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\"Under the United Nations Law of the Sea Convention, States have sovereign rights over the resources of their continental shelf out to 200 nautical miles from the coast. Where the physical shelf extends beyond 200 nautical miles, States may exercise rights over those resources to the outer limits of the continental shelf. More than 80 States may be entitled to claim sovereign rights over their continental shelf where it extends beyond 200 nautical miles from their coast, and the Commission on the Limits of the Continental Shelf is currently examining many of these claims. This book examines the nature of the rights and obligations of coastal States in this area, with a particular focus on the options for regulating activities on the extended continental shelf. Because the extended continental shelf lies below the high seas, the area poses unique legal challenges for coastal States that are different from those faced in respect of the shelf within 200 nautical miles. In addition, the United Nations Convention on the Law of the Sea imposes some specific obligations that coastal States must comply with in respect of the extended continental shelf. The book discusses the development of the concept of the extended continental shelf. It explores a range of issues facing the coastal State in regulating matters such as environmental protection, fishing, bioprospecting, exploitation of non-living resources and marine scientific research on the extended continental shelf. The book proposes a framework for navigating the intersection between the high seas and the extended continental shelf and minimising the potential for conflict between flag and coastal States\" --Flap of cover.

This research has been supported by the Spanish Inter-Ministerial Science and Technology Commission through the “IMPACTA” project (CICYT, CTM2013-48194-C3-1-R), “BASEMAN” project (PCIN-2015170-CO2-02), “2-2 ESMARME” project and by the European Union through the European Regional Development Fund (ERDF).

Denitrification is a critical process regulating the removal of bioavailable nitrogen (N) from natural and human-altered systems. While it has been extensively studied in terrestrial, freshwater, and marine systems, there has been limited communication among denitrification scientists working in these individual systems. Here, we compare rates of denitrification and controlling factors across a range of ecosystem types. We suggest that terrestrial, freshwater, and marine systems in which denitrification occurs can be organized along a continuum ranging from (1) those in which nitrification and denitrification are tightly coupled in space and time to (2) those in which nitrate production and denitrification are relatively decoupled. In aquatic ecosystems, N inputs influence denitrification rates whereas hydrology and geomorphology influence the proportion of N inputs that are denitrified. Relationships between denitrification and water residence time and N load are remarkably similar across lakes, river reaches, estuaries, and continental shelves. Spatially distributed global models of denitrification suggest that continental shelf sediments account for the largest portion (44%) of total global denitrification, followed by terrestrial soils (22%) and oceanic oxygen minimum zones (OMZs; 14%). Freshwater systems (groundwater, lakes, rivers) account for about 20% and estuaries 1% of total global denitrification. Denitrification of land-based N sources is distributed somewhat differently. Within watersheds, the amount of land-based N denitrified is generally highest in terrestrial soils, with progressively smaller amounts denitrified in groundwater, rivers, lakes and reservoirs, and estuaries. A number of regional exceptions to this general trend of decreasing denitrification in a downstream direction exist, including significant denitrification in continental shelves of N from terrestrial sources. Though terrestrial soils and groundwater are responsible for much denitrification at the watershed scale, per-area denitrification rates in soils and groundwater (kg N·km⁻²·yr⁻¹) are, on average, approximately one-tenth the per-area rates of denitrification in lakes, rivers, estuaries, continental shelves, or OMZs. A number of potential approaches to increase denitrification on the landscape, and thus decrease N export to sensitive coastal systems exist. However, these have not generally been widely tested for their effectiveness at scales required to significantly reduce N export at the whole watershed scale.

Large diversity and abundance of cetacean species occur along the Brazilian outer continental shelf and slope waters. In the present study, we analyzed carbon (δ13C) and nitrogen (δ15N) stable isotopes in skin biopsies of ten odontocete species (Delphinidae and Physeteridae) to assess the intra- and inter-specific patterns in the use of resources along the region. Our isotopic analysis allowed us to identify two potential subpopulations of Stenella frontalis. High core isotopic niche overlap between S. frontalis from the southern range of the study area and Delphinus delphis, especially in spring, suggested that they share similar resources and rely on spatiotemporal segregation to achieve niche differentiation and to minimize competition. Our isotopic data also pointed to high similarity among Tursiops truncatus, S. frontalis, and Globicephala melas in the use of resources. Steno bredanensis had the highest δ15N and δ13C, which agrees with its occurrence in neritic waters. S. longirostris showed consistently low δ15N values, indicating that they feed at relatively lower trophic levels, and lack of niche overlap with most delphinid species, except S. attenuata. Orcinus orca and G. melas had very similar δ13C and δ15N values, that were consistent with feeding in offshore waters. δ13C and δ15N in Physeter macrocephalus suggested that individuals feed on similar trophic levels, but over a wide spatial range. The analyses of stable isotopes in skin biopsies helped us to refine our knowledge about the intra-specific resource and habitat use, ecological niches, and the trophic interactions amongst co-occurring cetaceans from the oceanic waters of the subtropical western South Atlantic.

Data analysis of continental shelf currents and coastal sea level, together with the application of a semi-analytical model, are used to estimate the importance of remote wind forcing on the subinertial variability of the current in the central and northern areas of the South Brazil Bight. Results from both the data analysis and from the semi-analytical model are robust in showing subinertial variability that propagates along-shelf leaving the coast to the left in accordance with theoretical studies of Continental Shelf Waves (CSW). Both the subinertial variability observed in along-shelf currents and sea level oscillations present different propagation speeds for the narrow northern part of the SBB (~ 6–7 m/s) and the wide central SBB region (~ 11 m/s), those estimates being in agreement with the modeled CSW propagation speed. On the inner and middle shelf, observed along-shelf subinertial currents show higher correlation coefficients with the winds located southward and earlier in time than with the local wind at the current meter mooring position and at the time of measurement. The inclusion of the remote (located southwestward) wind forcing improves the prediction of the subinertial currents when compared to the currents forced only by the local wind, since the along-shelf-modeled currents present correlation coefficients with observed along-shelf currents up to 20% higher on the inner and middle shelf when the remote wind is included. For most of the outer shelf, on the other hand, this is not observed since usually, the correlation between the currents and the synoptic winds is not statistically significant.

On December 19, 2023, the U.S. Department of State announced the geographic coordinates defining the outer limits of the U.S. continental shelf in areas beyond 200 nautical miles from the coast. For convenience, the United States-and also this Essay-refers to the portion of a country's continental shelf that is beyond 200 nautical miles from the coast as the \"extended continental shelf,\" or ECS. The announcement states that the United States has ECS in seven different regions which collectively amounts to approximately a million square kilometers (about 380,000 square miles).