Intersection of ecosystem threat status and protection level

Estuarine realm

Lara van Niekerk1, 2 , Andrew L. Skowno3 , Kerry Sink3, 2 , Linda R. Harris2

1. Council for Scientific and Industrial Research

2. Nelson Mandela University

3. South African National Biodiversity Institute

Published

December 5, 2025

In the Estuarine realm, 32% of ecosystem types are both highly threatened and under-protected, these types are prevalent in the Cool Temperate and Subtropical biogeographical regions.

The Mbashe Estuary is representative of the threatened and under protected Large Fluvially Dominated ecosystem type currently classified as endangered. The Mbashe Estuary is one of the few estuaries contributing ecosystem type targets for a type that is in dire need of increased protection and management interventions. (© Nelson Mandela Univeristy)

Highly threatened and under-protected ecosystem types

In the Estuarine realm, 32% of ecosystem types are both highly threatened and under-protected. These types are prevalent in the Cool Temperate and Subtropical biogeographical regions, namely:

  • Cool Temperate Estuarine Lakes (Verlorenvlei, Zeekoei, Bot/Kleinmond, Klein)
  • Cool Temperate Large Fluvially Dominated (Orange)
  • Cool Temperate Predominantly Open (Olifants, Groot Berg, Uilkraals)
  • Cool Temperate Arid Predominantly Closed (Buffels, Swartlintjies, Spoeg, Groen, Sout (Noord), Wadrift)
  • Cool Temperate Large Temporarily Closed (Jakkals, Diep/Rietvlei, Sout (Wes), Disa, Wildevoëlvlei, Silwermyn, Zand, Eerste, Palmiet)
  • Subtropical Estuarine Bay (Durban Bay)
  • Subtropical Large Fluvially Dominated (Mbashe, Mzimvubu, uMvoti, uThukela, iMfolozi/uMsunduze)
Figure 1. Map of threatened and under-protected ecosystem types (size of the dot represents area of the individual estuary). The inset graph shows the number and proportion of ecosystem types that fall within each combined threat status and protection level category.
Table 1. Table summarising protection levels and threat status categories for the highly threatened and underprotected ecosystem types.
Threat status Not Protected Poorly Protected
Critically Endangered Subtropical Estuarine Bay
Endangered Cool Temperate Predominantly Open
Endangered Cool Temperate Arid Predominantly Closed
Endangered Cool Temperate Estuarine Lake
Endangered Cool Temperate Large Fluvially Dominated
Endangered Cool Temperate Large Temporarily Closed
Endangered Subtropical Large Fluvially Dominated

Highly threatened and under-protected ecosystem types are candidates for improved protection through formal protected areas expansion or other spatial management measures such as stewardship or Other Effective area-based Conservation Measures (OECMs).

In addition to the expansion of protection of these ecosystem types, it is important to improve ecosystem condition through flow restoration, management of pollution (wastewater, agricultural return flow or stormwater), reduced fishing pressure, restoration of degraded habitats, removal of invasive alien plants, and effective artificial breaching (where required).

Technical documentation

Code repositories

Protection level assessment: Skowno, A.L. 2025. SANBI-NBA Estuary ecosystem protection level [Source code]. GitHub repository available at https://github.com/askowno/EPL_est

Threat status assessment: Skowno, A.L. 2025. SANBI-NBA Estuary ecosystem threat status [Source code]. GitHub repository available at https://github.com/askowno/RLE_est.