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

OBIS biodiversity data  |  Status assessment and management recommendations

 

 

EBSA overview

The KwaZulu-Natal Bight and uThukela River is important for numerous ecological processes, including terrestrial-marine connectivity, larval retention, recruitment and provision of nursery and foraging areas. The area includes rare ecosystem types and supports some species known to exist in few localities. Cool productive water is advected onto the shelf through Agulhas-driven and wind-driven upwelling cells, and continental runoff from the large uThukela River is important for the delivery of detritus to the bight (which drives food webs), and maintenance of mud and other unconsolidated-sediment habitats. The turbid, nutrient-rich conditions are important for life-history phases (breeding, nursery and feeding) for crustaceans, demersal fish, migratory fish, turtles and sharks, some of which are threatened. Particularly vulnerable and fragile ecosystems and species include submarine canyons, cold-water corals and slow-growing sparids. This EBSA is particularly important for threatened ecosystem types. Of the 28 ecosystem types represented, 21 (75%) are threatened including one Critically Endangered, nine Endangered and 11 Vulnerable types, with a further three types that are Near Threatened.

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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

Boundary, name, description and criteria ranks all revised and updated based on new information.

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Revised EBSA description

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

 

General Information

Summary

The KwaZulu-Natal Bight and uThukela River is important for numerous ecological processes, including terrestrial-marine connectivity, larval retention, recruitment and provision of nursery and foraging areas. The area includes rare ecosystem types and supports some species known to exist in few localities. Cool productive water is advected onto the shelf through Agulhas-driven and wind-driven upwelling cells, and continental runoff from the large uThukela River is important for the delivery of detritus to the bight (which drives food webs), and maintenance of mud and other unconsolidated-sediment habitats. The turbid, nutrient-rich conditions are important for life-history phases (breeding, nursery and feeding) for crustaceans, demersal fish, migratory fish, turtles and sharks, some of which are threatened. Particularly vulnerable and fragile ecosystems and species include submarine canyons, cold-water corals and slow-growing sparids. This EBSA is particularly important for threatened ecosystem types. Of the 28 ecosystem types represented, 21 (75%) are threatened including one Critically Endangered, nine Endangered and 11 Vulnerable types, with a further three types that are Near Threatened.

 

Introduction of the area

The KwaZulu-Natal Bight and uThukela River is important for numerous ecological processes, including terrestrial-marine connectivity, larval retention, recruitment and provision of nursery and foraging areas. The area incorporates rare ecosystem types and supports some species known to exist in only a few localities. The terrigenous sediments underpin many of the river-influenced marine ecosystem types, and associated, productive communities. The turbid, nutrient-rich conditions are important for life-history phases (breeding, nursery and feeding) for crustaceans, demersal fish, migratory fish, turtles and sharks. The EBSA also includes a canyon, and numerous threatened ecosystem types.

Since the original description and delineation, the boundary of the EBSA has been revised to improve accuracy and better represent the underlying features based on the best available data (e.g., GEBCO Compilation Group 2019; Harris et al., 2014; Holness et al., 2014; Majiedt et al., 2013; Sink et al., 2012, 2019). Importantly, the lower reaches of the uThukela River are now included because it is the key driver of the system, particularly for the river-influenced marine ecosystem types. It is the conduit for sediment delivery to the near- and offshore ecosystems of the KwaZulu-Natal Bight, and provides the critical link between land and sea that underpins this EBSA. In fact, it was considered such an important addition that it prompted a name change for this EBSA, from Natal Bight to KwaZulu-Natal Bight and uThukela River. Further, recent research in the area has, inter alia, improved knowledge of the seabed composition, and thus the extent of the mud habitats and the bight itself is now better understood and mapped, allowing a more accurate delineation of the EBSA. New fine-scale mapping of the coast (Harris et al., 2019) also allowed a more accuracte coastal boundary to be delineated. It is presented as a Type 2 EBSA because it contains “spatially stable features whose individual positions are known, but a number of individual cases are being grouped” (sensu Johnson et al., 2018).

 

Description of the location

EBSA Region

Southern Indian Ocean

 

Description of location

East coast of South Africa, extending from Maphelane to Durban, from the shore to -2000 m, including the Thukela Banks, the KwaZulu-Natal Bight nursery area, the shelf edge and upper bathyal zone. The area is entirely within South Africa’s EEZ.

