Virtual Online Symposium - Plenary Session Plenary Session | General Session | Keynote Presentations | Oral Presentations | Moderated Discussion CE Credits : 0.3
04 Nov 2021 09:00 AM - 30 Nov 2021 11:15 AM(Africa/Johannesburg)
20211104T0900 20211104T1115 Africa/Johannesburg Session Sixteen: Alien and Invasive Species

Invasive and alien species have negative effects on biodiversity and ecosystem function, causing declines or even extinction of native species and loss of ecosystem services. Managing emerging invasive plant species often requires rapid interventions and the use of herbicides, and yet the administrative process to get herbicides tested and registered are cumbersome. In addition, there is often industry or public resistance to the implementation of control efforts which may delay efforts at a critical stage, necessitating a review of communication and engagement approaches and strategies. In the second part of the session, there will be a focus on innovative research and an emerging understanding of the invasion biology of the extralimital guttural toad.

Part A: Techniques, Approaches and AssessmentsNew techniques and technologies for invasive alien species control – gathering speed and momentumDr. Andrew TurnerCapeNatureCommunication and conflict in invasive alien species management projectsDr. Sarah DaviesIndependentAssessing the role of cemeteries in the spread of invasive alien plants in South AfricaNkhangweleni SikhauliSouth African National Biodiversity InstituteInvasive alien plants are used as alternative medicinal sources to indigenous species, Limpopo Province, South AfricaLesibana MaemaSouth African National Biodiversity InstituteThe New Zealand Christmas tree (Metrosideros excelsa): Its ecology, distribution and invasion potential in South ...

Virtual Online Symposium - Plenary Session The Conservation Symposium secretariat@conservationsymposium.com


Invasive and alien species have negative effects on biodiversity and ecosystem function, causing declines or even extinction of native species and loss of ecosystem services. Managing emerging invasive plant species often requires rapid interventions and the use of herbicides, and yet the administrative process to get herbicides tested and registered are cumbersome. In addition, there is often industry or public resistance to the implementation of control efforts which may delay efforts at a critical stage, necessitating a review of communication and engagement approaches and strategies. In the second part of the session, there will be a focus on innovative research and an emerging understanding of the invasion biology of the extralimital guttural toad.

Part A: Techniques, Approaches and Assessments
New techniques and technologies for invasive alien species control – gathering speed and momentum

Dr. Andrew TurnerCapeNature
Communication and conflict in invasive alien species management projects

Dr. Sarah DaviesIndependent
Assessing the role of cemeteries in the spread of invasive alien plants in South Africa

Nkhangweleni SikhauliSouth African National Biodiversity Institute
Invasive alien plants are used as alternative medicinal sources to indigenous species, Limpopo Province, South Africa

Lesibana MaemaSouth African National Biodiversity Institute
The New Zealand Christmas tree (Metrosideros excelsa): Its ecology, distribution and invasion potential in South Africa

Nicole MalanSouth African National Biodiversity Institute & Nelson Mandela University
A new invader? An eastern dwarf chameleon (Bradypodion ventrale) example

Dr. Andrew TurnerCapeNature
Part B: Invasion Biology – the Guttural Toad (Sclerophrys gutturalis)
The humble guttural toad (Sclerophrys gutturalis): Lessons of plasticity and adaptation following invasion

Prof. John MeaseyStellenbosch University
Introduction of guttural toads (Sclerophrys gutturalis) produces marked shifts in the endemic western leopard toad (Sclerophrys pantherina) gut microbiome

Carla WagenerUniversity of Oxford
Does urban adaptation enhance invasiveness? A case study of tadpoles of a successful invasive amphibian

Max MühlenhauptFreie Universität Berlin & Stellenbosch University
Conqueror toads: Comparing behaviour, performance and competitive potential in a successful invader and its native congeners

Dr. Andrea MelottoStellenbosch University
An army marches on its stomach: Diet composition and prey preference of guttural toad (Sclerophrys gutturalis) populations along a native-invasive and natural-urban gradient

Samuel PetaStellenbosch University


NOTE: The presentation by Thulisile Jaca (Assessment of invasive alien plants in urban municipal reserves, Gauteng Province, South Africa) has been withdrawn. Andrew Turner's (A new invader? An eastern dwarf chameleon (Bradypodion ventrale) example) has been added.

