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MARINE INVASIVE SPECIES: AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN Indian Ocean Commission Blue Tower 4th floor, rue de l’Institut Ebene, Mauritius Tel : +230 402 6100 MARINE INVASIVE SPECIES: [email protected] An emerging threat in the western indian ocean www.coi-ioc.org Marine invasive species (MIS) are recognised as one of the four major threats to marine and coas- Fax : +230 466 0160 tal ecosystems along with land-based sources of marine pollution, overexploitation of living marine © Indian Ocean Commission resources and habitat degradation. Definition: Invasive species are species which proliferate and spread in a manner which threatens ecosystems, habitats and/or other species, and which potentially cause socio-economic and/or environmental damage, or harm to human health. The majority of invasive species are alien (non- Photo credits : indigenous, exotic): species which have been intentionally or unintentionally introduced to a new Charles Griffiths, Commission de l’océan Indien, International Maritime Organisation, Marine and geographic location, area, or region outside of their natural distribution range. However, it is important to Coastal Management, Mauritius Oceanography Institute, Mercator Media, David Obura, Pierre Peries, note that indigenous species may also become invasive, usually under altered environmental conditions. Luc J.D. Ralaimarindaza, Andry Rasolomaharavo, Tamara Shiganova, Patsy Theresine Alien species can be introduced to new coastal or marine areas via a number of pathways: broadly defined as the underlying activity or purpose (e.g. mariculture, shipping, oil and gas exploitation, tourism or aquarium trade) for the intentional or unintentional translocation of species. Intentional introductions include species which are imported for fisheries or mariculture ventures, for coastal management initiatives (eg. erosion control), or display in aquaria. However, such introductions may also result in unintentional ones as a result of escape or subsequent deliberate (illegal) release from the facility, or spread from an unconfined site. The pathway responsible for the majority of unintentional introductions is shipping (including small craft as well as offshore platforms) which transports alien species in ballast water or as biofouling. The construction of canals linking previously unconnected water bodies is also important in some regions (eg. Suez Canal). This publication has been produced with the assistance of the European Union. The contents of this publication are the sole responsibility of the author and can in no way reflect the views of the European Union. 3 IMPACT ON FISHERIES: The comb jelly Mnemiopsis leidyi endemic to North America coast - was first recorded in the Black Sea in 1982. It became well established, occurring in massive numbers and changing the whole pelagic trophic web, with a devastating effect on the pelagic fisheries of the Black and Azov Seas. These fisheries target zooplanktivorous fish species such as anchovy, horse mackerel, sprat and kilka. Since Mnemiopsis also feeds on zooplankton, its presence led to a massive decline in the availability of food for the fish, causing the collapse of fisheries worth approximately $500 million per year. Landings of anchovy dropped to one-third of their previous levels, and many fishermen abandoned fishing. The situation has improved in recent years as a result of another accidental introduction: a second species of comb jelly which preys on Mnemiopsis, leading to a decline in its numbers. The management of invasive species is based on a hierarchical approach including the following: Biofouling : the biological communities which develop on submerged physical structures such as ship’s hulls, propellers etc, as well as fishing gear, mariculture cages and even marine debris. Slowmoving vessels and those which spend lengthy periods in one location and are cleaned infrequently are of particular concern as they harbour a greater number of species which can enter new areas by “jumping ship” or by releasing offspring into the surrounding waters. Biofouling is now recognised as the biggest source of marine invasives. Ballast water is used to provide stability to ships which are not carrying a full load of cargo. It is taken on board at the start of a journey and discharged in the port where the cargo is to be loaded. Most marine biota have a planktonic stage in their lifecycle and it has been estimated that up to 10 000 species may be present in ballast water at any given time. The sediments which accumulate in ballast tanks commonly contain dinoflagellate cysts which, once discharged can result in Harmful Algal Blooms (HABs). Marine Invasive Species may have a variety of impacts: • • 1. Prevention or minimization of introductions 2. Prevention of establishment and spread through early MOST DESIRABLE detection and rapid response 3. Eradication (where possible) 4. Containment 5. Ongoing control of established invasives. Prevention is the preferred and most cost-effective option particularly in the marine environment where eradication is extremely difficult and ongoing control very costly. Prevention measures can be applied to pathways and/or around borders and include: Pre-border: in the case of deliberate introductions for eg. mariculture, - Environmental Impacts Assessments to assess Ecological impacts: they can displace indigenous species through predation, competition, habitat the risk of invasion; for shipping – management of biofouling alteration and changes to the food-web. They can also disrupt ecological processes and compromise and on-board treatment of ballast water; ecosystem services. Border: compliance inspections, quarantine and/or treatment; Economic impacts: they can cause closure of recreational/coastal amenities as well as reductions in Post-border: monitoring for priority species (early detection) productivity of fisheries (see below) and efficiency of shipping – the latter due to biofouling which and rapid response plans. LEAST DESIRABLE also causes problems for coastal infrastructure, mariculture operations and industrial