South African Wetlands: Classification ofEcosystem Types

Dean J Ollis, Jennifer A Day, Namhla Mbona, and John A Dini

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Classification Systems Currently in Use in South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Marine Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Estuarine Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Inland Aquatic Ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Cross-References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

AbstractThis article describes the classification of marine, estuarine, and inland aquaticecosystems, including but not restricted to “true” wetlands as per the narrowdefinition (as in the South African National Water Act) and discusses recentdevelopments in the classification of aquatic ecosystems in South Africa. Marine,estuarine and inland aquatic ecosystems tend to be dealt with separately in SouthAfrica; it is thus not surprising that separate classification systems have beenindependently developed in the country for these broad groups of aquatic eco-systems. Significant progress has been made in the classification of marine,estuarine and inland aquatic ecosystems in South Africa, especially in the pastten years. Much of this advancement has been spurred on by national biodiversity

D.J. Ollis (*)Freshwater Research Centre, Cape Town, South Africae-mail: dean.ollis@gmail.com

J.A. DayFreshwater Research, Department of Biological Sciences, University of Cape Town, Cape Town,South Africa

N. Mbona • J.A. DiniSouth African National Biodiversity Institute, Pretoria, South Africa

# Springer Science+Business Media Dordrecht 2016C.M. Finlayson et al. (eds.), The Wetland Book,DOI 10.1007/978-94-007-6172-8_334-1

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assessments and the rollout of a number of regional systematic conservationplanning initiatives across the country. One of the biggest challenges, and oppor-tunities, that has arisen out of the independent development of separate classifi-cation systems for marine, estuarine and inland aquatic ecosystems in SouthAfrica over the past few years is the possibility of developing an integratedclassification system for all aquatic ecosystems in the country.

KeywordsClassification • Typing • South Africa • Aquatic ecosystems

Introduction

In many countries, the term “wetland” is defined more restrictively than in theRamsar definition, usually with specific reference to the presence of saturated soilsand/or hydrophytic vegetation. In South Africa, as a case in point, the definition ofwetlands in the National Water Act is “... land which is transitional betweenterrestrial and aquatic systems, where the water table is usually at, or near thesurface, or the land is periodically covered with shallow water and which land innormal circumstances supports, or would support, vegetation adapted to life insaturated soil” (Republic of South Africa 1998). The prolonged (permanent orperiodic) presence of water, on the land surface or in the soil, is a fundamentalfeature of wetlands, even when narrowly defined as above. An aquatic ecosystemcan be defined as “an ecosystem that is permanently or periodically inundated byflowing or standing water, or which has soils that are permanently or periodicallysaturated within 0.5 m of the soil surface” (after Ollis et al. 2013). Despite beinglegally or otherwise viewed as transitional systems, wetlands in South Africa areconsidered to be a type of aquatic ecosystem (where “aquatic” implies relating to,consisting of, or being in, water) and are classified as such. Wetlands, whetherdefined broadly (as per the Ramsar Convention, for example) or more narrowly(to exclude rivers and permanent standing waterbodies, for example), are generallytaken to exclude deep marine waters.

This article describes the classification of marine, estuarine, and inland aquaticecosystems, including but not restricted to “true” wetlands as per the narrowdefinition (as in the South African National Water Act), and discusses recentdevelopments in the classification of aquatic ecosystems in South Africa. Some ofthe future challenges and opportunities relating to the classification of wetlands andother aquatic ecosystems are alluded to.

Classification Systems Currently in Use in South Africa

Marine, estuarine, and inland aquatic ecosystems tend to be dealt with separately inSouth Africa. For example, there is separate (but overlapping) legislation, differentgovernment departments, different tertiary qualifications, and different scientific

2 D.J. Ollis et al.

specialists for each of these. It is thus not surprising that separate classificationsystems have been independently developed in the country for these broad groups ofaquatic ecosystems.

The primary criterion for differentiating between Marine, Estuarine, and InlandSystems is the degree of connectivity with the ocean, as explained in these definitions:

• Marine Systems are aquatic ecosystems that form part of the open ocean, rangingfrom deep water to the coastline, characterized along their landward edge byexposure to wave action and tidal fluctuations.

• Estuarine Systems are partially enclosed, permanent water bodies that are eithercontinuously or periodically open to the sea on decadal timescales, extending asfar as the upper limit of tidal action or penetration of salinity (after Van Niekerkand Turpie 2012).

• Inland Systems are aquatic ecosystems with no existing connection to the ocean,characterized by the complete absence of marine exchange and/or tidal influence(after SANBI 2009; Ollis et al. 2013).

