See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/286697295 Fish diversity in the Niokolo Koba National Park, middle Gambia River basin, Senegal Article in Ichthyological Exploration of Freshwaters · November 2012 CITATIONS READS 0 104 6 authors, including: Markéta Ondračková Barbora Vošlajerová Bímová Masaryk University and Institute of Vertebrat… The Czech Academy of Sciences 71 PUBLICATIONS 1,066 CITATIONS 18 PUBLICATIONS 459 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Evaluating water quality in central Europe using fish communities View project European Center of IchthyoParasitology (ECIP) View project All content following this page was uploaded by Martin Reichard on 08 July 2016. 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Erscheint jährl. viermal. – Aufnahme nach Vol. 1, No. 1 (1990) ISSN 0936-9902 Vol. 1, No. 1 (1990) – Copyright © 2012 by Verlag Dr. Friedrich Pfeil, München, Germany All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the copyright owner. Applications for such permission, with a statement of the purpose and extent of the reproduction, should be addressed to the Publisher, Verlag Dr. Friedrich Pfeil, Wolfratshauser Str. 27, 81379 München, Germany. Printed by Advantage Printpool, Gilching ISSN 0936-9902 Printed in the European Union Verlag Dr. Friedrich Pfeil, Wolfratshauser Str. 27, 81379 München, Germany Phone + 49 89 742827-0 · Fax + 49 89 7242772 · E-mail: info@pfeil-verlag.de · www.pfeil-verlag.de Copyright © Verlag Dr. Friedrich Pfeil 263 Ichthyol. Explor. Freshwaters, Vol. 23, No. 3, pp. 263-272, 2 figs., 2 tabs., November 2012 © 2012 by Verlag Dr. Friedrich Pfeil, München, Germany – ISSN 0936-9902 Fish diversity in the Niokolo Koba National Park, middle Gambia River basin, Senegal Radim Blažek*, **, ***, Markéta Ondracková*, Barbora Bímová Vošlajerová*, Lukáš Vetešník*, Ivona Petrášová*, ** and Martin Reichard* Sampling over five years (2004-2008) in Niokolo Koba National Park yielded 62 fish species from 22 families. Data are compared with records from the 1950s, yielding a conservative estimate of 73 fish species occurring in the park. Only native species are found. We compare species richness in five major habitat types (main river, tributaries, large oxbow lakes, temporary water bodies and spring pools) and thoroughly discuss putative differences observed in the fish community between the 1950s and 2000s. Introduction The River Gambia is unique in being the last major river in West Africa with a natural hydrological regime (WWF, 2006). The river flows through Guinea, Senegal and The Gambia. The large adjacent floodplains in the lower half of the river are seasonally inundated by floodwater (Lesack, 1986). There have been several plans to dam the river for generating hydropower, controlling floods, barraging salinity and tidewater and enabling irrigation-supported agriculture in adjacent areas at various locations along the river stretch, though none of these have obtained final approval (Mathes & Gilbert, 1985; Webb, 1992). The most recent plan for a hydroelectric power plant and dam on the River Gambia suggests damming the river at Sambangalou, on the Senegal-Guinea * border (DeGeorges & Reilly, 2007), with expected effects on the hydrology of the river having wide ecological consequences along the entire stretch of the River Gambia (Louca et al., 2008). The fish fauna of the River Gambia consists mainly of Nilo-Sudanian species, with Guinean species present in the upper part of the river (Johnels, 1954; Daget, 1960; Lévêque et al., 1991; see Figure 1 for distinction between the upper, middle and lower reaches of the river). Additionally, the lower part of the river has a long, brackish ecotone zone (250 km), affected by tidal water fluctuations and inhabited by many estuarine and marine species (Albaret et al., 2004). One hundred and eight fish species have been reported from along the whole course of the river, though none are endemic (Lévêque et al., 1991; Paugy et al., 2003). Several recent studies have described the Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, v.v.i., Kvetná 8, 603 65 Brno, Czech Republic. E-mail: demon@sci.muni.cz (RB), audrey@sci.muni.cz (MO), barabimova@centrum.cz (BBV), vetesnik@ivb.cz (LV), 151104@mail.muni.cz (IP), reichard@ivb.cz (MR) ** Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlárská 2, 611 37, Brno, Czech Republic. *** Corresponding author. Ichthyol. Explor. Freshwaters, Vol. 23, No. 3 Copyright © Verlag Dr. Friedrich Pfeil 264 ic habitats within the main stretch and floodplain of the middle reach of the River Gambia. The study was conducted over five years (2004-2008) as part of a project to catalogue vertebrate diversity in the Niokolo Koba National Park (NKNP). We compare our estimates with reports by Daget (1960, 1961) and discuss observed differences in the fish community following 50 years of existence of the national park. Our study can also be used as a reference for any future assessment of the effects of river damming on the fish community. Ma Mali Senegal Lowe cean tic O er Upp bia Gam n Atla r Gambie Gam mbie Gou Go Gouloumbou o oumb o ou M id ddle Gam biia a NKNP ia b Kedougou Kedo o Gam Guinea Guinea-Bissau Labé Fig. 1. River Gambia with gauging stations (Kédougou, Gouloumbou) and delimitation of the upper, middle and lower reaches. fish communities of the lower and estuarine parts of the River Gambia and its floodplains (e. g. Darboe, 2002; Albaret et al., 2004; Guillard et al., 2004; Vidy et al., 2004; Ecoutin et al., 2005; Simier et al., 2006; Louca et al., 2008). This is in sharp contrast to the sparse information available on the fish assemblages of the middle reach of the river, which was last intensively studied more than 50 years ago (Daget, 1960; Daget, 1961). During wet and dry seasons between 1955 and 1959, a total of 59 species were collected at various habitats (main river, tributaries, oxbow lakes and small pools) in the Niokolo Koba National Park, yielding 3 species new to science (Daget, 1959, 1961). Here, we present data on fish species richness and community composition from various aquat- TR2 Ri eri Ko Ga MR1 OX2 OX3 OX4 TS1TS2 TR3 MR2 MR3 mb OX1 Study area. The study was undertaken on the River Gambia and its floodplain within the NKNP and its surroundings, in Senegal, West Africa. The River Gambia has its source on the Fouta Djallon plateau in Guinea and flows into the Atlantic Ocean. It is approximately 1270 km long and has a catchment area of 78 000 km2 (Paugy et al., 1994). The last 500 km of the river only has a 1 m altitudinal difference and hence tidal effects can be observed along the entire lower reach of the river (Webb, 1992). The middle reach (480 km long) lies entirely within the political borders of Senegal (delimited by the town of Kédougou at the upstream point, 40 km downstream of the r ve Ni Gouloumbou Material and methods TR4 N i o kolo Ko ba Riv e r TR5 OX5 ia R i ve r 0 er u R iv n to u lo u Ko olo Niok Koba 5 km TS3 r R i v e TR6 MR4 SP2 i ve R SP1 a G am bi r TR1 Senegal Kédougou OX6 Sambangalou (planned dam) 0 50 km Guinea SP3 Fig. 2. Niokolo Koba National Park with sampling sites, Sambangalou projected dam and Gouloumbou and Kédougou gauging stations. Blažek et al.: Fishes of Niokolo Koba Copyright © Verlag Dr. Friedrich Pfeil 265 planned dam at Sambangalou), and the upper reach (290 km long) is separated from the middle reach by a series of rapids (Daget, 1960) (Fig. 1). An extensive floodplain is associated with the river along its lower 670 km (Louca et al., 2008), of which the uppermost part spans most of the NKNP. The most important tributaries are the Sandougou, the Koulountou, the Nieri Ko and the Niokolo Koba; the last three flowing through the NKNP (Fig. 2). The River Gambia is unique in not having been affected by environmental changes associated with landscape modification and with human disturbance (Lesack, 1986). Most of the middle reach of the River Gambia (almost 300 km) was included into the NKNP when it was established in 1954. The NKNP, which covers an area of 9130 km2, is the