Direct Zoom link (only use if the Join Live button above fails) - https://us02web.zoom.us/j/84610414416

Session Sixteen Introduction
Introductions & Discussions 09:00 AM - 09:05 AM (Africa/Johannesburg) 2021/11/04 07:00:00 UTC - 2021/11/30 07:05:00 UTC
Presenters Sebataolo Rahlao
Ezemvelo KZN Wildlife
New techniques and technologies for invasive alien species control – gathering speed and momentum Watch Recording
Presentation 09:05 AM - 09:17 AM (Africa/Johannesburg) 2021/11/04 07:05:00 UTC - 2021/11/30 07:17:00 UTC

Achieving conservation objectives frequently requires managing invasive alien species (across all kingdoms). Many existing invasive alien species management techniques do not operate at the speed and/or spatial scale required to achieve sustainable conservation success. There are several promising new technologies and techniques for managing invasive alien species. These include aerial basal bark application of herbicide, ballistic herbicide application, aerial bait drops, self-resetting kill traps, new biocontrol agents, and gene drives. These methods may provide opportunities for time frames of management implementation commensurate with the speed of spread and intensification of invasive alien species. However, few of these are implemented in practice and, even where they are being trialled, there are significant constraints and obstacles to effective implementation. These impediments range from legislation not suited to conservation purposes, slow bureaucratic procedures, little to no research and development budgets, hesitancy in using novel methods, and potentially hazardous substances. We need a platform to raise and discuss the constraints and obstacles to adopting these new methods on the ground and to find solutions that result in environmentally sound invasive alien species control operations. We also need the systems and support to efficiently trial new methods and bring them into operation as soon as they have proved their worth. We need both speed and momentum to catch up with the invasions.

Presenters Andrew Turner
CapeNature
Communication and conflict in invasive alien species management projects Watch Recording
Presentation 09:17 AM - 09:29 AM (Africa/Johannesburg) 2021/11/04 07:17:00 UTC - 2021/11/30 07:29:00 UTC

Traditionally, science policy-makers, communicators, and journalists tend to operate on the assumption that the public needs to know more about the projects we are working on, and once they understand our perspectives and the science behind them, they will support our efforts. This is known in science communication as the 'deficit' or knowledge transmission model, where information 'flows' in one direction: from the knowledge broker (scientist, manager, or conservation professional) to the audience, user group, or public. The deficit model may have worked in the past if societies were authoritarian, exceptionally science-literate, or in uncontroversial fields (e.g. particle physics), but it is also the reason why communication sometimes goes wrong or projects face opposition from the public that result in delays or stoppages. To use an example from invasive alien species management: which dedicated trout fisherman has been convinced of the need to list trout as Category 1 invaders due to the argument that trout are voracious predators causing extirpation of native fish and trophic cascades in our rivers? In this talk, I will cover four topics that provide practical guidance for invasive alien species communication: (1) techniques to identify and engage interested and affected groups in invasive alien species management projects, (2) international and South African experiences of project managers learning from audience perspectives to improve project implementation, (3) principles of good engagement including transparency, acknowledging value-based nature of people's views of invasive alien species, and communicating uncertainty, and (4) some tools for co-creation of solutions with interest groups.

Presenters Sarah Davies
Independent
Assessing the role of cemeteries in the spread of invasive alien plants in South Africa Watch Recording
Presentation 09:30 AM - 09:33 AM (Africa/Johannesburg) 2021/11/04 07:30:00 UTC - 2021/11/30 07:33:00 UTC

