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EBSA overview  |  Delineation |  Summary of description updates  | Revised description

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EBSA overview

The Agulhas Slope and Seamounts at the outer margin along the southern tip of the Agulhas Bank in South Africa represents a dynamic offshore area. It has high productivity and high pelagic and benthic habitat heterogeneity, including 4 pelagic and 10 benthic habitat types because the Agulhas and Southern Benguela ecoregions meet at this point, and sporadic shelf-edge upwelling enhances local productivity. The area is recognized as a spawning area for sardine, anchovy, horse mackerel and hake, and is a critical area for retention of spawning products. Local eddies help recirculate water inshore and link important nursery areas with spawning habitat on the shelf edge. Seabirds, sharks and leatherback turtles are also present at this site.

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Delineation

Open or collapse the legend as a sidebar by clicking the icon in the top left corner of the map. In the legend you can turn on/off the old/new extents of the EBSA. You can zoom in/out using the mouse or the +/- buttons on the map, and click on the features for more information.

 

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Summary of updates and revisions to the EBSA description

1 new reference added; major revisions to the feature description of the area. No further research has been conducted in the area.

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Revised EBSA description

NOTE: Read this here, or download the Word document on the right sidebar.

 

General Information

Summary

The outer margin along the southern tip of the Agulhas Bank represents a dynamic offshore area with high productivity and high pelagic and benthic habitat heterogeneity. The Agulhas and Southern Benguela ecoregions meet at this point, and sporadic shelf-edge upwelling enhances the productivity along the outer margin. The area is recognized as a spawning area for sardine, anchovy, horse mackerel and hake, and this apex area of the Agulhas Bank is recognized as a critical area for retention of spawning products. Eddies in this area help recirculate water inshore and link important nursery areas with spawning habitat on the shelf edge. This area was identified as a priority area through a national spatial plan because of high habitat diversity. Further research and in situ surveys of the unexplored hard shelf edge and seamounts is recommended in this area.

 

Introduction of the area

The Agulhas Slope and Seamounts includes the outer margin along the southern tip of the Agulhas Bank in South Africa, and is a dynamic offshore area with high pelagic and benthic habitat heterogeneity. The area includes outer shelf, shelf edge, slope and seamount habitats and ranges between approximately 200 and 1800 m in depth. The Agulhas and Southern Benguela ecoregions (Sink et al., 2012) meet at this point, and sporadic shelf edge upwelling enhances the productivity along the outer margin (Lagabrielle et al., 2009). The area is recognized as a spawning area for sardine, anchovy, horse mackerel and hake, and this apex area of the Agulhas Bank is recognized as a critical area for retention of spawning products (Hutchings et al., 2002). Eddies in this area help recirculate water inshore and link important nursery areas with spawning habitat on the shelf edge. Leatherback turtles also frequent these seamounts along their migrations (Harris et al., in review). This area was identified as a priority through a national plan to identify focus areas for offshore protection (Sink et al., 2011) because it has relatively high habitat diversity and can meet multiple benthic and pelagic habitat conservation targets in a small area.

 

Description of the location

EBSA Region

Southern Indian Ocean

 

Description of location

The apex area of the Agulhas Bank at the southern tip of the continental shelf edge off southern Africa bounded by approximately 35°S to 38°S and 21° to 23°E.

 

Geo-Location

SIO_2_EBSA.geojson

 

Area Details

Feature description of the area

The area includes benthic and pelagic features, including shelf edge, slope and seamounts, and shelf-edge driven upwelling. Habitat diversity is thus particularly high, with four pelagic habitat types and ten benthic habitats occurring in this dynamic area. It consequently supports numerous ecological processes, such as spawning and foraging, and comprises a rich diversity of both resident (e.g., benthic gorgonians) and transient (e.g., migrating leatherbacks) species.

 

Feature conditions and future outlook of the proposed area

The shelf edge and seamounts have not been sampled, although in-situ research is recommended in this area. Nevertheless, there are various fisheries operating in the area, but some of the hard grounds are outside of the trawl footprint.

 

References

Harris, L.R., Nel, R., Oosthuizen, H., Meyer, M., Kotze, D., Anders, D., McCue, S., Bachoo, S. Managing conflicts between economic activities and threatened migratory marine species towards creating a multi-objective blue economy. Conservation Biology, in review.

Hutchings L, Beckley LE, Griffiths MH, Roberts MJ, Sundby S, van der Lingen C. 2002. Spawning on the edge: spawning grounds and nursery areas around the southern African coastline. Marine and Freshwater Research 53: 307-318.