largest Biosphere Reserve in West Africa and is a UNESCO Endangered World Heritage site. There are no permanent settlements within the NKNP and fishing is limited to local poaching in marginal areas, with no commercial or large-scale fishing at present or in the past. The reserve is dominated by woodland savannah and semi-arid Soudanese forest, with significant areas of gallery forest and seasonal wetlands (Hejcmanová-Nežerková & Hejcman, 2006). The flow regime of the river is natural, with a peak discharge in September of 350-1200 m3 · s−1 recorded (between 1970 and 2007) at the Kédougou gauging station (Fig. 1; 800-1200 m3 · s−1 during our study period) and an annual minimum discharge of below 0.5 m · s−1 (complete stretch desiccation often recorded at the gauging station) from May to June. The discharge at Gouloumbou (located on the Senegal-Gambia border and forming the boundary between the lower and middle reaches of the river; Fig. 1) fluctuates between 4.5 m3 · s−1 and 1500 m3 · s−1 (Simier et al., 2006). Although no quantitative data from the NKNP are available, the discharge along the study stretch is comparable to that at the Gouloumbou gauging station (Lesack et al., 1984) and, while the main river stretch never desiccates, it may become disconnected and form isolated pools during periods of lowest flow. Floodplain habitats are seasonally inundated; however, temporal streams and pools disappear annually (typically from December to January). Oxbow lakes are connected to the main river during peak discharge but remain isolated for most of the year, and may desiccate completely depending on the intensity and length of the rainy season (White et al., 2012). Ichthyol. Explor. Freshwaters, Vol. 23, No. 3 Sampling. Five collecting trips were undertaken in the NKNP between 2004 and 2008, with a total of 22 localities sampled (Fig. 2; Table 1). Collections in 2004 and 2005 were completed soon after the end of the rainy season in October and November (high water level, temporary habitats present). The collections in 2006-2008 took place at the end of the dry season in March and April. Sampling during wet and dry seasons was required for associated ecological studies (Reichard, 2008; White et al., 2012). Water temperature at the study sites varied from 23 to 32 °C, pH from 5.7 to 7.5 and conductivity from 35 to 70 μS · m−1 (White et al., 2012). Variation in these parameters was negligible, especially compared to very high fluctuations in the lower stretch of the Gambia (Louca et al., 2008). We defined five general habitat types, to which we refer throughout the paper: main river channel (River Gambia; coded MR in the Fig. 2 and Tables 1-2), tributaries (the Nieri Ko, the Koulountou and the Niokolo Koba; coded TR), oxbow lakes subject to occasional desiccation, but typically with an open water surface and dense littoral vegetation (coded OX), temporal streams and pools undergoing regular annual desiccation (coded TS), and non-desiccating spring pools, typically at relatively higher altitudes (coded SP). Sampling was mainly conducted using seine and gill nets, with some data also obtained from angling using rod and line. Our initial trials included electrofishing (portable battery electrofishing backpack), cast nets, dip nets and fyke nets; however, we found these methods ineffective. Wherever possible, we used a seine (length 7 m, height 1 m, mesh size 4 mm) in combination with a set of gill nets (length 30 to 50 m, mesh size 18, 28, 38, 40 and 50 mm). While the seine was less effective in capturing large and nocturnal fishes, the use of gill nets was limited by the high abundance of Nile crocodiles and hippopotamuses in the large habitats suitable for this method. Additional data were obtained, therefore, by using rod and line at dusk and at night. After capture, fish were determined to species according to Paugy et al. (2003). Fish were either released at the capture site after determination or anaesthetised in clove oil and fixed in 4 % formaldehyde for later determination. Photographs of