scholarly journals Comparison of the sonar recording method and the aerial photography method for mapping seagrass meadows

2020 ◽  
Vol 60 (1) ◽  
pp. 7-20
Author(s):  
Mojca Poklar

This article presents a new perspective on the study of the spatial distribution of seagrass meadows, which—due to their sensitivity to coastal hydrodynamics, sediment transport, changes in nutrient content, and disruptions due to human intervention in their environment—are a good indirect indicator of the properties of seawater. Monitoring their extent and characteristics is essential for determining the properties of seawater, but this requires developing a precise methodology that involves acquiring data on the occurrence of seagrass meadows and mapping them. The base data for the survey presented are sonar recording and aerial photography data, which were utilized to create a seabed classification using geographic information systems (GIS). This provided information on the extent and characteristics of the seagrass meadows. Spatial analysis offers a new look at the coastal belt and reveals some new features.

2013 ◽  
Vol 663 ◽  
pp. 736-742
Author(s):  
Ya Jun Shi ◽  
Hang Qing Fan ◽  
Guang Long Qiu ◽  
Liang Hao Pan ◽  
Sen Li

Resorption of nutrients (C, N, P, Ca, Mg, Fe and Mn) from senescent leaves of Zostera japonica and the concentration of nutrients (C, N, P, Ca, Mg, Fe and Mn) in the sediment from three subtropical seagrass meadows (Guchenling, Zhulin and Ronggenshan) in Beihai, Guangxi, China were studied. Resorption efficiencies were quantitatively assessed by comparing nutrient content between the leaf with the highest content and the senescent leaves. In addition, the relationship between nutrient resorption efficiencies and nutrient sources (the sediment and the adult leaf) were evaluated. During the course of leaf development in Z. japonica (young leaf – adult leaf – senescent leaf), C content first rose and then declined; N and P contents gradually declined; but Ca, Mg, Fe and Mn gradually rose. During leaf senescence, resorption efficiencies of C, N, P, Ca, Mg, Fe and Mn were 2.1%, 19.5%, 45.1%, −61.1%, −12.0%, −27.1% and −72.3%, respectively. For Z. japonica, C, N and P contributed to new leaf growth, whereas Ca, Mg, Fe and Mn was not. The nutrient contents of the sediment and adult leaf were not significantly correlated to leaf nutrient resorption efficiencies. It was calculated that for Z. japonica approximately 13.8% of total N demand and 31% of total P demand could be met by internal resorption.


Ecosystems ◽  
2020 ◽  
Vol 23 (8) ◽  
pp. 1631-1642 ◽  
Author(s):  
Luuk Leemans ◽  
Isis Martínez ◽  
Tjisse van der Heide ◽  
Marieke M. van Katwijk ◽  
Brigitta I. van Tussenbroek

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.


Author(s):  
H.-J. Ou

The understanding of the interactions between the small metallic particles and ceramic surfaces has been studied by many catalyst scientists. We had developed Scanning Reflection Electron Microscopy technique to study surface structure of MgO hulk cleaved surface and the interaction with the small particle of metals. Resolutions of 10Å has shown the periodic array of surface atomic steps on MgO. The SREM observation of the interaction between the metallic particles and the surface may provide a new perspective on such processes.


1979 ◽  
Vol 10 (3) ◽  
pp. 145-151 ◽  
Author(s):  
Sallie W. Hillard ◽  
Laura P. Goepfert

This paper describes the concept of teaching articulation through words which have inherent meaning to a child’s life experience, such as a semantically potent word approach. The approach was used with six children. Comparison of pre/post remediation measures indicated that it has promise as a technique for facilitating increased correct phoneme production.


2012 ◽  
Vol 82 (3) ◽  
pp. 209-215 ◽  
Author(s):  
Simone Bell ◽  
Heikki Pakkala ◽  
Michael P. Finglas

Food composition data (FCD) comprises the description and identification of foods, as well as their nutrient content, other constituents, and food properties. FCD are required for a range of purposes including food labeling, supporting health claims, nutritional and clinical management, consumer information, and research. There have been differences within and beyond Europe in the way FCD are expressed with respect to food description, definition of nutrients and other food properties, and the methods used to generate data. One of the major goals of the EuroFIR NoE project (2005 - 10) was to provide tools to overcome existing differences among member states and parties with respect to documentation and interchange of FCD. The establishment of the CEN’s (European Committee for Standardisation) TC 387 project committee on Food Composition Data, led by the Swedish Standards Institute, and the preparation of the draft Food Data Standard, has addressed these deficiencies by enabling unambiguous identification and description of FCD and their quality, for dissemination and data interchange. Another major achievement of the EuroFIR NoE project was the development and dissemination of a single, authoritative source of FCD in Europe enabling the interchange and update of data between countries, and also giving access to users of FCD.


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