 

Geo-Location

SIO_5_EBSA.geojson

 

Area Details

Feature description of the area

The area is characterized by extensive alluvial deposits forming banks, primarily off the uThukela River but also off the Mgeni River to a lesser degree (see Sink et al., 2011). The seafloor is thus sedimentary in nature but varies in the degree to which it is consolidated. The banks are productive in terms of benthic and deposit feeeders, an attribute typical of such features. Cool, productive water is advected onto the shelf through Agulhas-driven and wind-driven upwelling cells, and continental runoff from the large uThukela River is important for the delivery of detritus to the bight (which drives food webs), and maintenance of mud and other unconsolidated-sediment habitats. The turbid, nutrient-rich conditions are important for life-history phases (breeding, nursery and feeding) for crustaceans, demersal fish, migratory fish, turtles and sharks. Some of these species are threatened (turtles, scalloped hammerhead) or overexploited (sparids and sciaenids), and the deep reef and palaeo-shoreline habitats are considered important for the recovery of overexploited deep-reef fish species. Other particularly vulnerable and fragile ecosystems and species include submarine canyons, cold-water corals and slow-growing sparids. One Critically Endangered and nine Endangered ecosystem types occur in this area and a further 11 are Vulnerable (Sink et al., 2019). The Thukela Banks have been identified as a priority area by two different systematic biodiversity plans, a national plan to identify focus areas for offshore protection (Sink et al., 2011) and a fine-scale provincial plan for the province of KwaZulu-Natal (Harris et al., 2011).

 

Feature conditions and future outlook of the proposed area

The National Biodiversity Assessment 2011, 2018 (Sink et al., 2012, 2019) indicated declining condition overall in the original EBSA (based on pressure data and an ecosystem-pressure matrix) with conditions ranging from fair to poor across the overall area. An updated assessment (Sink et al., 2019) on the new delineation shows ecological condition ranges from good to poor across the EBSA, with condition generally worse closer to the shore. Key pressures include the crustacean trawl fishery, a line fishery targeting sparids and sciaenids, and there are emerging mining and petroleum applications. A submarine cable has recently been laid in the area. Research on a number of the aforementioned aspects has been undertaken (but not all published) by the Oceanographic Research Institute in Durban. There is planned research in the area through the African Coelacanth Ecosystem Program Phase III.

 

References

Ezemvelo KZN Wildlife, 2012. Focus areas for additional marine biodiversity protection in Natal, South Africa. Unpublished Report - Jan 2012. Scientific Services, Ezemvelo KZN Wildlife: Durban. Pp 62.

Fennessy, S. 2016. Subtropical demersal fish communities on soft sediments in the KwaZulu-Natal Bight, South Africa, African Journal of Marine Science, 38: sup1, S169-S180.

GEBCO Compilation Group, 2019. GEBCO 2019 Grid (doi:10.5285/836f016a-33be-6ddc-e053-6c86abc0788e)

Harris, J.M., Livingstone, T., Lombard, A.T., Lagabrielle, E., Haupt, P., Sink, K., Mann, B., Schleyer, M. 2011 Marine Systematic Conservation Assessment and Plan for KwaZulu-Natal - Spatial priorities for conservation of marine and coastal biodiversity in KwaZulu-Natal. Ezemvelo KZN Wildlife.

Harris, L.R., Bessinger, M., Dayaram, A., Holness, S., Kirkman, S., Livingstone, T.-C., Lombard, A.T., Lück-Vogel, M., Pfaff, M., Sink, K.J., Skowno, A.L., Van Niekerk, L., 2019. Advancing land-sea integration for ecologically meaningful coastal conservation and management. Biological Conservation 237, 81-89.

Harris, L.R., Nel, R., Oosthuizen, H., Meyer, M., Kotze, D., Anders, D., McCue, S., Bachoo, S. 2018. Managing conflicts between economic activities and threatened migratory marine species towards creating a multi-objective blue economy. Conservation Biology, 32, 411-423.

Harris, P.T., Macmillan-Lawler, M., Rupp, J. and Baker, E.K. 2014. Geomorphology of the oceans. Marine Geology, 352: 4-24.

Haupt, P. 2010. Conservation assessment and plan for fish species along the KwaZulu-Natal coast. MSc Thesis, Nelson Mandela Metropolitan University, South Africa.

Holness, S., Kirkman, S., Samaai, T., Wolf, T., Sink, K., Majiedt, P., Nsiangango, S., Kainge, P., Kilongo, K., Kathena, J., Harris, L.R., Lagabrielle, E., Kirchner, C., Chalmers, R., Lombard, A., 2014. Spatial Biodiversity Assessment and Spatial Management, including Marine Protected Areas. Final report for the Benguela Current Commission project BEH 09-01.

Hutchings, L., Beckley, L.E., Griffiths, M.H., Roberts, M.J., 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.

Johnson, D.E., Barrio Froján, C., Turner, P.J., Weaver, P., Gunn, V., Dunn, D.C., Halpin, P., Bax, N.J., Dunstan, P.K., 2018. Reviewing the EBSA process: Improving on success. Marine Policy 88, 75-85.

