Aquatic invertebrate assessment of the Seekoeivlei Nature Reserve

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Aquatic invertebrate assessment of the

Seekoeivlei Nature Reserve

E Lubbe

orcid.org 0000-0002-6693-5760

Dissertation submitted in fulfilment of the requirements for the

degree

Master of Science in Environmental Sciences

at the

North-West University

Supervisor:

Dr CW Malherbe

Co-supervisor:

Prof V Wepener

Graduation May 2018

23441852

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ACKNOWLEDGEMENTS

I would like to acknowledge and extend my sincere gratitude to the following people and organisations who assisted me in various ways:

Firstly, I would like to thank my Heavenly Father for His love, grace and mercy throughout this study.

 My supervisor, Dr. Wynand Malherbe for granting me with this opportunity and for helping me in the field and laboratory and always having an open door, valuable insight and guidance.

 My co-supervisor, Prof Victor Wepener for always making time to respond to any questions and to read through my dissertation when there was no time.

 Ms. Anja Greyling, my friend who helped so much with fieldwork, assisted with creating the study area maps and assisted in formatting and support.

 Mr. Hannes Erasmus, my friend for his assistance with sampling and identification of aquatic macroinvertebrates.

 Ms. Jana Klem, for her assistance with sampling and unconditional support.  Ms. Lizaan de Necker, for her help with the identification of zooplankton

specimens and assistance in proofreading and formatting.

 Seekoeivlei Nature Reserve for allowing us to sample within the reserve.  The North-West University for use of laboratory equipment.

 The financial assistance of the Water Research Commission.

 Mr. Jonathan Joubert for his assistance in formatting and proofreading and for his unconditional support, understanding and patience.

 My parents, Pieter and Ria Lubbe, I thank both of them for their unconditional love and support.

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SUMMARY

The maintenance of wetlands is greatly encouraged because of their importance in the hydrological cycle and the habitat they provide for a variety of organisms. Wetlands are known for their connection between the terrestrial and aquatic environments that leads to a habitat of which certain organisms depend on for survival. The Ramsar Convention was originally adopted for the preservation of birds, their migratory routes and breeding areas that depends on wetland environments. Later the spectrum was broadened to preserve all aspects of wetlands as well as to encourage the wise use of wetlands. The Seekoeivlei Nature Reserve is one of the 23 wetlands that is designated as a Ramsar Wetland of International Importance in South Africa. The Seekoeivlei Wetland as a whole cover approximately 12 000 hectares and consists of approximately 220 oxbows formed by the meandering of the Klip River in the Frees State Province. The Seekoeivlei Wetland is considered important because of the Klip River, being an important tributary of the Vaal River. The Vaal River supplies the majority of water to the main industrial areas in Gauteng Province. However, very little is known about the aquatic biodiversity of the Seekoeivlei Wetland. Therefore, the aim of this research project was to establish the diversity, community structure and the distribution of the zooplankton and aquatic macroinvertebrates of the Seekoeivlei Nature Reserve.

Water and sediment samples were collected from 21 selected sites located throughout the Seekoeivlei Nature Reserve and just outside of the reserve. Zooplankton and aquatic macroinvertebrate samples were collected from 17 of the 21 selected sites whereas the remaining sites only water and sediment samples were collected. All samples were collected during three seasonal surveys in July 2016 (winter), December 2016 (summer) and March 2017 (autumn). Water and sediment samples were collected

in situ and transported back to the laboratory for further analyses. Water samples were

analysed to determine nutrient and metal concentrations. Sediment analyses were conducted to determine particle size, percentage organic and metal concentrations. Water and sediment samples showed natural levels of nutrients and sediment present in the Seekoeivlei Wetland.

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on the distribution of the zooplankton, but statistical analyses showed no significant differences between the various seasons. Wetland type were also hypothesised to have an impact on the zooplankton distribution and communities, and it was found that the majority zooplankton taxa were rather present in the oxbow and pan sites than in the river. A total of 87 macroinvertebrate taxa from 51 families and 14 orders were identified during this study. The zooplankton and macroinvertebrate diversity are potentially greater as many of the invertebrates could not be identified to species level due to inadequate keys. Functional feeding groups within the macroinvertebrate communities showed that the most abundant groups were the predators and grazers.

This study was successful in identifying and describing the diversity of zooplankton and aquatic macroinvertebrates present in the Seekoeivlei Nature Reserve. This project provided updated information regarding the aquatic invertebrate diversity that could potentially feed into the management plan as well as increasing the understanding of this dynamic ecosystem.

Keywords: Ramsar, Seekoeivlei Nature Reserve, floodplain wetland, water quality,

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LIST OF FIGURES

Figure 1.1: Map of South Africa with the 23 designated Ramsar sites. Figure 1.2: Regional setting of the town Memel in the Free State. Figure 2.1: Rainfall data of the Free State from 2012 - 2016

(www.dwa.gov.za/Hydrology/Provincial rain/Default.aspx) Figure 2.2: Conceptual overview of the classification system for wetland

ecosystems (Ollis et al., 2015).

Figure 2.3: Different land uses present in the study area of the Seekoeivlei Nature Reserve and Klip River during sampling surveys.

Figure 2.4: Map of the Seekoeivlei Nature Reserve with the selected sitesduring this study.

Figure 3.1: Physico-chemical water quality variables measured at the Seekoeivlei Nature Reserve for sampling surveys from 2016 – 2017 using spatial samples as replicates. Bars and error bars represent mean and standard error from each site (n=3).

Figure 3.2: Physico-chemical water quality variables measured at the Seekoeivlei Nature Reserve for sampling surveys from 2016 – 2017 using temporal samples as replicates. Bars and error bars represent mean and standard error from each site (n=21).

Figure 3.3: Water nutrient variables from selected sites in the Seekoeivlei Nature Reserve during winter (July, 2016), summer (December, 2016) and autumn (March, 2017). Bars indicate mean concentrations using temporal samples as replicates, whereas the error bars indicate the standard error (n=3).

Figure 3.4: Dissolved metal concentrations (µg/l) in water samples of the

Seekoeivlei Nature Reserve. Bars and error bars represent the mean and standard error of the concentrations from 2016 to 2017.