installations. Moreover, there are significant costs associated with their prevention and management. • Health impacts: pathogens such as cholera and phytoplankton cysts which form Harmful Algal Blooms are commonly found in ballast water and sediments. For example, a cholera outbreak in South America in 1991 was linked to ballast water discharges from a ship from Asia. 4 MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN 5 Marine invasive species in the Western IndIan Ocean Several species of red algae including Kappaphycus spp, Eucheuma denticulatum and Gracilaria Salicornia – are utilised for seaweed mariculture in a number of WIO countries. Tanzania is the biggest producer, but they are also cultivated in Kenya, Madagascar, Mauritius and Mozambique. They include both introduced (eg. Kappaphycus from the Philippines) and local species. They are all considered invasive in some parts of the world (eg. Hawaii) and as such are considered a serious danger to coral reefs and other benthic communities. There are reports of these species spreading outside of the farmed areas in the region and it is important that they are monitored. The Crown of Thorns Starfish (Acanthaster planci) is a large (up to 80cm in diameter) indigenous species which can become highly invasive under certain conditions. It feeds mainly on hard corals and when there are dense aggregations it can cause significant damage to coral reefs. It is of particular concern where there is already damage due to other factors such as coral-bleaching. Outbreaks have increased in recent years and have been linked to nutrient loading, El Nino events and a reduction in predators. They have been reported from Comoros, Madagascar, Mauritius, Reunion and Seychelles. Efforts to manage COTS should be coordinated at regional level. Bugula neritina is a bryozoan which is an abundant fouling organism that colonises any freely available substratum, including ships, piers, buoys and other man-made marine surfaces and structures. B. neritina populations tolerate high levels of pollution (including copper) which increases their competitive advantage and thus their potential to be a fouling pest. It has been reported in Kenya and Seychelles. SOMALIA KENYA Harmful Algal Blooms (HABs) are caused by a variety of species including dinoflagellates, diatoms, cyanobacteria or other types of micro-algae some of which can have acute impacts on biodiversity or human health as a result of toxicity or oxygen depletion. Dinoflagellates are commonly carried in the sediments of ballast tanks and, although some are indigenous, there are many examples of translocation. HAB events have been recorded off the coasts of Kenya, Mauritius, Somalia, South Africa and Tanzania and some 60 potentially toxic species were recorded in the region in a UNESCO-IOC led survey. Dinoflagellates included Amphidinium carterae, Dinophysis acuminata, Gambierdiscus toxicus and Protocentrum arenarium. UNITED REPUBLIC OF TANZANIA ZANZIBAR SEYCHELLES COMOROS MOZAMBIQUE MAURITIUS The Asian Mussel (Musculista senhousia) is a small mussel native to east Asia which has a history of invasion in various parts of the world. It can grow rapidly and settles in aggregations forming mats on the sediment. It can thus cause marked habitat alteration and dominate benthic communities. M. senhousia also deposits large amounts of organic matter in the sediment, which can result in the accumulation of toxic metabolites such as sulfide, which can have adverse effects on other species. It has been reported in Madagascar, Mauritius and Tanzania. 6 MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN MADAGASCAR A number of species of oyster, including the Pacific oyster (Crassostrea gigas), have been introduced to Mauritius for mariculture purposes. C.gigas has a history of invasiveness in other parts of the world (Europe and North America) and is reported to settle into dense aggregations which exclude native intertidal species, destroy habitats and cause eutrophication of the water bodies it invades. While it may not be as significant a threat in tropical areas, it should be carefully monitored. REUNION White spot syndrome is a viral disease which occurs in penaeid shrimps. It is SOUTH AFRICA highly lethal and contagious and has decimated cultured populations around the world. A variety of invertebrates can be vectors and there have been at least two outbreaks of the disease in the region – in Mozambique (2011) and Madagsacar (2012). Such events have major implications for the shrimp farming industry and appropriate precautions need to be put in place to try and prevent them. 7 Marine Invasive Species in the Western Indian Ocean An additional factor which is likely to heighten the risk of invasions is climate change. An analysis Relatively few alien marine species have been recorded in the countries of the WIO Region apart from tolerance range for environmental parameters such as salinity and temperature, as well as high South Africa, and in this case, many of the records are from the western part of the country and there- reproductive capacities. This gives them a competitive advantage in the face of climate change and fore outside of the WIO region. Even fewer of those recorded in the WIO have a history of invasiveness. environmental disturbances caused by other factors such as pollution. of species which tend to invade suggests that they have a number of specific traits, including a wide On the other hand, a number of indigenous or cryptogenic species (i.e. those whose natural distribution range is unclear) showing invasive behaviour have been reported. Examples of both alien and indigenous invasives in the region are shown on the map on the previous page. To a large extent, this can be attributed to the low number of targeted surveys in the region. This is supported by the fact that the growing interest in the subject has resulted in a number of new records between 2012 when an assessment was done under ASCLME and 2015 (Baseline assessment for the Biodiversity Project). Moreover, it is anticipated that the risk of introductions to the region is likely to Regulation of marine invasive species Increasing