Lara van Niekerk

• Doctor of Philosophy
• Principal Reseacher at Council for Scientific and Industrial Research, South Africa

This paper presents an environmental flow methodology that was developed to accommodate shallow, highly dynamic micro-tidal estuaries found along the wave-dominated coast of South Arica. This method differs to most other approaches that primarily focus on larger permanently open systems having unrestricted inlets. Following an adaptive, design scie...

Rapid urbanisation and industrial growth in South Africa increases the need for proactive allocation of freshwater resources on a regional scale. A nine-step method is described that sets long-term targets for water resource condition and future use with a focus on estuary water quantity and quality requirements. The approach specifically focuses o...

The NBA 2018 Synthesis report can be downloaded from the NBA website: http://nba.sanbi.org.za

For nearly three decades, the Whitfield (1992) characterisation scheme served as a reference framework to type South African estuaries. We outline a revised ecosystem classification scheme that incorporates biogeographicalzonation and introduces new types. Coastal outlets were re-categorised as estuaries or micro-systems. For functional estuaries,...

This study evaluates the feasibility of using medium-resolution satellite sensors to monitor changes in the extent of ecosystem functional groups (EFGs) in South African estuaries, for reporting on the 2030 targets of the Global Biodiversity Framework (GBF). Landsat and Sentinel-1 and -2 image collections in Google Earth Engine (GEE) were used to g...

Verlorenvlei is a globally important RAMSAR wetland on the arid west coast of South Africa. A prolonged drought between 2016 and 2021 and increasing competition for water from the agricultural sector resulted in extremely low water levels. We used historical aerial and satellite imagery from 1942 and rainfall and water level data for the past 50 ye...

This report presents the most up-to-date information and analyses of the status of marine fishery resources in South Africa at the time of compilation. The number of fish stocks covered has increased steadily from 43 in 2012 to 77 in the current report (Figure I). Among the species included for the first time are a further six sharks (bronze whaler...

This report presents a set of indicators, links and generic response curves that depict the relationships between physical-chemical-biological drivers and ecological-social responses in southern African rivers and estuaries. The idea being that the indicators, links and generic curves can be used to set up a coarse-level ecosystem based assessment...

Context Artificial breaching of intermittently closed estuaries has become more frequent in the face of global-change pressures. Aims This study aimed to determine whether the ecological health of the Great Brak Estuary has been affected by the prolonged loss of marine connectivity arising from below-average inflow and failed breaching attempts....

This review study investigated the response of low-inflow estuaries (LIEs) to dam releases as this type of estuary is particularly sensitive to freshwater inflow modification. LIEs occur in arid and semi-arid regions and are subject to periods of little to no freshwater inflow. Case studies were used to identify ecological health and societal benef...

South Africa has taken an iterative approach to marine ecosystem mapping over 18 years that has provided a valuable foundation for ecosystem assessment, planning and decision-making, supporting improved ecosystem-based management and protection. Iterative progress has been made in overcoming challenges faced by developing countries, especially in t...

Rapid degradation of ecosystems and loss of ecosystem services have sparked interest in developing approaches to report and integrate such change with socio-economic information systems, such as the System of National Accounts. Here we describe an approach and application of ecosystem accounting for individual estuaries, building on approaches prev...

This report contributes to an overarching aim to mainstream the conservation of aquatic ecosystems – rivers, inland wetlands (fresh or saline) and estuaries – within the national parks of South Africa. Specifically, it provides statistics of the status of aquatic ecosystems and explores options for improvement, guided by two objectives: Objective...

Latitudinal range limits for mangroves on high‐energy, wave‐dominated coasts are controlled by geomorphological features and estuarine dynamics. Mangroves reach a southern global range limit along the South African coastline, but the distribution is patchy, with stands occurring in only 16% of the estuaries in the region. Yet, the persistence of fo...

Blue carbon ecosystems (mangroves, salt marshes, and seagrasses) contribute towards climate change mitigation because they are efficient at sequestering atmospheric CO2 into long-term total ecosystem carbon stocks. Destruction or disturbance therefore reduces sink capacity and leads to significant CO2 emissions. This study reports the first nationa...

Ecosystem status assessments are generally separated into realm-specific analyses (terrestrial, freshwater, estuarine or marine), but without integrating these into a coherent assessment of coastal biodiversity across the land–sea interface. Trends in assessment indicators in coastal versus non-coastal areas have also rarely been considered. In thi...