In South Africa, cemeteries cover a significant amount of green space and are a vital part of urban green infrastructure. Generally, cemeteries belong to the municipality and those that are privately owned are often still maintained by municipalities. Different human activities occur during and after burial proceedings in cemeteries and usually ornamental plants are used for grave decoration. The activities that occur may disturb the soil structure and some plants might grow vegetatively or through seeds and may spread to other parts of the cemetery into natural areas. Several studies in South Africa have focused on assessing and monitoring pathways of invasion, such as roads, rivers, and dumping sites. However, the spread of invasive alien plants in and via cemeteries and the impact on biodiversity and socio-economies have not been investigated. It is therefore imperative that research on flora in cemeteries be explored. The aim of this study was to assess the role of cemeteries in the spread of invasive alien plants in South Africa. Here we present preliminary results from surveys conducted in the Gauteng and North West Provinces. Field surveys were conducted in 18 cemeteries. Distribution data was gathered through GPS devices, and specimens were collected and identified at the National Herbarium. For each species, abundance, stage of plant development, habitat, and growth habit were recorded. We recorded a total of 101 species in 18 cemeteries. The dominant lifeforms were herbs (n = 18 species), followed by succulents (n = 8) and shrubs (n = 7). Cactaceae was the dominant family contributing a total of 18% of the species. Most species were in alien invasive plant categories 1b (compulsory removal), 2 (regulated by area), and 3 (regulated by activity) of NEM:BA (National Environmental Management: Biodiversity Act 10 of 2004); only one unlisted species was recorded. We recommend that municipalities include management of alien invasive plants that occur in the cemeteries within their invasive alien plants' management plan.

Presenters Nkhangweleni Sikhauli
South African National Biodiversity Institute (SANBI)
Co-authors Thulisile Jaca
South African National Biodiversity Institute
Invasive alien plants are used as alternative medicinal sources to indigenous species, Limpopo Province, South Africa Watch Recording
Presentation 09:33 AM - 09:36 AM (Africa/Johannesburg) 2021/11/04 07:33:00 UTC - 2021/11/30 07:36:00 UTC

Many alien plant species have been introduced to South Africa for various purposes such as forestry and traditional medicine, and some have become invasive (IAPs). In recent years there have been increasing studies investigating the uses of alien plants in traditional medicine in South Africa. While there is a substantial body of literature on the uses of plants, the knowledge and motivation for using alien plants in traditional medicine are not well studied. An ethnobotanical survey was conducted to investigate the motives for using alien plants in herbal medicine in the northern areas of South Africa. Thirty traditional health practitioners (THPs) were interviewed. The majority (56%) of THPs used IAPs as alternatives to the indigenous plant species. The three main reasons reported for using IAPs were: (1) IAPs are accessed easily from home gardens and roadsides as opposed to the indigenous ones (47% of respondents), (2) both the indigenous and IAPs treat the same ailments (41% of respondents), and (3) IAPs are used so as to preserve indigenous species (12% of respondents). This study documented that THPs in the Waterberg District are using IAPs as an alternative medicinal source and that traditional use is dynamic and not fixed. The alternative use of IAPs under careful consideration could allow the recovery of endangered indigenous plants. The use of roots, seeds and stems in herbal medicine could be used as a management strategy to reduce dispersal capacity and control the spread of IAPs.

Presenters Lesibana Maema
South African National Biodiversity Institute (SANBI)
Co-authors Claude Moshobane
South African National Biodiversity Institute (SANBI)
The New Zealand Christmas tree (Metrosideros excelsa): Its ecology, distribution and invasion potential in South Africa Watch Recording
Presentation 09:37 AM - 09:40 AM (Africa/Johannesburg) 2021/11/04 07:37:00 UTC - 2021/11/30 07:40:00 UTC

Invasive alien plants are one of the greatest threats to biodiversity, with woody plants the most widely distributed group of invasive organisms globally. South Africa has the second-highest number of invasive alien trees, of which Metrosideros excelsa is an emergent invader in the Overberg region, Western Cape. Metrosideros excelsa, the New Zealand Christmas tree, was introduced as an ornamental plant and has subsequently invaded coastal fynbos on peat soils, thereby threatening rare flora and associated fauna. It flourishes with disturbance, which is common in its invaded peri-urban landscape. Fynbos wildfires increase these cumulative impacts. Additionally, the species exerts high propagule pressure through self-pollination and releasing large numbers of wind-dispersed seeds. A comprehensive risk assessment is required for this species. Therefore this study aims to assess the status of, and invasion risk posed by M. excelsa in South Africa, and explore the species ecology to inform appropriate management responses by 1) assessing the species current distribution and abundance, and conducting a risk assessment; 2) assessing post-fire regeneration success in terms of post-fire survival and resprouting vigour of established individuals, and recruitment from seed; 3) quantifying propagule pressure in terms of viable canopy-produced and soil-stored seed banks in burnt and unburnt stands; and possibly 4) determining the most effective foliar applied herbicide for treating post-fire resprouting individuals. The proposed study outcomes will inform appropriate legislative listing and relevant management approaches for the species in the interest of biodiversity conservation.