Lagabrielle E. 2009. Preliminary report: National Pelagic Bioregionalisation of South Africa. Cape Town: South African National Biodiversity Institute.

Lutjeharms JRE, Cooper J and Roberts M 2000. Upwelling at the inshore edge of the Agulhas Current. Continental Shelf Research, 20(7): 737 – 761.

Sink KJ, Attwood CG, Lombard AT, Grantham H, Leslie R, Samaai T, Kerwath S, Majiedt P, Fairweather T, Hutchings L, van der Lingen C, Atkinson LJ, Wilkinson S, Holness S, Wolf T. 2011. Spatial planning to identify focus areas for offshore biodiversity protection in South Africa. Unpublished Report. Cape Town: South African National Biodiversity Institute.

Sink K, Holness S, Harris L, Majiedt P, Atkinson L, Robinson T, Kirkman S, Hutchings L, Leslie R, Lamberth S, Kerwath S, von der Heyden S, Lombard A, Attwood C, Branch G, Fairweather T, Taljaard S, Weerts S, Cowley P, Awad A, Halpern B, Grantham H, Wolf T. 2012. National Biodiversity Assessment 2011: Technical Report. Volume 4: Marine and Coastal Component. South African National Biodiversity Institute, Pretoria.

 

Other relevant website address or attached documents

SIO_2_EBSA-GIS shapefile.zip (/api/v2013/documents/1E936E8D-16FF-B9FC-D89B-A7C4E9CF3F19/attachments/SIO_2_EBSA-GIS%20shapefile.zip)

 

Status of submission

Areas described as meeting EBSA criteria that were considered by the Conference of the Parties

 

COP Decision

dec-COP-12-DEC-22

 

Assessment of the area against CBD EBSA criteria

C1: Uniqueness or rarity Medium

Justification

This area includes 2 of 4 known seamounts within the Davie Seamount cluster (Sink et al., 2011, 2012). These seamounts are relatively isolated and are thus likely to host distinct communities.

C2: Special importance for life-history stages of species High

Justification

The Agulhas Slope and Seamounts is recognized as a spawning area for small pelagic fish (sardine, anchovy, horse mackerel) and hake (Hutchings et al., 2002, Sink et al., 2011). This apex area of the Agulhas Bank is also recognized as a critical area for retention of spawning products. Eddies in this area help re-circulate water inshore and link important nursery areas with spawning habitat on the shelf edge. The shelf edge constitutes foraging area for offshore seabirds (Birdlife data, see references below).

C3: Importance for threatened, endangered or declining species and/or habitats Medium

Justification

Threatened habitat types in this area include Agulhas hard outer shelf and shelf edge, Agulhas muddy outer shelf and Agulhas sandy shelf edge (Sink et al., 2012.). Critically Endangered leatherback turtles frequent this area (Petersen et al., 2009a; Harris et al., in review), and the shelf edge is a feeding area for offshore seabirds (Petersen et al., 2009b). One of the pelagic habitat types characterised by elevated productivity and frequent fronts (Lutjeharms et al., 2000, Lagabrielle 2009) due to shelf edge upwelling is also considered threatened (Sink et al., 2012).

C4: Vulnerability, fragility, sensitivity, or slow recovery High

Justification

This area includes hard shelf edge and seamounts (some of the hard grounds are untrawled). These are likely to support fragile long-lived biota. Video images of the shelf edge show cold-water corals, gorgonians and large sponges (Sink et al., 2011). Vulnerable biota that use this area include long-lived seabirds, turtles and sharks, and the area has been identified by analyses aimed at identifying priority areas for reducing by-catch in the large pelagic fishery (Sink et al., 2011.)

C5: Biological productivity High

Justification

There is higher productivity here, which is related to the eastern limit of the Benguela upwelling on the outer shelf (Pelagic habitat type Ab3) and very frequent SST and chlorophyll fronts (Lutjeharms et al., 2000, Lagabrielle 2009, Sink et al., 2011, 2012). Cool productive water is advected onto the shelf in this sheer zone through Agulhas Current–driven upwelling cells (Lutjeharms et al., 2000).

C6: Biological diversity High

Justification

This area has high pelagic and benthic habitat heterogeneity. Four pelagic habitat types (Ab3, Bc1, Cb3 and Cb4) and ten benthic habitats occur in this dynamic area, leading to its selection in a national systematic plan (Sink et al., 2011, 2012).

C7: Naturalness High

Justification

Rough grounds and strong currents already offer some protection from pressures to this area (Sink et al., 2011, 2012). Relatively lower levels of disturbance occur in this area (Sink et al., 2012), and most of the local hard areas fall outside of the hake trawl footprint (Sink et al., 2011).

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