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variance on the first axis and a further 19.21% of variance on the second axis. (DO – dissolved oxygen; EC – electrical conductivity). Figure 3.6: Sediment grain size distributions (percentages) of the Seekoeivlei

Nature Reserve for winter (July 2016), summer (December 2016) and autumn (March 2017) sampling surveys. Sites with no bars present is the sites where no samples were collected. Bars and error bars represent the mean and standard error of the of the mean percentages. (> 4000 µm = gravel, 2000-4000 µm = very coarse sand, 500-2000 µm = coarse sand, 212-500 µm = medium sand, 53-212 µm = very fine sand, <53 µm = mud)

Figure 3.7: Organic content (USEPA, 2001) of sediment for the selected sites of the Seekoeivlei Nature reserve taken in winter (July 2016), summer (December 2016) and autumn (March 2017). Figure 3.7A showing temporal variation and Figure 3.7B showing spatial variation with regards to organic content. Bars and error bars represent mean and standard deviation.

Figure 3.8: Spatial variation of Al, As, Cr, Fe, Ni and Pb concentrations in the sediment (µg/g) from the Seekoeivlei Nature Reserve sampled sites. Bars and error bars represent mean and standard error of the concentrations from July 2016-March 2017 (n=3).

Figure 3.9: Spatial variation of Zn, Mn, Co, Cu and Cd concentrations in the sediment (µg/g) from the Seekoeivlei Nature Reserve sampled sites. Bars and error bars represent a mean and standard error of the concentrations from July 2016-March 2017 (n=3).

Figure 3.10: PCA bi-plot of the combined sediment quality variables of the Seekoeivlei Nature Reserve. This bi-plot explains a total of 76.46% variance, with 65.49% explained on the first axis 65.49% and 10.97% on the second axis (> 4000µm - gravel; 2000-4000 µm - Very coarse sand; 500-2000 µm – Coarse sand; 212-500 µm – Medium sand; 53-212 µm – Very fine sand; <53 µm – Mud).

Figure 4.1: Diversity indices for the zooplankton taxa sampled in the Seekoeivlei Nature Reserve from 2016 to 2017. Bars and error bars represent mean

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and standard error of the mean with the error bars indicating temporal variation. (a) Total species, (b) Total individuals, (c) Margalef’s index, (d) Pielou’s evenness index, and (e) Shannon Wiener index.

Figure 4.2: Diversity indices for the zooplankton taxa sampled in the Seekoeivlei Nature Reserve during July 2016 (winter), December 2016 (summer) and March 2017 (autumn). Bars and error bars represent mean and standard error (n=17). (a) Total species, (b) Total individuals, (c) Margalef’s index, (d) Pielou’s evenness index, and (e) Shannon Wiener index.

Figure 4.3: Non-multidimensional scaling (NMDS) plot of the zooplankton data sampled in the Seekoeivlei Nature Reserve during winter (July 2016), summer (December 2016) and autumn (March 2017).

Figure 4.4: Redundancy Analysis (RDA) plot for all sampled sites during July 2016 (winter), December 2016 (summer) and March 2017 (autumn), in the Seekoeivlei Nature Reserve. The tri-plot explains 38.68% of the total variation in the data of which 22.37% is displayed on the first axis and 16.31% is displayed on the second axis.

Figure 4.5: RDA tri-plot (interactive forward selection) for all sampled sites during winter (July 2016), summer (December 2016) and autumn (March 2017) in the Seekoeivlei Nature Reserve. This tri-plot explains 22.34% of the total data variation of which 15.13% is displayed on the first axis and 7.21% is displayed on the second axis (p value: NO3 = 0.008, NO2 =

0.048, NH4 = 0.006, temperature = 0.002).

Figure 4.6: Venn diagrams representing unique and shared contribution of water quality variables (a) and different wetland structures (b) on the zooplankton community structure and diversity. Only 37.3% of the total data are explained.

Figure 4.7: CCA plot showing species present at the different wetland types for all sampled sites during the three surveys. With 10.81% total variation

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Figure 5.1: Diversity indices for the aquatic macroinvertebrate taxa sampled in the Seekoeivlei Nature Reserve for 2016 to 2017. Bars and error bars represent mean and standard error. The replicates at each site are represented by the seasonal survey data and therefore provide indication temporal variation (n=3). (a) Total species, (b) Total individuals, (c) Margalef’s index, (d) Pielou’s evenness index, and (e) Shannon Wiener index.

Figure 5.2: Diversity indices for the aquatic macroinvertebrate taxa sampled in the Seekoeivlei Nature Reserve during July 2016 (winter), December 2016 (summer) and March 2017 (autumn). Bars and error bars represent mean and standard deviation (n=17). (a) Total species, (b) Total individuals, (c) Margalef’s index, (d) Pielou’s evenness index, and (e) Shannon Wiener index.

Figure 5.3: Non-multidimensional scaling (NMDS) plot of the macroinvertebrate taxa sampled during winter (July 2016), summer (December 2016) and autumn (March 2017) in the Seekoeivlei Nature Reserve.

Figure 5.4: Redundancy Analysis (RDA) plot showing species diversity for all the sampled sites during the three surveys (July 2016 (winter); December 2016 (summer) and March 2017 (autumn)), in the Seekoeivlei Nature Reserve. This tri-plot explains 32.81% of the total data variation of which 17.66% is displayed on the first axis and remaining 15.15% is displayed on the second axis.

Figure 5.5: RDA tri-plot (interactive forward selection) using species and water quality variables for the sampled sites during winter (July 2016), summer (December 2016) and autumn (March 2017) in the Seekoeivlei Nature Reserve. This tri-plot explains 25.97% of total variation, 15.19% on the first axis and 10.78% on the second axis (p value: temperature = 0.002, Ni = 0.004, NO2 (nitrites) = 0.004, NO3 (nitrates) = 0.01, Mg =

0.016, K = 0.01, % DO (dissolved oxygen) = 0.062).

Figure 5.6: Venn diagrams representing unique and shared contribution of water quality variables (a) and different wetland types (b) on the aquatic macroinvertebrate diversity and community structure. Only 25.1% of the total data explained.

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Figure 5.7: CCA plot for all sampled sites during the three surveys. With 9.20% total variation explained, of which 6.44% explained on the first axis and the remaining 2.76% on the second axis.

Figure 5.8: Graph of Functional Feeding Groups present in the Seekoevlei Nature Reserve from 2016 to 2017. Percentage abundance within the Functional Feeding Groups (FFG) at each site. FFG = Shredder, scraper, scavenger, predator, parasitic/predator, omnivorous, grazer, filter-feeder, collector-gatherer and carnivorous.

Figure 5.9: PCA bi-plot containing the Functional Feeding Groups in the Seekoeivlei Nature Reserve. This bi-plot explains 60.39% of the explained variation. First axis explains 36.59% and the second axis the remaining 23.80%.

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LIST OF TABLES

Table 1.1: Attributes are given as functions and services of a wetland ecosystem (Richardson, 1994)

Table 2.1: Site description of Pampoen Spruit. Table 2.2: Site description of Site 1.

