Invasive South American Floating Plants Are a Successful Substrate For
Total Page：16
File Type：pdf, Size：1020Kb
Biol Invasions (2016) 18:1191–1201 DOI 10.1007/s10530-016-1061-1 ORIGINAL PAPER Invasive South American floating plants are a successful substrate for native Central African pleuston Janet Higuti . Koen Martens Received: 9 November 2015 / Accepted: 24 January 2016 / Published online: 9 February 2016 Ó Springer International Publishing Switzerland 2016 Abstract Eichhornia crassipes, commonly known distributed over 31 ostracod species in E. crassipes as water hyacinth, is a free-floating perennial aquatic and 27 in V. cuspidata. No South American invasive plant native to South America, which has been widely ostracod species were found in the Congolese introduced on different continents, including Africa. pleuston. Diversity and richness of Congolese ostra- E. crassipes is abundant in both the Congo (Africa) cod communities was higher in the invasive (Eich- and Amazon (South America) River catchments. We hornia) than in a native plant (Vossia). The highest performed a comparative analysis of the ostracod diversity and abundance of ostracod communities communities (Crustacea, Ostracoda) in the E. cras- were recorded in the Congo River. The result of sipes pleuston in the Amazon (South America) and principal coordinates analysis, used to evaluate the Congo (Africa) River catchments. We also compared (dis)similarity between different catchments, showed the ostracod communities from the invasive E. cras- significant differences in species composition of the sipes with those associated with stands of the native communities. However, a dispersion homogeneity test African macrophyte Vossia cuspidata. We recorded (PERMDISP) showed no significant differences in the 25 species of ostracods associated with E. crassipes in variability of the composition of species of ostracods the Amazon and 40 in the Congo River catchments, (beta diversity) within Congo and Amazon River catchments. It appears that local ostracod faunas have adapted to exploit the opportunities presented by the Electronic supplementary material The online version of this article (doi:10.1007/s10530-016-1061-1) contains supple- floating invasive Eichhornia, which did not act as mentary material, which is available to authorized users. ‘‘Noah’s Ark’’ by introducing South American ostra- cods in the Congo River. J. Higuti Nupelia, PEA, Universidade Estadual de Maringa´, Av. Colombo 5790, Maringa´, PR CEP 87020-900, Brazil Keywords Ostracoda Á Aquatic macrophytes Á Beta e-mail: [email protected] diversity Á Amazon Á Congo K. Martens (&) Freshwater Biology, Royal Belgian Institute of Natural Sciences, Vautierstraat 29, 1000 Brussels, Belgium e-mail: [email protected]; Introduction [email protected] Several aquatic plants native to South America have K. Martens Department of Biology, University of Ghent, K.L. successfully invaded other continents. E. crassipes Ledeganckstraat 35, 9000 Ghent, Belgium (Mart.) Solms, commonly known as the water hyacinth, 123 1192 J. Higuti, K. Martens has invaded freshwater systems in over 50 countries on introduction of aquatic organisms (periphyton, inver- five continents (Villamagna and Murphy 2010). Eich- tebrates) together with these invasive plants. Some hornia crassipes is a free-floating perennial aquatic biological features of ostracods could facilitate their plant and is especially pervasive throughout Southeast long-distance dispersal, such as the presence of Asia, the southeastern United States, central and drought-resistant eggs (Horne and Martens 1998)so western Africa and Central America (see overview in that they might colonize a new habitat and success- Villamagna and Murphy 2010). The water hyacinth is a fully establish a new population. Furthermore, the pest species in many waterbodies, this in spite of many reproduction of many species of ostracods happens by efforts to eliminate or at least control its populations. parthenogenesis (Martens et al. 2008), so that a new Introduction of this plant species in different parts of the population can be formed by a single founder spec- world might have been accidental and/or intentional. imen or egg. Indeed, intentional introductions to ponds have been The objectives of the present study were to common, as the water hyacinth is an ornamental plant determine (1) if Congolese Eichhornia comprises that also reduces nutrient concentrations and algae exclusive Congolese faunas or if also invasive (South blooms (Villamagna and Murphy 2010). American) species occur; (2) if ostracods communities Floating vegetation (i.e. not rooted in the sediment) in native (Vossia cuspidata (Roxb.) Griff.) and is a typical feature of South American floodplains, invasive (E. crassipes) macrophyte stands in the where its submerged system of mostly