Thomas George Bornman

South African Environmental Observation Network - Elwandle Node · Coastal

The carbon and nitrogen isotope ratios (δ¹³C and δ¹⁵N) of marine plankton record biogeochemical processes at the base of the food web. In the Southern Ocean, such data, predominantly from summer, have been used to infer surface CO2 concentrations and the potential for biological carbon export. However, variability in plankton δ¹³C and δ¹⁵N remains...

The Southern Ocean accounts for ∼30% of the ocean's CO2 sink, partly due to its biological pump that transfers surface‐produced organic carbon to deeper waters. To estimate large‐scale Southern Ocean carbon export potential and characterize its drivers, we measured the carbon and nitrogen isotope ratios of surface suspended particulate matter (δ¹³C...

Compared with the open ocean, knowledge of pH variability in coastal waters is rudimentary, especially in Africa. This is concerning as quantifying local pH conditions is critical when assessing the response of coastal species to future ocean acidification scenarios. The objective of this study was to capture some of the variability in pH at scales...

Our understanding of how zooplankton community composition varies in relation to harmful algal blooms remains limited, particularly in ecosystems where toxin-producing algae may have been introduced through anthropogenic activities. Harmful algal blooms (HABs) naturally occur on the coast of southern Africa, where they are predominantly associated...

Understanding the transport and accumulation of microplastics is useful to determine the relative risk they pose to global biodiversity. The exact contribution of microplastic sources is hard to elucidate; therefore, investigating the Antarctic Weddell Sea, an area known for its remoteness and little human presence (i.e. limited pollution sources),...

Haslea ostrearia represents the model species of blue diatoms, a cluster of benthic marine species all belonging to the genus Haslea, noticeable for producing a blue pigment called marennine famous for its greening activity on the gills of bivalves but also for its potential in biotechnology. The exact distribution of H. ostrearia is unknown. It ha...

An investigation into the ocean response to a protracted (>48 h) strong south-westerly wind event averaging 9.6 m/s on the eastern Agulhas Bank, South Africa, using in situ instrument data from Algoa Bay and a high resolution (dx ∼1 km) ROMS ocean model, is presented. A coastal trapped wave (CTW) was shown to be associated with the event, the peak...

Salt marshes are one of the most productive ecosystems in the world, however their continued existence is in doubt in the face of global sea-level rise, especially where development creates coastal squeeze preventing landward migration. Therefore, long-term survival of these ecosystems is in part dependent on sufficient and persistent sediment supp...

Benthic diatoms form an important component of the microphytobenthos and have long been utilised as suitable bioindicators in aquatic systems. However, knowledge on benthic diatom community succession on hard substrata (biofilm) remains understudied in austral marine coastal systems. In this study, we investigated benthic diatom colonisation on art...

The Weddell Sea represents a point of origin in the Southern Ocean where globally important water masses form. Biological activities in Weddell Sea surface waters thus affect large-scale ocean biogeochemistry. During January–February 2019, we measured net primary production (NPP), nitrogen (nitrate, ammonium, urea) uptake, and nitrification in the...

The Subantarctic Ocean is a sink for atmospheric CO2, largely due to its biological pump, which is enhanced by the influence of the Subantarctic islands on the plankton ecosystem (the so‐called “island mass effect”). The influence of the Prince Edward Islands archipelago in the Indian Subantarctic on the surrounding hydrography and benthos has been...

In coastal waters, nutrient supplies originate principally from allochthonous sources, such as inputs from rivers, estuaries or oceanic waters. Recently, it has been suggested that marine life contributes to the nutrient load, with penguin colonies being the largest contributor worldwide. This study aimed to quantify the nitrogen (N) and phosphorus...

Coastal wetlands are vulnerable to sea-level rise (SLR) but are also valued for their potential to provide effective nature-based solutions to climate change mitigation and adaptation. Ecological benefits from these ecosystems can be constrained under urban settings by anthropogenic disturbances and pressures, so restoration activities are promoted...