Table 2.3: Site description of Site 2a Table 2.4: Site description of Site 2b.

Table 2.5: Site description of Wildemans Spruit. Table 2.6: Site description of Site 3a.

Table 2.7: Site description of Site 3b. Table 2.8: Site description of Site 3c. Table 2.9: Site description of Site 3d. Table 2.10: Site description of Site 3e. Table 2.11: Site description of Site 4a. Table 2.12: Site description of Site 4b. Table 2.13: Site description of Site 4c. Table 2.14: Site description of Site 4d. Table 2.15: Site description of Site 5. Table 2.16: Site description of Site 6. Table 2.17: Site description of Site 7. Table 2.18: Site description of Site 8. Table 2.19: Site description of Site 9. Table 2.20: Site description of Site 10a. Table 2.21: Site description of Site 10b.

Table 3.1: The classification for sediment grain size analysis (Malherbe et al., 2010; Wentworth, 1922)

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Table 3.2: Classification of organic content in sediment (USEPA, 2001).

Table 3.3: Target water quality ranges for freshwater systems in South Africa (TWQR) (DWAF, 1996).

Table 3.4: Ecological categories for the classification of Wetlands in South Africa (adapted from Malan & Day, 2012).

Table 4.1: List of the zooplankton diversity sampled in the Seekoeivlei Nature Reserve for three surveys from 2016 to 2017.

Table 4.2: The SIMPER Analysis results showing the most abundant species present during each sampling survey (contribution cut off = 70%). Showing an average similarity of 32.29% during the winter survey (July 2016), 35.84% during the summer survey (December 2016) and 44.46% during the autumn survey (March 2017).

Table 5.1: List of aquatic macroinvertebrate diversity recorded in the Seekoeivlei Nature Reserve for three surveys from 2016 to 2017

Table 5.2: SIMPER Analysis results showing the most abundant species present during each sampling survey. Season 1 showed an average similarity of 33.11% during the winter survey (July, 2016), Season 2 showed 24.90% average similarity which was during the summer survey (December 2016) and the Season 3 showed 31.73% average similarity which was during the autumn survey (March 2017).

LIST OF APPENDICES

Appendix A: Water and Sediment Quality Appendix B: Zooplankton Diversity Appendix C: Macroinvertebrate Diversity

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LIST OF ABBREVIATIONS

ANOSIM Analysis of Similarity ANOVA Analysis of Variance

ASTM American Society for Testing and Materials CCA Canonical Correspondence Analysis

DO Dissolved Oxygen

DWAF Department of Water Affairs and Forestry, South Africa EC Electrical Conductivity

FROC Fish Reference Frequency of Occurrence

FS DTEEA Free State Department of Tourism, Environmental and Economic Affairs GSM Gravel, Sand, Mud

ICP-MS Inductively Coupled Plasma Mass Spectrophotometry LHC Lateral Hydrological Connectivity

NMDS Non-metric Multidimensional Scaling PCA Principle Component Analysis

Ps Pampoen Spruit

RDA Redundancy Analysis SIMPER Similarity Percentage TDS Total Dissolved Solids TWQR Target Water Quality Range

USEPA United States Environmental Protection Agency WHO World Health Organisation

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GENERAL INTRODUCTION

1.1. INTRODUCTION

1.1.1. Wetlands

Wetlands are among the most important ecosystems on earth (Mitsch & Gosselink, 2000), and provide many functions that are valuable to the environment and society. According to USEPA (2002), these functions include the transfer- and storage of water, decomposition of organic material, production of plants and animals, communities and habitats of living creatures within the ecosystem (Mitsch & Gosselink, 2015). In order to study a wetland, one must first understand what a wetland is and distinguish between different types of wetlands.

According to Ramsar Convention Secretariat (2013), wetlands are defined as areas where water is the primary factor that controls the environment and the associated plant and animal life. Ramsar Article 2.2 (2013) states that “Wetlands should be selected for

the List on account of their international significance in terms of ecology, botany, zoology, limnology, or hydrology” and indicates that “in the first instance, wetlands of international importance to a waterfowl at any season should be included.”

Batzer & Boix (2016) define wetlands as “…those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.”

The definition provided in the South African National Water Act (No 36 of 1998) is that a wetland is a: “land that is transitional between terrestrial and aquatic systems where the

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pg. 2 1.1.2. Wetland Importance, Functions and Values

Wetlands have a great importance in the environment, which includes fish nurseries, grazing, nutrient retention and many more services and products (Davies & Day, 1998). Previously mentioned functions lead to services such as the control of flooding, the cleaning and filtering of water and even recreational values (fishing and bird watching) (USEPA, 2002). Some functions of wetlands affect the water quality of downstream systems. Wetlands tend to slow water down during flood periods which reduces the volume of water reaching downstream systems. The flow rate of water will slow down after the flooding period, which will lead to the sediments present in the water being deposited (Reddy & Gale, 1994). During sediment deposition, the chemical constituents that are associated with these sediments also become deposited and trapped. These chemical constituents (nutrients and toxicants) get degraded to simpler molecules due to the action of bacteria, fungi and protozoa which are present in the wetland systems amongst the plant roots and sediments. Biota is considered one of the factors that remove dissolved constituents from the water column (Davies & Day, 1998). Thus, wetlands have been found to be efficient at removing chemical constituents from the water column i.e. nutrients.

Richardson (1994) states that wetland values are directly derived from wetland function. According to Maltby & Acreman (2011), recognized values of the wetland must be sustainable in such a way that the resources and services it provides must support sustainable development and not degrade the wetland. Table 1.1 shows the attributes (functions) and values (services) of wetland ecosystems. These functions and values are directly involved with the water quality of a wetland.

Table 1.1: Functions and services of a wetland ecosystem (Richardson, 1994)

Functions Services

Hydrological flux and storage Flood control and flood storage Biological productivity Sediment control

Biogeochemical cycling and storage

Waste water treatment system

Decomposition Nutrient removal from agricultural runoff and wastewater systems

Community/wildlife habitat Recreation Hunting

Preservation of flora and fauna Timber production.

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the differences between every wetland ecosystem. Richardson (1994) mentions four principles to list appropriate functions and values for a specific wetland. These four principles state that every wetland must be assessed before any disturbances and include the assessments of natural and constructed wetlands with their ecological, hydrological and biogeochemical functions (Richardson, 1994). Principle one states that all wetlands are not equal with regards to functions and values. The second principle states that a constructed wetland may or may not be equal to a natural wetland in the terms of functions and values (Richardson, 1994). The third principle states that the functions and values of wetland systems and other systems on the landscape are coupled together. And the last principle states that the functions and values that wetland ecosystems provide exceed their boundaries. Only after each wetland has been thoroughly assessed, can a decision be made on the way to protect the specific wetland ecosystem.

