Polycentric Regional Ocean Governance Opportunity in the Benguela Current Convention

The Benguela Current Convention (BCC) has been operational for a decade and has emerged from the precursor natural and fisheries science large marine ecosystem programs. This regional ocean governance institution emerged indigenously as an intergovernmental working arrangement across the Republics of Angola, Namibia, and South Africa. The Convention has been described as a Centralized Authority mode of regional ocean governance. This paper explores this description with reference to the ecosystem-based approach to marine management. The study is focused on the level of working arrangements within the Convention and its Commission across the national and regional scales. It finds that the BCC does meet the theoretical criteria of a polycentric governance mechanism at the resolution of its operations. Polycentric ocean governance mechanisms are valued in regional ocean governance as they potentially offer greater impact through higher levels of coordination, codesign, and integration. Polycentric governance systems incorporate multiple centers of authority that operate at different scales. Existing instances and further opportunities for polycentric governance mechanisms within the working arrangements of the Convention are identified for the Southeast Atlantic.

Benthic Foraminifera of the Agulhas Bank coastal shelf in the vicinity of Plettenberg Bay, South Africa: a reconnaissance survey

The study area is located on the inner Agulhas Bank around Plettenberg Bay, southern Cape Province, South Africa (Fig. 1). The Agulhas Bank is a transitional environment between the cold-temperate Benguela Current regime of the south-eastern South Atlantic and the warm-temperate Agulhas Current regime of the south-western Indian Ocean. Three distinct faunal assemblages (A, B and C) were identified in the study area. These are aligned in three consecutive, coast-parallel belts, assemblage A forming the inshore belt, assemblage C the offshore belt and assemblage B the in-between belt. Assemblage A is composed of Textularia-group individuals and Pararotalia sp., Cibicides lobatulus and Planorbulina mediterranensis. It occupies the nearshore belt up to 50 m water depth in sediments composed of very fine, fine and medium sands, with some coarse and very coarse sands. Assemblage B is composed of Bolivina cf. pseudopunctata, Cassidulina laevigata, Ammonia beccarii, Bolivina tortuosa and Bulimina elongata. It occupies water depths from 50–70 m, but may locally extend down to 90 m and, within the bay itself, upward to 20 m in fine and very fine sands containing some medium sand and mud. Assemblage C is dominated by Cassidulina laevigata, Bolivina cf. pseudopunctata, Bulimina elongata and Ammonia beccarii. In contrast to assemblage B which is dominated by B. cf. pseudopunctata, assemblage C is dominated by C. laevigata. Assemblage C is mainly confined to water depths of 70–100 m in sediments dominated by very fine sand (0.063–0.125 mm) containing some coarser sediment and mud. The distribution of the forams with respect to water depth, sediment composition and other environmental parameters suggests that it is mainly controlled by a combination of environmental parameters. No tangible relationship was found between the open shelf foraminifer communities and those of estuaries and lagoons along the South African coast.

Seabirds of the Benguela Ecosystem: Utilisation, Long-Term Changes and Challenges

The Benguela Current is used by c. 82 seabird species, of which seven are endemic to it. Eggs and guano of formerly abundant seabirds were heavily harvested in the 19th and 20th centuries but decreases in seabird populations led to cessation of these industries at islands. Guano is still scraped from platforms. Seabird ecotourism has grown. There were large recent decreases in numbers of African Penguins Spheniscus demersus, Cape Gannets Morus capensis and Cape Phalacrocorax capensis and Bank P. neglectus Cormorants and redistributions of these other species away from the centre of the Benguela ecosystem towards its northern or eastern boundaries. In 2020, seabirds endemic to the Benguela ecosystem and albatrosses and petrels migrating into it had high proportions of globally Near Threatened or Threatened species. The primary threat to four Endangered endemic birds was scarcity of forage resources. A Vulnerable endemic damara tern was susceptible to habitat degradation and disturbance. The principal threat to visiting albatrosses and petrels was by-catch mortality. Identification and effective protection of Important Bird Area breeding and marine foraging and aggregation sites, and a suite of complementary measures, are needed to conserve the seabirds and ensure continuation of their economic and ecosystem benefits into the future.

Assessing "Drake Passage Leakage" in an eddy resolving ocean model

<p>The upper limb of the Atlantic Meridional Overturning Circulation (AMOC) is supplied in the South Atlantic from Drake Passage (DP) and Agulhas Leakage (AL). The relative contributions from DP and AL influence the stratification as well as the properties of the upper limb return flow and potentially impact the formation of deep water in the North Atlantic. <br>While early studies suggested a clear dominance of the AL contribution, recent studies indicate that the DP contribution is not negligible. Here, we use a set of Lagrangian experiments in the eddy-resolving (1/20 degree) ocean model INALT20 to analyze the inflow from DP into the South Atlantic in more detail. We find that the majority of water, that enters the subtropical South Atlantic across 30° S from DP, originates from the upper 2000 m of the northern branch of the ACC that follows the Sub Antarctic Front (SAF). Before  entering the South Atlantic, the majority of theses particles turn northward east of DP and follow the SAF through the Brazil Malvinas Confluence, where the SAF meets the Sub Tropical Front. In or parallel to the South Atlantic Current, particles cross the basin and become part of the subtropical gyre to follow the Benguela Current northward. We further compare pathways, volume transports, transit times and thermohaline properties of particles entering through DP and leaking into the South Atlantic to those from particles not leaking into the South Atlantic. These analyses help exploring potential recipes for building a timeseries of “Drake Passage leakage”, complementary to the already established Agulhas Leakage timeseries.</p>

The Agulhas Bank Circulation

<p>The southern tip of Africa is the gateway between the Indian and Atlantic oceans, one of the most widely recognized chokepoints of the meridional overturning circulation (MOC). The oceanic circulation in this region connects a western boundary current, the Agulhas Current, to an eastern boundary current, the Benguela Current, a connection not replicated elsewhere and quite important, not only because of its peculiarity, but also because of its role in the MOC. During the last few decades numerous international research programs have collected large amounts of oceanographic data of this region. All these efforts, however, have been largely focused on the deep-ocean, leaving the coastal region practically unattended. In this presentation we will use the results of a suite of process-oriented numerical experiments to discuss the circulation along the Agulhas Bank (AB)—the shelf region sandwiched between the eastern and western margins of the African continent; in particular to illustrate its connections and interactions with the deep-ocean region. As we shall show these shelf/deep-ocean interactions, are not only important to the shelf but also to the Indian/Atlantic interoceanic exchange.</p>