National Estuarine Research Reserve: Areal extent and estimation of biomass. Mount Vernon, Wash: The Reserve, 1990.
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Illert, Christopher Roy. Botany Bay's seagrass meadows: An ecological overview. Semaphore Park, S. Aust., Australia: Illert Marine Research and Pub., 1986.
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Gullström, Martin. Seagrass meadows: Community ecology and habitat dynamics. Göteborg: Göteborg University, Faculty of Science, 2006.
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Phillips, Ronald C. The ecology of eelgrass meadows of the Pacific Northwest: A community profile. Washington, DC: The Team, 1985.
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T, Zieman Rita, Pendleton Edward C, National Wetlands Research Center (U.S.) e United States. Minerals Management Service., a cura di. The ecology of the seagrass meadows of the west coast of Florida: A community profile. Washington, DC: U.S. Dept. of the Interior, Fish and Wildlife Service, Research and Development, 1989.
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Rico, Sea Grant Puerto. Seagrass Meadows: Teacher's Guide. Universidad de Puerto Rico, Programa de Colegio Sea Grant, 2021.
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Morton, Michael D. Mapping seagrass meadows using Landsat-5 TM imagery and a microcomputer. 1988.
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Nacorda, Hildie Maria E. Burrowing Shrimps and Seagrass Dynamics in Shallow-Water Meadows off Bolinao (New Philippines). Taylor & Francis Group, 2008.
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E, Nacorda Hildie Maria. Burrowing Shrimps and Seagrass Dynamics in Shallow-Water Meadows off Bolinao (New Philippines). Taylor & Francis Group, 2008.
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Nacorda, Hildie Maria E. Burrowing Shrimps and Seagrass Dynamics in Shallow-Water Meadows off Bolinao: UNESCO-IHE PhD. Taylor & Francis Group, 2017.
Cerca il testo completoCapitoli di libri sul tema "Seagrass meadow"
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Costa, Valentina, Renato Chemello, Davide Iaciofano, Sabrina Lo Brutto e Francesca Rossi. "Seagrass detritus as marine macroinvertebrates attractor". In Ninth International Symposium “Monitoring of Mediterranean Coastal Areas: Problems and Measurement Techniques”, 619–26. Florence: Firenze University Press, 2022. http://dx.doi.org/10.36253/979-12-215-0030-1.58.
Testo completoAbstract (sommario):
Seagrass detritus is used as food, physical habitat and shelter. Using natural and artificial detritus, we tested if: 1) the colonisation was related to substrate availability rather than food 2) the assemblages were similar according to meadow structural complexity. A total of 11,270 invertebrates were identified. Neither the habitat complexity, nor the substrate type shown any effects on the colonisation, with both substrates acting as a faunal magnet. The detritus can be colonised by a rich and diverse community, highlighting its important role in maintaining the seagrass meadow biodiversity
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Mancini, Gianluca, Daniele Ventura, Edoardo Casoli, Andrea Belluscio e Giandomenico Ardizzone. "Colonization of transplanted Posidonia Oceanica: understanding the spatial dynamics through high-spatial resolution underwater photomosaics". In Ninth International Symposium “Monitoring of Mediterranean Coastal Areas: Problems and Measurement Techniques”, 719–28. Florence: Firenze University Press, 2022. http://dx.doi.org/10.36253/979-12-215-0030-1.68.
Testo completoAbstract (sommario):
Following the restoration of a P. oceanica meadow impacted by the Concordia shipwreck, we investigated the spatial dynamic of the most important and protected Mediterranean endemic seagrass over a two-year period applying three spatial metrics: number of patches, mean patch size and total cover. By means of underwater photomosaics, we noticed a diminution in the number of patches in favour of the mean size and total cover. The outcomes showed that, under suitable environmental conditions, P. oceanica colonizes rapidly the dead matte substrate.
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Al-Mansoori, Noura, e Himansu Sekhar Das. "Seagrasses of the United Arab Emirates". In A Natural History of the Emirates, 267–85. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37397-8_9.