1.1.3. The Ramsar Convention

The Convention on Wetlands was adopted in February 1971 in the Iranian city of Ramsar and is officially called The Convention on Wetlands of International Importance especially as Waterfowl Habitat. This Convention is defined as: “…an intergovernmental treaty which provides the framework for national action and international cooperation for the conservation and wise use of wetlands.” This reflects on the original emphasis on the conservation of wetlands as a habitat for waterfowl (Ramsar Convention Secretariat, 2013). Over the years the Ramsar Convention broadened its scope to the implementation of wetland conservation, which now includes all aspects of wetlands and the wise use thereof. The reason for this is that the treaty recognized wetlands as ecosystems that are vital for the conservation of biodiversity as well as the well-being of human communities. In 2013 the Ramsar Convention listed 2 060 wetlands globally, (covering 197 millions of hectares) as wetlands of international importance, which are called Ramsar sites. Today there are 2 271 wetlands listed over 169 countries with a coverage of 219 175 951 hectares (The Ramsar Secretariat, 2017).

For a wetland to be classified as a Ramsar site there are nine criteria to which it must adhere (Ramsar Convention on Wetlands, 1971). Criterion 1 is based on a wetland that

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pg. 4

support vulnerable or endangered species or threatened ecological communities, plant or animal species important for maintaining the biological diversity of a region and plant or animal species that are at a critical stage in their life cycle. Criteria 5 and 6 are based on water birds, meaning a wetland should regularly support 20 000 or more water birds and it should support 1% of the individuals in a population of one species or subspecies. Criteria 7 and 8 focus on the support of fish with regards to indigenous fish and if the wetland is an important habitat for the fish to spawn, feed and migrate. The ninth criterion is based on other taxa, meaning a wetland should support 1% of individuals in a population of one species or subspecies of “wetland-dependent non-avian animal species” (Ramsar Convention, 2013).

The Ramsar Convention in South Africa was established in December 1975. The first two sites that were designated was Barberspan in the North-West Province and De Hoop Vlei in the Western Cape Province. Currently, there are 23 sites (covering 557 028 hectares) that are designated as Ramsar Wetlands of International Importance in South Africa (Figure 1.1). The Seekoeivlei Nature Reserve is one of these Ramsar sites (declared in 1997) which covers 4 754 hectares (Ramsar Convention, 2013). The latest site, Bot – Kleinmond Estuarine System (Western Cape Province) was designated in 2017.

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Figure 1.1: Map of South Africa with the 23 designated Ramsar sites.

1.1.4. Wetlands in South Africa

In South Africa wetlands have been lost over the years due to different impacts. In certain areas such as on coastal plains, more than 50% of wetland habitats have already been lost (Shearer, 1997) and a large quantity of the remaining wetlands are under constant threat (Kotze, Breen & Quinn, 1995; Wamsley, 1988). Physical and direct impacts include draining for agriculture or forestry, urban development (e.g. the building of roads and dams), grazing, discharge of pollutants and the mining of wetland soils cause loss and degradation to/of wetlands.

The majority of research on wetlands includes bird diversity, ecosystem services such as flood attenuation and the provision of livestock grazing, the functions that wetlands

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According to Day & Malan (2010), there is a lack of research regarding aquatic biota in wetlands.

Of the 23 designated Ramsar sites, only 14 are freshwater wetlands which includes pans, freshwater lakes and floodplain wetlands. The Seekoeivlei Wetland can be classified as a floodplain depression (Ollis et al., 2015).

The Seekoeivlei Nature Reserve, near the town of Memel in the Free State (Figure 1.2), is considered important in providing ecosystem services such as water purification and flood attenuation. Furthermore, the wetland is important because it forms part of the upper reaches of the Klip River catchment, which is an important tributary of the Vaal River (Youthed, 2014). The Klip River contributes approximately 46% of surface water flow in the upper Vaal River catchment (DWAF, 2004). According to Wepener et al. (2011), the Vaal River has been described as one of the most important rivers in South Africa. It is an important source of water not only for Gauteng but also for parts of neighbouring provinces such as the Free State, North-West and Mpumalanga (Tempelhoff, 2009).

1.1.5. Seekoeivlei Nature Reserve

The Seekoeivlei Wetland is considered a Ramsar site for four reasons. Firstly, it is the only protected area in the Free State that covers Amersfoort Highveld Clay Grassland and the Eastern Temperate Freshwater Wetland veld type (McCarthy et al., 2010) which is poorly protected according to the Free State Department of Tourism, Environmental and Economic Affairs (FS DTEEA, 2008). Secondly, when looking at the interior of South Africa it is the largest protected area of wetlands (Mucina & Rutherford, 2006). Thirdly, it provides habitat for numerous plant and animal species that are threatened in the Free State Province; and lastly, this is considered an important breeding site for numerous bird species, including those that are endangered (McCarthy et al., 2010). This wetland also provides food for livestock and game during winter times.

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Figure 1.2: Regional setting of the town Memel in the Free State.

Before Seekoeivlei was declared as a nature reserve in 1978 (McCarthy et al., 2010), the wetland was impacted by artificial drainage channels because of commercial farming. These human interventions had an impact on wetland geo-hydrological processes that led to the decrease in function and integrity of the Seekoeivlei Wetland (Youthed, 2014). Dirt roads that run through the wetland were also identified to cause erosion or sedimentation of the wetland (Zabala, 2008).

The Seekoeivlei Wetland is approximately 16 km long and varies in width from a few hundred meters up to 2 km in places (McCarthy et al., 2010). In the Wetland Rehabilitation Plan completed by Youthed (2014) the study looked at hydrology, geomorphology, and vegetation, with no research on the aquatic micro- and macroinvertebrate assemblages.

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comparing wetlands and rivers, the water chemistry differs, spatially and temporally (Malan & Day, 2012). Rivers are sources of sediment while wetlands are sinks. Furthermore, wetlands are accumulating systems meaning it will have an impact on water quality through the accumulation of sediments. According to Malan & Day (2012), nutrient levels that can be the cause of eutrophication is important in accumulation systems and is the reason why there is a poor understanding of the water quality of wetlands in South Africa, whether under natural or impacted conditions. A few main factors that indeed have an influence on the water quality of wetlands is the water source, drainage pattern, residence time and inundation depth of the wetland (Malan & Day, 2005).