Marine Ecosystems

In 2011, the South African National Biodiversity Institute (SANBI) developed anupdated classification system for marine and coastal habitats in South Africa, andthis system was subsequently used in the marine and coastal component of the 2011National Biodiversity Assessment (NBA) (Sink et al. 2012). According to thisclassification system (Table 1), at a broad level, Marine Systems can be dividedinto “offshore” areas, “inshore” areas, and “the coast.” Offshore areas include the“offshore pelagic” and “offshore benthic” zones, while the inshore zone consists ofareas with “rocky” or “unconsolidated” substrate. The coast is divided into areas of“rocky coast,” “mixed coast,” and “sandy coast.”

Wave exposure, grain size, geology, and/or beach state are taken into account tofurther subdivide the above-mentioned categories into a total of 14 broad marineecosystem groups. Biogeographical differences (based on the delineation of marine“ecozones” and “ecoregions”) can then be used, in combination with these broadecosystem groups, to regionalize the classes. This results in a total of 136 marine andcoastal habitat types for South Africa, of which 41 represent shallower habitats (<5 mdeep) where marine and coastal wetlands could occur (as highlighted in Table 1).

Estuarine Ecosystems

One of the most widely used classification systems for estuarine ecosystems inSouth Africa to date is that of Whitfield (1992). For example, it was used in theestuary component of the 2004 National Spatial Biodiversity Assessment (Turpie2005). Five types of estuaries are recognized, primarily on the basis of landform andhydrodynamics, namely:

South African Wetlands: Classification of Ecosystem Types 3

Table

1Schem

aticillustratingthehierarchicalclassificatio

nof

coastaland

marinehabitattyp

esinSou

thAfrica.Num

bersof

habitattyp

esineach

catego

ryareshow

nin

parenthesis,

andshallower

habitats

(<5m

deep)where

marine/coastalwetland

scouldoccurarehigh

lighted

ingreen

(Adapted

from

Sinketal.2

012)

4 D.J. Ollis et al.

1. Estuarine Bay2. Permanently Open Estuary3. River Mouth4. Estuarine Lake5. Temporarily Open Estuary

One of the problems with this typology is that most estuaries in South Africa fallinto the “temporarily open/closed estuary” category, with 75 % of the 259 mappedestuaries along the coast being of this type. More recently, the classification systemfor the Estuary component of the 2011 NBA (Van Niekerk and Turpie 2012) was,therefore, based on a different approach that takes into account the following fourkey physical features:

1. Estuary size – large (>100 ha), medium (100–10 ha) or small (<10 ha)2. Mouth state – permanently open or temporarily open/closed3. Salinity structure – fresh or mixed4. “Catchment type” – turbid, black or clear (referring to the dominant color and/or

turbidity of the inflowing river(s))

In the NBA 2011, the categorization of these features was combined with thecategorization of the biogeographical region (Cool Temperate vs. Warm Temperatevs. Subtropical), to derive a total of 46 estuarine ecosystem types for South Africa.

The classification of estuarine ecosystems, following either of the above-mentionedsystems, does not in itself distinguish between those portions of an estuary that mightbe considered to be wetlands (as per the “narrow” definition of the National Water Act)and those that would not. Such a distinction can only be made through the delineationof habitat types within an estuary. For the mapping of estuarine habitats in the NBA2011 (Van Niekerk and Turpie 2012), the following estuarine habitat types weredistinguished: water surface (estuary channel), sand and mudflats, rock, and a numberof plant community types (intertidal/subtidal macroalgae, submerged macrophytes,intertidal/supratidal salt marsh, reeds and sedges, mangroves, and swamp forest). Mostof these habitat types would qualify as estuarine wetlands, except for the “watersurface” (or at least the deeper portions of this) and “rock” habitats. Interestingly,these non-wetland habitat types together make up approximately 60 % of the totalextent of estuarine habitat mapped for the whole country (Van Niekerk and Turpie2012), which implies that approximately 40% of the total estuarine habitat potentiallyrepresents “true” wetlands of one kind or another.

Inland Aquatic Ecosystems

Inland aquatic ecosystems include rivers, open waterbodies (permanently inundatedlentic systems), and wetlands. Most historical attempts to develop a nationallyapplicable classification system for wetlands and other inland aquatic ecosystemsin South Africa followed the so-called Cowardin approach to wetland classification

South African Wetlands: Classification of Ecosystem Types 5

(after Cowardin et al. 1979), which is based on the use of structural features todistinguish between primary types of aquatic ecosystems. In recent years, thedevelopment and use of classification systems based on the so-calledhydrogeomorphic (HGM) approach to classification (after Brinson 1993) hasbecome widespread in South Africa, particularly for inland wetlands in the “narrow”sense of the word.