Presenters Nicole Malan
South African National Biodiversity Institute (SANBI) / Nelson Mandela University
Co-authors Sjirk Geerts
Cape Peninsula University Of Technology
A new invader? An eastern dwarf chameleon (Bradypodion ventrale) example Watch Recording
Presentation 09:40 AM - 09:52 AM (Africa/Johannesburg) 2021/11/04 07:40:00 UTC - 2021/11/30 07:52:00 UTC

Rapid accumulation of occupancy records of the alien Eastern Cape dwarf chameleon (Bradypodion ventrale) in the historical range of the Cape dwarf chameleon (B. pumilum) and the western dwarf chameleon (B. occidentale) in the Cape Town metropole over the past four years indicates that this species may be establishing within the city boundary. This example highlights the challenges of identifying novel alien species and developing a timely management response. This is critical as early actions have been shown to result in more cost-effective outcomes. Therefore, a rapid assessment is required to devise a rapid and effective response.

Presenters Andrew Turner
CapeNature
Co-authors
KT
Krystal Tolley
SANBI
Sarah Davies
Independent
Question and Answer Session with Moderated Discussion: Part A: Techniques, Approaches and Assessments
Introductions & Discussions 09:52 AM - 10:10 AM (Africa/Johannesburg) 2021/11/04 07:52:00 UTC - 2021/11/30 08:10:00 UTC
Presenters Sebataolo Rahlao
Ezemvelo KZN Wildlife
Co-authors Andrew Turner
CapeNature
Sarah Davies
Independent
Nkhangweleni Sikhauli
South African National Biodiversity Institute (SANBI)
Lesibana Maema
South African National Biodiversity Institute (SANBI)
Nicole Malan
South African National Biodiversity Institute (SANBI) / Nelson Mandela University
The humble guttural toad (Sclerophrys gutturalis): Lessons of plasticity and adaptation following invasion Watch Recording
Presentation 10:10 AM - 10:22 AM (Africa/Johannesburg) 2021/11/04 08:10:00 UTC - 2021/11/30 08:22:00 UTC

Invasive species represent the successful outcome of natural experiments of relocation of populations into novel settings away from their evolved areas of distribution. As such, they provide insights into the potential that some species have to exhibit plastic and adaptive responses to environmental challenges. Here, I present the outcome of multiple studies on the guttural toad, Sclerophrys gutturalis, that demonstrate the adaptive nature of its morphology, physiology, behaviour, and immunology. All studies feature comparisons of native populations from Durban, South Africa, and invasions in Cape Town (~20 years ago) and/or Mauritius and Reunion (~100 years ago). Remarkably, studies show hitherto unappreciated levels of plasticity and adaptivity in what appears to be an otherwise unremarkable common or garden species. Given the opportunities afforded to the guttural toad, I ask how many other native fauna could become so invasive in South Africa and beyond?

Presenters John Measey
Stellenbosch University
Introduction of guttural toads (Sclerophrys gutturalis) produces marked shifts in the endemic western leopard toad (Sclerophrys pantherina) gut microbiome Watch Recording
Presentation 10:22 AM - 10:34 AM (Africa/Johannesburg) 2021/11/04 08:22:00 UTC - 2021/11/30 08:34:00 UTC