Water sources of a wetland can vary from an underground spring to overland run-off. The shorter the retention of water, the less evaporation will occur; and salts and other constituents cannot concentrate. The length of residence time of the water has an influence on the period of time that the water is in contact with the sediment (Malan & Day, 2005) i.e. the time that it takes for exchange processes between the water column and sediments. According to Malan & Day (2012), nitrogen in organic matter can be changed when there are lower water levels, which causes the surrounding substrate to become more aerated, which leads to an increase in decomposition.

1.1.7. Sediment quality

De Klerk et al. (2012) mention stressors such as metal contamination and nutrient enrichment have a direct impact on water and sediment quality in wetlands. Not only water quality is affected by pollutants but the sediment quality as well (Malan & Day, 2012). Sediments can be regarded as a sink for contaminants such as metals and sometimes sediments contain higher concentrations of pollutants than the surrounding water body (de Klerk et al., 2012).

According to Karbassi et al. (2007), the deposition of contaminants such as metals have the potential to be toxic to aquatic biota. Sediments play an important role in the adsorption of metals and can be a potential reservoir for metals that can influence water quality. Metals and pollutants not only bind to sediments but to organic matter too, which can change the chemical and physical conditions of sediments (de Klerk et al., 2012).

Grain size is considered as a fundamental property of sediments of its effect on the transport and depositing properties of sediment particles (Blott & Pye, 2001). Organic

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matter is another factor to be included in the analyses since organic content of sediment is an important factor that determines the sorption potential of the system (Schorer, 1997).

1.1.8. Aquatic invertebrates

Aquatic invertebrates are found in freshwater rivers and wetlands and live either in or on the bottom substrate, swim in the water column or live on the surface of the water (Suren & Sorrell, 2010). According to Batzer & Boix (2016), ecologists tend to focus on groups of invertebrates, i.e. microinvertebrates (or zooplankton) and macroinvertebrates. Although zooplankton of wetlands are not as well studied as macroinvertebrates, both groups are important food sources and an important component for a healthy ecosystem.

According to Ferreira et al. (2012), the most prominent feature of wetland ecosystems, are the aquatic invertebrate communities (zooplankton and macroinvertebrates). The invertebrate communities are considered as very important because they are regarded as possible indicators of the ecological integrity of wetlands (Bird & Day, 2009). They can provide insight into seasonal variation in biological assemblages and the ecological services that the wetland can provide (Chipps et al., 2006). Distribution of invertebrates in wetlands can also be affected by the vegetation present. Biotopes with more vegetation tend to contain higher invertebrate diversity than more open-water biotopes (Bird et al., 2014).

1.2. PROBLEM STATEMENT

It is said that floodplain wetlands, with associated biota, are important for the biota in rivers that specifically depend on the link between the two wetland structures, i.e. floodplain wetland and river (Malherbe et al., 2015). However, little information is available in South Africa to support this statement. Recent studies of floodplain wetlands in South Africa include the Phongolo floodplain (Dube et al., 2017) and the floodplain wetlands associated with the Harts River (Malherbe et al., 2015). In both these studies the importance of the link between the river and the wetland system was demonstrated.

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include physical studies on the hydrology and geomorphology (Tooth et al., 2002). Biotic studies are limited to bird diversity and nematode diversity.

There is thus a need to obtain baseline information on the Seekoeivlei Wetland and the associated Klip River. This information will be important for future management and monitoring actions in the reserve.

1.3. HYPOTHESIS

The following hypotheses will be tested during this study:

Water and sediment quality has an influence on the aquatic invertebrate diversity of the Seekoeivlei Nature Reserve.

Aquatic invertebrate diversity will show seasonal variation in the Seekoeivlei Nature Reserve.

Different wetland types have an influence on the community structure of the aquatic invertebrate diversity.

1.4. AIMS AND OBJECTIVES

The aims of this study were to determine the changes in water and sediment quality together with the aquatic invertebrate diversity (zooplankton and macroinvertebrates) in relation to hydrological regime and inundation of the floodplain wetlands. To achieve these aims the following objectives were set:

1. The assessment of the water and sediment quality of the Seekoeivlei Wetland during three surveys representing three different hydrological periods.

2. Determine the zooplankton and aquatic macroinvertebrate diversity of the Seekoeivlei Wetland during three surveys representing three different hydrological periods.

3. Relating water and sediment quality together with hydroperiod to changes in different wetland types in the Seekoeivlei Wetland.

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1.5. CHAPTER BREAKDOWN

Chapter 1: General introduction: contains the introduction to wetlands, importance of

the wetlands, overview of the Ramsar Convention and introductory comments on important aspects of the study. The problem statement, aims, objectives and hypotheses are presented for the project.

Chapter 2: Study area and site selection: the available information on the Seekoeivlei

Nature Reserve will be reviewed as well as the classification of the wetland. The 21 selected sites will be described in terms of habitat availability and wetland type.

Chapter 3: Water and sediment analysis: in this chapter the methodology of sample

collection, results and analyses of the water and sediment in the Seekoeivlei Nature Reserve is provided. The spatial and temporal data results are discussed.

Chapter 4: Zooplankton diversity: this chapter includes the methodology of the

zooplankton sample collection, results and analyses of the Seekoeivlei Nature Reserve. Results include graphic representations of the statistical analyses. The spatial and temporal trends in community structure are discussed.

Chapter 5: Macroinvertebrate diversity: methods used to collect and identify the

macroinvertebrates in the Seekoeivlei Nature Reserve are presented. Macroinvertebrates were divided in functional feeding groups, and the results presented in this chapter. Statistical analyses were performed and used to create the appropriate graphic representations. The spatial and temporal trends in community structure are discussed.

Chapter 6: General conclusion and recommendations: provides some concluding

remarks and recommendations that emanated from the study.

Chapter 7: References: A list of all the references used throughout this dissertation is

presented.

Appendices: Raw data of the water and sediment, zooplankton diversity and aquatic

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pg. 12

SEEKOEIVLEI NATURE RESERVE

AND SITE SELECTION

2.1. BACKGROUND

The Seekoeivlei Nature Reserve is situated in the Free State Province, just outside the small town of Memel. This reserve was declared a nature reserve in 1979 and a Ramsar site in 1997 (Zabala & Policy, 2008).

The Free State Department of Tourism, Environmental and Economic Affairs (FS DTEEA, 2008) states that there are 18 Nature reserves in the Free State with a cover of approximately 107 996 km2_{and 18 735 mapped wetlands with an estimated cover of 2} 129 km2

. The Seekoeivlei Nature Reserve covers an estimated area of 4 754 ha (McCarthy et al., 2010) and the wetland covers 3 000 ha of the reserve. The Seekoeivlei Wetland as a whole is approximately 12 000 ha and consists of 220 oxbows which formed over centuries by the meandering course of the Klip River (Tooth & McCarthy, 2007). This wetland consists of distinctive aquatic habitats that contain numerous oxbow lakes, active and abandoned channels and back swamps (McCarthy et al., 2010). This floodplain complex is 28 km long and up to 1.5 km wide.

