Academic literature on the topic 'Seagrass ecosystems'
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Journal articles on the topic "Seagrass ecosystems"
1
Khalifa, Muta Ali, Ani Rahmawati, Forcep Rio Indaryanto, Luky Adrianto, Syamsul Bahri Agus, Fery Kurniawan, Aldi Agus Setiawan, Desy Aryani, and Agustin Rustam. "The Impact of Tsunami on Seagrass Ecosystem in Tanjung Lesung, Banten, Indonesia." Omni-Akuatika 16, no. 3 (December 30, 2020): 78. http://dx.doi.org/10.20884/1.oa.2020.16.3.859.
Full textAbstract:
The Sunda Strait Tsunami (end of 2018) has an impact on the seagrass ecosystem in Tanjung Lesung. This paper described the seagrass ecosystem’s changes after the tsunami disaster. Sentinel-2 satellite image processing in 2018 and 2019 was used to see changes in the seagrass area. The field data were collected from May–July 2019, including the types of seagrass ecosystems based on data seagrass existence, density and biomass. Then, the seagrass sample was analyzed biomass after the tsunami disaster. The results showed that the data from 2018 – 2019 showed decreased seagrass area from 105.86 to 77.07 ha. Seagrass density dropped quite dramatically, and the species of Halodule uninervis was no longer found. The ratio of after tsunami BG/AbG dry biomass has doubled compared to before the tsunami, which indicates the seagrass's lower biomass is higher than the upper part allegedly due to tsunami impacts. Based on the results obtained, it can be concluded that the seagrass ecosystems changed and disrupted by the tsunami. Keywords: Seagrass, Tanjung Lesung, Tsunami, Sentinel-2
2
Munandar, Rizqan Khairan, Sulistiono Sulistiono, and Isdrajad Setyobudiandi. "Pengelolaan Ekosistem Lamun untuk Keberlanjutan Populasi Kuda Laut di Desa Sebong Pereh, Kabupaten Bintan." Jurnal Ilmu Pertanian Indonesia 25, no. 3 (July 29, 2020): 405–11. http://dx.doi.org/10.18343/jipi.25.3.405.
Full textAbstract:
This research is about studying ecosystems that was designed to analyze the relationship between seagrass ecosystem, environmental competition, and seahorse participation to analyze the distribution of seagrass ecosystems and the abundance of sea horses, and to analyze seahorse-based ecosystem management strategies. This research was conducted in March–June 2017. The determination of the research station was based on purposive sampling technique. Retrieval of seagrass ecosystem data was conducted using a quadrant with the size of 50 x 50 cm transect. Seahorse data were collected using visual census on seagrass transect with a plot of 100 x 100 cm. The relationships between environmental parameters, seagrass ecosystems, and seahorses were calculated using XL Starting 2015. Management of seagrass ecosystems was analyzed using SWOT. Analysis of seagrass included type, density, and INP. Seahorse analysis calculated the abundance of seahorse. The results found 6 species of seagrasses, namely Enhalus acoraides (Ea), Thalassia hemprichii (Th), Halophila ovalis (Ho), Syringodium isoetifolium (Si), Cymodocea serrulata (Cs), and Thalassodendron ciliatum (Tc) with a density that covered sea horse abundance, and INP which had several types of roles in the research location. The management is carried out with the objectives of sustainable resources.
Keywords: seagrass ecosystem, seahorse, Sebong Pereh Village
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Ramesh, Chatragadda, and Raju Mohanraju. "Seagrass Ecosystems of Andaman and Nicobar Islands: Status and Future Perspective." Environmental and Earth Sciences Research Journal 7, no. 4 (December 31, 2020): 169–74. http://dx.doi.org/10.18280/eesrj.070407.
Full textAbstract:
Seagrasses are unique marine flowering plants that play an important ecological role by yielding primary production and carbon sequestration to the marine environment. Seagrass ecosystems are rich in organic matter, supporting the growth of bio-medically important epi and endophytic microorganisms and harbor rich marine biodiversity. They are an essential food source for endangered Andaman state animal Dugongs. Seagrasses are very sensitive to water quality changes, and therefore they serve as ecological bio-indicators for environmental changes. The benthic components in and around the seagrass beds support a significant food chain for other Micro and organisms apart from fishery resources. The epiphytic bacterial communities of the leaf blades support the sustenance against the diseases. Recent reports have shown that the loss of seagrass beds in tropical and temperate regions emphasizes the depletion of these resources, and proper management of seagrass is urgent. The decline of seagrass will impact primary production, biodiversity, and adjacent ecosystems, such as reefs. Therefore, restoring the seagrass meadows could be possible with effective implementing management programs, including seagrass meadows in marine protected areas, restoration projects, seagrass transplantation, implementation of legislative rules, monitoring coastal water quality and human activities in the coastal zone. Lacunas on the seagrass ecosystem management in Andaman & Nicobar Islands are addressed.
4
Reid, T. "Seagrass in Australia. A Strategic Review and Development of a Research and Development Plan." Pacific Conservation Biology 6, no. 2 (2000): 178. http://dx.doi.org/10.1071/pc00178a.
Full textAbstract:
Australia possesses the highest diversity of seagrasses and the most extensive seagrass meadows world-wide. Unfortunately, Australia also has claim to some of the most significant declines of this habitat over the last 50 years. Seagrass in Australia reflects the shift from viewing seagrass species or even habitats as separate unconnected entities. Instead, it views them as components of larger ecosystems which incorporates the author's aim to develop a comprehensive, ecosystem based management plan.
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Leemans, Luuk, Isis Martínez, Tjisse van der Heide, Marieke M. van Katwijk, and Brigitta I. van Tussenbroek. "A Mutualism Between Unattached Coralline Algae and Seagrasses Prevents Overgrazing by Sea Turtles." Ecosystems 23, no. 8 (February 18, 2020): 1631–42. http://dx.doi.org/10.1007/s10021-020-00492-w.
Full textAbstract:
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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Karlina, Ita, Aditya Hikmat Nugraha, Dony Apdillah, Jelita Rahma Hidayati, and Esty Kurniawati. "Sosialisasi penyemaian bibit dari buah Enhalus acoroides untuk menjaga keberlanjutan ekosistem Lamun di Desa Pengudang Pulau Bintan." Unri Conference Series: Community Engagement 3 (November 18, 2021): 148–55. http://dx.doi.org/10.31258/unricsce.3.148-155.
Full textAbstract:
Seagrass ecosystems contribute to food security, climate change mitigation, and biodiversity, yet they are vulnerable to changes in the environment. Environmental factors, both natural and human-caused, are the primary cause of the loss in the area of seagrass ecosystems. Transplanting or sowing seagrass is one method for addressing this issue. The goal of this project is to maintain the seagrass environment and give coastal people with knowledge so that they may contribute to the conservation of coastal habitats, particularly seagrass ecosystems, in Pengudang Village, Bintan. The seeding process starts with a search for seagrass in areas with a dense seagrass habitat. Enhalus acoroides was chosen as the seeding object in this investigation. The findings revealed that 78% of respondents were highly aware of the existence of seagrass ecosystems (perception), 28% were very aware of the function and existence of seagrass ecosystems (understanding), and 86% significantly participated in seagrass ecosystem conservation (participation).
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Duarte, Carlos M. "The future of seagrass meadows." Environmental Conservation 29, no. 2 (June 2002): 192–206. http://dx.doi.org/10.1017/s0376892902000127.
Full textAbstract:
Seagrasses cover about 0.1–0.2% of the global ocean, and develop highly productive ecosystems which fulfil a key role in the coastal ecosystem. Widespread seagrass loss results from direct human impacts, including mechanical damage (by dredging, fishing, and anchoring), eutrophication, aquaculture, siltation, effects of coastal constructions, and food web alterations; and indirect human impacts, including negative effects of climate change (erosion by rising sea level, increased storms, increased ultraviolet irradiance), as well as from natural causes, such as cyclones and floods. The present review summarizes such threats and trends and considers likely changes to the 2025 time horizon. Present losses are expected to accelerate, particularly in South-east Asia and the Caribbean, as human pressure on the coastal zone grows. Positive human effects include increased legislation to protect seagrass, increased protection of coastal ecosystems, and enhanced efforts to monitor and restore the marine ecosystem. However, these positive effects are unlikely to balance the negative impacts, which are expected to be particularly prominent in developing tropical regions, where the capacity to implement conservation policies is limited. Uncertainties as to the present loss rate, derived from the paucity of coherent monitoring programmes, and the present inability to formulate reliable predictions as to the future rate of loss, represent a major barrier to the formulation of global conservation policies. Three key actions are needed to ensure the effective conservation of seagrass ecosystems: (1) the development of a coherent worldwide monitoring network, (2) the development of quantitative models predicting the responses of seagrasses to disturbance, and (3) the education of the public on the functions of seagrass meadows and the impacts of human activity.
