South Africa should sort out the bad from the really bad on its invasive species list



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Managing trout is a contentious issue with conflicting views about whether they pose a risk, or are beneficial.
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Tsungai Zengeya, South African National Biodiversity Institute

This article is the third in a series The Conversation Africa is running on invasive species.

Alien species have been introduced to Africa for a variety of reasons. They provide food, raw materials for industry, ornamental plants, recreation in the form of sport fishing, hunting and pets. Some that are highly valued have been moved around widely. And in some areas they now form prominent components of societies and ecosystems like the domestic cat for example.

Many alien species bring considerable benefits. But some have become invasive, causing a loss of biodiversity, changes to ecosystems, economic losses and, in some cases, even affecting people’s health.

The shrub Prosopis or mesquite is an example. It was introduced to South Africa to provide fodder, firewood and shade in arid parts of the country. But it’s also a major water user. And two trout species (S. trutta and O. mykiss) are used for recreational angling and commercial aquaculture. But they’ve also been implicated in having a negative effect on the environment.

Managing invasive species is therefore critical. In South Africa the movement and use of 552 listed invasive species are managed under the Biodiversity Act and regulations attached to it. But not all the species on the list are equally harmful. Several may in fact be relatively harmless.

All the listed species under these regulations require management. Given that the capacity is limited, regulations should arguably focus on priority species because not all are necessarily harmful to the extent that would justify spending large amounts of time and effort on keeping them under control.

The question then is: are there some species that could be removed from the list? In our recent study we set out to answer this question by classifying species as inconsequential, beneficial, destructive or conflict generating species. This was done by assessing the relative degree of benefit they brought and their negative effects.

Beneficial and harmful species

The classification was done by using a simple scoring system. It had two categories for the negatives (ecological and socio-economic) and two for the benefits (economic and intrinsic).

  1. Inconsequential species: these make up 55% of the species listed under the act and in the regulations. They were associated with relatively low costs and low benefits to society. Species in this group had limited distribution or no known impact and were largely introduced as ornamentals or pets. Some examples include the eastern grey squirrel (Sciurus carolinensis), European perch (Perca fluviatilis), and the Père David’s Deer (Elaphurus davidianus).

  2. Destructive species: these make up 29% of the list. They don’t bring substantial benefits to society or the environment, but they have a highly negative impact. Many were introduced accidentally and are regarded largely as pests and weeds. Examples include invasive rodents like the black rat (Rattus rattus) which causes damage to infrastructure and transmission of zoonotic diseases and pitch canker (Fusarium circinatum) a growing threat to pine plantations and forests worldwide.

The jacaranda is an iconic tree species in the city of Pretoria where it’s regarded as part of the identity.
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  1. Beneficial species: they make up 10% of the list and have clear social or environmental benefits. For example the jacaranda (Jacaranda mimosifolia) is an iconic tree species in the city of Pretoria where the species is regarded as part of the identity and “sense of place” of the city. Active management is not necessary or should only be done in particular cases.

  2. Conflict-generating organisms: these can be either beneficial or destructive, depending on one’s perspective or what value is placed on them. They make up only 6% of the list. There’s huge disagreement about whether these species should be controlled, or how they should be controlled. Examples include woody plants introduced for forestry, erosion control, sand dune stabilisation, agriculture and as ornamentals. Acacias and pines are examples. Animal examples include species like the Himalayan tahr which was introduced to the Table Mountain National Park. The goat has been the focus of eradication attempts, despite strong opposition. It also includes species introduced for aquaculture like maroon and brown trout. Managing trout has been highly contentious with conflicting views about whether they pose a risk, or deliver a benefit. This has led to them being listed and delisted. The trout fraternity refuse to acknowledge that trout are invasive species and highlight the lack of scientific evidence of the risks they pose.

Finding common ground

We need to keep sight of the fact that there is general agreement on 94% of listed species. By identifying the small number that are generating the greatest tension, it’s more likely discussions can be held to reach common ground on regulation.

Most countries in Africa don’t have invasive species regulations. But there’s growing recognition that they’re needed. South Africa offers useful lessons on how this could be done.

The control of species listed under the country’s biodiversity act is compulsory. This means that plans to manage them have to be drawn up and implemented. But this doesn’t seem sensible given that not all are equally harmful and resources are limited. Our study suggests that some of the species currently regulated could be removed from the list.

Countries wanting to set up a system of managing invasive species could start by classifying a prospective list of candidates. Policymakers could then quickly bring out legislation against the most damaging and destructive ones. At the same time, discussions could be had on the ones that generate conflict with the aim of reaching consensus.

The ConversationThis would allow managers and regulators to focus on the most destructive species – as well as those that are at the centre of fierce disagreement.

Tsungai Zengeya, Researcher at the South African National Biodiversity Institute, South African National Biodiversity Institute

This article was originally published on The Conversation. Read the original article.

