Mapeamento de bancos de algas e fanerógamas na área de proteção ambiental dos recifes de corais: RN utilizando geotecnologias
Seaweeds and seagrasses associated with coral reefs comprise one of the most productive environments on the planet. Seaweeds have several roles in ecosystem services, including primary production, reef construction, facilitation of coral establishment and habitat formation for numerous other spec...
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| Formato: | doctoralThesis |
| Idioma: | por |
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/24520 |
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| Resumo: | Seaweeds and seagrasses associated with coral reefs comprise one of the most productive
environments on the planet. Seaweeds have several roles in ecosystem services, including
primary production, reef construction, facilitation of coral establishment and habitat formation
for numerous other species. On the other hand, they are potentially sensitive to environmental
changes, especially the impacts caused by climate change and the pressure of human
activities. Because of these environmental changes, studies that can explain the impacts that
these changes cause in these organisms and, thus, establish strategies for the conservation and
restoration of these environments are needed. Remote sensing techniques combined with in
situ observations have been widely used to map algal beds around the world. The Coral Reef
Environmental Preservation Area / RN - APARC shelters a large diversity of algal species;
however, although it is a conservation unit, its resources are likely to be depleted due to
anthropic activities, such as tourism and fishing, and changes in global climate, such as
changes in ocean temperature and acidity. In this sense, this study applied Advanced Land
Observing Satellite (ALOS) satellite data, an Advanced Visible and Near Infrared Radiometer
(AVNIR-2) instrument to verify the distribution of seaweeds and seagrasses in APARC, more
precisely in the Maracajaú and Rio do Fogo reefs. For this, unsupervised classifications and a
series of soft and hard supervised classifications were performed. Finally, the Digital
Bathymetric Model (MDB) and the Digital Slope Model (MDS) were also generated in order
to understand the relationship between seaweed and seagrass establishment and development
with the water depth and the slope of the reef body.The supervised classification Maxlike
generated the thematic maps of both reefs. In the Maracajaú reef, the Maxlike identified seven
classes: (1) Dense seaweed; (2) Sand; (3) Sparse seagrass; (4) Dense seagrass; (5) Calcareous
seaweed; (6) Sparse seaweed; and (7) Fine sand. The Kappa coefficient (0.84) was considered
excellent. Concerning Rio do Fogo reef, the Maxlike identified six classes: (1) Seaweed; (2)
Calcareous seaweed concretions; (3) Sand; (4) Sand with limestone; (5) Seagrass; and (6)
Coral Reefs. The Kappa coefficient (0.75) was considered substantial. In both reefs, seaweeds
are predominantly in the central area, mainly between isobaths -1 and -3 m. This region is a
relatively flat area, with a 2% slope in Maracajaú and a 3% slope in Rio do Fogo. Calcareous
seaweed, forming or not concretions, are located mainly in the reef extremities, especially in
the reef front, in depths of up to -5 m. Seagrasses occur mainly in the back reef, between
isobaths -2 and -6 m. The edges of the reefs are the regions with the highest slopes, up to 5%
in Maracajaú reef and up to 7% in Rio do Fogo reef. In both reefs, the following
morphofunctional groups were recorded: foliose, leathery, corticated, articulated calcareous
and crustose seaweed. This work may provide support for the planning and management of
APARC, leading to the increasingly sustainable use of this conservation unit. |
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