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Childs Bank

Childs Bank is a unique submarine bank feature, rising from 400 m to 200 m depth on the western continental margin of South Africa. This EBSA includes portions of five benthic habitat types, including hard and unconsolidated sediments, one of which is Critically Endangered, and another two which are Vulnerable. Although comprising threatened habitats, the benthic area of the bank itself is in good condition. Childs Bank and associated habitats are known to support structurally complex cold-water corals, hydrocorals, gorgonians and glass sponges; all of which species constitute vulnerable marine ecosystems. Further, adjacent to Childs Bank, the shelf edge area is a biodiversity hotspot for demersal fish and cephalopods, and the benthic communities contain a high abundance and biomass of infauna and epifauna.

EBSA Description: Childs Bank

General Information

Summary

Childs Bank and Shelf Edge is a unique submarine bank feature occurring within South Africa’s EEZ, rising from ‑400 m to -180 m on the western continental margin on South Africa. This area includes five benthic habitat types, including the bank itself, the outer shelf and the shelf edge, supporting hard and unconsolidated habitat types. One habitat type within this area is assessed to be “Critically Endangered” and another two as “Vulnerable”. However, the benthic area of the bank itself is considered to be in “Good” natural state indicating that the ecological patterns and processes are intact. Childs Bank and associated habitats are known to support structurally complex cold-water corals, hydrocorals, gorgonians and glass sponges; species that are particularly fragile, sensitive and vulernable to disturbance, and recover slowly. The Childs Bank and Shelf Edge area is highly relevant in terms of the following EBSA criteria: “Uniqueness or rarity”, “Vulnerability, fragility, sensitivity or slow recovery” and “Naturalness”. Since its original description, the boundary of this EBSA has been refined to improve precision based on new bathymetry data, ecosystem information (condition and threat status of local benthic and pelagic ecosystem types, and presence of key features including fragile species), and to align with current MPA expansion initiatives.

MARISMA updates

The site description has been updated; changes to the delineation are being discussed. 

Introduction of the area

Childs Bank is the only known submarine bank in South Africa. It’s a rugged limestone feature found on the shelf, close to the shelf edge, on the western continental margin of South Africa, approximately 125 km offshore. It rises from a depth of -260 m in the east, -350 m in the west, to form a large, flattened plateau at ‑200 m (De Wet 2012). The margins of the bank slope gently on the north, east and south sides, but the western edge is a slump-generated outer face of 150 m in height that lies at the edge of the continental shelf, dropping steeply from -350 to ‑1500 m across a short distance of <60 km (De Wet 2012; Birch and Rogers 1973). The bank area has been estimated to cover 1450 km2 (Sink et al., 2012a). The EBSA focus area includes Childs Bank, the shelf and the shelf edge adjacent to the bank, the latter of which is considered likely to host vulnerable hard ground species. The sediment adjacent to the bank is predominantly fine sand with approximately 25% mud, and in some locations small amounts of gravel have been detected (Atkinson 2010). This area was identified as a priority area for protection through two planning studies identifying areas for offshore protection (Sink et al., 2011, Majiedt et al., 2013). Benthic protection in the region of Childs Bank and Shelf Edge would ensure protection of the only submarine bank within South Africa’s EEZ, some protection of the adjacent shelf edge and protection of areas where coral records have been detected.

Description of location

The Childs Bank and Shelf Edge area is located approximately 125 km off Hondeklipbaai on the west coast of South Africa, with its northern edge about 90 km from national border with Namibia. It lies entirely within South Africa’s national jurisdiction, largely on the outer shelf but also extending across the shelf edge and slope in some places.

 

Area details

Feature description of the area

Childs Bank is a unique offshore submarine bank habitat type within South Africa’s EEZ, defined as the Southern Benguela Submarine Bank (Sink et al., 2012a). No other known submarine banks occur within South Africa’s EEZ. The Childs Bank and Shelf Edge area also includes four other benthic habitats: the Southern Benguela Hard Outer Shelf, Hard Shelf Edge, Sandy Outer Shelf and Shelf Edge (Sink et al., 2012a). Two areas of Southern Benguela Hard Shelf Edge habitat at the shelf edge adjacent to Childs Bank are defined as Critically Endangered (Sink et al., 2012a). A further two habitat types within the area, the Southern Benguela Hard Shelf Edge and Sandy Shelf Edge, are defined as Vulnerable (Sink et al., 2012a). 37% of the Childs Bank and Shelf Edge slopes (Southern Benguela Submarine Bank habitat) are trawled (Sink et al., 2012b). However, there are several very fragile, vulnerable and sensitive species present in the area: hydrocorals (e.g. Stylaster sp.) in the area, cold-water coral fragments, gorgonians (Acbaria rubra) and glass sponges (Rossella antarctica) were sampled at a virtually untrawled site adjacent to Childs Bank (Atkinson 2010; see also Gilchrist 1922, 1925, Van Bonde 1928, Atkinson et al., 2011). Further, skippers and deck hands from the trawl industry report fragments of corals sometimes caught in isolated locations in this area and that there are several patches of hard ground, requiring additional footrope protection (e.g., bobbins and rockhopper gear, Sink et al., 2012b).