In 2005, the Water Research Commission and SANBI initiated a project todevelop a classification system for the South African National Wetland Inventory.One of the specific requirements for the classification system was that it had to caterfor the broad suite of “wetlands” as defined by the Ramsar Convention, includingestuarine and shallow marine systems. A prototype classification system was ini-tially produced (Ewart-Smith et al. 2006), followed by further development andrefinement (SANBI 2009). The refined version was used in the National FreshwaterEcosystems Priority Areas (NFEPA) project (Nel et al. 2011) and the “freshwater”component of the NBA 2011 project (Nel and Driver 2012).

The resulting classification system is six-tiered (see Fig. 1), progressing fromSystems (Marine vs. Estuarine vs. Inland) at the broadest spatial scale (Level 1),through to HGM Units (Level 4) as the core units of classification. “Secondarydiscriminators” can be applied at Level 5 to classify the tidal/hydrological regime ofan HGM Unit and “descriptors” at Level 6 to categorize a range of biophysical andchemical attributes.

PR

IMA

RY

DIS

CR

IMIN

AT

OR

S

SECONDARYDISCRIMINATORS

(Spatial Framework)

DESCRIPTORS (to categorise characteristics/features of wetlands and other aquatic ecosystems)

GEOLOGY(LITHOLOGY)

NATURAL vs.ARTIFICIAL

SUBSTRATUMTYPE

LEVEL 1:SYSTEM

LEVEL 2:REGIONAL SETTING

LEVEL 3:SUBSYSTEM/

LANDSCAPE UNIT

LEVEL 4:HYDROGEOMORPHIC UNIT

LEVEL 5: TIDAL /HYDROLOGICAL REGIME

LEVEL 6: DESCRIPTORS

FUNCTIONAL UNIT

VEGETATIONCOVER TYPE

SALINITY pH

Connectivity toopen ocean

Physiographic &biogeographic features

- Permanence of connection to ocean [Estuarine Systems]- Landscape setting [Inland Systems]

Landform &hydrology/hydrodynamics

- Tidal regime [Marine / Estuarine Systems]- Perenniality [Rivers]- Inundation/saturation period[Inland Systems, exceptrivers]

Fig. 1 Conceptual overview of the classification system for wetlands and other aquatic ecosys-tems, showing how “primary discriminators” are applied up to Level 4 to classify Hydrogeomorphic(HGM) Units, with “secondary discriminators” applied at Level 5 to classify the tidal/hydrologicalregime, and “descriptors” applied at Level 6 to categorize the biophysical characteristics of systemsclassified up to Level 5 (From SANBI 2009)

6 D.J. Ollis et al.

The seven primary HGM types at Level 4 are the focal point of the SANBIclassification system for inland aquatic ecosystems, together with the hydrologicalregime at Level 5 if this is known (Fig. 2; SANBI 2009; Ollis et al. 2013). Theprimary HGM types were derived from the HGM types recognized in the widelyused WET-Health tool for assessing the present ecological condition (Macfarlaneet al. 2007; Kotze et al. 2012) and WET-EcoServices tool for assessing the ecosys-tem services (Kotze et al. 2007) of palustrine inland wetlands in South Africa, with“rivers” and “wetland flats” introduced as additional HGM types. Levels 2 and 3 ofthe SANBI classification system provide the broad regional context and landscapesetting for an inland aquatic ecosystem, while the “descriptors” at Level 6 provide amore detailed description of the characteristics of a particular HGM Unit or “Func-tional Unit.” A Functional Unit is an HGM Unit and its hydrological regime, takentogether to describe the functional characteristics of a particular portion of an inlandaquatic ecosystem (e.g., a “seasonally inundated, permanently saturateddepression”).

The primary HGM types for inland aquatic ecosystems (Fig. 3) can be split intomore refined HGM Units (according to Table 2), if required. This would assist, forexample, in distinguishing between “exorheic” and “endorheic” depressions.