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Macreadie, Peter I., Stacey M. Trevathan-Tackett, Charles G. Skilbeck, Jonathan Sanderman, Nathalie Curlevski, Geraldine Jacobsen, and Justin R. Seymour. "Losses and recovery of organic carbon from a seagrass ecosystem following disturbance." Proceedings of the Royal Society B: Biological Sciences 282, no. 1817 (October 22, 2015): 20151537. http://dx.doi.org/10.1098/rspb.2015.1537.
Full textAbstract:
Seagrasses are among the Earth's most efficient and long-term carbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate. Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas, which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences.
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Omollo, Derrick, Virginia Wang’ondu, Michael Githaiga, Daniel Gorman, and James Kairo. "The Contribution of Subtidal Seagrass Meadows to the Total Carbon Stocks of Gazi Bay, Kenya." Diversity 14, no. 8 (August 11, 2022): 646. http://dx.doi.org/10.3390/d14080646.
Full textAbstract:
Seagrass beds occur globally in both intertidal and subtidal zones within shallow marine environments, such as bays and estuaries. These important ecosystems support fisheries production, attenuate strong wave energies, support human livelihoods and sequester large amounts of CO2 that may help mitigate the effects of climate change. At present, there is increased global interest in understanding how these ecosystems could help alleviate the challenges likely to face humanity and the environment into the future. Unlike other blue carbon ecosystems, i.e., mangroves and saltmarshes, seagrasses are less understood, especially regarding their contribution to the carbon dynamics. This is particularly true in regions with less attention and limited resources. Paucity of information is even more relevant for the subtidal meadows that are less accessible. In Kenya, much of the available information on seagrasses comes from Gazi Bay, where the focus has been on the extensive intertidal meadows. As is the case with other regions, there remains a paucity of information on subtidal meadows. This limits our understanding of the overall contribution of seagrasses in carbon capture and storage. This study provides the first assessment of the species composition and variation in carbon storage capacity of subtidal seagrass meadows within Gazi Bay. Nine seagrass species, comprising of Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, Halodule uninervis, Halophila ovalis, Halophila stipulacea, Syringodium isoetifolium, Thalassia hemprichii, and Thalassodendron ciliatum, were found. Organic carbon stocks varied between species and pools, with the mean below ground vegetation carbon (bgc) stocks (5.1 ± 0.7 Mg Cha−1) being more than three times greater than above ground carbon (agc) stocks (0.5 ± 0.1 Mg Cha−1). Mean sediment organic carbon stock (sed Corg) of the subtidal seagrass beds was 113 ± 8 Mg Cha−1. Combining this new knowledge with existing data from the intertidal and mangrove fringed areas, we estimate the total seagrass ecosystem organic carbon stocks in the bay to be 196,721 Mg C, with the intertidal seagrasses storing about 119,790 Mg C (61%), followed by the subtidal seagrasses 55,742 Mg C (28%) and seagrasses in the mangrove fringed creeks storing 21,189 Mg C (11%). These findings are important in highlighting the need to protect subtidal seagrass meadows and for building a national and global data base on seagrass contribution to global carbon dynamics.
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Lazaren, Cornelia Coraima, Made Antara, and Ida Ayu Astarini. "KONDISI EKOSISTEM DAN VALUASI EKONOMI LAMUN DI PANTAI SAMUH, NUSA DUA, BALI." ECOTROPHIC : Jurnal Ilmu Lingkungan (Journal of Environmental Science) 14, no. 2 (December 24, 2020): 201. http://dx.doi.org/10.24843/ejes.2020.v14.i02.p10.
Full textAbstract:
Seagrass ecosystems in addition to providing economic benefits also have ecological functions, so it is highly recommended to conserve these ecosystems in order to preserve spawning areas, nurseries and habitats for fish and other marine biota. This study aims to identify the condition of seagrass ecosystems in Samuh Beach, Nusa Dua, estimating the economic value of the seagrass ecosystems in Samuh Beach, Nusa Dua and formulating for sustainable management of seagrass ecosystems in Samuh Beach, Nusa Dua. The study was conducted in January-March 2020 at Samuh Beach, Nusa Dua, Bali. Data collected includes secondary data and primary data. Secondary data were collected from related institutions, while primary data were collected through purposive sampling and questionnaires. The analysis used was description analysis, calculation of the economic value of marine resources through a Total Economic Value (TEV) and DPSIR analysis. This study found that the actual condition of the seagrass ecosystem resources in Samuh Beach is currently in the category of less rich/less healthy due to natural factors (substrate conditions) and human activity (anthropogenic). The economic value of seagrass ecosystems at Samuh Beach Nusa Dua, Bali showed the total economic value reached IDR. 327,843,325 per year and seagrass ecosystem management strategies that can be applied in the coastal area of ??Samuh Beach are the development of marine ecotourism, stock enrichment, and rehabilitation of seagrass beds.
Keywords: Seagrass condition; TEV; economic valuation; Samuh beach.
Dissertations / Theses on the topic "Seagrass ecosystems"
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au, keulen@murdoch edu, and Michael van Keulen. "Water Flow in Seagrass Ecosystems." Murdoch University, 1998. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040518.91242.
Full textAbstract:
Water motion has been shown to influence almost every aspect of the ecology of seagrass communities; seagrass communities have likewise been shown to significantly influence water movement around them. This thesis examines the important role of water motion on seagrass ecosystems by integrating field and laboratory studies of several aspects of seagrass ecology influenced by water motion.
To facilitate the study of hydrodynamics of seagrass ecosystems, a solid state electronic current meter was designed and developed, using thermistors as flow sensing devices. Important characteristics of the meters include: no moving parts, compact size, high sensitivity (resolution
better than ± 0.5 cm s-1), and high sampling rate (greater than 0.2 Hz). Deployment of the meters in field measurements provided reliable and meaningful results of flow conditions through seagrass canopies, and they show great potential for use in many studies of marine ecology.
Field studies of water velocity profiles revealed significant differences between the shapes of profiles of different seagrass species, particularly between species of Posidonia and Amphibolis. Of particular note is the observation of a region of high water velocity beneath the leafy canopy of Amphibolis, which was not present in the Posidonia plants.
Water velocity profile measurements, sediment grain size analyses and standing stock measurements were conducted across an exposure gradient in a Posidonia sinuosa meadow.
These studies revealed that, while the exposed location experienced a higher ambient water velocity than the sheltered site, the baffling influence of the seagrass canopy reduced the water velocity to approximately the same at both sites, within the meadow, although the effects varied seasonally. It was also observed that the seagrass meadow produced apparent skimming flow under the low flow conditions measured at the sheltered location; this phenomenon reflects the capacity for flow redirection over the canopy, and has important implications for the sub-canopy ecosystem and the protective role of seagrasses on the seabed.
Field and laboratory studies on the role of seagrass density on the hydrodynamic nature of seagrass ecosystems revealed that water velocity profiles through meadows of reduced densities, and different shoot arrangements, were markedly different to natural profiles, implying the
existence of a critical density (approximately 25 % of natural meadow density) with regard to canopy hydraulics.
The role of water motion at an individual leaf scale was investigated with a series of laboratory flume studies of photosynthetic rates of seagrass and algae. The results show that the response of photosynthetic rate to water velocity depends very much on the plant species, with the algae markedly more productive (on a unit chlorophyll basis) than the seagrasses tested. Increases in
photosynthetic rate were observed at water velocities above approximately 2.5 cm s-1; negligible photosynthetic activity was observed below this velocity. Calculation of P v. I curves indicated that the Posidonia species had high Ik values at low velocities (1360 :mol quanta m-2 s-1 for P. australis and 250.8 :mol quanta m-2 s-1 for P. sinuosa at 1.58 cm s-1), which decreased with increasing water velocity (to 138.9 and 24.77 :mol quanta m-2 s-1 for P. australis and P. sinuosa respectively), while the algal species had relatively constant values of Ik across all water velocities (85.42 to 312.7 :mol quanta m-2 s-1 for Ulva lactuca and 169.7 to 573.9 :mol quanta m-2 s-1 for
Laurencia cruciata). Dye visualization studies showed that the algae remained quite rigid at all the velocities tested, while the seagrass leaves compressed as velocity increased. This resulted in an increased rate of turbulence creation by the algae, which is believed to enhance photosynthetic rates, through improved nutrient exchange rates across the boundary layer adjacent to the thallus.
Further dye visualization studies revealed the significance of blade morphology on the creation of microscale turbulence at the surface of seagrass leaves. Epiphytic growth on seagrass leaves was observed to play an important role in breaking up water flow across the leaf surface, thereby enhancing the creation of microscale turbulence.