Invasive species and their co-introduced parasites are of great concern to the environments they colonize and its native inhabitants, but do the introduction of invasive species impact the microbiome of native species? Despite recent literature on laboratory animals highlighting the importance of gut microbial symbionts (collectively known as the gut microbiome) to beneficial functions or traits, such as enhanced nutrition and physiological plasticity, few efforts have been made to understand how environmental change, such as the introduction of invasive species, alters the gut microbiome in native species. Our study addresses this knowledge gap by comparing the faecal microbial composition, determined through 16S amplicon sequencing, of invasive Guttural Toads (Sclerophrys gutturalis, GT) and endemic Western Leopard Toads (S. pantherina, WLT) in sites invaded and uninvaded by GT. The introduction of GT produces marked shifts in both the beta diversity and differential abundance of gut microbes in native WLT. Additionally, WLT in sites invaded by GT exhibit higher heterogeneity across WLT individuals compared to those present in uninvaded sites, possibly pointing towards homeostatic disruption of the WLT population gut microbiome. Gut microbiomes of WLTs in invaded sites are enriched with a variety of new species from the Lachnospiraceae, Bacteroidaceae and Akkermansiaceae bacterial families, known for metabolizing dietary components more efficiently. This can indicate a dietary shift or even diet restriction of WLT due to direct competition with GT. Known opportunistic pathogens, specifically species from the genus Odoribacter, Parabacteroides and Aeromonas, significantly increase abundance in WLT gut microbiomes present in GT invaded areas. We argue that these substantial shifts disrupting microbial homeostasis in the native WLT gut microbiomes can have potential knock-on effects on host health and physiology. While it is well known that invasive plant and insect microbiomes have severe impacts on native biodiversity; our study is the first to demonstrate that we should not only consider the impact of vertebrate hosts released in the wild, but also the spread of their co-introduced microbial communities. To facilitate and improve conservation efforts we need to further our understanding of host-microbiome associations in the face of environmental change.

Presenters Carla Wagener
University Of Oxford
Co-authors John Measey
Stellenbosch University
Does urban adaptation enhance invasiveness? A case study of tadpoles of a successful invasive amphibian Watch Recording
Presentation 10:35 AM - 10:47 AM (Africa/Johannesburg) 2021/11/04 08:35:00 UTC - 2021/11/30 08:47:00 UTC

Cities are focal points of the introduction of invasive species. The "Anthropogenically Induced Adaptation to Invade" (AIAI) hypothesis posits that urban evolution can facilitate the success of invasive species in recipient urban habitats. This research seeks to test this hypothesis in a successful amphibian urban coloniser and invader, the guttural toad (Sclerophrys gutturalis). We compared developmental, morphological, and performance traits of native-rural, native-urban, and invasive-urban tadpoles reared in a common garden experiment to test for innate trait differences. The invasive-urban tadpoles showed significantly slower developmental rates (e.g. the proportion of tadpoles reaching a developmental landmark at age 40 days) than native-urban tadpoles. Yet, tadpoles did not differ in growth rate or any morphological or performance traits we examined. These findings suggest that urban evolution in tadpole traits likely does not play an important role in facilitating the invasion success of guttural toads into other urban habitats. We suggest that evolutionary changes in tadpole traits after colonisation (e.g. developmental rate), together with the potential for decoupling of other traits between life-stages, and phenotypic plasticity might explain how this species is so successful in colonising extra-limital urban habitats.

Presenters Max Mühlenhaupt
FU Berlin And CIB Stellenbosch
Co-authors James Baxter-Gilbert
Stellenbosch University
Julia Riley
Dalhousie University
Buyisile Makhubo
University Of KwaZulu-Natal
John Measey
Stellenbosch University
Conqueror toads: Comparing behaviour, performance and competitive potential in a successful invader and its native congeners Watch Recording
Presentation 10:47 AM - 10:50 AM (Africa/Johannesburg) 2021/11/04 08:47:00 UTC - 2021/11/30 08:50:00 UTC

Human activities are driving the global mixing of biota, with species being increasingly introduced into novel ecosystems and becoming exposed to unprecedented adaptive challenges. In the majority of cases, after introduction, species fail to survive and to establish stable populations in the novel environment, but those that succeed may pose severe threats to native biodiversity. Identifying key traits characterising successful invaders and understanding mechanisms allowing species to colonise novel habitats represents a crucial conservation task. Traits such as boldness, elevated dispersal ability, and effective anti-predator response can be favoured and positively selected for when invading a new environment. The present study addresses this issue by comparing multiple behavioural (anti-predator and boldness) and performance traits (climbing ability and endurance) of three congeneric toad species present in the Western Cape, South Africa: the guttural toad (Sclerophrys gutturalis, GT), raucous toad (S. capensis, RT), and western leopard toad (S. pantherina, WLT). The GT is invasive in the Cape Town area (for ~20 years), while the RT is present in most of the Western Cape, but has failed to establish in the Cape Peninsula, where the westernmost populations of the WLT occur. GTs showed a greater capacity to overcome artificial barriers than native WLTs (p = 0.012), and displayed increased boldness, exiting refuges earlier and faster than both native species (both p < 0.001). Moreover, when disturbed, both GTs and RTs were more prone to flee than WLTs, which showed a strong tendency to stand and face threats, displaying their aposematic dorsal patterning (p < 0.001). Variation in adaptive traits among these toad species may contribute to the success of GTs as invaders, and our findings provide key insights for delineating a profile for invasive toad species.

