Search Results (5)

Black Sea cetaceans are isolated and nominated as endemic subspecies listed in the IUCN Red List of Endangered species: the harbour porpoise and bottlenose dolphin as Endangered (EN) and the common dolphin as Vulnerable (VU). Studies of their distribution and abundance are scarce but obligatory for assessment of their conservation status. Being highly mobile apex predators entails large variations in spatial and temporal distribution. Two vessel line–transect distance sampling surveys were conducted in 2017 in the Bulgarian shelf with the aim to estimate the density, abundance and distribution during spring and autumn. Results have revealed a shift from the coastal to offshore shelf of harbour porpoises with marked southern movement. Density of porpoises varied from 1.423 ind./km² (CV = 25.4%) in spring to 0.576 ind./km² (CV = 43.43%) in autumn. The density of common dolphins was also decreasing, from 0.391 ind./km² (CV = 36.84%) to 0.088 ind./km² (CV = 42.13%), which was more significant in offshore (0.031 ind./km², CV = 58.04%) than in the coastal shelf (0.138 ind./km², CV = 48.59%). Bottlenose dolphins had almost constant density in both seasons in the coastal shelf: 0.211 ind./km² (CV = 52.15%) and 0.187 ind./km² (CV = 52.13%) but a very low density in the offshore shelf in autumn: 0.042 ind./km² (CV = 71.07%). The importance of existing NATURA 2000 sites for the harbour porpoise (BG0000621 Shabla-Ezerets, BG0000573 Kompleks Kaliaka, BG0001001 Ropotamo and BG0001007 Strandzha) and bottlenose dolphin (BG0000621 Shabla-Ezerets, BG0000573 Kompleks Kaliaka, BG0001501 Emona and BG0001001 Ropotamo) were confirmed. Full article

Coastal wetlands provide essential ecosystem services, while usually experiencing land transformation or degradation mainly due to intense anthropogenic activities and climate changes. Understanding the changes in wetlands ecosystem services is essential to decision makers for generating sound coastal planning. Hangzhou Bay is rich in wetland resources, and the urbanization of Hangzhou Bay in the past three decades has caused fundamental changes in the wetlands in the region. Based on the remote sensing images of the Hangzhou Bay area from 1990 to 2020, this paper analyzes the land use situation of the Hangzhou Bay area in seven periods. This paper calculates the area transfer matrix of various types of wetlands. It uses the InVEST model to evaluate the changes in the function of wetland ecosystem services in the Hangzhou Bay area. Hangzhou Bay wetlands show a trend of transferring natural wetlands to artificial and non-wetlands from 1990 to 2020. Carbon stocks fell by 14.24%. The annual water production decreased by 33.93% and then returned to the original level. The area of habitat degradation increased by 79.94%. The main influencing factors are paddy field degradation, increase in non-wetland area, and decrease in sea area. This paper proposes that the development and construction of farmland in the “red line” area and established wetland reserves are prohibited, and to strengthen the training of wetland management personnel, establish a sound decision-making consultation mechanism, and increase the scientific research expenditure on wetlands in the region. Full article

Egypt is highly exposed to flash flood hazards, particularly in Sinai Peninsula and along the Red Sea coast, causing sudden and huge damages to constructions and huge losses in human lives during a very short time. This paper investigates the dominant characterization of morphometrical features and their relationships with the hydrological behaviors along an important strip of the western Red Sea coast. The study focuses on analyzing the October 2009 and 2019 storm events along the coastal area between EL-Qussier and Marsa Alam in order to intiate a preliminary flood risk assessment model. Morphometric features along the entire study zone provide a complete scenario of the nature of the catchments and sub-catchments development. Numerous morphometric indexes such as catchments geometry, areal indexes, linear indexes, and relief indexes were examined through processing different sets of data. Modern techniques such as remote sensing and geospatial analysis were applied to process different spatial and spectral data. The hydrological model (HEC-HMS) in the WMS software was run to delineate the catchments and sub-catchments and extract the peak flow hydrograph curves for the main catchments. The results of the water amounts and peak flow were calculated using the SCS unit hydrograph approach. The hydrological characteristics of the major catchments reveal conditions for moderate levels of flash flooding. The study ended with a number of recommendations that could minimize the negative effects of the flash flood hazards. Full article