From these studies, it is clear that water motion influences all aspects of the functioning of all
components of seagrass communities, playing a role in nutrient supply, reproduction, physical stability, temperature and metabolic functions. The influence of seagrass meadows on coastal hydrodynamics is also apparent, with potential impacts on sediment stability, recruitment of benthic species and coastal erosion. This thesis has clearly demonstrated that water motion is
an important parameter in seagrass ecology, and requires serious consideration in seagrass research, conservation and rehabilitation programmes.
2
van, Keulen Michael. "Water flow in seagrass ecosystems." Thesis, van Keulen, Michael ORCID: 0000-0001-6235-5788 (1998) Water flow in seagrass ecosystems. PhD thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/377/.
Full textAbstract:
Water motion has been shown to influence almost every aspect of the ecology of seagrass communities; seagrass communities have likewise been shown to significantly influence water movement around them. This thesis examines the important role of water motion on seagrass ecosystems by integrating field and laboratory studies of several aspects of seagrass ecology influenced by water motion.
To facilitate the study of hydrodynamics of seagrass ecosystems, a solid state electronic current meter was designed and developed, using thermistors as flow sensing devices. Important characteristics of the meters include: no moving parts, compact size, high sensitivity (resolution better than plus-minus 0.5 cm s-1), and high sampling rate (greater than 0.2 Hz). Deployment of the meters in field measurements provided reliable and meaningful results of flow conditions through seagrass canopies, and they show great potential for use in many studies of marine ecology.
Field studies of water velocity profiles revealed significant differences between the shapes of profiles of different seagrass species, particularly between species of Posidonia and Amphibolis. Of particular note is the observation of a region of high water velocity beneath the leafy canopy of Amphibolis, which was not present in the Posidonia plants.
Water velocity profile measurements, sediment grain size analyses and standing stock measurements were conducted across an exposure gradient in a Posidonia sinuosa meadow. These studies revealed that, while the exposed location experienced a higher ambient water velocity than the sheltered site, the baffling influence of the seagrass canopy reduced the water velocity to approximately the same at both sites, within the meadow, although the effects varied seasonally. It was also observed that the seagrass meadow produced apparent skimming flow under the low flow conditions measured at the sheltered location; this phenomenon reflects the capacity for flow redirection over the canopy, and has important implications for the sub-canopy ecosystem and the protective role of seagrasses on the seabed.
Field and laboratory studies on the role of seagrass density on the hydrodynamic nature of seagrass ecosystems revealed that water velocity profiles through meadows of reduced densities, and different shoot arrangements, were markedly different to 'natural' profiles, implying the existence of a 'critical density' (approximately 25 % of natural meadow density) with regard to canopy hydraulics.
The role of water motion at an individual leaf scale was investigated with a series of laboratory flume studies of photosynthetic rates of seagrass and algae. The results show that the response of photosynthetic rate to water velocity depends very much on the plant species, with the algae markedly more productive (on a unit chlorophyll basis) than the seagrasses tested. Increases in photosynthetic rate were observed at water velocities above approximately 2.5 cm s-1; negligible photosynthetic activity was observed below this velocity. Calculation of P v. I curves indicated that the Posidonia species had high Ik values at low velocities (1360 :mol quanta m-2 s-1 for P. australis and 250.8 :mol quanta m-2 s-1 for P. sinuosa at 1.58 cm s-1), which decreased with increasing water velocity (to 138.9 and 24.77 :mol quanta m-2 s-1 for P. australis and P. sinuosa respectively), while the algal species had relatively constant values of Ik across all water velocities (85.42 to 312.7 :mol quanta m-2 s-1 for Ulva lactuca and 169.7 to 573.9 :mol quanta m-2 s-1 for Laurencia cruciata). Dye visualization studies showed that the algae remained quite rigid at all the velocities tested, while the seagrass leaves compressed as velocity increased. This resulted in an increased rate of turbulence creation by the algae, which is believed to enhance photosynthetic rates, through improved nutrient exchange rates across the boundary layer adjacent to the thallus.
Further dye visualization studies revealed the significance of blade morphology on the creation of microscale turbulence at the surface of seagrass leaves. Epiphytic growth on seagrass leaves was observed to play an important role in breaking up water flow across the leaf surface, thereby enhancing the creation of microscale turbulence.
From these studies, it is clear that water motion influences all aspects of the functioning of all components of seagrass communities, playing a role in nutrient supply, reproduction, physical stability, temperature and metabolic functions. The influence of seagrass meadows on coastal hydrodynamics is also apparent, with potential impacts on sediment stability, recruitment of benthic species and coastal erosion. This thesis has clearly demonstrated that water motion is an important parameter in seagrass ecology, and requires serious consideration in seagrass research, conservation and rehabilitation programmes.
3
van, Keulen Michael. "Water flow in seagrass ecosystems." van Keulen, Michael (1998) Water flow in seagrass ecosystems. PhD thesis, Murdoch University, 1998. http://researchrepository.murdoch.edu.au/377/.
Full textAbstract:
Water motion has been shown to influence almost every aspect of the ecology of seagrass communities; seagrass communities have likewise been shown to significantly influence water movement around them. This thesis examines the important role of water motion on seagrass ecosystems by integrating field and laboratory studies of several aspects of seagrass ecology influenced by water motion.
To facilitate the study of hydrodynamics of seagrass ecosystems, a solid state electronic current meter was designed and developed, using thermistors as flow sensing devices. Important characteristics of the meters include: no moving parts, compact size, high sensitivity (resolution better than plus-minus 0.5 cm s-1), and high sampling rate (greater than 0.2 Hz). Deployment of the meters in field measurements provided reliable and meaningful results of flow conditions through seagrass canopies, and they show great potential for use in many studies of marine ecology.
Field studies of water velocity profiles revealed significant differences between the shapes of profiles of different seagrass species, particularly between species of Posidonia and Amphibolis. Of particular note is the observation of a region of high water velocity beneath the leafy canopy of Amphibolis, which was not present in the Posidonia plants.
Water velocity profile measurements, sediment grain size analyses and standing stock measurements were conducted across an exposure gradient in a Posidonia sinuosa meadow. These studies revealed that, while the exposed location experienced a higher ambient water velocity than the sheltered site, the baffling influence of the seagrass canopy reduced the water velocity to approximately the same at both sites, within the meadow, although the effects varied seasonally. It was also observed that the seagrass meadow produced apparent skimming flow under the low flow conditions measured at the sheltered location; this phenomenon reflects the capacity for flow redirection over the canopy, and has important implications for the sub-canopy ecosystem and the protective role of seagrasses on the seabed.
Field and laboratory studies on the role of seagrass density on the hydrodynamic nature of seagrass ecosystems revealed that water velocity profiles through meadows of reduced densities, and different shoot arrangements, were markedly different to 'natural' profiles, implying the existence of a 'critical density' (approximately 25 % of natural meadow density) with regard to canopy hydraulics.
The role of water motion at an individual leaf scale was investigated with a series of laboratory flume studies of photosynthetic rates of seagrass and algae. The results show that the response of photosynthetic rate to water velocity depends very much on the plant species, with the algae markedly more productive (on a unit chlorophyll basis) than the seagrasses tested. Increases in photosynthetic rate were observed at water velocities above approximately 2.5 cm s-1; negligible photosynthetic activity was observed below this velocity. Calculation of P v. I curves indicated that the Posidonia species had high Ik values at low velocities (1360 :mol quanta m-2 s-1 for P. australis and 250.8 :mol quanta m-2 s-1 for P. sinuosa at 1.58 cm s-1), which decreased with increasing water velocity (to 138.9 and 24.77 :mol quanta m-2 s-1 for P. australis and P. sinuosa respectively), while the algal species had relatively constant values of Ik across all water velocities (85.42 to 312.7 :mol quanta m-2 s-1 for Ulva lactuca and 169.7 to 573.9 :mol quanta m-2 s-1 for Laurencia cruciata). Dye visualization studies showed that the algae remained quite rigid at all the velocities tested, while the seagrass leaves compressed as velocity increased. This resulted in an increased rate of turbulence creation by the algae, which is believed to enhance photosynthetic rates, through improved nutrient exchange rates across the boundary layer adjacent to the thallus.
Further dye visualization studies revealed the significance of blade morphology on the creation of microscale turbulence at the surface of seagrass leaves. Epiphytic growth on seagrass leaves was observed to play an important role in breaking up water flow across the leaf surface, thereby enhancing the creation of microscale turbulence.
From these studies, it is clear that water motion influences all aspects of the functioning of all components of seagrass communities, playing a role in nutrient supply, reproduction, physical stability, temperature and metabolic functions. The influence of seagrass meadows on coastal hydrodynamics is also apparent, with potential impacts on sediment stability, recruitment of benthic species and coastal erosion. This thesis has clearly demonstrated that water motion is an important parameter in seagrass ecology, and requires serious consideration in seagrass research, conservation and rehabilitation programmes.