Rhinos should be conserved in Africa, not moved to Australia


Matt Hayward, Bangor University

Rhinos are one of the most iconic symbols of the African savanna: grey behemoths with armour plating and fearsome horns. And yet it is the horns that are leading to their demise. Poaching is so prolific that zoos cannot even protect them. The Conversation

Some people believe rhino horns can cure several ailments; others see horns as status symbols. Given horns are made of keratin, this is really about as effective as chewing your finger nails. Nonetheless, a massive increase in poaching over the past decade has led to rapid declines in some rhino species, and solutions are urgently needed.

One proposal is to take 80 rhinos from private game farms in South Africa and transport them to captive facilities in Australia, at a cost of over US$4m. Though it cannot be denied that this is a “novel” idea, I, and colleagues from around the world, have serious concerns about the project, and we have now published a paper looking into the problematic plan.

Conservation cost

The first issue is whether the cost of moving the rhinos is unjustified. The $4m cost is almost double the anti-poaching budget for South African National Parks ($2.2m), the managers of the estate where most white rhinos currently reside in the country.

The money would be better spent on anti-poaching activities in South Africa to increase local capacity. Or, from an Australian perspective, given the country’s abysmal record of mammal extinctions, it could go towards protecting indigenous species there.

In addition, there is the time cost of using the expertise of business leaders, marketeers and scientists. All could be working on conservation issues of much greater importance.

Bringing animals from the wild into captivity introduces strong selective pressure for domestication. Essentially, those animals that are too wild don’t breed and so don’t pass on their genes, while the sedate (unwild) animals do. This is exacerbated for species like rhinos where predation has shaped their evolution: they have grown big, dangerous horns to protect themselves. So captivity will likely be detrimental to the survival of any captive bred offspring should they be returned to the wild.

It is not known yet which rhino species will be the focus of the Australian project, but it will probably be the southern white rhino subspecies – which is the rhino species least likely to go extinct. The global population estimate for southern white rhinos (over 20,000) is stable, despite high poaching levels.

This number stands in stark contrast to the number of northern white (three), black (4,880 and increasing), great Indian (2,575), Sumatran (275) and Javan (up to 66) rhinos. These latter three species are clearly of much greater conservation concern than southern white rhinos.

There are also well over 800 southern white rhinos currently held in zoos around the world.

With appropriate management, the population size of the southern white is unlikely to lose genetic diversity, so adding 80 more individuals to zoos is utterly unnecessary. By contrast, across the world there are 39 other large mammalian herbivore species that are threatened with extinction that are far more in need of conservation funding than the five rhino species.

Exploitation

Rhinos inhabit places occupied by other less high profile threatened species – like African wild dogs and pangolins – which do not benefit from the same level of conservation funding. Conserving wildlife in their natural habitat has many benefits for the creatures and plants they coexist with. Rhinos are keystone species, creating grazing lawns that provide habitats for other species and ultimately affect fire regimes (fire frequency and burn patterns). They are also habitats themselves for a range of species-specific parasites. Abandoning efforts to conserve rhinos in their environment means these ecosystem services will no longer be provided.

Finally, taking biodiversity assets (rhinos) from Africa and transporting them to foreign countries extends the history of exploitation of Africa’s resources. Although well-meaning, the safe-keeping of rhinos by Western countries is as disempowering and patronising as the historical appropriation of cultural artefacts by colonial powers.

Conservation projects are ultimately more successful when led locally. With its strong social foundation, community-based conservation has had a significant impact on rhino protection and population recovery in Africa. In fact, local capacity and institutions are at the centre of one of the world’s most successful conservation success stories – the southern white rhino was brought back from the brink, growing from a few hundred in South Africa at the turn of the last century to over 20,000 throughout southern Africa today.

In our opinion, this project is neo-colonial conservation that diverts money and public attention away from the fundamental issues necessary to conserve rhinos. There is no evidence of what will happen to the rhinos transported to Australia once the poaching crisis is averted, but there seems nothing as robust as China’s “panda diplomacy” where pandas provided to foreign zoos remain the property of China, alongside a substantial annual payment, as do any offspring produced, for the duration of the arrangement.

With increased support, community-based rhino conservation initiatives can continue to lead the way. It is money that is missing, not the will to conserve them nor the expertise necessary to do so. Using the funding proposed for the Australian Rhino Project to support locally-led conservation or to educate people to reduce consumer demand for rhino horn in Asia seem far more acceptable options.

Matt Hayward, Senior Lecturer in Conservation, Bangor University

This article was originally published on The Conversation. Read the original article.

How insight into southern Africa’s dolphins is being deepened


Simon Elwen, University of Pretoria

South Africa has a wide range of oceanographic conditions around the coast. As a result, there is a diversity of cetacean species. These are large-bodied, fast-moving top predators like dolphins and whales. Globally, at least a quarter of these species are listed as endangered. Understanding how these species move and live is crucial to understanding their ecological relationships with the environment.

The E3C – Effect of Climate Change on Cetaceans – project looks at the impact climate change has on these species. The Conversation Africa’s energy and environment editor Ozayr Patel spoke to Dr Simon Elwen, a researcher with South Africa’s University of Pretoria working on the project.

Globally, at least a quarter of whale and dolphin species have been listed as endangered. What are the main reasons?

