O Estado como força, segundo Alessandro Passerin D´Entreves

Resumo: Este artigo resulta de pesquisa iniciada no doutorado acerca do pensamento político de Alessandro Passerin D´Entreves e apresenta considerações introdutórias à perspectiva da doutrina do Estado formulada por esse autor. No texto são analisados fenômenos que possibilitam compreender o Estado como força, o que corresponde à primeira parte da doutrina de Estado formulada por D´Entreves.Palavras-chave: Filosofia política; Estado; Passerin D´Entreves

Long-Term NDVI and Recent Vegetation Cover Profiles of Major Offshore Island Nesting Sites of Sea Turtles in Saudi Waters of the Northern Arabian Gulf

Vegetation is an important ecological component of offshore islands in the Arabian Gulf (AG), which maintains long-term resilience of these islands. This is achieved by influencing sediment retention and moisture acquisition via condensation during periods of high humidity and by providing a variety of microhabitats for island fauna. The resilience of offshore islands’ ecosystems in the Saudi waters is important because they host the largest number of nesting hawksbill and green turtles in the AG. This study defines the characteristics and the long-term trends in vegetation cover of the offshore islands used by sea turtles as nesting grounds in the northern AG. To establish a ground-validated baseline for vegetation profiles, a 50 m × 50 m grid system is developed on Karan and Jana islands (Is.) with photo-quadrats taken at each grid intersection. The 1,317 and 444 photo-quadrats, for Karan and Jana Is., respectively, were analyzed for maximum plant height and percent cover of living (green) plants, dead plants, and bare sand. Landsat 7 and 8 satellite top-of-atmosphere reflectance images were used to calculate the Normalized Difference Vegetation Index (NDVI) from 1999 through 2018 to analyze the long-term vegetation profiles of the islands. Monthly rainfall data from five meteorological stations along the Eastern Province of Saudi Arabia and Oceanic Niño Index (ONI) are presented to provide a context of the long-term NDVI time series variability. The ground-validated vegetation profiles provided baseline data during the onset of summer in 2017 and revealed differences in maximum plant height and the extent of living, dead vegetation and sand cover on Jana Is. (28.3 cm, 19.9%, 63.3%, and 16.8%) and Karan Is. (21.7 cm, 20.6%, 48.7%, and 30.7%), respectively. The NDVI data for both islands are grouped into three periods, namely: 2001–2007 - high winter, low summer; 2008–2013 – low winter, low summer; 2014–2018 – irregular high/low winter, low summer. The long-term trend showed a slightly decreasing NDVI when compared in the context of the high NDVI measured for the two islands during the early 2000 s, particularly during the winter time. An extended reduction in winter NDVI was recorded for six years from 2008 to 2013, which coincided with reduced rainfall in the region and prolonged La Niña. Five extreme dips in winter NDVI values coincided with strong (2000, 2008, and 2011) and moderate (2012 and 2018) La Niña events. Long-term vegetation profiles of the offshore islands seemed to be tightly coupled with long-term rainfall patterns

Multidecadal Analysis of Beach Loss at the Major Offshore Sea Turtle Nesting Islands in the Northern Arabian Gulf

Undocumented historical losses of sea turtle nesting beaches worldwide could overestimate the successes of conservation measures and misrepresent the actual status of the sea turtle population. In addition, the suitability of many sea turtle nesting sites continues to decline even without in-depth scientific studies of the extent of losses and impacts to the population. In this study, multidecadal changes in the outlines and area of Jana and Karan islands, major sea turtle nesting sites in the Arabian Gulf, were compared using available Kodak aerographic images, USGS EROS Declassified satellite imagery, and ESRI satellite images. A decrease of 5.1% and 1.7% of the area of Jana and Karan islands, respectively, were observed between 1965 and 2017. This translated to 14,146 m2 of beach loss at Jana Is. and 16,376 m2 of beach loss at Karan Is. There was an increase of island extent for Karan Is. from 1965 to 1968 by 9098 m2 but comparing 2017 with 1968, Karan Is. lost as much as 25,474 m2 or 2.6% of the island extent in 1968. The decrease in island aerial extent was attributed to loss of beach sand. The southern tips of the island lost the most significant amount of sand. There was also thinning of beach sand along the middle and northern sections that exposed the rock outcrops underneath the beach. The process of beach changes of both islands was tracked by the satellite imagery from Landsat 1,3,5,7 and Sentinel-2 during 1972 to 2020. Other factors including the distribution of beach slope, sea level changes, as well as wind & current from both northward and eastward components were analyzed to show its impact on the beach changes. The loss of beach sand could potentially impact the quality and availability of nesting beach for sea turtles utilizing the islands as main nesting grounds. Drivers of beach loss at the offshore islands are discussed in the context of sea level rise, dust storms, extreme wave heights and island desertification

Coarser taxonomic resolutions are informative in revealing fish community abundance trends for the world’s warmest coral reefs

The Arabian Gulf is a natural laboratory to examine how subtropical coral reef ecosystems might change in responding to recurring heating events because of uniquely high water temperature and relatively low fish diversity. Several statistical methods were applied to long-term (30 yrs) monitoring data in the western Arabian Gulf to extract clean signals of the fish abundances, to reveal common trends in the multivariate time series, and to test for nonlinear and lagged effects of coral coverage and sea surface temperature as predictors. Data were analyzed at three taxonomic resolutions: species (29 species out of a total of 148 species, contributing to 69% of total observations), genus (24 genera, 81%), and family (19 families, 96%), to test the taxonomic sufficiency hypothesis, which asserts that there is no significant loss of information at higher taxonomic levels for detecting changes in the fish assemblages. Multivariate abundance time series can be summarized by dynamic factor models of four common trends, which were supported by time series clustering and good model fitting performances. The taxonomic sufficiency hypothesis is supported for the first two common trends, which showed similarity among the three taxonomic resolutions. The effects of changes in coral coverage on the fish community are nonlinear and significantly lagged with lags mostly of 8 yrs, while the effects of mean sea surface temperature were significant but inconclusive. The fish communities in the coral reefs of the western Arabian Gulf are degrading in general with decreasing abundance at the three taxonomic resolutions. Analyzing data at coarser taxonomic resolutions can be informative in revealing the general trends of the abundance of coral reef fish communities, at the cost of ignoring variations at finer resolutions. This study further highlights the importance of long-term and continuous monitoring of the coral reef ecosystem at the finest possible taxonomic level to fully reveal slow but crucial changes in fish communities, as well as to detect signs of communities' degradation to take timely restoration actions.info:eu-repo/semantics/publishedVersio