4
Sanmartí, Boixeda Neus. "Biological interactions and resilience of seagrass ecosystems." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/672259.
Full textAbstract:
Our world is subjected to a panoply of drivers of change. In this context, the understanding on how our biosphere resists, absorbs or is altered by the changes, appears as a hot question in ecology. In this respect, two ecological concepts appear as essential, resilience and biotic interactions. Resilience is related to how ecosystems persist under stress or suffering disturbances. Interactions among species are to a large part responsible for the delivery of ecosystem functions, and form the architecture of biodiversity. Moreover, a substantial part of ecosystem resilience is founded on species interactions. This thesis is an attempt to shed some light on these issues through the deep exploration of specific case studies in seagrass ecosystems, in particular how seagrasses respond to external drivers (or how resilient they are), how these responses affect species interactions and which mechanisms allow coexistence of species linked by positive and negative interactions. Our approach is based upon field observations and field manipulative experiments.
Chapter 1 shows how an increase of organic matter in sediment weakens the mutualism between the bivalve Loripes lucinalis and the seagrass Cymodocea nodosa. The mechanism implied is the effect of this increase (and, probably, the resulting anoxia) on seagrass root morphology (plant trait), which results in a lower provision of habitat for the bivalves, whose abundance decreases. The weakening of the mutualism can potentially decrease the resilience of these ecosystems to eutrophication and, therefore, compromise their persistence.
Chapter 2 describes a facilitative cascade in which the seagrass C. nodosa favors the abundance of the pen shell Pinna nobilis, which positively affects the sea urchin Paracentrotus lividus, which in turn consumes the seagrass. We suggest that the persistence of this three-species assemblage rests on the very local impact of sea urchins on the seagrass, likely driven by behavioural and denso-dependent processes.
Chapter 3 and 4 show that fast-growing species such as C. nodosa are highly resilient to stress or disturbances when affecting only the aboveground parts, recovering fast (within two weeks) from a single event of disturbance. C. nodosa shows several mechanisms of tolerance, such as compensatory growth, reallocation of internal resources and enhancement of the formation of new modules, when coping to repeated defoliation simulating herbivory. However, when the
belowground parts are lost by disturbances, recovery is highly delayed up to two years and is dependent on the characteristics of the disturbance such as size and timing.
Overall, this research has contributed to increase our understanding on how ecosystems respond to changes and how species interactions are maintained and disrupted. We have shown that environmental changes can alter the functioning of seagrass ecosystems at least in two directions. Firstly, by altering fundamental biological interactions, such as the seagrass-lucinid mutualism and, secondly, by affecting the resilience of ecosystems dominated by a foundation species, which promote species coexistence. Advances in the two complementary and interlinked directions will be crucial to better manage and preserve ecosystems and prevent their potential collapse under the increasing human-induced change the world is submitted to.El nostre món està sotmès a un ampli ventall de forces que tendeixen a provocar canvis. En aquest context, entendre com la biosfera resisteix, absorbeix o és alterada per aquestes forces resulta una qüestió candent, especialment per l'ecologia. Al respecte, dos conceptes ecològics esdevenen essencials: la resiliència i les interaccions biològiques. La resiliència és la capacitat de persistència o recuperació que tenen els ecosistemes sotmesos a estrès o pertorbacions. Les interaccions entre espècies (efectes de l'existència d'una espècie sobre la fitness d'una altra) contribueixen al manteniment de les funcions ecosistèmiques i, en un cert sentit, constitueixen l'arquitectura de la biodiversitat. A més, la resiliència dels ecosistemes depèn , en gran part, d’aquestes interaccions. Aquesta tesi és un intent d’aprofundir en els aspectes esmentats a través d'una sèrie de casos d’estudi en ecosistemes d’angiospermes marines. Concretament, el que fem és estudiar com els ecosistemes d’angiospermes marines responen a les forces causants de canvis, com aquestes respostes vénen mitjançades per canvis en la interacció entre espècies, i provar d'esbrinar els mecanismes que permeten la coexistència d’espècies que es troben vinculades per interaccions positives i negatives. La nostra aproximació es basa tant en observacions com en experiments en el camp. El Capítol 1 mostra com un increment de matèria orgànica en el sediment debilita el mutualisme entre el bivalve Loripes lucinalis i l’angiosperma marina Cymodocea nodosa. El mecanisme implicat que es proposa per explicar-ho està relacionat amb la plasticitat morfològica de la planta. Així, un increment en la matèria orgànica del sediment (i, probablement, l’anòxia que se'n segueix), fa que la planta modifiqui la morfologia de les seves arrels, que esdevenen molt menys ramificades i fan disminuir per tant la disponibilitat d'hàbitat per als bivalves. Una debilitació del mutualisme pot, potencialment, disminuir la resiliència d’aquests ecosistemes a l’eutrofització i, per tant, comprometre la seva persistència. El Capítol 2 descriu una cascada de facilitació en la qual l’angiosperma marina C. nodosa afavoreix l’abundància del gran bivalve Pinna nobilis, que ajuda a incrementar l'abundància de la garota Paracentrotus lividus, que al seu torn consumeix l’angiosperma. Suggerim que la persistència d’aquest sistema de tres espècies, aparentment inestable (tres interaccions concatenades circularment, dues de positives i una de negativa) es basa en què la interacció negativa (l’efecte de les garotes sobre l’angiosperma) té un abast molt limitat, probablement degut tant al seu comportament alimentari com a les defenses de la planta enfront de l'herbivorisme. Els Capítols 3 i 4 mostren que les espècies de creixement ràpid, com ara C. nodosa, són altament resilients a l'estrès o a les pertorbacions quan aquestes afecten només les parts aèries de les plantes (defoliació parcial o total), recuperant-se ràpidament (dues setmanes) després d'una pertorbació puntual en el temps. C. nodosa mostra diversos mecanismes de tolerància a la defoliació, com ara el creixement compensatori, la reassignació de recursos interns i l’increment en la taxa de formació de nous mòduls. Tanmateix, quan les pertorbacions provoquen la pèrdua de les parts subterrànies (rizomes i arrels), la recuperació és molt més lenta, i triga fins a dos anys. A més, aquesta recuperació depèn de les característiques de la pertorbació com ara la mida de l'àrea afectada i l’època de l'any en què es produeix. En general, aquesta tesi ha contribuït a comprendre millor les respostes dels ecosistemes als canvis. Hem pogut documentar alguns processos que permeten la coexistència entre espècies, així com mecanismes de resiliència específics que esdevenen ecosistèmics quan es manifesten en espècies fundadores d'hàbitat. També hem demostrat com els canvis, més enllà d'afectar espècies individuals més o menys emblemàtiques, poden provocar alteracions de formes més subtils, com ara erosionant la seva resiliència mitjançant la modificació d’interaccions biològiques. Els avenços en totes aquestes direccions complementàries i interrelacionades són crucials per a gestionar i preservar els ecosistemes i evitar el seu possible col·lapse.
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Eklöf, Johan S. "Anthropogenic Disturbances and Shifts in Tropical Seagrass Ecosystems." Doctoral thesis, Stockholm University, Department of Systems Ecology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7285.
Full textAbstract:
Seagrasses constitute the basis for diverse and productive ecosystems worldwide. In East Africa, they provide important ecosystem services (e.g. fisheries) but are potentially threatened by increasing resource use and lack of enforced management regulations. The major aim of this PhD thesis was to investigate effects of anthropogenic distur-bances, primarily seaweed farming and coastal fishery, in East African seagrass beds. Seaweed farming, often depicted as a sustainable form of aquaculture, had short- and long-term effects on seagrass growth and abundance that cascaded up through the food web to the level of fishery catches. The coastal fishery, a major subsistence activity in the region, can by removing urchin predators indirectly increase densities of the sea urchin Tripneustes gratilla, which has overgrazed seagrasses in several areas. A study using simulated grazing showed that high magnitude leaf removal – typical of grazing urchins – affected seagrasses more than low magnitude removal, typical of fish grazing. Different responses in two co-occurring seagrass species furthermore indicate that high seagrass diversity in tropical seagrass beds could buffer overgrazing effects in the long run. Finally, a literature synthesis suggests that anthropogenic disturbances could drive shifts in seagrass ecosystems to an array of alternative regimes dominated by other or-ganisms (macroalgae, bivalves, burrowing shrimp, polychaetes, etc.). The formation of novel feedback mechanisms makes these regimes resilient to disturbances like seagrass recovery and transplantation projects. Overall, this suggests that resource use activities linked to seagrasses can have large-scale implications if the scale exceeds critical levels. This emphasizes the need for holistic and adaptive management at the seascape level, specifically involving improved techniques for seaweed farming and fisheries, protection of keystone species, and ecosystem-based management approaches.