Testo completoAbstract (sommario):
AbstractThe Arabian Gulf’s coastal and marine ecosystems are being negatively impacted by various factors such as population growth, coastal development, industrial and desalination plant discharge, and offshore oil and gas activities. However, seagrass meadows continue to show resilience and provide ecosystem values and services. This paper provides an overview of the seagrass meadows in the United Arab Emirates (UAE) in terms of their extent, species composition, threats, and conservation initiatives. The UAE’s coastline supports three seagrass species that are home to numerous marine species such as dugongs, green sea turtles, fish, and benthic invertebrates. With an area of around 2950 km2, subtidal seagrasses grow to a depth of 16 m and are one of the largest marine ecosystems in the Emirates. Seagrass beds also contribute significantly to blue carbon, with Abu Dhabi seagrasses estimated to have over 52 tonnes per hectare. The primary threats to seagrass meadows include dredging, landfill, and associated sedimentation, as well as environmental extremes such as high summer sea temperatures. However, conservation initiatives such as marine protected areas (MPAs) and federal laws have been implemented to protect these crucial coastal ecosystems.
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Alongi, Daniel M. "Seagrass Meadows". In Blue Carbon, 37–51. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-91698-9_4.
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Huntley, Brian John. "The Mangrove Biome". In Ecology of Angola, 383–91. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-18923-4_17.
Testo completoAbstract (sommario):
AbstractThe cold Benguela Current passing along Angola’s Atlantic Ocean coast accounts for its mangrove communities lying 20° latitude north of those of the Indian Ocean Coast of Africa, bathed by the warm Mozambique Current. This chapter draws on the limited literature available on Angola’s mangrove forests and seagrass meadows that constitute its Mangrove Biome. Comprising only five of the world’s 55 mangrove species, and two of the world’s 70 species of seagrasses, Angola’s mangrove communities cover a very limited area compared with other tropical countries. This is due to Angola’s steeply shelving coastline, with small lagoons and mudflats at the mouths of its rivers. However, they provide excellent opportunities for the study of the complex adaptations of plants to regular changes in water salinity and to growth in waterlogged, anoxic soil. The adaptations include stilt roots, with specialised absorptive pores, roots containing porous aerenchyma tissue for oxygen transfer, and reproductive propagules that develop into seedlings while still attached to the tree. The mudflats of coastal lagoons support two species of seagrass (highly specialised angiosperms that are permanently submerged). Seagrass meadows provide habitat for a wide diversity of marine animals, while mangrove forests shelter several crocodile and primate species.
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Akçalı, Barış, Ergün Taşkın, Gökhan Kaman, Alper Evcen e Hayati Çalık. "Posidonia oceanica monitoring system on the coast of Aegean Sea of Turkey". In Proceedings e report, 475–82. Florence: Firenze University Press, 2020. http://dx.doi.org/10.36253/978-88-5518-147-1.47.
Testo completoAbstract (sommario):
Seagrass monitoring is a basic tool for measuring the condition of meadows in parallel to the environmental conditions. Posidonia oceanica meadows are very sensitive to anthropogenic effects. In the present study, two monitoring stations of Posidonia oceanica meadows were established on the Aegean coasts of Turkey in the years 2018 and 2019, at 26 m depth in Ildır Bay (İzmir, Turkey), and at 33 m depth in Kara Ada (İzmir, Turkey). The P. oceanica meadows upper and lower limits were defined by balisage systems. In the laboratory, lepidochronological, morphometric, and phenological parameters were also studied.
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Coles, Robert G., Michael A. Rasheed, Alana Grech e Len J. McKenzie. "Seagrass Meadows of Northeastern Australia". In The Wetland Book, 1–9. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-007-6173-5_266-1.
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Coles, Robert G., Michael A. Rasheed, Alana Grech e Len J. McKenzie. "Seagrass Meadows of Northeastern Australia". In The Wetland Book, 1–9. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-007-6173-5_266-2.
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Coles, Robert G., Michael A. Rasheed, Alana Grech e Len J. McKenzie. "Seagrass Meadows of Northeastern Australia". In The Wetland Book, 1967–75. Dordrecht: Springer Netherlands, 2018. http://dx.doi.org/10.1007/978-94-007-4001-3_266.
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Duarte, Carlos M., Marianne Holmer e Núria Marbà. "Plant-microbe interactions in seagrass meadows". In Coastal and Estuarine Studies, 31–60. Washington, D. C.: American Geophysical Union, 2005. http://dx.doi.org/10.1029/ce060p0031.
Testo completoAtti di convegni sul tema "Seagrass meadow"
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Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada e Kuninao Tada. "NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b938251aa95.85691438.
Testo completoAbstract (sommario):
Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
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Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada e Kuninao Tada. "NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS". In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b4316623b72.
Testo completoAbstract (sommario):
Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
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Arredondo, Rachel Ann, Ofri Dar, Kylon Chiang, Arielle Blonder e Lining Yao. "Blue Ceramics: Co-designing Morphing Ceramics for Seagrass Meadow Restoration". In C&C '22: Creativity and Cognition. New York, NY, USA: ACM, 2022. http://dx.doi.org/10.1145/3527927.3531453.