This review evaluates the vulnerability of South African estuaries to Climate Change in a data-limited environment. The regional-scale assessment is based on physical characteristics and predicted/measured changes in the abiotic drivers and ecosystem responses. The major Climate Change stressors were identified in order of importance as change in c...

Despite the increasing number of tools and indicators to measure biodiversity status and trends, many developing countries struggle to initiate and advance coastal and marine assessments needed to monitor and track national and international progress in biodiversity targets. We identified five key challenges that hinder progress in this context, ba...

The transdisciplinary research synthesised in this book represents an endeavour by a group of coastal researchers and policy analysts to learn from a cross-comparison of seven international case studies on tidal inlet or estuary mouth management situations, located in South Africa, Sri Lanka, California, Suriname, Ireland and the Netherlands. The c...

Recent studies on compound flooding have considered the interaction of storm-tide and fluvial or pluvial flood drivers, whereas the contribution of waves to compound flooding so far has been neglected. In this study, we investigate compound flooding from waves, tides and river discharge at Breede Estuary, South Africa, using a hydrodynamic model. W...

Globally, the ability of estuaries to sustain functionality and productivity is deteriorating rapidly under ever-increasing anthropogenic pressures. We present a systematic approach to identify, characterise and rank global change pressures affecting estuaries. Six main pressure categories are reviewed: freshwater flow modification; pollution; expl...

Situated at the land-sea interface, estuaries are susceptible to land- and sea-based sources of pollution. Despite growing scientific evidence of deterioration in water quality, quantitative methods to translate such information in support of effective environmental management and planning practice is lacking, particularly in data-limited environme...

Recent studies have drawn special attention to the significant dependencies between flood drivers and the occurrence of compound flood events in coastal areas. This study investigates compound flooding from tides, river discharge (Q), and specifically waves using a hydrodynamic model at the Breede Estuary, South Africa. We quantify vertical and hor...

Restoration of salt marsh is urgent, as these ecosystems provide natural coastal protection from sea-level rise impacts, contribute towards climate change mitigation, and provide multiple ecosystem services including supporting livelihoods. This study identified potential restoration sites for intervention where agricultural and degraded land could...

The South African National Ecosystem Classification System Handbook: First Edition.

Africa's range-restricted subtropical-temperate coastal forested wetlands are facing interlinking threats of climate and anthropogenic pressures. We assessed their conservation status using the criteria of the International Union for Conservation of Nature (IUCN). Their total areal extent was hind-casted to the reference epoch 2000, followed by the...

We review the possible impacts of non-native biota on the indigenous fishes of South African estuaries, including macrophytes, algae, pathogens, invertebrates, and fishes. Freshwater macrophytes are one of the primary non-native groups in the oligohaline reaches of some predominantly open estuaries, lake and river mouth type estuaries, as well as t...

River inflow plays an integral role on the water quality characteristics of estuaries, including pH. This study aimed to investigate pH variability in river inflow to South African estuaries and how these might be influenced by catchment characteristics. Specifically, three hypotheses were tested: 1) catchment geology is a dominant influencing fact...

Africa’s range-restricted and transitional subtropical-temperate coastal forested wetlands are facing interlinking threats of climate and anthropogenic pressures. We assessed their conservation status using the criteria of the International Union for Conservation of Nature (IUCN). Their total areal extent was hind-casted to the reference epoch 2000...

Recent studies have drawn special attention to the significant dependencies between flood drivers and the occurrence of compound flood events in coastal areas. This study investigates compound flooding from tides, river discharge (Q) and specifically waves using a hydrodynamic model at Breede Estuary, South Africa. We quantify vertical and horizont...

Increased nutrient loading associated with rapid population growth is the leading cause of deteriorating water quality in urbanized estuaries globally. Small estuaries are particularly sensitive to changes when connection with the marine environment is restricted, or lost, because of high water retention. The temporarily closed Hartenbos Estuary (S...

The science needed to inform management of environmental flows to temporarily closed estuaries and coastal lagoons is decades behind the state of knowledge for rivers and large embayments. These globally ubiquitous small systems, which are often seasonally closed to the ocean’s influence, are under particular threat associated with hydrologic alter...

This report summarises the findings of the stakeholder engagement, literature review and data inventory conducted for the National Coastal Assessment project, on behalf of the National Department for Environment, Forestry and Fisheries, with funding from the GIZ GmbH.

South Africa’s coastal zone is an attractive space for economic and recreational activities. Approximately 60% of the South African economy depends on coastal natural resources and trade infrastructure such as ports. As of 2013, an estimated 3.5 million people are residing within 5-7 km from the coast line, 60% thereof in dense metropolitan areas1....