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Sweatman, Jennifer L. "Gammaridean Amphipods as Bioindicators in Subtropical Seagrass Ecosystems." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2603.
Full textAbstract:
Anthropogenic disturbances are ubiquitous in coastal marine ecosystems. As such, more intensive monitoring efforts are necessary to conserve these valuable habitats. Bioindicators, organisms that predictably respond to changes in environmental variables, may be utilized in monitoring efforts to assess ecosystem functioning. To incorporate organisms into monitoring programs as bioindicators managers need to first understand the difference between the natural phenology of the focal organisms and their responses to different forms of anthropogenic disturbance.
To determine if gammaridean amphipods could be used as indicators of changes in environmental quality in sub-tropical seagrass ecosystems, I conducted spatial and temporal surveys of amphipod communities in south Florida. Amphipod community structure varied significantly across sites and seasons. Variation in community structure was largely driven by macrophyte biomass, food availability, seasonally variable factors (epiphyte abundance, dissolved oxygen, salinity, and temperature), water-column nitrogen concentration, and factors related to freshwater input, including low Thalassia testudinum and high Halodule wrightii densities, and salinity.
Amphipods are also susceptible to mechanical damage in seagrass habitats and could be used as indicators of ecological functioning of a region. A major source of mechanical damage in seagrass ecosystems is caused by boat propellers. I simulated propeller scars in continuous seagrass beds to investigate the effects of scarring on seagrass ecosystem functioning. Seagrasses located adjacent to propeller scars experienced a shift in the limiting resource from light to phosphorus. Amphipod community structure, however, was not impacted by scarring, but amphipod density was reduced in fragmented patches. To determine if plant-herbivore interactions were impacted by propeller scarring, we removed amphipods from half of the experimental plots and measured epiphyte biomass and community composition. Top-down control on epiphyte biomass or community composition by amphipods was not affected by fragmentation, despite reduced amphipod densities.
My dissertation research demonstrates that amphipods could be incorporated into existing management programs in sub-tropical seagrass ecosystems as environmental indicators. Reduced amphipod densities in fragmented seagrass beds suggests that amphipods could also be used as ecological indicators, but more research is needed to determine the extent of the impacts of fragmentation on higher trophic levels.
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Eklöf, Johan S. "Anthropogenic disturbances and shifts in tropical seagrass ecosystems /." Stockholm : Department of Systems Ecology, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7285.
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Howard, Jason Lee. "PATTERNS OF CARBON METABOLISM, STORAGE, AND REMINERALIZATION IN SEAGRASS ECOSYSTEMS." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3719.
Full textAbstract:
Coastal marine sediments have recently been identified as globally important stocks of organic carbon (Corg) that, if compromised, could significantly exacerbate global greenhouse gas emissions. While resource managers and policy makers are eager to incorporate this ecosystem service into seagrass ecosystem valuation frameworks, similar to those already in existence for terrestrial forests, there has been insufficient information regarding how environmental conditions and seagrass ecology control carbon storage. These include the influence of the seagrass to the production and preservation of soil organic matter, the fate of stored carbon following conversion of coastal wetlands, and the interactions between organic and inorganic carbon cycling. This dissertation intends to to understand the drivers of Corg storage and preservation to better prioritize and evaluate the worth of seagrasses to large scale carbon cycles and greenhouse gas mitigation planning.
Long-term experiments and thorough field surveys reveal that seagrasses are not categorically necessary nor sufficient for long-term Corg storage. Soil Corg stocks as well as their recalcitrance and breakdown rates are all correlated with sediment grain size, where muddy, fine sediments have higher Corg stocks that are less likely to breakdown. Sediment grain size can be influenced by the presence of seagrasses at some sites, likely where the leaf canopy can modify local hydrology enough to create a depositional environmental that wouldn’t otherwise exist. However, similar depositional environments that collect and store Corg can be obtained through local geomorphological features and natural hydrology, independent of benthic flora. This distinction has important implications on how soil C is managed to continue its preservation.
The relation between seagrass Corg and CO2 can be blurred by calcification and carbonate dissolution processes that occur concurrently, and have direct but antagonistic effects on CO2. Carbonate processes are dependent on local environmental factors, though augmented by biological processes, thus the ability of carbonate processes to interfere with seagrass Corg storage and loss is limited to geographic areas where processes can occur. Warm, shallow waters, like those in Florida Bay, encourage calcification, though the magnitude of soil inorganic and organic carbon interaction can vary locally as well.
Seagrasses are declining globally thus additional ecosystem value via greenhouse gas mitigation could greatly benefit conservation efforts. To make conservation efforts worthwhile to greenhouse gas mitigation, these findings help to consider and prioritize sites where risk and impact of Corg lost is more severe.
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Buñuel, Moreno Xavier. "The role of behavioural and feedback mechanisms in mediating herbivory processes in Mediterranean seagrass ecosystems." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/673886.
Full textAbstract:
The role of consumer-resource relationship is the basis of the structure and functioning of ecological communities. The traditional lens for studying such interactions have tended to omit the importance of the species behaviour, particularly in the case of plant-herbivore interactions. However, they way the herbivore exploits the plant and the way the plant responds to that pressure is crucial in determining the stability of the interaction. Thus, both herbivore and plant performances, contextualised in the environment where the interaction takes place, can act as drivers of the resilience of the system. This thesis focuses on Posidonia oceanica ecosystems and specifically on the interaction between this seagrass and its two main herbivores – the fish Sarpa salpa and the sea urchin Paracentrotus lividus –. I assess the importance of herbivore behaviour (the aggregation patterns and feeding behaviour of S. salpa and the canopy cover dependence of
P. lividus) and the resilience provided feedback mechanisms (direct responses of the plant and indirect ecosystem processes) under changing conditions resulting from global change. Disentangling these components of the interaction allows us to assess its sensitivity to each of the components and to test the response and resilience of the system under different conditions.
Chapter 1 shows the importance of body size of Sarpa salpa individuals in their individual feeding activity, shoaling aggregation patterns and shoal feeding strategies, as well as the potential consequences of this on the seagrass P. oceanica. On the one hand, the larger the individuals are, the more feeding activity they show. On the other hand, S. salpa individuals tend to aggregate with conspecifics of the same body size and group size is positively related to the size of the individuals in the group. In addition, feeding strategies increase in complexity with group size and tend to be focused on very specific spots within the meadow. Thus, as individuals grow, they increase their potential impact on the seagrass, both in terms of their consumption capacity and the formation of large shoals capable of concentrating their consumption in very specific areas of the meadow. This distribution of herbivory can lead to spatial heterogeneity with consequences for the functioning of the ecosystem dominated by P. oceanica.
In chapter 2, a number of regulatory mechanisms arising from an episode of intense herbivory are found to provide resilience to Posidonia oceanica system once its canopy height is reduced. Four of the mechanisms evaluated function as feedback mechanisms, one of them being actively deployed by the plant (compensatory growth) while the other three (preference for an alternative resource, increased risk of predation and reduced urchin numbers due to competition for the resource and loss of cover) are triggered indirectly and their effectiveness is based on inducing changes in the behaviour of the herbivore Paracentrotus lividus. The results obtained show how
P. oceanica is able to invest efforts in recovering part of the lost leaf biomass while the system itself is able to regulate herbivory pressure as long as the environmental conditions are appropriate
to the occurrence of these mechanisms. The role of these mechanisms is key to avoid the potential collapse of P. oceanica meadows under the stress caused by an episode of intense herbivory.
In chapter 3, the effect of global warming on the Posidonia oceanica – Sarpa salpa interaction is assessed through a combination of gradient approaches in the field and manipulative laboratory experiments. On the one hand, the results show that increasing water temperature significantly increases S. salpa growth rates during its larval stage, reducing its larval period (fewer days in the water column) and limiting its dispersal, while showing no effect on feeding behaviour during its adult phase. On the other hand, warming negatively affects the growth rates of P. oceanica and makes it more palatable towards S. salpa according to the results from the preference experiment. Our study shows that S. salpa could develop faster in warmer environments during its most vulnerable stage, increasing its survival but decreasing its dispersal capacity. At the same time, it could increase its preference for P. oceanica in its adult stage, which, together with the reduction of seagrass growth, could considerably intensify the strength of the interaction under warming conditions.