The shelf edge area adjacent to Childs Bank is also a biodiversity hotspot for demersal fish and cephalopods in the southern Benguela (Kirkman et al., 2013). Benthic communities sampled adjacent to the Childs Bank mound revealed high abundance and biomass of benthic infauna and epifauna (Atkinson 2010, Atkinson et al., 2011), indicating that a rich benthic fauna occurs in this region. Two species of burrowing urchins (Spatangus capensis and Brissopsis lyrifera capensis) and a burrowing anemone species (Actinauge granulosus) were detected in high abundances in the Childs Bank and Shelf Edge region, contributing to the bioturbation and oxygenation of sediment, important ecological functions.

The boundary of this EBSA has been refined since its original delineation to improve precision based on new information. The new delineation was based on new bathymetry data, new ecosystem information (site selection frequency in two systematic conservation plans covering the area to meet biodiversity targets, the condition and threat status of the local benthic and pelagic ecosystem types, key features including the bank itself and associated fragile species), and focus areas for MPA expansion in South Africa. The new boundary comprises about two thirds of the original EBSA area and falls mostly within the previous delineation, except for a protrusion along the south east edge.

Feature conditions and future outlook of the proposed area

Childs Bank and Shelf Edge is currently in Good ecosystem condition, based on cumulative impact scores from multiple anthropogenic pressures (Sink et al., 2012a). Good-condition sites are those which, based on the low levels of pressure, are expected have both biodiversity pattern and process largely intact and hence can be considered to be in a largely "natural" or "pristine" state. However, the area south and towards the shelf edge of Childs Bank were categorized as Fair and Poor, indicating that there is some impact on biodiversity pattern and/or ecological processes in a small component of the broader area (Sink et al., 2012a).

The trawl fishing intensity in the northern region of the fishing grounds, including Childs Bank and Shelf Edge, has declined since the mid-1990s (Russell Hall, Sea Harvest pers. comm.), and it is unlikely that this region was as intensively fished as the western grounds, closer to the port of Cape Town. No trawling occurs on the top of the bank, with most fishing taking place around the slope where hard ground, supporting vulnerable habitat-forming species, is most likely to occur. There is scope to protect this feature with limited, if any, adverse impact on the fishery (Sink et al., 2012b).

 

Assessment of the area against CBD EBSA criteria

 Uniqueness or rarity

 

Rank: High

The Childs Bank submarine mound is the only such feature known to occur within South Africa’s EEZ and therefore represents a highly unique feature in this region (Sink et al., 2011, Sink et al., 2012, Majiedt et al., 2013). The selection of this area in a systematic biodiversity plan for the South African west coast is driven by the uniqueness of the site and reduced cost values (few anthropogenic pressures) in the area (Majiedt et al., 2013).

 Special importance for life-history stages of species

 

Rank: Low

There is no evidence to suggest that the Childs Bank and Shelf Edge area is of special importance for life history stages of particular species or populations; however, the habitat type is a unique feature within South Africa’s EEZ, and it is possible it may support key ecological processes that are, as yet, unstudied (Sink et al., 2011). Tuna fishers report that this area is a feeding area for tuna (Sink et al., 2011).

 Importance for threatened, endangered or declining species and/or habitats

 

Rank: Medium

There are some threatened habitat types in Childs Bank and Shelf Edge: Southern Benguela Hard Shelf Edge (Critically Endangered), Southern Benguela hard outer shelf (Vulnerable) and Southern Benguela sandy shelf edge (Vulnerable; Sink et al., 2012a). This area also has some importance for declining species. Some long-lived pelagic species (e.g., blue shark (IUCN Near Threatened) and mako shark (IUCN Vulnerable)) are also caught in fair numbers (~15% of total Atlantic catch) around Childs Bank (DAFF Linefish Section). Populations of these species are believed to be in global decline (Camhi et al., 2009).