Many of the large whale species and populations that were subjected to commercial whaling have been very slow to recover, notably the Antarctic blue whale and the North Atlantic right whale. But the majority of large whale populations have been increasing slowly over the past few decades. Species are gradually leaving the threatened lists, thanks to wide-ranging international conservation efforts. The most important of these is the end of whaling, showing that stopping directed take – in other words “not killing animals” – is one of the most effective conservation strategies.

But the bad news is that many dolphin and porpoise populations are the ones now facing extirpation. The Maui’s dolphin of New Zealand and the vaquita of the gulf of California are both critically endangered. The baiji, the Chinese river dolphin, has already been declared extinct due almost entirely to habitat loss in the Yangtze River in China.

What is the state of dolphin species around Africa’s coasts? What threats do they face?

In southern Africa most dolphin populations are thought to be fairly healthy. There are five species that are regularly seen from shore, including the Heaviside’s and dusky dolphin on the west coast and the Indo-Pacific bottlenose and Indian Ocean humpback dolphin, which are found to the east of Cape Point in Cape Town. There are several other species that inhabit the shelf and offshore waters, with the common dolphin being one of the few of these regularly seen close to shore, especially along the south-eastern part of the continent. The only species that is currently thought to be of concern is the humpback dolphin, Sousa plumbea.

The humpback dolphin lives along the southern Cape coast and off northern KwaZulu-Natal province. This entire population in South Africa likely numbers less than 1,000 individuals and lives extremely close to shore, where it regularly encounters humans. This results in things like boat traffic, pollution, habitat loss and prey depletion having an impact on these species.

Why are dolphins, in particular, important in the ocean’s ecosystem?

Dolphins and whales are large, highly mobile top predators. They can eat a lot of food and respond quickly to changes in the environment by moving large distances, depending on the species. As large predators, they can have a top-down role in ecosystems, suppressing the numbers of prey animals. What this means is that sometimes species near the bottom of the food chain, like sardine or anchovy, can increase when medium-level predators are removed by top predators such as seals, sharks and dolphins, a result shown in a number of ecosystems globally.

Dolphins and
whales are known to be top predators.

Simon Elwen

What is unique about the South African coast that makes it so diverse?

South Africa’s marine life at all trophic levels is remarkably diverse, thanks largely to the diversity of habitats available around the coast. It ranges from tropical at the Mozambique border, to temperate along the south coast and cool-temperate along the west coast.

From a mammal point of view, the cold waters of the Benguela ecosystem along the west coast provide a link to sub-Antarctic environments, so some species that are usually only found south of 40 degrees of latitude also occur in the Benguela, like southern right whale dolphins and pygmy right whales.

Commercial fishing practices, gill nets and pollution are viewed as the most serious challenge to dolphins. Are these serious problems in African and South African waters?

To the best of my knowledge, bycatch – the unintentional catching of a species – is thankfully not a major problem in South Africa. There is no gill netting in South Africa. Coastal net fisheries are scarce and most of the large-scale commercial fishing activities in South Africa occur in deeper waters than most of our coastal dolphin species occur.

But entanglement in lobster and octopus trap lines is an increasing concern for large whales in coastal waters. Recent data on organic pollutants in dolphins from the east coast suggests that DDT and polychlorinated biphenyls are still a concern, especially for coastal dolphin species like the humpback and bottlenose.

What effect is climate change having on dolphins?

Essentially, assuming no other changes in the ecosystem – which is somewhat naive – we expect a general pole-ward shift in the distribution ranges of most cetacean species. This isn’t likely to be a major problem for animals that move large distances in the relatively uniform and connected environment of the open ocean. But it will potentially have major impacts on some coastal species, especially those that live in habitats that are “dead ends” in this respect (like the southern coast of Africa).

Along the South African coast, several dolphin species live in the Benguela, which is currently thought to be cooling – against the general trend of climate change – due to increased winds and upwelling of cold water. Right now we don’t really know how adaptable these animals are to massive changes in temperature in either direction, should they occur.

What other major conservation tactics are used to help dolphins survive and thrive?

1) Don’t kill them! In any form, including entanglement or bycatch, hunting or pollutants.

2) Stop polluting the oceans – including noise, plastics and organic pollutants.

3) Stop harassing them – obey the laws and use responsible tour operators.

4) Don’t steal their food – eat sustainably caught fish

You have started a project involving citizen scientists. Why have you taken this route?

Citizen science projects have been extremely successful both locally and internationally. Modern communication methods like mobile phones and the internet allow scientists to rapidly communicate with thousands of interested and knowledgeable observers to increase the number of eyes and ears available to collect data. We can’t be everywhere, and our boat surveys and acoustic methods are limited in the amount of area or time they can cover, so we are trying to take advantage of the large number of keen whale and dolphin watchers around our Cape Town’s coasts to report sightings to us.

Remarkably, the area around Cape Town itself has been quite poorly studied by cetacean scientists in the past. So citizen science offers us a potentially powerful route to massively increase the number of data points of dolphin and whale sightings around the area.

The Conversation

Simon Elwen, Research Fellow, Mammal Research Institute, University of Pretoria

This article was originally published on The Conversation. Read the original article.