All in all, the results of this study have contributed to confirm the relevance of herbivores’ behaviour in the way they exploit P.oceanica, mainly the feeding strategies of S. salpa, and how feedback mechanisms, provide resilience and allow the ecosystem to be maintained in an vegetated state. All of this gets relevant when contextualised within the process of global change, with a probable strengthening of the plant-herbivore interaction. Understanding the sensitivity of the interaction equilibria to each of its components is crucial to decide where to invest conservation efforts in these ecosystems and to be able to anticipate how changes in the contextual conditions may alter the final balance of the interaction.El papel de la relación consumidor-recurso es la base de la estructura y el funcionamiento de las comunidades ecológicas. La óptica tradicional usada en el estudio de estas interacciones ha tendido a omitir la importancia del comportamiento de las especies, sobre todo en el caso de las interacciones planta-herbívoro. Sin embargo, tanto la forma en la que el herbívoro explota a la planta y como la manera en que ésta responde a esa presión son cruciales para determinar la estabilidad de la interacción. Por lo tanto, las actuaciones del herbívoro y la de la planta, contextualizadas en el entorno en el que tiene lugar la interacción, pueden actuar como mediadores de la resiliencia del sistema. Esta tesis se centra en los ecosistemas de Posidonia oceanica y, concretamente, en la interacción entre esta fanerógama con sus dos principales herbívoros -el pez Sarpa salpa y el erizo de mar Paracentrotus lividus-. En esta tesis se evlaúa la importancia del comportamiento de los herbívoros (los patrones de agregación y las estrategias de alimentación de S. salpa y la dependencia de la cobertura foliar de P. lividus) y la resiliencia proporcionada por los mecanismos de retroalimentación (respuestas directas de la planta y procesos indirectos del ecosistema) bajo condiciones cambiantes resultantes del cambio global. Desentrañar estos componentes de la interacción nos permite evaluar su sensibilidad a cada uno de los dichos componentes y comprobar la respuesta y la resiliencia del sistema bajo diferentes condiciones. En el capítulo 1 se muestra la importancia del tamaño del cuerpo de los individuos de Sarpa salpa en sus tasas de consumo individual, en sus patrones de agregación y en las estrategias alimenticias de grupos, además de las potenciales consecuencias de estos procesos sobre la fanerógama Posidonia oceanica. Por un lado, cuanto mayores son los individuos, mayores tasas de consumo muestran. Por otro, los individuos de S.salpa tienden a agregarse con conspecíficos de la misma talla, mientras que el tamaño de los grupos se relaciona positivamente con la talla de los individuos que lo forman. Además, las estrategias de alimentación aumentan en complejidad con el tamaño del grupo y tienden a focalizarse en puntos muy concretos de la pradera. Así, a medida que los individuos crecen, aumentan su potencial impacto en la fanerógama, tanto por su capacidad de consumo como la formación de grandes bancos capaces de concentrar su herbivoría en áreas muy concretas de las praderas. Esta distribución de la herbivoría puede provocar una heterogeneidad espacial con consecuencias sobre el funcionamiento del ecosistema dominado por P. oceanica En el capítulo 2 se comprueba la existencia de una serie de mecanismos reguladores surgidos de un episodio de herbivoría intensa que aportan resiliencia al sistema de Posidonia oceanica una vez disminuida su bóveda foliar. Cuatro de los mecanismos evaluados funcionan como mecanismos de retroalimentación, siendo uno de ellos desplegado activamente por la planta (crecimiento compensatorio) mientras que los tres restantes (preferencia por un recurso alternativo, incremento del riesgo de depredación y disminución del número de erizos por competencia por el recurso y pérdida de cobertura) se desencadenan de forma indirecta y su eficacia se basa en inducir cambios en el comportamiento del herbívoro Paracentrotus lividus. Los resultados obtenidos muestran como P. oceanica es capaz de invertir esfuerzos en recuperar parte de la biomasa foliar perdida, mientras que el mismo sistema es capaz de regular la presión de herbivoría siempre que las condiciones del entorno sean propicias para la aparición de dichos mecanismos. El papel resiliente de estos mecanismos es clave para evitar el potencial colapso de las praderas de P. oceanica bajo el estrés provocado por un episodio de herbivoría intensa. En el capítulo 3 se evalúa el efecto del calentamiento global en la interacción Posidonia oceanica – Sarpa salpa a través de una combinación de aproximaciones de gradiente en campo con experimentos manipulativos de laboratorio. Por un lado, los resultados muestran que el aumento de la temperatura del agua incrementa significativamente las tasas de crecimiento de S.salpa durante su etapa larval, acorta su período en dicha etapa (menos días en la columna de agua) y limita su dispersión, mientras que no muestra ningún efecto en la actividad herbívora durante su fase adulta. Por otro lado, el calentamiento afecta negativamente las tasas de crecimiento de P. oceanica y la vuelve más palatable frente a S. salpa de acuerdo con los resultados en el experimento de preferencia. Nuestro estudio muestra que S. salpa podría desarrollarse más rápido en su etapa más vulnerable, aumentando su supervivencia, pero disminuyendo su capacidad de dispersión, mientras que podría incrementar su preferencia por P. oceanica en su etapa adulta, lo que, junto con la reducción del crecimiento de la fanerógama, podría intensificar considerablemente la fuerza de la interacción. En definitiva, los resultados de esta tesis han servido para constatar la relevancia del comportamiento de los herbívoros en su forma de explotar el recurso, principalmente las estrategias de alimentación de S. salpa, y como los mecanismos de retroalimentación aportan resiliencia y permiten al ecosistema mantenerse en un estado óptimo. Todo ello cobra más importancia al contextualizarlo dentro del proceso del cambio global, dado el probable fortalecimiento de la interacción planta-herbívoro. Conocer la sensibilidad de la interacción a cada uno de los componentes es crucial para decidir donde hay que invertir los esfuerzos de conservación en estos ecosistemas y poder así anticiparnos a como los cambios en las condiciones de contorno pueden alterar el equilibrio final de la interacción.
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Leiva, Dueñas Carmen. "The environmental change in coastal ecosystems during the Late Holocene as recorded in seagrass sedimentary archives." Doctoral thesis, Universitat de Barcelona, 2021. http://hdl.handle.net/10803/674010.
Full textAbstract:
Coastal ecosystems, especially the vegetated areas, are among the most threatened ecosystems in the world, undergoing a fast and constant decline. Their losses are of serious concern due to their elevated production, providing many ecosystem services essential to the well-being of our societies. Behind the regressive trends of the coastal ecosystems, there is a plethora of adverse human pressures, going from local and regional impacts, including anthropogenic activities in and outside the coastal regions, to large-scale drivers of change, such as the global warming. Nevertheless, there is a critical lack of long-term information about the vegetated coastal ecosystems, information that can provide baseline ecological data of their natural dynamics and vulnerability.
Seagrasses are marine plants, engineering species that form underwater meadows, which, among many other services, provide essential habitat for many other organisms. Seagrasses meadows are experiencing a widespread decline since the early 20th century. This regression is accelerated for the Mediterranean endemic seagrass species Posidonia oceanica. Long-term studies are of particular interest in P. oceanica meadows because this species is a large-slow growing and long-lived seagrass, which substantial changes and responses manifest over time scales of decades to centuries. A deeper understanding of seagrass long-term dynamics can help managers to apply meadow-specific actions and act at the appropriate temporal scales. The discipline of paleoecology allows the study of long-term ecosystem dynamics on time scales of centuries to millennia, and it can be used in seagrass meadows thanks to the organic deposits accumulated below P. oceanica meadows. Paleoreconstructions using seagrass deposits are still scarce and have mainly focused on allogenic (externally controlled) processes.
In this dissertation, a paleoecological approach at a regional spatial-scale was used to explore the long-term dynamics of the autogenic and biotic ecological components of Mediterranean seagrass meadows, mainly P. oceanica meadows. Initially, we investigated the usefulness of several biogeochemical proxies and a technique (FTIR-ATR spectroscopy) so far unexplored in seagrass deposits, as well as which were the main biogeochemical processes recorded by them. We described the long-term dynamics of the seagrass ecosystem, the main drivers of change, and their relative importance. The results indicated that seagrass long-term dynamics are oscillating. Even though most meadows showed regressive trends during the last 150 years, seagrass trends varied spatially, with the main spatial differences occurring at the inter-regional level. Differences in long-term dynamics between local sites seemed mostly dependent on the environmental background of each site, which also affected seagrass long- term resilience. The major factors responsible for long-term variability of seagrass ecosystem dynamics were multiple and at both, local and large spatial scales. However, the balance between the contribution of local and large-scale drivers varied spatially. The influence of climate seemed especially crucial in meadows surrounded by more turbid waters, under the influence of higher fluvial discharges. These meadows showed lower long-term ecosystemic resilience.