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

Lutjeharms, J.R.E., Gründlingh, M., Carter, R.A. 1989. Topographically induced upwelling in the Natal Bight. South African Journal of Science, 85: 310 -316.

Lutjeharms, J.R.E., Cooper, J., Roberts, M. 2000.Upwelling at the inshore edge of the Agulhas Current. Continental Shelf Research, 20: 737 – 761.

Roberson, L.A., Lagabrielle, E., Lombard, A.T., Sink, K., Livingstone, T., Grantham, H., Harris, J.M. 2017. Pelagic bioregionalisation using open-access data for better planning of marine protected area networks. Ocean & Coastal Management, 148: 214-230.

Roberts, M.J., Nieuwenhuys, C. 2016. Observations and mechanisms of upwelling in the northern KwaZulu-Natal Bight, South Africa, African Journal of Marine Science, 38: S43-S63.

Scharler, U.M., van Ballegooyen, R.C. Ayers, M.J. 2016. A system-level modelling perspective of the KwaZulu-Natal Bight ecosystem, eastern South Africa, African Journal of Marine Science, 38: S205-S216.

Sink, K.J., Attwood, C.G., Lombard, A.T., Grantham, H., Leslie, R., Samaai, T., Kerwath, S., Majiedt, P., Fairweather, T., Hutchings, L., van der Lingen, C., Atkinson, L.J., 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.

Sink, K.J., van der Bank, M.G., Majiedt, P.A., Harris, L.R., Atkinson, L., Karenyi, N., Kirkman, S. (eds) 2019. National Biodiversity Assessment 2018 Technical Report Volume 4: Marine Realm. South African National Biodiversity Institute, Pretoria. http://hdl.handle.net/20.500.12143/6372.

Taylor, F.E., Arnould, M.N., Bester, M.N, Crawford, R.J.M., Bruyn, P.J.N, Delords, K., Makhado, A.B., Ryan, P.G., Tosh, C.A., Weimerskirchs, H. 2011. The seasonal distribution and habitat use of marine top predators in the Southern Indian Ocean, and implications for conservation. WWF report, South Africa.

 

Status of submission

The Natal Bight EBSA was recognized as meeting EBSA criteria by the Conference of the Parties. The revised name, description and boundaries still need to be submitted to COP for approval.

 

COP Decision

dec-COP-12-DEC-22

 

Assessment of the area against CBD EBSA criteria

C1: Uniqueness or rarity Medium

Justification

Endemic and rare species include: Spotted legskate (Anacanthobatis marmoratus), Porcupine stingray (Urogymnus asperrimus); the Bearded Goby (Taenioides jacksoni) is also endemic (Haupt 2010, Livingston et al., 2012). There are rare gravel and mud ecosystem types in the area, as well as a submarine canyon of limited extent (Sink et al., 2012). There is also a unique demersal fish community near the Thukela Banks (Fennesey 2016), and it is the only portion of the South African east coast that has a relatively wide shelf area.

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

Justification

The KwaZulu-Natal Bight and uThukela River supports important life-history stages for a myriad of species. These functions include serving as a migration corridor for fish (e.g., Geelbek – Atractoscion aequidens, White stumpnose – Rhabdosargus holubi, Shad - Pomatomus saltatrix, Dusky kob - Argynosomus japonicas (Vulnerable), and Garrick – Lichia amia). It is also part of the migration route and spawning area for sardine – Sardinops sagax; many shark and fish species also spawn in the KwaZulu-Natal Bight (e.g., Bull shark – Carcharhinus leucas, Sand tiger shark – Carcharias taurus, Black musselcracker – Cymatoceps nasutus, and King mackerel – Scomber japonicas). The KwaZulu-Natal Bight and uThukela River is also an important nursery area for sharks and fish (e.g., Scalloped hammerhead – Sphyrna lewini (EN), Slinger – Chrysoblephus puniceus, Black musselcracker – Cymatoceps nasutus), and an important feeding and migration area for Critically Endangered leatherback turtles (Dermochelys coriacea; Haupt 2010, Harris et al., 2011, Vogt 2011, Sink et al., 2011, Ezemvelo KZN Wildlife 2012; Harris et al., 2018). There are also critical linkages between the Thukela Bank prawn-trawling ground and the estuarine nursery areas, emphasising the area’s role in ecosystem connectivity and supporting recruitment of many commercially important species (Scharler et al., 2016).