recognition of the impacts of marine invasive species over the past few decades has led to the development of a relatively comprehensive international regulatory regime which comprises the following: • The Convention on Biological Diversity (CBD, 1992) - the only global instrument to provide a comprehensive basis for measures to protect all components of biodiversity against invasive alien increase with the expansion of activities related to the primary pathways for marine species. species (IAS); • The United Nations Convention on the Law of the Sea (UNCLOS) (1982) • The International Convention for the Control and Management of Ship’s Ballast Water and Sediments (BWM Convention) (2004) Seaborne trade in the region, for example, has and this trend is likely to continue particularly in light of the recent discoveries of oil and gas (2010 – 2014) in the areas off of Tanzania and • Trade volumes through WIO ports increased significantly over the past few years (2001). In addition, the following voluntary agreements are relevant: 10,000,000 • Mozambique – and the potential for further such finds in the region. Commercial vessels as well as offshore rigs increase the risk of introductions via International Convention on the Control of Harmful Anti-fouling Systems on Ships (AFS Convention) The IMO Voluntary Guidelines on Biofouling (2011) – which may eventually provide the basis for a new legal instrument; and • 5,000,000 An FAO Framework for the management of intentional introductions which includes provisions of the 1995 Code of Conduct for Responsible Fisheries. biofouling and ballast water. Source : the WIO State of the Coast Report (2015) Chapter 26 and UNCTAD Reviews of Maritime Transport. 0 Another important document is the CBD’s Strategic Plan for Biodiversity 2011- 2020, which includes 2003 2004 2010 2011 2012 a number of targets, of which Aichi Target 9 states that: “By 2020, invasive alien species and pathways are identified and prioritized, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment.” Although Tanzania is one of the top mariculture producers in Africa (mainly red seaweeds), production from other countries in the region is relatively low. Once constraints to growth – such as the lack of skills, technology and infrastructure - have been addressed, it is anticipated that it will expand throughout the region. Another driver for mariculture development is the growing decrease in returns from capture fisheries. Source : the WIO State of the Coast Report (2015) Chapter 22. Role of the Nairobi Convention The UNEP Regional Seas Programmes have historically been used as platforms to implement a number of international conventions, including the CBD, IMO Conventions on pollution from ships, and the FAO Code of Conduct for the Responsible Management of Fisheries. Since invasive alien species are, by definition, transboundary, they are naturally best addressed by harmonizing management efforts at the regional level. While the Nairobi Convention itself does not include articles dealing with invasive species, Article 7 of the Protocol Concerning Protected Areas and Wild Fauna and Flora in the Eastern African Region states that: “The Contracting Parties shall take all appropriate measures to prohibit the intentional or accidental introduction of alien or new species which may cause significant or harmful changes to the Eastern African region.” It is proposed that this be strengthened to provide a sound basis for the management of marine invasive species and the achievement of Aichi Target 9 in the WIO Region. 8 MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN 9 IOC Biodiversity Project The Eastern and Southern Africa and the Indian Ocean (ESA-IO) region includes island and coastal states with rich and vulnerable biodiversity. These natural resources underpin important sectors of the economies of the countries in the region, particularly fisheries and tourism, and provide livelihood opportunities and income for local communities. However in recent decades these ecosystems have been degraded as a result of increasing pressure from human population expansion and uncontrolled, sometimes inappropriate, coastal development. In this context, the Indian Ocean Commission (IOC) signed a financing agreement with the European Union in January 2013, to implement the Biodiversity Project “Coastal, Marine and Island Specific Biodiversity Management in ESA-I0 Coastal States”. The countries participating in the Biodiversity project are: Comoros, Madagascar, Mauritius, Seychelles, Kenya and Tanzania with Reunion Island participating using its own resources. The project document refers to the need to “implement mechanisms to harmonise policies and regulations at regional level pertaining to (…) alien invasive species, (…) in association with on-going initiatives at national level”. Initially the intention was to focus on terrestrial invasive alien species. However, during the first Biodiversity Project Technical Meeting, in July 2014, the representatives of the participating countries expressed an interest in complementing the terrestrial IAS activities with a marine IAS component. The IOC therefore recruited consultants to update an existing MIS baseline assessment and organise a regional workshop to agree on priorities for a second phase. Proposed activities include: • Liaison with the Nairobi Convention to strengthen its provisions relating to MIS; • Development of awareness-raising materials; • Capacity development through a port baseline survey Partners IOC The Indian Ocean Commission, through the Biodiversity programme, is one of the first institutions that deals with the marine invasive species (MIS) in the region. It encourages synergy and policy harmonization between countries of the East Africa and members of the IOC. EU European Union supports financially the Biodiversity programme through the 10th EDF (European Development Funds) up to 15 million EUR. 10 MARINE INVASIVE SPECIES : AN EMERGING THREAT IN THE WESTERN INDIAN OCEAN Indian Ocean Commission Blue Tower, 4th floor, rue de l’Institut Ebene, Mauritius Tel : +230 402 6100 Fax : +230 465 6798 [email protected] www.coi-ioc.org