In summary, this research showed that seagrass long-term dynamics can be studied through their paleoecological record, providing a valuable frame of reference for evaluating the magnitude of current changes and consequences of combined diverse impacts on these marine ecosystems. The results of this thesis indicated that despite some spatial variability of the long-term dynamics, the major changes occurred over the last century, predominating trends of seagrass decline or community compositional changes. Moreover, our results point to a more acute negative impact of present climate change in meadows where light availability is compromised due to local factors. The overall spatial variability regarding seagrass long-term dynamics highlights the need for meadow-specific local management with background information, information that can be obtained from paleoecological studies.Los ecosistemas costeros, especialmente aquellos dominados por macrófitos sumergidos o semi-sumergidos, se encuentran entre los ecosistemas más amenazados del mundo, sufriendo un rápido y constante declive. Sus pérdidas son motivo de grave preocupación debido a su elevada producción, y a que proporcionan muchos servicios ecosistémicos esenciales para el bienestar de nuestras sociedades. Detrás de las tendencias regresivas de los ecosistemas costeros, se encuentra una plétora de presiones humanas adversas, que van desde impactos locales y regionales, incluidas actividades antropogénicas dentro y fuera de las regiones costeras, hasta agentes de cambio a gran escala, como el calentamiento global. Sin embargo, existe una falta crítica sobre el cambio a largo plazo de los ecosistemas costeros vegetados, información que puede proporcionar datos ecológicos de referencia sobre sus dinámicas naturales y vulnerabilidad. Las fanerógamas marinas son plantas superiores creadoras de estructuras tridimensionales complejas que, entre otros muchos servicios, dan lugar a un hábitat de elevada biodiversidad. Estos macrófitos están experimentando un declive generalizado desde principios del siglo XX, regresión especialmente acelerada para la especie endémica mediterránea, Posidonia oceanica. Los estudios a largo plazo son de particular interés en las praderas de P. oceánica, pues al ser una planta marina de gran tamaño, de crecimiento lento y de vida larga, sus cambios y respuestas sustanciales se manifiestan en escalas de tiempo de décadas a siglos. Una comprensión más profunda de la dinámica a largo plazo de las fanerógamas marinas puede ayudar a los gestores a aplicar acciones específicas y actuar en las escalas temporales adecuadas. La disciplina de la paleoecología permite el estudio de la dinámica de los ecosistemas a largo plazo en escalas de tiempo de siglos a milenios, y se puede aplicar en praderas de fanerógamas de P. oceanica gracias a los depósitos orgánicos acumulados bajo ellas. Las reconstrucciones paleoecológicas que usan suelos de praderas marinas aún son escasas y las que hay se han centrado principalmente en procesos alogénicos del ecosistema (controlados externamente). En esta tesis se ha hecho uso de reconstrucciones paleoecológicas en praderas de fanerógamas mediterráneas, principalmente de P. oceánica, a una escala espacial regional con el objetivo de explorar la dinámica a largo plazo de los componentes ecológicos autogénicos y bióticos. Inicialmente, se investigó la utilidad de varios proxies (indicadores) biogeoquímicos y de una técnica (espectroscopía FTIR-ATR) hasta ahora inexplorados en depósitos de praderas marinas, así como cuáles eran los principales procesos biogeoquímicos registrados por estos depósitos. Los resultados obtenidos permitieron describir la dinámica a largo plazo de las praderas marinas, así como sus principales impulsores del cambio a largo plazo y su importancia relativa. Se observó que la dinámica a largo plazo es oscilante, y que la mayoría de las praderas mostraban tendencias regresivas durante los últimos 150 años. Sin embargo, estas tendencias de declive variaban espacialmente, ocurriendo las principales diferencias a escala interregional. Las diferencias en la dinámica a largo plazo entre localidades parecían depender principalmente del contexto ambiental de cada sitio, lo que también afectaba a la resiliencia a largo plazo de las praderas. Los resultados revelan que los principales factores responsables de la variabilidad a largo plazo son múltiples, incluyendo factores de carácter local pero también regional y global. Sin embargo, la contribución relativa entre los factores de influencia local y de gran escala varia espacialmente. La influencia del clima parece especialmente crucial en praderas creciendo en aguas más turbias, bajo la influencia de descargas fluviales más abundantes. Estas praderas mostraron una menor resiliencia ecosistémica a largo plazo. En resumen, esta investigación ha demostrado que las dinámicas a largo plazo de las fanerógamas marinas se pueden estudiar a través de su registro paleoecológico, proporcionando un valioso marco de referencia para evaluar la magnitud de cambios actuales y las consecuencias de diversos impactos combinados en estos ecosistemas marinos. Los resultados de esta tesis revelan que, a pesar de cierta variabilidad espacial de las dinámicas a largo plazo, los cambios más importantes han ocurrido durante el último siglo, predominando las tendencias de declive de la fanerógama o cambios en la composición de las comunidades que alberga. Además, nuestros resultados apuntan a un impacto negativo más agudo del actual cambio climático en aquellas praderas donde la disponibilidad de luz se ve comprometida debido a causas locales. La variabilidad espacial general de las dinámicas a largo plazo de las praderas marinas destaca la necesidad de una gestión local específica a cada pradera, con información previa contextual, información que se puede obtener a partir de estudios paleoecológicos.
Books on the topic "Seagrass ecosystems"
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Indonesian Seagrass Committee. Policy, strategy, and action plan for management of seagrass ecosystem in Indonesia. Jakarta: Indonesian Institute of Sciences, 2003.
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Indonesian Seagrass Committee. Assessment of institution and legal aspects relevant to management of seagrass ecosystem in Indonesia. Jakarta: Indonesian Institute of Sciences, 2003.
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Sea otter heroes: The predators that saved an ecosystem. Minneapolis, MN: Millbrook Press, 2017.
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(Editor), Peter C. Pollard, Isao Koike (Editor), Hiroshi Mukai (Editor), and Alistar I. Robertson (Editor), eds. Tropical Seagrass Ecosystems. CSIRO Publishing, 1993.
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Tropical seagrass ecosystems: Structure and dynamics in the Indo-West Pacific. Australia: CSIRO, 1993.
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Ecosystem Modeling And Its Application For Seagrass Beds. Nova Science Publishers, 2011.
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Geological Survey (U.S.), ed. Seagrasses in northern Gulf of Mexico: An ecosystem in trouble. [Reston, Va.]: U.S. Dept. of the Interior, U.S. Geological Survey, 2000.
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Geological Survey (U.S.), ed. Seagrasses in northern Gulf of Mexico: An ecosystem in trouble. [Reston, Va.]: U.S. Dept. of the Interior, U.S. Geological Survey, 2000.
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Geological Survey (U.S.), ed. Seagrasses in northern Gulf of Mexico: An ecosystem in trouble. [Reston, Va.]: U.S. Dept. of the Interior, U.S. Geological Survey, 2000.
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Silliman, Brian R., Brent B. Hughes, Y. Stacy Zhang, and Qiang He. Business as usual leads to underperformance in coastal restoration. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198808978.003.0027.
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This chapter shows that coastal wetland projects are underperforming because of confirmation bias. Despite two decades of work showing that top-down control can be essential to marsh restoration, the potential role of top predators is typically ignored by those responsible for restoring or maintaining marshes. Similarly ignored are experiments that indicate positive interaction between marsh plants and can enhance the pace and success of restoration. By planting marsh plants at higher densities, marsh restoration success can double, and seagrass restoration can succeed in the face of increasing drought and eutrophication effects. Continued failure to integrate top-down control and facilitative species interactions into coastal restoration designs will result in widespread underperformance of wetland conservation projects and unrealized generation of important ecosystem services.
Book chapters on the topic "Seagrass ecosystems"
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Kirkman, Hugh. "Near-Coastal Seagrass Ecosystems." In Ecology and the Environment, 457–82. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4614-7501-9_20.
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Kirkman, Hugh. "Near-Coastal Seagrass Ecosystems." In Ecology and the Environment, 1–23. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-7612-2_20-1.
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Raghukumar, Seshagiri. "The Seagrass Ecosystem." In Fungi in Coastal and Oceanic Marine Ecosystems, 103–13. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54304-8_7.
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York, Paul H., Glenn A. Hyndes, Melanie J. Bishop, and Richard S. K. Barnes. "Faunal Assemblages of Seagrass Ecosystems." In Seagrasses of Australia, 541–88. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-71354-0_17.
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Mishra, Amrit Kumar, Rajalaxmi Sahoo, Saumya S. Samantaray, and Deepak Apte. "Seagrass Ecosystems of India as Bioindicators of Trace Elements." In Coastal Ecosystems, 45–65. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-84255-0_3.
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Serrano, Oscar, Ariane Arias-Ortiz, Carlos M. Duarte, Gary A. Kendrick, and Paul S. Lavery. "Impact of Marine Heatwaves on Seagrass Ecosystems." In Ecosystem Collapse and Climate Change, 345–64. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71330-0_13.