roots hosts rich Congo River catchment differ and (3) if ostracod communities of invertebrate (and fish) taxa; these biodiversity within and between the Amazon and communities are called pleuston. Congo River catchments are significantly different. Ostracods are small bivalved crustaceans inhabit- ing sediments (Pieri et al. 2007; Van der Meeren et al. 2010; Szlauer-Lukaszewska 2014) and aquatic macro- Materials and methods phytes (Higuti et al. 2010; Liberto et al. 2012; Mazzini et al. 2014; Matsuda et al. 2015), which are common in Study area inland waters. There are about 2000 species of non- marine Ostracoda described in approximately 200 The Amazon River in South America is the second genera in various non- marine environments in the longest in the world and by far the largest by water world (Martens et al. 2008), of which about 275 flow with an average discharge of approximately 214 species in 55 genera are known from South and million liters per second. During the rainy season, the Central America (Martens and Behen 1994; Martens water discharged in the Atlantic Ocean travels et al. 2008), while nearly 500 species in 84 genera of approximately 160 km out into sea. The Amazon has ostracods have been described from African inland the largest river basin in the world, occupying more waters (Martens 1984, 1998; Martens et al. 2008). than 6.8 million km2; rainfall is evenly distributed Currently, 117 species represented by 37 genera spatially and temporally, ranging from 1500 to have been reported from Brazil (Martens and Behen 2500 mm annually, for about 6 months a year (Gould- 1994; Martens et al. 2008;Wu¨rdig and Pinto 2001; ing et al. 2003). The Amazon River and its tributaries Pinto et al. 2003, 2004, 2005a, b, 2008; Higuti et al. are accompanied along their middle and lower courses 2009, 2013; Higuti and Martens 2012a, b, 2014). In by large fringing floodplains that cover an area of both Africa and South America, more than 80 % of all about 300,000 km2, the flooded forest is known as species are endemic to their continent and zoogeo- va´rzea (Irion et al. 1997). graphical region. The Congo River has the second highest discharge Eichhornia crassipes, native to South America and (1325 km3/year or 42 million liters/s) of any river in invasive in Africa, is abundant in both the Congo the world after the Amazon (Coynel et al. 2005). It (Democratic Republic of Congo) and Amazon (Brazil) drains 3.7 million km2 of the African continent River catchments. Many studies reported on the (Campbell 2005). It covers about 25 % of the total negative impact of invasive aquatic plants on their wet tropical zone and is responsible for almost 3.4 % own communities and/or on the ecosystems in general. of the freshwater inputs to the Atlantic Ocean (Probst However, there is little information about the and Tardy 1987). In the wet season, most of the forests 123 Invasive South American floating plants are a successful substrate 1193 are flooded, while in the dry season they dry out. The were filtered in a hand net (mesh size c 160 lm). Congo Basin has a humid tropical climate: the mean Ostracods in Vossia stands were collected directly by annual precipitation, calculated between 1980 and moving the handnet through the rooted plants for c 1990 is close to 1550 mm (Mahe´ 1993). 5 min. Ostracods were killed by adding 97 % ethanol The Amazon and Congo systems, situated across to the wet residual; all samples were washed again in the equator, are characterized by tropical rain forest the lab and were transferred to fresh ethanol (70 %). and by extensive floodplains. However, there are Samples were sorted under a microscope stereoscopic. major differences in catchment characteristics. For Specimens were identified using valves (Scanning example, the runoff in the Amazon River is higher Electron Microscopy) and appendages (soft parts (Filizola 2003) because the headwaters of the Amazon dissected in slides with light microscopy). catchment are located in high mountains in contrast The environmental variables measured in the field with the plateaus or hills of the Congo catchment included water temperature (°C) and dissolved oxygen (Meybeck et al. 2001). (mg L-1) (oxymeter-YSI), pH and electrical conduc- tivity (lScm-1) (YSI 63). Some geographical, phys- Collections and measurements ical, and chemical features of the waterbodies of Amazon and Congo River catchments are listed in The ostracod collection of the Amazon floodplain used Table 1. in the present study results from a project in the SISBIOTA program (National System of Biodiversity Data analyses Research) funded by CNPq/Fundac¸a˜o Arauca´ria. The project covered four Brazilian floodplains (in addition Richness, abundance, Shannon–Wiener diversity and to the Amazon: Parana´, Araguaia and Pantanal). Two evenness were calculated to assess