live representative specimens of all the species were taken and a collection of preserved specimens is deposited at the Institute of Vertebrate Biology, Academy of Sciences, Brno, Czech Republic. Copyright © Verlag Dr. Friedrich Pfeil 266 Data analysis. Only presence/absence data are presented in this study due to the uneven sampling effort among habitats and sampling sites, and the differing effectiveness of our sampling gear/methods in capturing various species. Numerical estimates would clearly overestimate shoaling and nearshore species and underestimate benthic and nocturnal species. We report the number of sites (22 in total) where each species was present and list particular sites. We further give details on the sampling method that yielded particular species and overall frequency of occurrence for a total of 51 sampling occasions (sites sampled across several years included as separate sampling occasions). Quantitative data on fish abundance were collected from 2004 to 2007. In 2008, we only targeted new species records and overall numerical abundance in samples was only estimated visually, after which most fish were released. Between 2004 and 2007, we collected 13 408 fish by seine, 845 fish in gill nets and 230 fish using rod and line. Samples from 2008 increased the total number of fish collected to approximately 15 000 individuals using seine, 1000 individuals from gill nets and 380 individuals from angling. Results We collected a total of 62 fish species, belonging to 22 families and 9 orders, from 20 sites in the NKNP and from two sites close to the park. The most common species were ‘Barbus’ macrops, Rhabdalestes septentrionalis, Hemichromis fasciatus and Tilapia guineensis, captured at 15 (68 %) of the 22 sites. In contrast, Brienomyrus brachyistus, Brycinus longipinnis, ‘Barbus’ salessei, Heterobranchus bidorsalis, Malapterurus occidentalis, Synodontis clarias and Scriptaphyosemion geryi were only collected at a single site. Pooling all samples together (total of 51 samples), ‘Barbus’ macrops and Brycinus nurse were the most frequent species (found in 75 % of samples), followed by Rhabdalestes septentrionalis (71 %) and Tilapia guineensis (67 %) (Table 2). Brienomyrus brachyistus, ‘Barbus’ salessei, Heterobranchus bidorsalis and Synodontis clarias were only recorded during one sampling occasion (< 2 %), with only a single specimen of H. bidorsalis caught on that occasion (Table 2). We found that seine was the most effective sampling method, followed by gill netting and rod and line; however, a combination of all three methods proved useful in obtaining highest species richness as all were complementary. Seine was effective in capturing most of the recorded species (54 of 62), with 17 species captured only by seine. Gill netting provided 40 species, with 3 species (Polypterus senegalus, Distichodus rostratus and Synodontis clarias) collected exclusively by this method. Angling catches yielded 27 species, with two species (Malapterurus occidentalis and Heterobranchus bidorsalis) captured by rod and line exclusively. A total of 19 species were collected by all three sampling methods (Table 2). Highest species richness was recorded at Simenti, on the River Gambia’s main course, and at Passage Koba on the River Niokolo Koba, a tributary of the River Gambia (41 species at each site). Conversely, only a single species was found in the Mare de Woeni oxbow lake (late stage of desiccation) and in a small temporal stream (site TS3) on the NKNP’s periphery (Table 1). Discussion Published summaries of fish species richness in the Gambia River Basin give a total of 84 species (Lévêque, 2006), 89 species (Hugueny, 1989), 91 (including estuarine) species (Lévêque et al., 1991), 95 (including 18 estuarine) species (Daget, 1961) or 108 (including 25 estuarine) species (Paugy et al., 2003). For the middle reach of the Gambia Basin, Daget (1961) reported the occurrence of 59 fish species within the area of the NKNP, collected during several expeditions between 1955 and 1959. This is comparable