2.1.1. Rainfall and climate

In the upper Klip River catchment, the mean annual rainfall ranges from 700 mm to 1200 mm, falling mainly from November to March (McCarthy et al., 2010) (rainfall data of the Free State is presented in Figure 2.1), with annual potential evaporation of 1600 mm to 1800 mm (Tooth et al., 2002). According to Marren et al. (2006), the maximum mean monthly temperature in the summer is between 13 ˚C and 25 ˚C and the minimum mean monthly temperature in the winter is -1 ˚C and 15 ˚C.

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Figure 2.1: Rainfall data of the Free State from 2012 - 2016 (www.dwa.gov.za/Hydrology/Provincial rain/Default.aspx)

2.1.2. Geology and soils

The Seekoeivlei Wetland is underlain by sediments consisting of the lower Beaufort and Upper Ecca Groups of the Karoo Sequence (du Preez & Marneweck, 1996). The Beaufort group consists of various mudstones and sandstones which form part of the Normandien formation (McCarthy et al., 2010). Highly resilient dolerite dykes and sills cut through the sediments and occur throughout the reserve (Tooth & McCarthy, 2007). According to Tooth & McCarthy (2007), erosion of the sandstone/shale valleys is restricted to lateral erosion which, over time, creates space for meanders. This process is only possible to the level of the dolerite. The moment the river enters a dense thick valley of dolerite the meandering will stop abruptly. The Seekoeivlei Nature Reserve is generally flat to slightly undulating, which becomes more uneven in the mountainous catchment that is south-east of the floodplain (du Preez & Marneweck, 1996).

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pg. 14

occur where the sandstone are present on one or both sides of the valley, whereas the narrow valleys occur where the dolerite are present on both sides of the valley. According to Tooth et al. (2002), when looking at the longitudinal profile of the Klip River, the narrowing of the river because of the dolerite valleys is associated with a steepening channel-bed gradient.

Wetlands that are vulnerable to erosion will result in sediment that is removed rather than deposited. This will lead to the formation of deep gullies that drains the water, and thereby destroys the function and values of the wetland (Collins, 2005).

2.1.4. Terrestrial vegetation

The vegetation of the reserve can be characterised as grassland, woodland and thicket as well as hygrophilous communities (du Preez & Marneweck, 1996). With the altitude as high as 1 680 m to 1 700 m above sea level the catchment is characterised by Afromontane grassland, which is dominated by Themeda triandra and Tristachya

leucothrix. Other dominating grass species in the floodplain is Aristida junciformis and Eragrostis curvula which is part of the drier floodplain. The grassland terrain is

vulnerable to overgrazing and trampling effect of livestock that are present (McCarthy et al., 2010). Most of the tree species present were introduced by commercial farmers such as Pinus spp. (pines); Eucalyptus spp. (gums); Salix spp. (willows) and Populus spp. (poplars) which is also considered invasive species (McCarthy et al., 2010).

2.1.5. Wetland classification

The Classification System for Wetlands and other Aquatic Ecosystems in South Africa (Ollis et al., 2013) should be referred to, in order to identify what type of wetland Seekoeivlei is. An example of the classification table given by Ollis et al. (2015) is presented in Figure 2.2. According to Ollis et al. (2015), Seekoeivlei falls within the North Eastern Uplands ecoregion and landscape setting is defined as a plain. Seekoeivlei is distinguished as a floodplain wetland (Ollis et al., 2015). To further classify the specific wetland, it is necessary to look at the source of water and how it moves into, through and out of the wetland system, in other words, the hydrological regime (Ollis et al., 2015). The Klip River, which is the primary source of water for the Seekoeivlei, is classified as a perennial river. Based on the water quality parameters, Seekoeivlei is classified as a natural freshwater wetland (Ollis et al., 2015). With a mean pH of 7.36, the Seekoeivlei Wetland is categorised as a circum-neutral wetland.

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Substratum and soil present in the Seekoeivlei Wetland consist of the full scale ranging from boulders, gravel, very coarse sand, coarse sand, medium sand, very fine sand and mud (Ollis et al., 2015; Wentworth 1922). Aquatic vegetation consists of floating attached aquatic vegetation as well as submerged aquatic vegetation. In the Seekoeivlei Wetland three types of wetland structures were classified, i.e. river, pans and oxbow lakes. The pans represent the waterbodies that were further from the river than the oxbow lakes. Oxbow lakes are old river channels that flow near the river.

Figure 2.2: Conceptual overview of the classification system for wetland ecosystems (Ollis et al., 2015).

2.1.6. Fauna

There is an assemblage of rare, vulnerable and endangered animal species in the Seekoeivlei Nature Reserve. In the reserve itself, 31 mammal species have been reported including the Hippopotamus amphibious (hippopotamus), which was reintroduced in 1999. A number of these species are important in terms of their conservation status including the Hippotragus equinus (roan antelope), Ourebia ourebi

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pg. 16

(buffalo), Redunca arundinum (reedbuck), Alcelaphus buselaphus caama (red hartebeest), Equus zebra (zebra), small antelope and smaller mammals (mongoose and rodents) (du Preez & Marneweck, 1996 & FS DTEEA, 2008). Mammals present in the Seekoeivlei Nature Reserve that have a near-threatened status on the Red Data List includes the Mellivora capensis (honey badger), Rhinolophus capensis (Cape horseshoe bat), Rhinolophus clivosus (Geoffroy’s horseshoe bat), Myotis myotis (mouse-eared bat) as well as the Hydrictis maculicollis (spotted-necked otter) (FS DTEEA, 2008 & MammalMAP, 2017).

According to the Fish Reference of Occurrence (FROC; Kleynhans et al., 2007),

Austroglanis sclateri (rock catfish), Labeobarbus aeneus (smallmouth yellowfish), Enteromius anoplus (chubbyhead barb), Enteromius neefi (sidespot barb), Cyprinus carpio (common carp), Labeo capensis (mudfish) and Labeo umbratus (moggel) can be

expected in this Vaal River catchment area. Of these species, the largemouth yellowfish, smallmouth yellowfish, moggel, mudfish and sharptooth catfish are commercially and recreationally important species in the Free State (FS DTEEA, 2008).