Extreme coastal flooding along the South African coast can be caused by the co-occurrence of waves, storm surges and tides. Importantly, in low-lying areas such as estuaries, the additional influence of river discharge can further exacerbate flooding intensity. The CASISAC* project aims to assess these compound flood impacts on a local scale by mod...

Invasive alien aquatic plants (IAAPs) are rapidly spreading in South African estuaries because of anthropo-genic nutrient loading and persistent freshwater conditions. This study investigated changes in IAAP cover in relation to development pressures in the temporarily closed, subtropical uThongathi Estuary. Changes over time (1937-2018) were asses...

Temporarily closed estuaries require seasonal opening to tidal flows to maintain normal ecological processes. Each estuary has specific environmental flow (EFlow) requirements based on the relationship between freshwater inflow, coastal dynamics, rate of sandbar formation, and the open/closed state of the mouth. Key abiotic processes and ecosystem...

Description of the national wide detection of coastal hotspots where land use conflicts arise. Conducted on behalf of the the National Department of Environmental Affairs – Branch Oceans and Coasts, Cape Town

This Reflections article highlights the growing pressures that southern African estuaries are experiencing in the Anthropocene, as identified by the research presented in this Special Medal Issue. Estuaries are exposed to multiple stressors, and their responses to climate change are becoming increasingly evident. As the health of estuaries deterior...

The possible impacts of extreme events on the ecology of selected aquatic biota within the Mbhashe Estuary were investigated during a four year (2010–2013) spring sampling programme. During periods of low to average flow conditions the estuary is shallow, turbid and characterised by the presence of fluid mud and the build-up of mud and clay deposit...

Nutrient pollution in South African estuaries is described using a Driver-Pressure-State-Impact-Response framework. The root cause (‘driver’) of deteriorating water quality is rapid population growth that leads to increasing inputs from wastewater treatment works (WWTWs), stormwater run-off and agricultural return flow (‘pressures’). Nationally, ha...

The Knysna Estuary is South Africa's most important estuary in terms of conservation, containing an estimated 42% of all estuarine biodiversity. Despite formal protection the estuary is open access and vulnerable to resource exploitation, development, pollution and freshwater inflow alterations. Through a review of current research and available da...

The improved representation of freshwater and estuarine ecosystems and associated data was a key component of the 2018 National Biodiversity Assessment, and is an essential step in enhancing defensible land use planning and decision making. This paper reports on the enhancement of the National Wetland Map (NWM) version 5 for South Africa and other...

Over the past three decades, marine resource management has shifted conceptually from top-down sectoral approaches towards the more systems-oriented multi-stakeholder frameworks of integrated coastal management and ecosystem-based conservation. However, the successful implementation of such frameworks is commonly hindered by a lack of cross-discipl...

In 1994 South Africa adopted a power-sharing democracy as basis for its political system, and this pluralistic slant also is evident in post-1994 environmental legislation, including that pertaining to the coastal marine environment. Notwithstanding the legislative progress made in the facilitation of integrated environmental governance, a large pr...

p>Mangrove distribution patterns at regional scales are influenced by additional factors besides temperature and rainfall regimes. This study identified abiotic drivers of mangrove area cover along the high-energy, wave-dominated coastline of South Africa. This is one of the southernmost locations globally for mangroves. A structural equation model...

Coasts are among our most valuable natural assets but are under intense pressure from human use and climate change. Despite this, coasts – as a coherent ecological unit – have been poorly included in conservation plans, largely because they are inadequately delineated. There are usually gaps and overlaps at the edges of the separate terrestrial-, e...

The improved representation of inland aquatic (freshwater) and estuarine ecosystems and associated data was a key component of the 2018 National Biodiversity Assessment, and is an essential step in enhancing defensible land use planning and decision making. This paper reports on this enhancement of the National Wetland Map version 5 (NWM5) for Sout...

The aims of this project were described in the original proposal document as follows: a) To determine the extent of blue carbon ecosystems in South Africa and estimate blue carbon storage using the IPCC assessment methods. b) To quantify the loss of blue carbon habitats and associated ecosystem services. c) To predict the responses of blue carbon e...

In South Africa more than 80% of estuaries are small, dynamic and predominantly linear systems. Nutrient characteristics in these systems are mostly influenced by external catchment processes, except during extended periods of closure. However, a small percentage of the country’s estuaries (< 3%) comprise larger estuarine lakes mostly evolved from...