to our results of 62 fish species from the same area 50 years later. The species list overlap, however, is far from complete. Our samples included 22 species not reported by Daget (1961) and, in contrast, Daget (1961) mentioned 19 species not observed in the present study. There are several reasons for this inconsistency. First, in accordance with recent literature (Lévêque et al., 1991; Darboe, 2002; Paugy et al., 2003; Albaret et al., 2004; Louca et al., 2008), it is likely that 4 species (‘Barbus’ ablabes, Chrysichthys walkeri, Schilbe mystus, Scriptaphyosemion roloffi) were misidentified by Daget (1961) and are as ‘Barbus’ macrops, Chrysichthys maurus, Schilbe intermedius, and Scriptaphyosemion geryi, respectively, in our samples. Second, Malapterurus electricus was recently recognised as a group of species (Norris, 2002), with Malapterurus occidenBlažek et al.: Fishes of Niokolo Koba Copyright © Verlag Dr. Friedrich Pfeil 267 talis actually inhabiting the middle Gambia. Third, Tylochromis jentinki and Ctenopoma kingsleyae, reported by Daget (1961) from the NKNP, are almost certainly identical to Tylochromis intermedius and Ctenopoma petherici present in our samples. Ctenopoma petherici and C. kingsleyae are difficult to separate morphologically, but current distributional data support our identification that only C. petherici occurs in the NKNP (Norris & Douglas, 1992); our determination was confirmed by S. Norris (pers. comm.). Distinction between T. jentinki and T. intermedius relies on a relative comparison between a set of individuals (mouth more or less horizontal vs. inclined at an angle of 15-20°, and lip thickness) and both species apparently co-occur in the Gambia Basin (Paugy et al., 2003). While our determination suggested that we recorded T. intermedius, it is possible that either both species co-occur in the NKNP or, more conservatively, that there is a single species of Tylochromis that has been incorrectly determined by us or Daget (1961). We note that these inconsistencies can be settled by direct examination of Daget’s material deposited in Muséum National d’Histoire Naturelle, Paris, though it was not possible for the purpose of the current study. Taking these circumstances into account, this gives a distinction of 12 species recorded by Daget (1961) but not represented in our samples and 15 species recorded by us but not by Daget (1961), and a total of 47 species shared between collections from the 1950s and 2000s. For the 11 species reported exclusively by Daget (1961), three species (Nannaethiops unitaeniatus, Clarias macromystax and Kribia nana) are likely the result of mistaken determination of Neolebias unifasciatus, Clarias buettikoferi and Kribia kribensis, respectively, as reflected in both recent compendia on West Af- Table 1. Name, code, coordinates and altitude of each sampling site in Niokolo Koba National Park, years of sampling, total species richness (richness) and sampling methods used (S, seine; G, gill net; A, rod and line). sampling site code River Gambia, Gué de Damantan altitude sampling year MR1 13°02.712' N 13°19.266' W 15 River Gambia, Simenti MR2 13°01.395' N 13°17.350' W 16 River Gambia, Camp du Lion MR3 13°01.493' N 13°14.491' W 16 River River River River River MR4 TR1 TR2 TR3 TR4 12°55.066' N 12°39.478' N 13°21.429' N 13°01.522' N 13°03.928' N 13°08.837' W 13°19.852' W 13°21.340' W 13°13.220' W 13°10.144' W 20 30 19 24 28 River Niokolo Koba, Lengekountou River Niokolo Koba, Post Niokolo Mare de Wouring Oxbow Mare de Kountadala Oxbow Mare de Simenti Oxbow TR5 TR6 OX1 OX2 OX3 13°01.938' N 13°04.395' N 13°13.229' N 13°01.964' N 13°01.790' N 13°04.898' W 12°43.232' W 13°18.199' W 13°18.605' W 13°17.608' W 30 62 16 20 21 Mare de Woeni Oxbow Mare de Sitandi Oxbow Mare de Fadiga Oxbow Temporary stream near Simenti Temporary stream near Camp du Lion Temporary stream near Post Niokolo Spring pool, Dalaba Spring pool, Assirik Spring pool, Dindefello OX4 OX5 OX6 TS1 TS2 TS3 SP1 SP2 SP3 13°01.827' N 13°02.843' N 12°33.171' N 13°01.652' N 