Theme: Mainstreaming Biodiversity; Sustaining People and their Livelihoods
What is biodiversity or biological diversity?
Biodiversity is Life. The 1992 United Nations Earth Summit defined "biological diversity" as "the variability among living organisms from all sources, including, 'inter alia', terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems." This definition is used in the United Nations Convention on Biological Diversity.
Background and rationale
Biodiversity underpins people’s livelihoods and enables sustainable development in all aspects of life. It is the foundation for life and for the development of economic sectors such as agriculture, forestry, fisheries and tourism. Biodiversity is critical in contributing towards mitigation of threats, such as climate change, floods, droughts, and many more. It is central in supporting food security, medicinal material, cultural value, etc., and is the foundation for ecosystem resilience. The International Day for Biological Diversity was first created by the Second Committee of the UN General Assembly in late 1993, and was initially celebrated on 29 December (the date of entry into force of the Convention of Biological Diversity), but moved to 22 May from 2001 onward (date of the adoption of the text of the Convention) due to the challenges associated with celebrating the Day within the traditional holiday season. The purpose of the Day remained the same, i.e., to increase citizens' understanding and awareness about the importance of biodiversity.
Why Conserve Biodiversity?
South Africa within her borders contains a wealth of biodiversity, with seven major biomes, giving the country the 3rd highest biodiversity globally. Just one of these biomes, the Cape Floristic region, is recognized as one of the six floral kingdoms of the world as it harbours the fifth highest number of plant species in the world. However, there is serious pressure on our biodiversity and heritage. This is particularly relevant in freshwater environments and the National Spatial Biodiversity Assessment of 2004 found that 44% of freshwater ecosystems associated with main rivers in South Africa are critically endangered, compared with 5% of our terrestrial ecosystems. The major threats to most of these species are habitat loss due to poorly managed water abstraction, and alien invasive fishes. Alien fish species introduced to South Africa for sport fishing, particularly smallmouth bass (Micropterus dolomieu) and largemouth bass (Micropterus salmoides) have had significant negative impacts on indigenous fish species and aquatic ecosystems in general.
As an example, the invasion of the Rondegat River in the Cederberg, Western Cape, by smallmouth bass may have resulted in the local extinction of Clanwilliam sandfish and sawfin, indigenous species, leading to significantly altered invertebrate communities in the invaded river. Alien invasive fish, through direct predation pressure, can completely override the effects of habitat quality on native fish population integrity. These facts were confirmed in a recently published study funded by the Water Research Commission (WRC), and jointly implemented by the South African Institute for Aquatic Biodiversity (SAIAB) and CAPE Nature. The SAIAB team of researchers, through five years of intensive monitoring of the Rondegat River, have shown that the alien bass severely depleted the indigenous fish community, with at least three and possibly as many as six species driven to local extinction in the invaded zone. Extinctions of this nature are likely to have impact on future tourism and job creation. Further research studies are planned in the near future to quantify this aspect. The National Freshwater Priority Areas (NFEPA) framework is a very practical and strategic document in conserving our biodiversity-sensitive sites and limited water resources, and is currently being improved so that it can be even more applicable to protecting biodiversity at a site-specific level
Our lives depend on biodiversity. The goods and services that characterise healthy ecosystems can only continue to benefit communities, in both formal and informal economies and particularly in rural areas, if used wisely. Benefits emanating from functional ecosystems include clean water, clean air and food. In addition, ecosystem services extend to medicinal, cultural, recreational and other uses. These benefits must continue to be enjoyed by future generations; hence our role is to protect biodiversity.
How can research support conservation of the Cape Floristic Region Biodiversity Hotspot?
SAIAB and CAPE Nature, in a WRC-funded project, conducted surveys in the Rondegat River (see map) to document the short-term impact and efficacy of rotenone (a piscicide, see box insert) treatments and assess recovery rates of indigenous fishes and invertebrates following treatment.
Map of the Rondegat River indicating the four areas: treatment (red) and below treatment (yellow) areas in the invaded zone and the control (green) and pristine (blue) areas in the non- invaded zone.
Fish populations were monitored at 42 sites between February 2010 and March 2015. Macro-invertebrate monitoring was conducted seasonally at three monitoring sites within the treatment area, and three monitoring sites in the control area upstream of the treatment section, as well as at a monitoring site downstream of the treatment area. The study provided the answers to the most asked question by the public and media: "Is Rotenone safe to use in rivers for eradication of alien invasive species?" The study proved beyond doubt that rotenone is safe to use when following the approved international standard methods. The study also generated guidelines for future monitoring projects to assess the efficacy of rotenone treatments with regard to removing alien fish, and for monitoring the responses by macro-invertebrates and fish to these treatments. The study is expected to strongly influence the policy on biodiversity management in the country. Amongst the key legislations likely to be affected by this study are: the National Water Act (Act No.36 of 1998) and National Environmental Management: Biodiversity Act (Act No. 10 of 2004), national strategies, such as the National Biodiversity Strategy and Action Plan and National Water Resource Strategy, all of which seek to achieve sustainable utilization, conservation and wise use of biodiversity, including all its threatened species and ecosystems.
These strategies feed into higher-level visionary plans, such as the National Development Plan 2030, global plans, such as the Sustainable Development Goals 2030, the 2063 African agenda and many more. South Africa shares her biodiversity and water resources with bordering countries in SADC through a number of agreements; hence it is critical to look beyond our borders.
Through her internationally recognized research and development strategies, many of which have been funded by the Water Research Commission, South Africa has produced numerous reports and expertise on conservation aimed at achieving a balanced use of natural resources for the benefit of current and future generations.
Please visit www.org.za for more information. For further details, please do not hesitate to contact Mr Bonani Madikizela of the Water Research Commission on 012 3300340 or email@example.com
An overview of the piscicide rotenone
Rotenone is a natural toxic chemical (Empirical formula: C23H22O6) found in the roots of many tropical plants of the Leguminosae family. The most common commercial source is the derris plant (Derris eliptica), the roots of which contain on average 5% rotenone. The chemical acts as an inhibiter of cell metabolism, resulting in the failure of respiratory functions and death by tissue anoxia. While highly toxic at sufficient doses to many organisms, lethal concentrations vary greatly among different animal groups, although it is extremely toxic to fish. The chemical does not have any endocrine disrupting properties, does not appear to be carcinogenic, and breaks down rapidly under natural conditions. While it has been shown to produce Parkinson’s Disease–like symptoms when injected at high concentrations into lab rats, subsequent research indicates that people exposed to piscicides containing rotenone are unlikely to develop Parkinson’s Disease. Rotenone is highly sensitive to light and air, and quickly breaks down when exposed to sunlight. It has a half-life in water of 1 to 3 days, losing its toxicity faster in warm water than in cold water. Rotenone does not leach easily into the soil, thus limiting the threat to ground water. Its toxicity can be quickly neutralised by exposure to potassium permanganate (KMnO4).
Ground-up roots containing rotenone have been used for centuries by the indigenous peoples of South America and South-East Asia to narcotise (render unconscious) fish for human consumption. It has been used extensively as a pesticide on food crops, particularly in the United States, and as a piscicide for fisheries management. Freshwater and marine scientists also use rotenone as a fish-sampling tool, where it is used to capture cryptic species. Rotenone is considered to be the most environmentally benign fish toxicant in use today.
Information adapted from Ling (2003) and Muller (2009)