Okavango) Catchment, Angola
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Southern African Regional Environmental Program (SAREP) First Biodiversity Field Survey Upper Cubango (Okavango) catchment, Angola May 2012 Dragonflies & Damselflies (Insecta: Odonata) Expert Report December 2012 Dipl.-Ing. (FH) Jens Kipping BioCart Assessments Albrecht-Dürer-Weg 8 D-04425 Taucha/Leipzig Germany ++49 34298 209414 [email protected] wwwbiocart.de Survey supported by Disclaimer This work is not issued for purposes of zoological nomenclature and is not published within the meaning of the International Code of Zoological Nomenclature (1999). Index 1 Introduction ...................................................................................................................3 1.1 Odonata as indicators of freshwater health ..............................................................3 1.2 African Odonata .......................................................................................................5 1.2 Odonata research in Angola - past and present .......................................................8 1.3 Aims of the project from Odonata experts perspective ...........................................13 2 Methods .......................................................................................................................14 3 Results .........................................................................................................................18 3.1 Overall Odonata species inventory .........................................................................18 3.2 Odonata species per field site ................................................................................24 3.3 Species assemblages and potential indicator value ...............................................71 3.4 Observed and potential threats to Odonata and their habitats ................................73 3.5 Updated checklist of the Odonata of the Okavango River catchment ..................... 74 3.6 Updated checklist of the Odonata of Angola ...........................................................82 5 Conclusion and outlook ..............................................................................................90 6 Acknowledgements .....................................................................................................91 7 References ...................................................................................................................92 8 Photographs ................................................................................................................98 2 1 Introduction 1.1 Odonata as indicators of freshwater health Indicators on the state of global biodiversity show continued decline at a rapid rate, while pressure on biodiversity keeps rising (BUTCHART et al. 2010). Threats to biodiversity include, among others, resource consumption, invasive alien species, pollution, overexploitation, and climate change (TYLIANAKIS et al. 2008). Freshwater habitats represent one of the most threatened ecosystems in the world (DUDGEON et al. 2006) and, despite occupying less than 1% of the Earth's surface, they contain 10% of all known species (STRAYER & DUDGEON 2006). The living planet index for tropical freshwater species has declined by 69% between 1970 and 2007 (WWF 2010). Additionally freshwater habitats and species are poorly protected as most protected areas target terrestrial ecosystems (DUDGEON et al. 2006). Similar to the challenges for general biodiversity, freshwater biodiversity specifically faces loss of hydrologic connectivity (PRINGLE 2001), nitrogen pollution, resource over-exploitation, flow alteration and water over- extraction, invasion by alien species, and climate change impacts such as temperature warming and shifts in precipitation and runoff patterns (ABELL et al. 2007). Africa’s rich freshwater biodiversity is critical to the wellbeing of the continent’s human population (DARWALL et al. 2011). However, with increasing development and population growth water resources are under increasing pressure. Conservation actions are needed to ensure that the provided benefits are maintained, as is the biodiversity. Planning such actions, e.g. establishing protected areas and conducting inventories (GASTON et al. 2008), requires good spatial knowledge of patterns of biodiversity and threat. Unfortunately, prioritization has been largely directed at terrestrial habitats, focusing on vertebrates as target species (e.g. BROOKS et al. 2004, RODRIGUES et al. 2004). Nonetheless, patterns of richness and threat for freshwater species differ from those of terrestrial animals and surrogacy values are low between taxa from different realms (RODRIGUES & BROOKS 2007). Moreover, it is generally unknown whether the global biodiversity hotspots (MYERS et al. 2000) apply to invertebrates, which make up over 95% of the Earth’s known animal species diversity (GASTON & HUDSON 1994). Consequently, the biodiversity hotspots website of CONSERVATION INTERNATIONAL (2007) does not even attempt to consider endemic insect species when reporting the vital signs of the respective hotspots. In a more recent study about fine-scale prioritization of areas of conservation concern using dragonflies on the African continent it could be clearly shown that areas of high Odonata diversity and endemism only partly fall together with the defined biodiversity hotspots, and especially southern central Africa as an outstanding and rich area is not adequately covered by those (SIMAIKA et al. 2013). Because conservation priorities based on terrestrial vertebrates may not adequately represent freshwater species, separate bioindicators are needed for freshwater habitats. Dragonflies (Insecta: Odonata) are excellent model organisms and flagship species in freshwater conservation because they are: (i) a key component of species assemblages in freshwater ecosystems; (ii) sensitive to changes in both the aquatic and terrestrial environments, because their larval phase is completed in water, while adults are mobile predators in the air and on land; 3 (iii) abundant in all continents except Antarctica, with tropical forests being especially species-rich (KALKMAN et al. 2008), and; (iv) taxonomically well-resolved in comparison to other invertebrate groups (e.g. DIJKSTRA 2003, 2007c). They are employed successfully as indicators of ecosystem health in environmental impact assessments, in particular because of their amphibious nature (e.g. CLARK & SAMWAYS 1996, OERTLI 2008, SAHLÉN & EKESTUBBE 2001, SIMAIKA & SAMWAYS 2011). Although their conservation status is well-documented (CLAUSNITZER & JÖDICKE 2004), little was known until recently about overall levels of threat to the world’s dragonflies. An assessment of 1500 randomly sampled species indicated that 9% of all 5680 known species is threatened with extinction (CLAUSNITZER et al. 2009), highlighting that a compre- hensive assessment is required if we are to effectively identify priority conservation actions and sites for this group. Indeed, in their study on the effectiveness of surrogate species and their representativeness of freshwater species on the African continent, DARWALL et al. (2011a, b) found that dragonflies are effective surrogates for birds, mammals, and amphibians, but that the inverse of this relationship does not hold. Furthermore, the Freshwater Biodiversity Assessment of Africa (DARWALL et al. 2011b) confirms that patterns of richness and threat are remarkably similar among dragonflies, fishes, molluscs and crabs at the continental scale, particularly in Mediterranean North Africa, the Cape region of South Africa, equatorial West Africa, and of the afro-montane regions of East Africa. 4 1.2 African Odonata The African continent is in comparison to other tropical continents relatively poor in Odonata species. Whereas more than 2500 species can be found in South-East Asia and South America respectively the African continent holds about 730 valid species (DIJKSTRA 2003, 2007c). A database with point locality records was created during the last 12 or more years, based on literature, collections and field notes. Material was checked by various experts, often resulting in revisions and taxonomic changes (DIJKSTRA et al. 2011 and references therein). The Odonata Database of Africa (ODA) is the first continent-wide, expert-reviewed database of freshwater insects (KIPPING et al. 2009). The database is updated continually, and now contains over 95.000 records, representing 710 species from over 10.000 localities. Figure 1 shows the spatial distribution of the records that are currently in ODA. First studies to analyze this dataset resulted in two papers recently published and that deal with patterns of diversity and conservation concern (CLAUSNITZER et al. 2012, SIMAIKA et al. 2013). Methods of both used either GIS or spatial modeling to predict species diversity. Base is a set of inferred range maps that were created during the Freshwater Biodiversity Assessments of Africa (DARWALL et al. 2011) that combine point locality records from ODA and expert knowledge. The smallest units on the maps are sub-basins of an edited version of the Hydro1k layer (ESRI, Redlands, CA). In general the areas of highest diversity on the continent (over 100 species in each sub- basin), extending from Guinea and Angola on the Atlantic to Kenya and KwaZulu-Natal on the Indian Ocean, is flanked by two vast impoverished areas (less than 25 species locally) to the north (Sahara) and south (Namib-Kalahari), with rather abrupt diversity gradients in- between. In four core areas