Despite mounting evidence of the harm associated with excessive nutrient loading to estuaries, tools to translate this body of knowledge into sound environmental management and planning practices in data-poor environments are lacking. In this paper, a design science approach is adopted to develop a screening (box) model for the water quality assess...

The Chief Directorate: Water Ecosystems (CD: WE) of the Department of Water and Sanitation (DWS) initiated a study for the Development of Procedures to Operationalise Resource Directed Measures (RDM). The study objectives were: • Develop a framework for Reserve determination. • Standardise methodologies for Reserve determination. • Develop a framew...

The Chief Directorate: Water Ecosystems (CD: WE) of the Department of Water and Sanitation (DWS) initiated a study for the Development of Procedures to Operationalise Resource Directed Measures (RDM). The study objectives were: • Develop a framework for Reserve determination. • Standardise methodologies for Reserve determination. • Develop a framew...

Wetland and estuarine vegetation is often difficult to detect and separate from adjacent land covers with multispectral sensors for a number of reasons. The spatial resolution of space-borne sensors is often insufficient for these features which occur along narrow gradients in the landscape.

This paper examines the value of very high-resolution multispectral satellite imagery and LiDAR-derived digital elevation information for classifying estuarine vegetation types. Satellite images used are from the WorldView-2, RapidEye, and SPOT-6 sensors in 2 m and 5 m resolution, respectively, acquired between 2010 and 2014. Ground truthing refere...

Freshwater abstraction for human activities threatens the health and provisioning of ecosystem services supplied by aquatic ecosystems. Estuaries are sensitive to a reduction in freshwater inflow, which is the main driver of their dynamic, variable nature. Input of discharge from waste water treatment works and agricultural return flow can result i...

This study investigated whether the current lateral boundary for estuaries in South Africa, i.e. the estuarine functional zone (EFZ), includes all estuarine habitats. The EFZ covers 173 930 ha in 304 estuaries/outlets nationally. Field surveys and analysis of available aerial images showed that 82 (12 956.70 ha) of these estuaries (26%) had estuari...

This book is available online at http://press.anu.edu.au

The aim of this project was to develop a desktop method for the Provisional EcoClassification (the term used for the Ecological classification process under the NWA) for estuaries that provided for a comparative, regional scale assessment. The Provisional EcoClassification – in the context of this study – refers to the Present Ecological Status (PE...

Final report on WRC Project K5/2268. The project assessed the use of high and very high resolution satellite imagery for assessing estuarine processes and health.

This report is a summary of the findings of the Reserve Determination for the Mzimvubu Estuary, prepared in support of the broader feasibility study for the Mzimvubu Water Project. The assessment has followed the methods supported in Version 2 of the Reserve Determination methods outlined by the Department of Water Affairs. Summer and winter sampl...

This study follows from a proposal that was compiled by the CSIR based on discussions between the CSIR and the DEA. The proposal was drafted by a number of CSIR staff including Mr Andre Theron, Mr Marius Rossouw, Dr Melanie Luck-Vogel, Dr Christo Rautenbach, Ms Lara van Niekerk, Dr Susan Taljaard and Dr Louis Celliers; in collaboration with Dr Alan...

Communities worldwide are increasingly affected by natural hazards such as floods, droughts, wildfires and storm-waves. However, the causes of these increases remain underexplored, often attributed to climate changes or changes in the patterns of human exposure. This paper aims to quantify the effect of climate change, as well as land cover change,...

Estuaries are dynamic and their physical and chemical characteristics can change over a scale of hours to years. Consequently, estuarine fish assemblages often exhibit large temporal variations in abundance and composition related to changes in a range of parameters such as river flow, estuarine mouth phase, habitat availability, temperature, salin...

South Africa is a middle-income, developing country with a transforming society and as such is beset with economic and social challenges. This paper outlines the context within which coastal and marine spatial planning is enabled by a structured model of institutions, policy, legislation and tools. Coastal and marine spatial planning is a necessity...

Presentation of CSIR conceptual project work.

Over the past six years international interest in multi-use marine spatial planning (MSP), as a practical process to launch integrated coastal management (ICM), exploded. This paper explores the extent to which existing national legal frameworks can support this process, focusing on the coastal marine environment. First the characteristics of an ap...

This manual sets out a standardised and tested method for assessing the health of an estuary as a baseline and against which to set future objectives and measure progress according to management targets. Its intention is for use in the determination of the freshwater Reserve for estuaries (for which the method was originally developed by Turpie 199...