The Weddell Sea (WS) represents a point of origin in the Southern Ocean where globally-important water masses form. Biological activities in WS surface waters thus affect large-scale ocean biogeochemistry. During summer 2018/2019, we measured net primary production (NPP), nitrogen (nitrate, ammonium, urea) uptake, and nitrification in the western W...

Marine epilithic diatom abundance and species richness are highly variable along the South African coastline. To determine the variability in spatial diversity and benthic-pelagic exchanges, we conducted a baseline study of the Bird Island ecosystem in Algoa Bay. Diatom samples were collected from the rocky substrate and the adjacent water column i...

There is a general need for a broader base of information on the finer detail of ocean processes in the Eastern Agulhas Bank region. In this thesis, the Regional Ocean Modelling System (ROMS) was applied to resolve high resolution (~1km) bay and shelf scale ocean processes along the south eastern coastline of South Africa using an offline multi-nes...

Spring and summer Southern Ocean phytoplankton communities have been well characterized, but winter communities are often overlooked. Diatoms are a major contributor to Southern Ocean particulate organic carbon (POC) production and export, and exert a strong control on Antarctic surface and Subantarctic ther-mocline nutrient concentrations, thus in...

Microbial mats were the dominant habitat type in shallow marine environments between the Palaeoarchean and Phanerozoic. Many of these (termed ‘microbialites’) calcified as they grew but such lithified mats are rare along modern coasts for reasons such as unsuitable water chemistry, destructive metazoan influences and competition with other reef-bui...

Microfibers are ubiquitous contaminants of emerging concern. Traditionally ascribed to the “microplastics” family, their widespread occurrence in the natural environment is commonly reported in plastic pollution studies, based on the assumption that fibers largely derive from wear and tear of synthetic textiles. By compiling a global dataset from 9...

The knowledge on the composition and spatial distribution of marine benthic diatoms around the coast of South Africa remains limited. Epilithic diatom assemblages from natural intertidal rocky substrate and physico-chemical variables were investigated during July–August in 2016 and 2017 along the South African coastline. A total of 85 diatom taxa f...

Multi-date remotely sensed images comprising Landsat TM images of 1984, 1993 and 2003 and, Landsat OLI images of 2013 were used to reconstruct long-term changes in land cover in the Swartkops River Estuary by mapping changes in vegetation distribution over a period of ~ 30 years between 1984 and 2013. These images were complemented by high-resoluti...

Sea-level rise is a significant threat to salt marshes. However, these habitats can respond by increasing their relative elevation, or by migrating into adjacent areas. Here we provide the first report on surface elevation change for salt marsh at the Knysna Estuary, South Africa, and predict the responses of these habitats to sea-level rise using...

In the original article, there was a mistake in the legend for Figure 1 as published. After publication, it was brought to the authors’ attention that DEIMS-SDR also included not-LTER sites (Wohner et al., 2019) and the so called LTER “parent sites,” at the same hierarchical level of the research sites they are made of, generating some duplicates....

Microfibres are one of the most ubiquitous particulate pollutants, occurring in all environmental compartments. They are often assumed to be microplastics, but include natural as well as synthetic textile fibres and are perhaps best treated as a separate class of pollutants given the challenges they pose in terms of identification and contamination...

Understanding the threats to global biodiversity and ecosystem services posed by human impacts on coastal and marine environments requires the establishment and maintenance of ecological observatories that integrate the biological, physical, geological, and biogeochemical aspects of ecosystems. This is crucial to provide scientists and stakeholders...

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...

Algoa Bay represents a complex suite of aquatic ecosystems that support high biodiversity and provide significant socio-economic benefits. Since land-ocean interactions are central to shaping the structure and functioning of these ecosystems, the aim of this study was to quantify land-derived inorganic nutrient loads entering the coastal waters of...

New molecular and morphological insights are presented on Campylosira africana and two new species, Extubocellulus cupola sp. nov. and Plagiogrammopsis castigatus sp. nov. Species descriptions were based on LM/SEM micrographs and a dataset with concatenated sequences of SSU, rbcL and psbC loci constructed from 56 cymatosiroid strains isolated from...