2.1.7. Anthropogenic activities

In the Seekoeivlei Nature Reserve, there are two dominant human activities i.e. agricultural activities and tourism. McCarthy et al. (2010) mentioned that commercial farming began in the late nineteenth century which led to the existence of the town Memel in the early twentieth century. This commercial farming brought some changes to the wetland such as trees, mainly poplars and willows that were introduced. This introduction can be a good explanation for the great bird diversity present today (McCarthy et al., 2010).

Cattle and sheep were also introduced to the area which led to an increase in grazing. According to Collins (2005), grazing can have both positive and negative impacts on the wetland. The diversity of habitats is increased because of some short grazed areas and other areas left with tall grass. Unfortunately, there are some areas that are completely grazed and leads to the decrease of habitats. This heavy grazing can cause important grazing species to be replaced with less productive species in a specific area (Collins, 2005). Grazing and trampling can lead to erosion in some wetlands or even some areas of a wetland. The different land use zones in relation to the samplings sites (described in the following section) are shown in Figure 2.3.

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Figure 2.3: Different land uses present in the study area of the Seekoeivlei Nature Reserve and Klip River during sampling surveys.

2.2. SITE SELECTION

Sites were selected according to the different wetland types and habitats present in the Seekoeivlei Nature Reserve. This floodplain wetland consists of the Klip River, floodplain depressions and flats. It is important to sample in different habitats to make a conclusion about the biodiversity present in the wetland. The study was conducted at 21 preselected sites (Figure 2.4) in the Klip River (Sites 1, 4c, 6, 7 10a), Pampoen Spruit (Site Ps), Wildemans Spruit (Site Ws) and wetland sites (Sites 2a, 2b, 3a, 3b, 3c, 3d,

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pg. 18

Figure 2.4: Map of the Seekoeivlei Nature Reserve with the selected sites during this study.

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Table 2.1: Site description of Pampoen Spruit.

Pampoen Spruit (Ps)

Coordinates 27°40'9.50" S; 29°33'48.15" E

Altitude 1 708 m

Classification Inland stream naturally, permanently inundated.

Description Small tributary from the rural development, Zamani (Zabala, 2008) just outside Memel. Shallow stream (on the western side of the Klip River), with no vegetation present. Pollution is present in the stream in the form of litter and potential effluent from the township Zamani. The water level was the highest during the third survey (average depth of approximately 60 cm). Grazing in the riparian zone evident by horses, cattle and goats.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 20

Table 2.2: Site description of Site 1.

Site 1 (Klip River)

Coordinates 27° 41' 12.8" S; 29° 34' 43.4" E

Classification River.

Description Klip River flowing towards the town Memel – sampled downstream of the R34 road bridge. Shallow water where sediment and water samples were collected. Water levels were two to three meters higher in the third survey. No riparian vegetation except for the one willow tree. Run in the river present in the deeper middle section of the river. Grazing evident by cattle.

Survey 1 (July 2016)

Survey 2 (December 2016)

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Table 2.3: Site description of Site 2a

Site 2a

Coordinates 27° 39' 00.3" S; 29° 35' 10.1" E

Classification Natural floodplain depression, permanently saturated and inundated.

Distance from Klip River

163 m

Average depth of approximately 3 m.

Description Biggest floodplain depression (on the eastern side of the river), large bird activity present. Vegetation around the pan present such as Cyperus fastigiatus (tall slender sedge) and

Juncus effusus (soft rush). The fringing vegetation covered

approximately 2-3 m. Grazing present by the sheep and cattle on the farm.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 22

Table 2.4: Site description of Site 2b.

Site 2b

Coordinates 27° 38' 34.4" S; 29° 35' 02.1" E

Classification Natural floodplain oxbow lake, permanently inundated.

Distance from Klip River

18.3 m

Average depth of 5 m

Description Floodplain oxbow lake on the eastern side of the river). Some vegetation present along the edges of the lake. Deeper water (approximately 5 m) to the middle with Isolepis fluitans (watergrass) present. Could not sample during survey 3 because of the rain which caused flooding. Grazing evident by the cattle.

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Table 2.5: Site description of Wildemans Spruit.

Wildemans Spruit (Ws)

Coordinates 27° 37' 52.0" S; 29° 35' 32.4" E

Classification Inland stream naturally, permanently inundated.

Description Small tributary flowing into reserve, from the upper north-eastern reaches through agricultural land, towards the southern side of the reserve.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 24

Table 2.6: Site description of Site 3a.

Site 3a

Coordinates 27° 38' 37.87" S; 29° 34' 44.66" E

Classification Natural floodplain oxbow lake, permanently saturated and inundated.

Description Oxbow lake one of five, west side of the river. There is a clear difference between the seasons when looking at the abundance of vegetation and taking the depth in consideration. Little to no vegetation was present during the first survey and during the third survey the sampling area was a complete marshland, with complete vegetation cover. Open water was much deeper during the third survey (deeper than 1 m), whereas during the second survey it had an average depth of not more than 1 m and the first survey not more than approximately 50 cm. Little to no grazing present in this part of the nature reserve.

Survey 1 (July 2016)

Survey 2 (December 2016)

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Site 3b

Coordinates 27° 38' 43.7" S; 29° 34' 45.5" E

Classification Natural floodplain oxbow lake, permanently saturated and inundated.

Description Oxbow lake number two on the west side of the river. Deep water is over 1 m deep. Vegetation such as Cyperus

fastigiatus (tall slender sedge), Persicaria lapathifolia (pale

persicaria), Lagarosiphon major (curly water thyme) is present on the outer edges of the lake. Little to no grazing present in this part of the nature reserve.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 26

Table 2.8: Site description of Site 3c.

Site 3c

Coordinates 27° 38' 48.2" S; 29° 34' 41.1" E

Description Oxbow lake number three, on the west side of the river. More shallow (average depth of 60 cm up to 1 m) than the first two oxbow lakes. Again much more vegetation was present the third survey, which includes Cyperus fastigiatus (tall slender sedge), Persicaria lapathifolia (pale persicaria), Typha

capensis (short bulrush). Little to no grazing present in this

part of the nature reserve.

Survey 1 (July 2016)

Survey 2 (December 2016)

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Table 2.9: Site description of Site 3d.

Site 3d

Coordinates 27° 38' 50.0" S; 29° 34' 39.0" E

Description Oxbow lake number four, on the west side of the river. During survey one it was not deeper than 30 cm, second survey it had an average depth of no more than 1 m and during third survey the water depth was approximately 1 m. Vegetation present on outer edges as well as deeper sections in the lake. Vegetation includes Cyperus fastigiatus (tall slender sedge),

Persicaria lapathifolia (pale persicaria), Typha capensis (short

bulrush). Little to no cattle grazing present in this part of the nature reserve. There are only antelope present in this part of the reserve.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 28

Table 2.10: Site description of Site 3e.

