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

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EBSA overview

The 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 habitat types and supports some species known to exist in few localities. Cool productive water is advected onto the shelf through Agulhas- 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. Endangered habitat types occur in this area, with the remaining portions of such habitats in good condition.

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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 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 habitat types and supports some species known to exist in few localities. Cool productive water is advected onto the shelf through Agulhas- 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. Endangered habitat types occur in this area, with the remaining portions of such habitats in good condition.

 

Introduction of the area

The 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 habitat types and supports some species known to exist in few localities. Cool productive water is advected onto the shelf through Agulhas- 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. Endangered habitat types occur in this area with the remaining portions of such habitats in good condition. 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).

Since the original description and delineation, the boundary of the EBSA has been revised to improve precision and better represent the underlying features. Importantly, the lower reaches of the uThukela River are now included because it is a key driver of the system because it is the conduit for sediment delivery to the near- and offshore ecosystems of the 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 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.

 

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 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.

 

Feature conditions and future outlook of the proposed area

The National Biodiversity Assessment 2011 (Sink et al., 2012) indicated declining condition overall in this area (based on pressure data and an ecosystem-pressure matrix) with conditions ranging from fair to poor across the overall area. Key pressures include the crustacean trawl fishery, a line fishery targeting sparids and sciaenids and 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 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.

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., 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.

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

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.

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.

 

Other relevant website address or attached documents

Summary of habitat types and threat status for the Natal Bight and uThukela River EBSA. Data from Sink et al. (2012).

Threat Status

Ecosystem Type

Area km2

Area (%)

Endangered

Natal Inshore Reef

64.4

1%

 

Natal Muddy Inshore

38.1

0%

 

Natal Muddy Shelf

391.3

3%

Endangered Total

 

493.9

4%

Vulnerable

Natal Canyon

314.8

3%

 

Natal Mixed Shore

16.0

0%

 

Natal Sandy Inshore

673.4

6%

 

Natal Sandy Shelf

3,908.6

33%

 

Natal Shelf Reef

224.7

2%

 

Natal-Delagoa Intermediate Sandy Coast

79.6

1%

 

Natal-Delagoa Reflective Sandy Coast

18.8

0%

Vulnerable Total

 

5,235.9

44%

Least Threatened

Natal Exposed Rocky Coast

0.1

0%

 

Natal Gravel Shelf

312.2

3%

 

Natal Sandy Shelf Edge

1,189.5

10%

 

Natal Shelf Edge Reef

4.9

0%

 

Natal-Delagoa Dissipative-Intermediate Sandy Coast

55.5

0%

 

Natal-Delagoa Estuarine Shore

5.7

0%

 

Southwest Indian Upper Bathyal

4,540.4

38%

Least Threatened Total

 

6,108.3

52%

Grand Total

 

11,838.1

100%

 

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: 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 habitat types in the area, as well as a submarine canyon (Natal) 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 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 Natal Bight (e.g., Bull shark – Carcharhinus leucas, Sand tiger shark – Carcharias taurus, Black musselcracker – Cymatoceps nasutus, and King mackerel – Scomber japonicas). The 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 Natal Bight and uThukela River contains at least 11 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), and bearded goby (Taenioides jacksoni). There are also endemic sparids of conservation concern: Polysteganus coeruleopunctatus, as well as Near Threatened loggerheads (Caretta caretta).

Ten threatened habitat types in the Natal Bight and uThukela River include: the Endangered Natal muddy shelf and Natal inshore reef; and Vulnerable Natal Shelf Reef, Natal sandy shelf, Natal canyon, and Pelagic habitat Cb3 (Haupt 2010, Sink et al., 2011).

 

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

Justification

The 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 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 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 Natal Bight and uThukela River, particularly of the benthic communities which dominate the local food webs (Scharler et al., 2016).

 

C6: Biological diversity Medium

Justification

There is fairly high habitat heterogeneity in the Natal Bight and uThukela River, as indicated by selection in two systematic conservation plans (Ezemvelo KZN Wildlife 2012, Sink et al., 2011), and new evidence of diverse demersal fish communities in the area (Fennessey 2016).

 

C7: Naturalness Medium

Justification

The National Biodiversity Assessment highlighted that 73% of the area was in good condition and 14% in fair condition (Sink et al., 2012).

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