Harmful algal blooms (HABs) and the high biomass associated with them have afflicted marine desalination plants along coastal regions around the world. Few studies of HABs have been conducted in the Red Sea, where desalination plants along the Saudi Arabian Red Sea coast provide drinking water for millions of people. This study was conducted along the Saudi Arabian Red Sea coast from 2014 to 2015 to assess the potential for using Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing of chlorophyll a (Chl a) or fluorescence line height (FLH) to identify risks for biofouling at these desalination plants. Ship-based surveys of phytoplankton were conducted along the Saudi Arabian coastline offshore of desalination plants at Jeddah, Al Shoaibah and Al Qunfudhuh to assess the density of phytoplankton populations and identify any potential HAB species. Ship-based surveys showed low to moderate concentrations of phytoplankton, averaging from 1800–10,000 cells L⁻¹ at Jeddah, 2000–11,000 cells L⁻¹ at Al Shoaibah and 1000–20,500 cells L⁻¹ at Al Qunfudhuh. Sixteen different species of potentially toxigenic HABs were identified through these surveys. There was a good relationship between ship-based total phytoplankton counts and monthly averaged coastal MODIS Chl a (R² = 0.49, root mean square error (RMSE) = 0.27 mg m⁻³) or FLH (R² = 0.47, RMSE = 0.04 mW m⁻² µm⁻¹ sr⁻¹) values. Monthly average near shore Chl a concentrations obtained using MODIS satellite imagery were much higher in the Red Sea coastal areas at Al Qunfudhuh (maximum of about 1.3 mg m⁻³) than at Jeddah or Al Shoaibah (maximum of about 0.4 and 0.5 mg m⁻³, respectively). Chlorophyll a concentrations were generally highest from the months of December to March, producing higher risks of biofouling desalination plants than in other months. Concentrations decreased significantly, on average, from April to September. Long-term (2005–2016) monthly averaged MODIS Chl a values were used to delineate four statistically distinct zones of differing HAB biomass across the entire Red Sea. Sinusoidal functions representing monthly variability were fit to satellite Chl a values in each zone (RMSE values from 0.691 to 0.07 mg m⁻³, from Zone 1 to 4). December to January mean values and annual amplitudes for Chl a in these four sinusoidal functions decreased from Zones 1–4. In general, the greatest risk of HABs to desalination occurs during winter months in Zone 1 (Southern Red Sea), while HAB risks to desalination plants in winter months are low to moderate in Zone 2 (South Central Red Sea), and negligible in Zones 3 (North Central) and 4 (Northern). Full article

Increasing demand for land resources at the coast has exerted immense pressure on vulnerable environments. Population and economic growth in coastal cities have combined to produce a scarcity of suitable space for development, the response to which has frequently been the reclamation of land from the sea, most prominently in China. Urbanization is a key driver of such changes and a detailed investigation of coastal land reclamation at the city scale is required. This study analyzed remote sensing imagery for the period 1990 to 2018 to explore the trajectories of coastal land reclamation in nine major urban agglomerations across the three largest deltas in China using the JRC Global Surface Water (Yearly Water Classification History, v1.1) (GSW) dataset on the Google Earth Engine platform. The results are considered in the context of major national policy reforms over the last three decades. The analysis reveals that total land reclaimed among nine selected cities had exceeded 2800 km² since 1984, 82% of which occurred after 2000, a year following the enactment of China’s agricultural ‘red line’ policy. Shanghai exhibited the greatest overall area of land extension, followed by Ningbo and Tianjin, especially in the period following the privatization of property rights in 2004. In analyzing annual trends, we identified the developmental stages of a typical coastal reclamation project and how these vary between cities. Scrutiny of the results revealed voids in nighttime light satellite data (2014–2018) in some localities. Although these voids appeared to be characterized by construction, they were occupied by vacant buildings, and were therefore examples of so-called “ghost cities.” In China, as elsewhere, continual land reclamation needs to be considered in relation to, inter alia, sea level rise and land subsidence that pose significant challenges to the vision of sustainable urban development in these three deltaic megacities. Full article