DEALING WITH INVASIVE ALIEN SPECIES IN LAKE TANGANYIKA BASIN by Prof. Laurent NTAHUGA PhD in Biology, Kassel, FRG Bujumbura, 29th November 2011

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN IMPACTS OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

LAKE TANGANYIKA AUTHORITY, LTA

INTRODUCTION PURPOSE OF LTA IAS PROGRAMME: Efficient management of invasive Species: mainly alien but also native species Part of LT biodiversity Monitoring in the Lake and in its catchment. Part of the overall LTRIEMP: LT Regional Integrated environmental Monitoring Programme

Article 10. CONSERVATION OF BIOLOGICAL DIVERSITY 1. The Contracting States, acting separately or jointly, shall develop, adopt, implement and enforce appropriate legal, administrative and technical measures: a. to conserve rare, fragile and representative ecosystems and rare, depleted, or threatened species and populations of flora and fauna and their habitats that form part of the Lake Basin; b. to prevent the introduction of, control and eradicate exotic species that threaten ecosystems, habitats or species and the genetic resources that form part of the Lake Basin; c. to prevent the deliberate or accidental introduction of species into areas of the Lake Basin in which they do not naturally occur. 2. A Contracting State shall not permit the introduction of any exotic species of organism into the Lake Basin or into any other place where there is an appreciable risk of the organism entering the Lake Basin, unless the other Contracting States have been consulted and have given their consent, which shall not be withheld unreasonably.

INA WORKSHOP MARCH 2010 IS WORKSHOP MARCH 2011

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN IMPACTS OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

Eichhornia crassipes Water Hyacinth Amazon river basin, South America Grows in LT shallow waters and adjacent swamps On top of other IS and seeds can last for 20 years

AZOLLA FILICULOIDES (here associated with PISTIA STRATIOTES) Red Water Fern South America: Argentina, Brazil, Uruguay and Peru Delta swamps of the Rusizi river in DRC

PISTIA STRATIOTES Water Lettuce or Nile Cabbage Widespread in the tropics and sub-tropics but probably originating from South America Grows in quiet waters in the Rusizi river Delta, DRC

MIMOSA PIGRA Giant sensitive tree South and Central America Grows in lake side wetlands

MIMOSA DIPLOTRICHA Giant sensitive plant Brazil Smothers lakeside plants and terrestrial agricultural plant biodiversity (Cassava)

LANTANA CAMARA Wild lantana or Wild sage Tropical America Is found at many places in the catchment on drylands, moist lands and in shrublands

OTHERS Salvinia molesta Lemna spec.: Kariba weed Aquatic fern native to South-Eastern Brazil Lemna spec.: Mature plants of a species of Lemnaceae, with P. stratiotes in a wetland in Bujumbura

OREOCHROMIS NILOTICUS Nile tilapia Africa: north, west, central and east. Freshwater fish, used for aquaculture, but escaped into wild water systems, destroy vegetation and fish faunas and hybridize with local species – but big benefit to some!

OTHERS Tithonia diversifolia Canna indica Leucaena leucocephala VOSSIA CUSPIDATA

OTHERS Hydrilla verticillata Potamogeton crispus Senna occidentalis Senna hirsuta

PROCAMBARUS CLARKII Louisiana crayfish Southern USA, spread to Europe and Africa Omnivorous freshwater crustacean, Decapoda, present in the region but not yet assessed from the lake or the catchment

IAS IN THE LT BASIN Very apparent presence, mainly for plant species: water hyacinth, red water fern, water lettuce, sensitive plant species; Nile tilapia, etc. Most of them alien but also fewer species from the region:Vossia cuspidata, Oreochromis niloticus One invasive alien species feared: Procambarus clarkii, omnivorous crustacean species, threat to wetland and aquatic fauna and flora. Assessments conducted in the 4 countries: Uvira, Rusizi floodplain, Bujumbura, Kigoma, Mpulungu, but need for more surveys (Kalemie, Burton bay, non hotspot areas, etc.)