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Ballard, Megan S., Kevin M. Lee, Jason D. Sagers, Gabriel R. Venegas, Andrew R. McNeese, Abdullah F. Rahman, Justin T. Dubin e Preston S. Wilson. "Measurements and modeling of acoustic propagation in a seagrass meadow". In 175th Meeting of the Acoustical Society of America. Acoustical Society of America, 2018. http://dx.doi.org/10.1121/2.0000812.
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Jerome, Thomas S., Megan S. Ballard, Kevin M. Lee, Colby W. Cushing, Kyle A. Capistrant-Fossa, Andrew R. McNeese, Preston S. Wilson e Kenneth H. Dunton. "Effective medium modeling of acoustic propagation in a seagrass meadow". In 185th Meeting of the Acoustical Society of America. ASA, 2023. http://dx.doi.org/10.1121/2.0001839.
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Felisberto, Paulo, Orlando C. Rodríguez, João P. Silva, Sérgio Jesus, Hugo Q. Ferreira, Pedro P. Ferreira, Maria E. Cunha, Carmen B. de los Santos, Irene Olivé e Rui Santos. "Monitoring bubble production in a seagrass meadow using a source of opportunity". In 173rd Meeting of Acoustical Society of America and 8th Forum Acusticum. Acoustical Society of America, 2017. http://dx.doi.org/10.1121/2.0000584.
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Weidmann, Franz, Jonas Jager, Gereon Reus, Stewart T. Schultz, Claudia Kruschel, Viviane Wolff e Klaus Fricke-Neuderth. "A Closer Look at Seagrass Meadows: Semantic Segmentation for Visual Coverage Estimation". In OCEANS 2019 - Marseille. IEEE, 2019. http://dx.doi.org/10.1109/oceanse.2019.8867064.
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James, Dorothée, Antoine Collin e Agathe Bouet. "Drone-Based Spatio-Temporal Assessment of a Seagras Meadow: Insights into Anthropogenic Pressure". In ECRS 2023. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/ecrs2023-15851.
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Letard, Mathilde, Antoine Collin, Dimitri Lague, Thomas Corpetti, Yves Pastol, Anders Ekelund, Gerard Pergent e Stephane Costa. "Towards 3D Mapping of Seagrass Meadows with Topo-Bathymetric Lidar Full Waveform Processing". In IGARSS 2021 - 2021 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2021. http://dx.doi.org/10.1109/igarss47720.2021.9554262.
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"Predicting the temporal response of seagrass meadows to dredging using Dynamic Bayesian Networks". In 21st International Congress on Modelling and Simulation (MODSIM2015). Modelling and Simulation Society of Australia and New Zealand, 2015. http://dx.doi.org/10.36334/modsim.2015.f5.wu.
Testo completoRapporti di organizzazioni sul tema "Seagrass meadow"
1
Merk, Christine. Summary report on Workshop 1 laypersons’ perceptions of marine CDR, Deliverable 3.1. OceanNETs, marzo 2021. http://dx.doi.org/10.3289/oceannets_d3.1.
Testo completoAbstract (sommario):
This deliverable reports about the successful completion of three group discussions on marine carbon dioxide removal (CDR) with laypersons in Germany. The 2-hour group discussions were held online. 5 participants discussed these three topics: (1) the environmental state of the oceans, (2) four selected marine CDR approaches, and (3) responsible research and innovation. The four approaches were ocean fertilization, ocean alkalinization via ocean liming and electrochemical weathering in desalination plants, artificial upwelling, and blue carbon management via kelp forests, mangroves and seagrass meadows.
2
Veland, Siri. Summary report on Workshop 2 laypersons’ perceptions of marine CDR, Deliverable 3.2. OceanNETs, aprile 2021. http://dx.doi.org/10.3289/oceannets_d3.2.
Testo completoAbstract (sommario):
This deliverable reports about the successful completion of three group discussions on marine carbon dioxide removal (CDR) with laypersons in Norway. The 2-hour group discussions were held online. In three groups, and a pilot group, between 2 and 7 participants discussed these three topics: (1) the environmental state of the oceans, (2) four selected marine CDR approaches, and (3) responsible research and innovation. The four approaches were ocean fertilization, ocean alkalinization via ocean liming and electrochemical weathering in desalination plants, artificial upwelling, and blue carbon management via kelp forests, mangroves and seagrass meadows.