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Baroli, M., A. Cristini, A. Cossu, G. De Falco, V. Gazale, C. Pergent-Martini, and G. Pergent. "Concentrations of Trace Metals (Cd, Cu, Fe, Pb) in Posidonia oceanica Seagrass of Liscia Bay, Sardinia (Italy)." In Mediterranean Ecosystems, 95–99. Milano: Springer Milan, 2001. http://dx.doi.org/10.1007/978-88-470-2105-1_13.
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Olsen, Ylva S., Catherine Collier, Yan X. Ow, and Gary A. Kendrick. "Global Warming and Ocean Acidification: Effects on Australian Seagrass Ecosystems." In Seagrasses of Australia, 705–42. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-71354-0_21.
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Chanda, Abhra. "Blue Carbon Dynamics in the Indian Ocean Seagrass Ecosystems." In Blue Carbon Dynamics of the Indian Ocean, 145–69. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-96558-7_5.
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Miyajima, Toshihiro, and Masami Hamaguchi. "Carbon Sequestration in Sediment as an Ecosystem Function of Seagrass Meadows." In Blue Carbon in Shallow Coastal Ecosystems, 33–71. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1295-3_2.
Full textConference papers on the topic "Seagrass ecosystems"
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Elobaid, Elnaim, Bruno Welter Giraldes, Hamad Al-Kuwari, Jassim Al-Khayat, Fadhil Sadooni, and Ekhlas Elbary. "Towards Sustainable Management of Coastal and Offshore Islands in Arabian Gulf Typology: Sensitivity Analysis, Ecological Risk Assessment of Halul and Al-Alyia Islands." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2021. http://dx.doi.org/10.29117/quarfe.2021.0035.
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The great majority of marine ecosystems in Qatar are in fast decline and nearing collapse, where most ecosystem has lost the biological and economic functionality. Aiming to support the decision makers in the management and restoration strategies for recovering the biological and economic functionality of the ecosystems/natural resources of Qatar, we conducted 1) a typology mapping of the main components of the ecosystem of two islands, 2) a sensitivity and vulnerability assessment according to the known guidelines and standards. Highlighting the potential ecological risk and required recommendations for sustainable management plans, within the frame of Qatar National Vision 2030 (QNV 2030). The Islands present different anthropogenic pressure. As expected, Al Alyia the coastal Island is under real risk, with critical areas of sensibility but still presenting a potential for recovering its economy and ecological functionality, highlighting the collapsed stage of the very sensitive coral reefs, the vulnerability of oyster beds and seagrass and the functionality of the mangrove (expanding) and Sabha with massive birds nesting. The offshore Island Halul presented in the typology mapping the coral reefs as the main ecosystem but with the presence of seagrass, algae bed, sandy beach, and Sabha. The coral reef still presents a certain functionality, with corals covering several hard substrates, however with high sensitivity and high vulnerability, especially the coral in the shallow areas with scattered colonies, and the vulnerable nesting of marine turtles on beaches. As the management, we recommend increasing the restoration effort of targeted ecosystems, mainly involving coral reefs for increasing the marine biodiversity in general and restoring the oyster beds for recovering the filtration service. Strategies must be made for recovering the ecosystems’ functionality and restore the productivity of the Qatari fishing stock. We recommend applying this mapping method and sensitivity classification for all marine areas around Qatar for supporting the management plans.
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Kamal, Muhammad, and Pramaditya Wicaksono. "Spectral response of healthy and damaged leaves of tropical seagrass Enhalus acoroides, Thalassia hemprichii, and Cymodocea rotundata." In Remote Sensing for Agriculture, Ecosystems, and Hydrology, edited by Christopher M. Neale and Antonino Maltese. SPIE, 2017. http://dx.doi.org/10.1117/12.2278027.
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Kokubu, Hideki, and Hideki Kokubu. "A FUNDAMENTAL STUDY ON CARBON STORAGE BY ZOSTERA MARINA IN ISE BAY, JAPAN." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b93b173b5e4.64557120.
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Blue Carbon, which is carbon captured by marine organisms, has recently come into focus as an important factor for climate change initiatives. This carbon is stored in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds and salt marshes. The recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration. Therefore, it is necessary to improve scientific understanding of the mechanisms that stock control C in these ecosystems. However, the contribution of Blue Carbon sequestration to atmospheric CO2 in shallow waters is as yet unclear, since investigations and analysis technology are ongoing. In this study, Blue Carbon sinks by Zostera marina were evaluated in artificial (Gotenba) and natural (Matsunase) Zostera beds in Ise Bay, Japan. 12-hour continuous in situ photosynthesis and oxygen consumption measurements were performed in both areas by using chambers in light and dark conditions. The production and dead amount of Zostera marina shoots were estimated by standing stock measurements every month. It is estimated that the amount of carbon storage as Blue Carbon was 237g-C/m2/year and 197g-C/m2/year in the artificial and natural Zostera marina beds, respectively. These results indicated that Zostera marina plays a role towards sinking Blue Carbon.
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Kokubu, Hideki, and Hideki Kokubu. "A FUNDAMENTAL STUDY ON CARBON STORAGE BY ZOSTERA MARINA IN ISE BAY, JAPAN." In Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b4315b8e806.
Full textAbstract:
Blue Carbon, which is carbon captured by marine organisms, has recently come into focus as an important factor for climate change initiatives. This carbon is stored in vegetated coastal ecosystems, specifically mangrove forests, seagrass beds and salt marshes. The recognition of the C sequestration value of vegetated coastal ecosystems provides a strong argument for their protection and restoration. Therefore, it is necessary to improve scientific understanding of the mechanisms that stock control C in these ecosystems. However, the contribution of Blue Carbon sequestration to atmospheric CO2 in shallow waters is as yet unclear, since investigations and analysis technology are ongoing. In this study, Blue Carbon sinks by Zostera marina were evaluated in artificial (Gotenba) and natural (Matsunase) Zostera beds in Ise Bay, Japan. 12-hour continuous in situ photosynthesis and oxygen consumption measurements were performed in both areas by using chambers in light and dark conditions. The production and dead amount of Zostera marina shoots were estimated by standing stock measurements every month. It is estimated that the amount of carbon storage as Blue Carbon was 237g-C/m2/year and 197g-C/m2/year in the artificial and natural Zostera marina beds, respectively. These results indicated that Zostera marina plays a role towards sinking Blue Carbon.
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Clementz, Mark T. "MEASURING ENVIRONMENTAL CONDITIONS IN PAST AND PRESENT SEAGRASS ECOSYSTEMS THROUGH STABLE ISOTOPE ANALYSIS OF SIRENIAN SKELETAL REMAINS." In GSA Annual Meeting in Denver, Colorado, USA - 2016. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016am-287063.
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Kholis, N., M. P. Patria, and T. Soedjiarti. "Composition and diversity of fish species in seagrass bed ecosystem at Muara Binuangeun, Lebak, Banten." In INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2016 (ISCPMS 2016): Proceedings of the 2nd International Symposium on Current Progress in Mathematics and Sciences 2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4991223.
Full textReports on the topic "Seagrass ecosystems"
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Harrison, P. G., and M. Dunn. Fraser River delta seagrass ecosystems, their distributions and importance to migratory birds. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2004. http://dx.doi.org/10.4095/215808.
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Andersen, Gisle, Christine Merk, Marie L. Ljones, and Mikael P. Johannessen. Interim report on public perceptions of marine CDR. OceanNets, 2022. http://dx.doi.org/10.3289/oceannets_d3.4.
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This deliverable synthesizes the results on public perceptions of marine CDR methods from the first two years of OceanNETs. The purpose is to inform the other work packages in OceanNETs and stakeholders about our results in a timely and brief manner about the ways members of the public view marine CDR specifically but also in the broader context of net-zero targets and climate policy. The deliverable summarises results of two studies: (1) focus groups held in Germany and Norway that covered ocean fertilization, ocean alkalinity enhancement, artificial upwelling and blue carbon management and (2) a deliberative survey in Norway that covered ocean alkalinity enhancement, macroalgae farming with BECCS or biomass sinking and land-based BECCS and enhanced weathering as terrestrial approaches for comparison. Participants in both studies emphasise the importance of reducing emissions and changing consumptions patterns. They hardly discuss the need to remove CO2 from the atmosphere to reach the Paris climate goal and the concept of negative emissions seems difficult for them to engage with. Among the methods, participants prefer ecosystem-based approaches like mangrove or seagrass restoration over other methods like alkalinity enhancement or ocean fertilization. Participants are concerned about the actual feasibility of deployment at a relevant removal scale and for a longer period. Connected to this are concerns about the controllability of the deployment and the methods’ impact, like difficulties to control negative environmental effects from biomass sinking at the seafloor. They also question the buildup of additional infrastructure or additional interventions into nature on top of already existing human interference. The opportunity to deliberate the methods increases participants’ certainty about their assessment but only slightly changes the direction of the assessment.