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN IMPACTS OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

NEGATIVE EFFECTS ON INVADED HABITATS (1) Aquatic plant species : Compete with other species for the space Constitute a barrier to light, oxygen for organisms under the formed plant carpet Reduce (quantity & quality of) biological diversity, including fish biodiversity obstruct the water way for water vehicles and large animal wildlife (Hippos, etc.) Increase water lost through evapo-transpiration Cause pollution

NEGATIVE EFFECTS ON INVADED HABITATS (2) Terrestrial plant species: Compete with other species for space smother other plant species including agricultural plants Agro-biodiversity very much affected Grow relatively fast Long lasting seeds (up to 50 years for Mimosa diplotricha) Spines on leaves & stem with pods covered with hairs that can stick to skin of animals, which contribute to their propagation (Mimosa sp.)

OVERALL: NEGATIVE OUTCOME Serious threats to ecosystems: ecological interruptions, followed by decline of related goods & services, and deceleration of socio-economic development Most likely to increase in the context of global warming: LT already known as an aquatic ecosystem experiencing decrease of productivity (fisheries) partly as a consequence of surface temperature increase due to current climate change influence.

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN KEY ISSUES OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

RELEVANCE OF IAS MONITORING Purpose of the monitoring exercise: Accumulate knowledge on concerned plant and/or animal species: status, movements & mapping, biology and environmental impacts (time & space). Possess a tool of IAS management Appreciate results of actions undertaken Allow to address root causes of given biological invasions with the aim of finding out appropriate management actions restore affected species and/or habitats.

PROCESS OF MONITORING IAS National institutions: Ministries with a stake in the LT and its catchment area: Environment, Agriculture, Fisheries, Lacustrine Transportation, etc. NEMAs, Universities, Research institutes, Civil society (ACVE) Regional/International institutions: LTA, Directorate of Environment, Supporting Initiatives: UNDP/GEF: LTRIEMP IUCN (Assessments already done by ESARO)

MZEE GEOFFREY AT WORK

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN IMPACTS OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

BASIC STEPS TO MANAGE IAS (1) Prevention of their introduction Best done at points of entry after risk assessment Cheapest and best way of IAS management See Article 10 of LT Convention (1, b & c). Eradication in early stages of a new invasion Destruction of mature, immature individuals including their reproductive means (eggs, seeds, etc.) Relevance of regular & efficient monitoring system The earlier the better, especially in budgetary terms

BASIC STEPS TO MANAGE IAS (2) Containment of new invasions Animals can be fenced in a ring of poison or repellant before destruction Plants can be weeded especially before seed set Management of already established IS Mechanical control: little success as plant may leave seed bank behind, can be expensive. Used in TZ to clear water intake points and landing sites

2011 LAKE TANGANYIKA DAYS 21-23 July In BUJUMBURA

BASIC STEPS TO MANAGE IAS (3) Management of already established IS Chemical Control: expensive & high risk of polluting water and affecting the ecosystem, spraying of the Water Hyacinth in Mazabuka in ZM; limited success as well due to reproduction cycle (seed-bank left behind) Biological Control: use of host-specific enemy(ies), preferred Control method for an already established IS. Weevils, Neochetina eichhorniae, and N bruchi, at many places in the region with interesting results against the water hyacinth. Integrated Control: Strategic use of combinations of mechanical, chemical and biological control methods to manage biological invasions

WHO SHOULD BE THE ACTORS? Government: Lake Tanganyika Day (Ministry of WELUP in BDI) National Invasive Species Strategy encouraged (Zambia with draft NISS and Action Plan) Governmental Agencies National Environmental Management Authorities (NEMAs), Research Institutions (Universities and others) Research on biological control of Hydrilla verticillata in BDI, on Lantana sp using natural enemies in ZM, etc. Civil Society ACVE: Water Hyacinth, mechanic removal in Muyinga and in LT basin involving Fishermen, among others.

OUTLINE INTRODUCTION IAS PRESENCE IN LT BASIN IMPACTS OF IAS MONITORING OF IAS MANAGEMENT OF IAS IN LT BASIN CONCLUDING OBSERVATIONS

IAS A REALITY IN LT BASIN IAS, plant & animal species, have been recorded from lake and catchment area. IAS are real threats to the LT basin and to goods and services from its ecosystems, basis for socio-economic development. Need for a regional monitoring tool, part of the planned LTRIEMP (LTA - UNDP/GEF Project) Biological control preferred for already established IAS and need for national & regional coordination of management actions.

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