Southern Africa occupies a critical position within the southern hemisphere for the study of broadscale global change and the three oceans around South Africa (the Atlantic, Indian and Southern Oceans) play a vital role in determining local and regional climate and weather patterns. Oceans and coasts also provide various resources and services (e.g...

Chapter published in The IPBES regional assessment report on biodiversity and ecosystem services for Africa, pp. 1-76

The summer of 2012/2013 signified the end of the dry phase in the St Lucia estuarine system that lasted for over a decade. The increased rainfall coupled with the partial re-connection of the Mfolozi River to the estuarine system shifted St Lucia to a new limnetic state. With the increased availability of habitat due to the higher water level, it w...

Recently-discovered peritidal stromatolite ecosystems in South Africa form at the interface of freshwater seeps and the ocean intertidal zone, sharing several similarities with both tidal pool and estuarine ecosystems. While the overall ecology of tidal rock pools has been well studied, the dynamics of the phytoplankton assemblage have been compara...

The family Cymatosiraceae, composed of two subfamilies (Cymatosiroideae and Extubocelluloideae), are elongate, non-pennate diatoms and are commonly reported in marine planktonic and benthic assemblages all over the world. The combination of the gross bilateral symmetry of the frustule and radial symmetry of the valve poration, distinct pore fields...

Living peritidal stromatolites forming at the interface of coastal groundwater seepage and regular marine input are known from only a few locations globally, including South Africa, Western Australia and Northern Ireland. In contrast to modern stromatolites from exclusively fresh or marine waters, which persist due to high calcium carbonate saturat...

The seamounts of the southern Indian Ocean remain some of the most poorly studied globally and yet have been subject to deep-sea fishing for decades and may face new exploitation through mining of seabed massive sulphides in the future. As an attempt to redress the knowledge deficit on deep-sea benthic and pelagic communities associated mainly with...

A survey of six seamounts and two transects through the subtropical convergence zone (SCZ) in the South Indian Ocean in November and December 2009 showed a strong latitudinal gradient from the subtropics to the Sub-Antarctic Front. Concentrations of oxygen, nitrate, nitrite, soluble reactive phosphorous as well as phytoplankton biomass (measured as...

The polar regions are more critically affected by climate change than any other region on our planet. On the Antarctic continent and in its surrounding oceans, the effects of climate change are likely to be dramatic, and include largescale catastrophic ice melt, loss of habitat and biodiversity, and global sea level rise. The 'Southern Ocean' refer...

This study represents the first report of an invasive species associated with modern, living stromatolites. The presence and potential impacts of the reef-forming tubeworm Ficopomatus enigmaticus (Fauvel, 1923) in unique stromatolite ecosystems of South Africa are addressed. Data on F. enigmaticus populations and a suite of environmental variables...

Salt marshes are highly productive and biologically diverse coastal wetlands that are threatened by rising sea-level. Salt marsh habitats within the Swartkops Estuary were examined to determine their structure along an elevation gradient and how this structure has changed over the past seven decades, what the primary drivers of this structure were...

Extant marine stromatolites act as partial analogues of their Archean counterparts, but are rare due to depleted ocean calcium carbonate levels and suppression by eukaryotic organisms. Unique, peritidal tufa stromatolites at the interface between marine and freshwater inputs were discovered in South Africa in the past decade. Our aim was to investi...

Six large solitary meanders in the Agulhas Current, so-called Natal Pulses, propagated down the eastern coast of South Africa between 2009 and 2011. Their influence on the coastal waters between Port Alfred and Algoa Bay, on the far eastern Agulhas Bank, was measured by thermistor strings moored at 30–80 m bottom depths and two current metres (30 m...

Following the first description of living marine stromatolites along the South African east coast, new investigations along the south coast have revealed the occurrence of extensive fields of actively calcifying stromatolites. These stromatolites have been recorded at regular distances along a 200-km stretch of coastline, from Cape Recife in the ea...