Site 3e

Coordinates 27° 38' 56.7" S; 29° 34' 41.6" E

Description Oxbow lake number five, on the west side of the river, but closer to the river (see map). A shallow lake, not deeper than 1 meter. Because of the flooding during the third survey, site 3e could not be reached. Cyperus fastigiatus (tall slender sedge), Persicaria lapathifolia (pale persicaria), Typha

capensis (short bulrush) were noted as the vegetation present

during the second survey. During the third survey, the whole area of the oxbow lakes (Sites 3a, 3b, 3c, 3d & 3e) was a complete flooded marshland. Little to no grazing present in this part of the nature reserve.

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Site 4a

Coordinates 27° 37' 32.5" S; 29° 34' 55.7" E

Classification Inland floodplain depression (pan), permanently saturated.

Description Floodplain site inside the reserve on the western side of the river. Very shallow pan (average depth of approximately 30 cm) with a lot of Isolepis fluitans (watergrass) present. This site was inaccessible during the third survey. Little to no grazing present in this part of the nature reserve.

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pg. 30

Site 4b

Coordinates 27°37'35.59" S; 29°35'1.29" E

Classification Permanently saturated floodplain depression (pan).

Description Floodplain site, closer to the river (western side of the river) than site 4a (approximately 100 m from the Klip River). Still, shallow open water present with not much vegetation than

Isolepis fluitans (watergrass). As with site 4a, site 4b could

not be reached during the third survey. Both sites 4a and 4b are shallow pans, not deeper than 1 m. Little grazing evident from Syncerus caffer (buffaloes) and Hippopotamus

amphibious (hippopotami) in this part of the nature reserve.

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Table 2.13: Site description of Site 4c.

Site 4c (Klip River)

Coordinates 27° 37' 47.0" S; 29° 35' 09.8" E

Classification Inland river, permanently inundated.

Description Klip River site next to the fence in the reserve at the south side of the reserve. Stones and boulders were present with little vegetation. As can be seen from the pictures above, specifically the third survey the whole system from the upper reaches were flooded due to large amounts of water that came into the reserve. Due to large amounts of rain the river was much deeper during the third survey, this site can be classified as a run.

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 32

Table 2.14: Site description of Site 4d.

Site 4d

Coordinates 27° 37' 31.5" S; 29° 35' 11.3" E

Classification Permanently saturated and inundated floodplain depression.

Description Floodplain depression on the east side of the river.

Hippopotamus amphibious (hippopotamus) present on the

site. The open water had an average depth of 2 m, which is deep enough for the hippopotamus to move about. Vegetation such as Isolepis fluitans (watergrass) made it difficult to sample sediment. This site was inaccessible during the third survey. Little grazing evident from the hippopotami.

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Site 5

Coordinates 27° 37' 02.0" S; 29° 34' 38.7" E

Classification Inland, natural depression, permanently inundated and saturated.

Description Big pan on the west side of the river inside the reserve. Flamingos were present during the first survey Not much vegetation present except for the Isolepis fluitans

(watergrass) on the floor of the pan. This site was inaccessible during the third survey. Little to none grazing present at this site.

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pg. 34

Site 6

Coordinates 27° 35' 30.6" S; 29° 35' 31.7" E

Classification Inland natural river permanently inundated.

Description This open water section of the river in the reserve, which is at a bird hide, is the sampling area. Vegetation present at the edges of the site is Juncus effuses (soft rush), Utricularia

stellaris (bladderworts), Spirodela spp. (duckweed), Typha capensis (short bulrush), Cyperus marginatus (sedge), Phragmites australis (common reed), Persicaria lagarosiphon

(pale persicaria). Only edges of the site are shallow enough to sample. Approximate depth of 1 m up to 6 m. Grazing present mostly by Redunca arundinum (reedbuck) and

Connochaetes gnou (black wildebeest).

Survey 1 (July 2016)

Survey 2 (December 2016)

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Site 7

Coordinates 27° 34' 57.8" S; 29° 35' 09.1" E

Classification Inland natural river, permanently inundated.

Description Further downstream is the second bird hide next to a river site that expands into open water and forms a deep depression of over 1 m deep. Otters and birds werepresent at the site. During the first and second surveys this site were accessible from the eastern side but during the third survey, the eastern side was inaccessible and the site could only be reached from the western side of the reserve. Typha capensis (short bulrush), Phragmites australis (common reed) are the vegetation present at this site. Grazing present mostly by

Redunca arundinum (reedbuck) and Connochaetes gnou

(black wildebeest).

Survey 1 (July 2016)

Survey 2 (December 2016)

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pg. 36

Site 8

Coordinates 27°33'32.79" S; 29°35'8.76" E

Classification Natural oxbow lake, permanently saturated and inundated.

Description Small depression (mostly backwater) directly next to the river on the western side and lower reaches of the river in the northern part of the reserve. Deep water body, over 1 m deep. Vegetation is dominated by Phragmites australis (common reed). This site was inaccessible during the third survey. Grazing present mostly by Redunca arundinum

(reedbuck), Equus zebra (zebra) and Connochaetes gnou (black wildebeest).

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Site 9

Coordinates 27°33'22.2" S; 29°35'28.1" E

Classification Natural oxbow lake, permanently saturated.

Description Oxbow site on the eastern side of the river, close to the boundary of the reserve. Water present only during rainy season. During the third survey, this site was flooded and could not be reached. Isolepis fluitans (watergrass) present in the water. Pan is shallow (average depth of 1 m) enough to sample effectively. Grazing present mostly by Redunca

arundinum (reedbuck) and Connochaetes gnou (black

wildebeest).

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pg. 38

Site 10a (Klip River)

Coordinates 27°32'24.35" S; 29°35'12.13" E

Classification Inland river, permanently inundated.

Description Lower reaches of the river at the northern side of the reserve. Can be classified as a run. Present vegetation at the site is

Cyperus marginatus (sedge). This site was inaccessible

during the third survey. Little to no grazing present at this site.

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Site 10b

Coordinates 27°32'26.13" S; 29°35'7.59" E

Classification Small natural depression (mostly backwater), permanently saturated and inundated.

Description Small pan on the western side of the river in the northern part of the reserve. Riparian vegetation had a greater abundance during the second survey. The dominant vegetation is

Cyperus marginatus (sedge) and Isolepis fluitans

(watergrass). Deeper than 1 meter to the middle reaches of the pan with a steep decline (average depth of 5 m). This site was inaccessible during the third survey. Grazing evident from Redunca arundinum (reedbuck) and Connochaetes

gnou (black wildebeest).

Aquatic invertebrate assessment of the Seekoeivlei Nature Reserve