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

Justification

The KwaZulu-Natal Bight and uThukela River contains many threatened species, including: the Critically Endangered Seventy-four (Polysteganus undulosus), leatherbacks (Dermochelys coriacea) and hawksbills (Eretmochelys imbricata); Endangered Scalloped hammerhead (Sphyrna lewini), great hammerhead (Sphyrna mokarran), dageraad (Chrysoblephus christiceps), red stumpnose (Chrysoblephus gibbiceps), and green turtles (Chelonia mydas); and Vulnerable Flapnose houndshark (Scylliogaleus quecketti), porcupine stingray (Urogymnus asperrimus), dusky kob (Argynosomus japonicas), bearded goby (Taenioides jacksoni), and Natal shyshark (Haploblepharus kistnasamyi). There are also endemic sparids of conservation concern: Polysteganus coeruleopunctatus, as well as Near Threatened loggerheads (Caretta caretta). There are 20 threatened ecosystem types, including nine Endangered types, and 11 Vulnerable types (Sink et al., 2019).

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

Justification

The KwaZulu-Natal Bight and uThukela River contains features and species that are slow growing, fragile, and sensitive to disturbance, e.g., submarine canyons, shelf edge, deep reefs and cold-water corals (Sink et al., 2011, 2012).

C5: Biological productivity High

Justification

The KwaZulu-Natal Bight and uThukela River contains Indian Ocean water, with high but variable chlorophyll-a levels associated with very frequent SST and chlorophyll-a fronts (Lagabrielle 2009, Roberson et al., 2017). This pelagic habitat (Cb3) is characterised by cool productive water that has been advected onto the shelf in this sheer-zone through Agulhas Current-driven upwelling cells (Lutjeharms et al., 2000, Lutjeharms et al., 2000). Upwelling in the KwaZulu-Natal Bight is largely wind-driven (Roberts & Nieuwenhuys, 2016). Further, it has recently been discovered that substantial inputs of (mainly terrigenous) detritus from the uThukela River drive food webs in the KwaZulu-Natal Bight and uThukela River, particularly of the benthic communities which dominate the local food webs (Scharler et al., 2016).

C6: Biological diversity High

Justification

There is high habitat heterogeneity in the KwaZulu-Natal Bight and uThukela River EBSA, with 27 ecosystem types represented (Sink et al., 2019) and new evidence of diverse demersal fish communities in the area (Fennessey 2016).

C7: Naturalness Medium

Justification

Half (52%) of the area is in poor ecological condition, however, there is still 48% of the EBSA that is in good (15%) or fair (33%) ecological condition (Sink et al., 2019).

 

Other relevant website address or attached documents

Summary of ecosystem types and threat status for the KwaZulu-Natal Bight and uThukela River EBSA. Data from Sink et al. (2019).

Threat Status

Ecosystem Type

Area (km2)

Area (%)

Critically Endangered

Subtropical Estuarine Bay

0.1

0.0

Endangered

Durnford Inner Shelf Reef Complex

460.5

4.3

 

Natal Bight Deep Shelf Edge

1654.6

15.6

 

Natal Bight Mid Shelf Reef Complex

23.0

0.2

 

Natal Bight Mid Shelf Reef Sand Mosaic

534.7

5.0

 

Natal Bight Sandy Inner Shelf

145.9

1.4

 

Subtropical Estuarine Lake

1.7

0.0

 

Subtropical Large Fluvially Dominated Estuary

13.0

0.1

 

Subtropical Large Temporarily Closed Estuary

1.0

0.0

 

Subtropical Predominantly Open Estuary

2.7

0.0

Vulnerable

Durnford Mid Shelf Reef Complex

431.8

4.1

 

Natal Bight Muddy Inner Shelf

328.7

3.1

 

Natal Bight Muddy Shelf Edge

400.6

3.8

 

Natal Bight Outer Shelf Coarse Sediment Reef Mosaic

647.8

6.1

 

Natal Mixed Shore

13.9

0.1

 

Natal-Delagoa Reflective Sandy Shore

5.7

0.1

 

St Lucia Sandy Mid Shelf

496.0

4.7

 

Subtropical Small Temporarily Closed Estuary

0.5

0.0

 

uThukela Mid Shelf Coarse Sediment Reef Mosaic

789.4

7.4

 

uThukela Mid Shelf Mud Coarse Sediment Mosaic

1348.7

12.7

 

uThukela Outer Shelf Muddy Reef Mosaic

531.8

5.0

Near Threatened

Natal Exposed Rocky Shore

0.7

0.0

 

Natal-Delagoa Intermediate Sandy Shore

23.3

0.2

 

uThukela Canyon

417.8

3.9

Least Concern

Natal-Delagoa Dissipative-Intermediate Sandy Shore

12.2

0.1

 

Southwest Indian Mid Slope

0.8

0.0

 

Southwest Indian Upper Slope

2281.4

21.5

 

St Lucia Sandy Inner Shelf

31.6

0.3

Grand Total

 

10599.8

100.0


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