 Vulnerability, fragility, sensitivity, or slow recovery

 

Rank:  High

This area has hard ground habitats on the outer shelf and shelf edge that are considered sensitive to demersal trawling and mining (FAO 2006, FAO 2009, Rogers et al., 2008, Sink et al., 2011, 2012a, 2012b). Samples of cold-water corals, sponges and gorgonians have been reported from this area (Gilchrist 1922, Von Bonde 1928 and Atkinson 2010, 2011) and more recently, skippers and deck hands from commercial trawl vessels have indicated occurrences of such species in their nets when fishing in this area (Sink et al., 2012b).

 Biological productivity

 

Rank: Low

Fine-scale variability within this area has not been examined but this area falls within the highly productive shelf area of the Benguela upwelling region (Lagabrielle 2009, Sink et al., 2011, Roberson et al., 2017).

 

 Biological diversity

 

Rank: Medium

This area is considered to host high levels of biodiversity, e.g., infauna and epifauna (Atkinson 2010, Atkinson et al., 2011), demersal fish and cephalopods (Kirkman et al., 2013) and fragile and sensitive habitat-forming species.

 

 Naturalness

 

Rank: High

Childs Bank and Shelf Edge is in “Good” ecosystem condition, based on cumulative impact scores from multiple anthropogenic pressures (Sink et al., 2012a). This suggests that, based on the low levels of pressure, the site is expected have both biodiversity pattern and process largely intact and hence can be considered to be in a largely "natural" or "pristine" state.

 

References

Atkinson, L.J. 2010. Effects of demersal trawling on marine infaunal, epifaunal and fish assemblages: studies in the southern Benguela and Oslofjord. PhD dissertation, University of Cape Town pp. 141.

Atkinson, L.J., Field, J.G., Hutchings, L. 2011. Effects of demersal trawling along the west coast of southern Africa: multivariate analysis of benthic assemblages. Marine Ecology Progress Series: 430:241- 244. doi:10.3354/meps08956.

Camhi, M.D., Valenti, S.V., Fordham, S.V., Fowler, S.L. and Gibson, C. 2009. The Conservation Status of Pelagic Sharks and Rays: Report of the IUCN Shark Specialist Group Pelagic Shark Red List Workshop. IUCN Species Survival Commission Shark Specialist Group. Newbury, UK. x + 78 p.

Birch GF and Rogers J. 1973. Nature of the sea floor between Luderitz and Port Elizabeth. South African Shipping News and Fishing Industry Review 18(7): 1-7.

FAO. 2006. Management of Demersal Fisheries Resources of the Southern Indian Ocean. FAO Fisheries Circular No. 1020 FAO Rome 2006.

FAO. 2009. Annex F of the Report of the Technical Consultation on International Guidelines for the Management of Deepsea Fisheries in the High Seas. Rome, 4–8 February and 25-29 August 2008.

Gilchrist, J.D.F. 1925. List of fishes, etc., procured. Annexure A in Report of the Fisheries and Marine Biological Survey for the period June, 1923 – June, 1925 4: xxiii-xliii.

Kirkman SP, Yemane D, Kathena J, Mafwila S, Nsiangango S, Samaai T, Axelsen B, Singh L. 2013. Identifying and characterizing of demersal biodiversity hotspots in the BCLME: Relevance in the light of global changes. ICES Journal of Marine Science: 70, 943–954.

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

Majiedt P, Holness S, Sink K, Oosthuizen A, Chadwick P. 2013. Systematic Marine Biodiversity Plan for the West Coast of South Africa. South African National Biodiversity Institute, Cape Town.

Rogers A.D., Clark M.R, Hall-Spencer K.M and Gjerde K.M. 2008. The Science behind the Guidelines: A Scientific Guide to the FAO Draft International Guidelines (December 2007) For the Management of Deep-Sea Fisheries in the High Seas and Examples of How the Guidelines May Be Practically Implemented. IUCN, Switzerland.

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. 2012a. National Biodiversity Assessment 2011b: Technical Report. Volume 4: Marine and Coastal Component. South African National Biodiversity Institute, Pretoria.

Sink KJ, Wilkinson S, Atkinson LJ, Sims PF, Leslie RW, Attwood CG. 2012b. The potential impacts of South Africa’s demersal hake trawl fishery on benthic habitats: historical perspectives, spatial analyses, current review and potential management actions. Unpublished report. Cape Town: South African National Biodiversity Institute.

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ChildsBank

EBSA criteria met at a high (red), medium (orange) or low (yellow) rank. 

 

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icon Childs Bank KMZ 2018 (14.78 kB)

 

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