Presenters Andrea Melotto
Stellenbosch University
Co-authors Carla Wagener
Department Of Zoology
James Baxter-Gilbert
Mount Allison University
Julia Riley
Dalhousie University
John Measey
Stellenbosch University
An army marches on its stomach: Diet composition and prey preference of guttural toad (Sclerophrys gutturalis) populations along a native-invasive and natural-urban gradient Watch Recording
Presentation 10:50 AM - 10:53 AM (Africa/Johannesburg) 2021/11/04 08:50:00 UTC - 2021/11/30 08:53:00 UTC

Understanding factors driving the range expansion and invasion success of alien species, including those along natural-urban gradients, relies on niche-based invasion hypotheses and their applications. Here, we examine trophic niche breadth to test for potential diet shifts, flexibility and preferences of guttural toads, Sclerophrys gutturalis, from native-natural (rural Durban), native-urban (city Durban), invasive-urban (Cape Town), and invasive-natural populations (Mauritius). We predict that invasive populations will exhibit broader trophic niche breadth compared to native populations and that the diet composition of urban populations will contain more invasive prey. Prey items were identified, assigned to a feeding functional group, and classified as native or invasive. We compared diets across populations using an index of relative importance to quantify diet composition, Pielou's evenness, as a measure of trophic niche breadth, and an electivity index to determine prey preference. We found that omnivorous, phytophagous and scavenger feeding groups are the most common prey. Our findings align with our predictions, with Mauritius invasive populations having broader niche breadth compared to other populations and natural populations having a broader niche breadth compared to urban ones. Our electivity index found that insects are preferred in most cases, except in Mauritius (amphipods and gastropods). Contrary to our predictions, invasive prey items are consumed at low rates, including within urban populations. Our findings indicate that this toad is a generalist predator, however at the population level, expanding and contracting trophic niche breadths and noticeable dietary shifts between well-established populations likely reflect the toads' ability to readily adapt to local ecosystems. This dietary adaptation outside native ranges is likely to drive the invasion success of this toad and warrant management resolution to mitigate the impact on native species; in particular in Cape Town, where the guttural toad invasion range overlaps with the endangered and endemic western leopard toad, Sclerophrys pantherina, raising issues of dietary competitionThe same applies in Mauritius where endemic gastropod species were found in the toad's diet.

Presenters Samuel Peta
DST-NRF Centre Of Excellence For Invasion Biology
Co-authors James Baxter-Gilbert
Stellenbosch University
John Measey
Stellenbosch University
Question and Answer Session with Moderated Discussion: Part B: Invasion Biology – the Guttural Toad (Sclerophrys gutturalis)
Introductions & Discussions 10:53 AM - 11:15 AM (Africa/Johannesburg) 2021/11/04 08:53:00 UTC - 2021/11/30 09:15:00 UTC
Presenters Sebataolo Rahlao
Ezemvelo KZN Wildlife
Co-authors John Measey
Stellenbosch University
Carla Wagener
University Of Oxford
Max Mühlenhaupt
FU Berlin And CIB Stellenbosch
Andrea Melotto
Stellenbosch University
Samuel Peta
DST-NRF Centre Of Excellence For Invasion Biology
CapeNature
Independent
South African National Biodiversity Institute (SANBI)
South African National Biodiversity Institute (SANBI)
South African National Biodiversity Institute (SANBI) / Nelson Mandela University
+ 5 more speakers. View All
Dr. Sebataolo Rahlao
Ezemvelo KZN Wildlife
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