Gridded SST products developed particularly for offshore regions are increasingly being applied close to the coast for biogeographical applications. The purpose of this paper is to demonstrate the dangers of doing so through a comparison of reprocessed MODIS Terra and Pathfinder v5.2 SSTs, both at 4 km resolution, with instrumental in situ temperat...

Spartina alterniflora Loisel., widely recognised as an aggressive invader of estuaries and salt marshes around the world, was discovered growing in the temporarily open/closed Great Brak Estuary on the southern Cape coast of South Africa in 2004. This is the first record of this invasive plant in Africa as well as its first occurrence in an estuary...

The South African Environmental Observation Network (SAEON) is the principal investigator in a study to examine the influence of predicted climate change and sea-level change on the diversity, distribution, abundance and community composition of salt marshes in selected estuaries in South Africa. Coastal wetlands could experience substantial losses...

With a view of implementing operational oceanography in South Africa, the scientific community in 2009 initiated a demonstration project, OceanSAfrica, which integrates ocean modelling, in situ observations, remote sensing, and data dissemination and products. This paper presents progress towards establishing the in situ observations component. Led...

The Atlantic Ocean receives warm, saline water from the Indo-Pacific Ocean through Agulhas leakage around the southern tip of Africa. Recent findings suggest that Agulhas leakage is a crucial component of the climate system and that ongoing increases in leakage under anthropogenic warming could strengthen the Atlantic overturning circulation at a t...

The Orange Estuary lost 27% (276 ha) of its wetland area near the mouth as a result of bad management practices during the 1980s. The salt marsh has been unable to recover over the last 20 years because of the persistently high soil and groundwater salinity. In 2006, a 1 in 5 year flood occurred that completely covered the desertified salt marsh an...

In 2005/2006 a multidisciplinary research programme that included studies on the hydrodynamics, sediment dynamics, macronutrients, microalgae, macrophytes, zoobenthos, hyperbenthos, zooplankton, ichthyo-plankton, fish and birds of the temporarily open/closed East Kleinemonde Estuary was conducted. Particular attention was given to the responses of...

The Olifants Estuary is one of only three permanently open estuaries on the West Coast and is ranked third in terms of conservation importance of all estuaries in South Africa. It has the largest supratidal (143 ha) and floodplain (797.1 ha) salt marshes in the country. Intertidal salt marsh covers 91.94 ha, reeds and sedges 60.05 ha and the submer...

An ambitious multinational programme, with generous funding for an initial five years, aims to provide understanding of marine resources for the benefit of impoverished island and coastal populations in a much-neglected ocean region.

The Orange River estuary is a Ramsar site that has been placed on the Montreux Record following the degradation of 300ha of salt marsh. The groundwater and surface sediments are hypersaline and above the tolerance range of the dominant plant Sarcocornia pillansii. This study measured the sediment characteristics in 2005 (dry conditions) and in 2006...

The distribution of Sarcocornia pillansii (Moss) A.J. Scott was determined by water-table depth and electrical conductivity (EC) of the groundwater. Where the groundwater was accessible (<1.5 m) and had a low EC (<80 mS cm−1), S. pillansii extended its roots down to the water-table where a suitable water potential gradient was shown to exist betwee...

The desertified floodplain of the Orange River Mouth (ORM) is characterised by large areas completely devoid of vegetation. Although barren areas are a natural feature of salt marshes on the west coast of southern Africa, more than 70 ha of salt marsh have been lost through bad management practices. Salt marsh plants have adapted to the low rainfal...

The desertified floodplain of the Orange River Mouth (ORM) is characterised by large areas completely devoid of vegetation. Although barren areas are a natural feature of salt marshes on the west coast of southern Africa, more than 70 ha of salt marsh have been lost through bad management practices. Salt marsh plants have adapted to the low rainfal...

When rivers are impounded, the reduction in downstream flow can produce important and often adverse effects, especially in the estuarine environment. One or more dams have been proposed for the Olifants River system in the Western Cape, South Africa. This estuary has an extensive area of salt marsh that was examined to see whether it required occas...