Level 5 of the SANBI classification system for inland aquatic ecosystems pro-vides for the categorization of the hydrological regime and of the inundation depth-class for permanently inundated systems. The classification of the hydrologicalregime is dealt with differently for rivers than for the other six HGM types.The flow regime (i.e., perenniality) is taken as the major discriminator for thehydrological regime of rivers, whereas the inundation and saturation period (togetherconstituting the hydroperiod) are taken as the major discriminating factors for other

Fig. 2 Illustration of the conceptual relationship of primary HGM types (at Level 4A) to the higherand lower levels of the classification system for inland aquatic ecosystems (Aadapted from SANBI2009)

South African Wetlands: Classification of Ecosystem Types 7

HGM types (see Table 3). For permanently inundated systems (i.e., openwaterbodies), two depth classes are included at Level 5C to allow for the categori-zation of the maximum depth of inundation. A depth of 2 m (at the average annuallow-water level of an open waterbody) has been used to separate deeper “limnetic”systems from shallower “littoral” systems, thus allowing for a distinction between“deepwater habitats” (sensu Cowardin et al., 1979), such as lakes or reservoirs, andmore shallowly inundated areas where emergent vegetation tends to occur. This isoften an important distinction to make because littoral systems/habitats are morelikely to be “true” wetlands, in the “narrow” understanding of the term.

One of the important distinctions that can be made at Level 6 is between“artificial” and “natural” inland aquatic ecosystems, using the “naturalvs. artificial” descriptor. The application of this descriptor is particularly importantif the classification system is to be used for biodiversity/conservation planninginitiatives.

A User Manual for the SANBI classification system for inland aquatic ecosys-tems (Ollis et al. 2013) provides illustrated, practical guidelines for applying thedifferent levels of the system. It also includes a comprehensive glossary and a seriesof dichotomous keys for identifying HGM Units, Landscape Units, and the hydro-logical regime. A peer-reviewed paper has also been published (Ollis et al. 2015)describing the classification system and its development.

Fig. 3 Illustration of the seven primary HGM types for inland aquatic ecosystems and their typicallandscape settings (By Andrew “Chip” Snaddon, from Ollis et al. 2013)

8 D.J. Ollis et al.

Conclusions

Significant progress has been made in the classification of marine, estuarine, andinland aquatic ecosystems in South Africa, especially in the past ten years. Much ofthis advancement has been spurred on by national biodiversity assessments

Table 2 Hydrogeomorphic (HGM) Units for inland aquatic ecosystems at Level 4 (From Olliset al. 2013, 2015)

South African Wetlands: Classification of Ecosystem Types 9

(undertaken in 2004 and 2011) and the rollout of a number of regional systematicconservation planning initiatives across the country. The classification system forinland aquatic ecosystems described in this article was, as a case in point, applied tothe National Wetland Map generated through the National Wetland Inventory in anautomated manner (using GIS modeling) to derive wetland ecosystem types. Thesewetland ecosystem types represent a “wetland vegetation group” derived from thegrouping of vegetation types from the most recent national vegetation map forSouth Africa (Mucina and Rutherford 2006) (as determined at Level 2 of theclassification system), together with an HGM type (as determined at Level 4A ofthe classification system), in an attempt to depict the diversity of wetland ecosystemsacross the country. The NFEPA project used the wetland ecosystem types that werederived in this manner as the basis for identifying Freshwater Ecosystem PriorityAreas (FEPAs) to meet national biodiversity goals for freshwater ecosystems (Nelet al. 2011), while the freshwater component of NBA 2011 used them as the basis for

Table 3 Hydroperiod and inundation depth-class categories for inland aquatic ecosystemsother than rivers, at Level 5 of the classification system (From Ollis et al. 2013, 2015)

10 D.J. Ollis et al.

categorizing, for the first time ever, the degree of threat to wetland ecosystems acrossthe country. A rather disturbing finding of NBA 2011 was that 65% of the wetlandecosystem types derived using the classification system for inland aquatic ecosys-tems are threatened, making wetlands the most threatened of all ecosystems in thecountry (Nel and Driver 2012). The NFEPA maps have been used in the determina-tion of management classes and the setting of resource quality objectives for inlandwater resources, as required in terms of the Resource Directed Measures of theNational Water Act (Republic of South Africa 1998). It is envisaged that theclassification system for inland aquatic ecosystems will also enable the mapping ofwetlands as “ecological infrastructure,” by allowing the actual or potential provisionof particular ecosystem services by individual wetlands to be inferred from thehydro-geomorphological information contained in the classification.

One of the biggest challenges, and opportunities, that has arisen out of theindependent development of separate classification systems for marine, estuarine,and inland aquatic ecosystems in South Africa over the past few years is thepossibility of developing an integrated classification system for all aquatic ecosys-tems in the country. Such a classification system could build on the initial efforts bySANBI (2009) to create a structural framework for an integrated classificationsystem for marine, estuarine, and inland aquatic ecosystems, and it could incorporatesome of the advances made in the classification of these broad groups of aquaticecosystems through the NBA 2011 project.

Cross-References

▶Ramsar Definition

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