13°01.692' N 13°06.967' N 12°44.954' N 12°52.786' N 12°21.034' N 13°13.006' W 23 13°09.914' W 25 12°12.086' W 109 13°15.482' W 27 13°14.858' W 26 12°47.628' W 71 13°16.562' W 70 12°50.879' W 77 12°19.243' W 426 2005, 2006, 2007, 2008 2004, 2005, 2006, 2007, 2008 2004, 2005, 2006, 2007, 2008 2006,2007 2006, 2007 2005, 2007 2008 2004, 2005, 2006, 2007, 2008 2006, 2007 2005, 2006 2007, 2008 2004, 2006 2004, 2005, 2006, 2008 2008 2006, 2007 2007 2004, 2005 2004, 2005 2005 2006, 2007 2006, 2007 2007 Gambia, Badoye Koulountou, Gué de Sambailo Nieri Ko, Wassadougou Niokolo Koba, Pont Suspendu Niokolo Koba, Passage Koba Ichthyol. Explor. Freshwaters, Vol. 23, No. 3 coordinates rich- method ness 35 S,G,A 41 S,G,A 26 S,G,A 19 23 23 17 41 S,G S,G S S S 21 19 31 6 38 S,G S,G S,G S S,G,A 1 2 6 24 13 1 7 10 3 S S S S S S S S S Copyright © Verlag Dr. Friedrich Pfeil 268 Table 2. Fish species recorded in and around Niokolo Koba National Park, with presence (+) or absence (−) in our samples [OS] and those reported in Daget (1961) [Dag], Lévêque et al. (1991) [Lev], and Paugy et al. (2003) [Pau]. For species recorded in our samples, sites where a given species was recorded (sites of observation), number of sites where it was recorded (N sites, from a total of 22), sampling method by which it was captured (method; see Table 1) and frequency of occurrence (% freq, from a total of 51 samplings across years). Species not recorded in middle reach of Gambia by Daget (1961), but cited as present in lower (LR) or upper reaches (UR) and species reported under a different name (DN) also included. family / species Protopteridae Protopterus annectens (Owen, 1839) Polypteridae Polypterus bichir Lacepède, 1803 Polypterus senegalus Cuvier, 1829 Clupeidae Pelonulla leonensis Boulenger, 1916 Osteoglossidae Heterotis niloticus (Cuvier, 1829) Notopteridae Papyrocranus afer (Günther, 1868) Mormyridae Brienomyrus brachyistus (Gill, 1862) Brienomyrus niger (Günther, 1866) Marcusenius senegalensis (Steindachner, 1870) Mormyrops anquilloides (Linnaeus, 1758) Mormyrus hasselquistii Valenciennes, 1847 Mormyrus rume Valenciennes, 1847 Petrocephalus bovei (Valenciennes, 1847) Pollimyrus isidori (Valenciennes, 1847) Gymnarchidae Gymnarchus niloticus Cuvier, 1829 Hepsetidae Hepsetus odoe (Bloch, 1794) Characidae Alestes baremoze (Joannis, 1835) Brycinus leuciscus (Günther, 1867) Brycinus longipinnis (Günther, 1864) Brycinus nurse (Rüppell, 1832) Hydrocynus brevis (Günther, 1864) Rhabdalestes septentrionalis (Boulenger, 1911) OS Dag Lev Pau N meth- % sites od freq − + + + − + + + + + + + + MR1-4, TR1,4, OX1 OX1,3 7 S, G, A 17.65 2 G 7.84 + + + + MR1-3, TR3-5, OX1 7 + + + + TR4, OX1-3 4 + LR + + MR1,2, TR4, OX3 4 S, G, A 11.76 + + + + + + + + + + + + + LR LR + + + + + + + + + + + + + − + + + SP2 OX2,3 OX3, TS1,2, SP1 MR2, OX3 MR1,2 MR2, OX3 TR2,4, OX3, TS1,2 TR1,4 1 2 4 2 2 2 5 2 + + + + MR2, OX2,3 + + + + MR1, TR1,4,6, OX1,3, TS1 + + + + + + + + − + + + + + + + + + MR1-3, TR1,2,4, OX1,3 + + MR1-3, TR1-6, OX1,3, TS1 TR1 + + MR1-4, TR1-6, OX1,3,6, TS1 + MR1-4, TR2-4, OX1,3, TS2 MR1-4, TR1-6, OX1,3, + TS1,2, SP2 8 12 1 14 10 15 S, G, A S, G, A S S, G, A S, G, A S, G, A 31.37 58.82 3.92 74.51 29.41 70.59 + + − + − + + + − − MR1-4, TR1,2,4,5, TS1 + + − + MR1-3, TR1-6, OX1,3, TS1,2 − 9 − 13 − S − S − 31.37 − 49.02 + LR + + + + + LR + − + + − + − − + MR1-3, TR1-5, OX1,3,4, TS1 + MR2, TR4-6, OX1-3, TS1,2, SP1 MR1-3, TR1-6, OX1,3,6, + TS1, SP1,2 Distichodontidae Nannaethiops unitaeniatus Günther, 1872 − Nannocharax ansorgii Boulenger, 1911 + Neolebias unifasciatus Steindachner, 1894 − Paradistichodus dimidiatus (Pellegrin, 1904) + Citharidae Citharinus citharus (Geoffroy Saint-Hilaire, 1809) + Distichodus rostratus Günther, 1864 + Cyprinidae − ‘Barbus’ ablabes (Bleeker, 1863) + ‘Barbus’ baudoni Boulenger, 1918 + ‘Barbus’ leonensis Boulenger, 1915 ‘Barbus’ macrops Boulenger, 1911 sites of observation + MR1-3, TR2-4,6, OX1,3 MR1, OX1,3 − − S − 25.49 S, G 11.76 S 1.96 S, G 3.92 S, G 9.80 G, A 7.84 G, A 3.92 G, A 3.92 S, G 13.73 S 5.88 3 S, G, A 7.84 7 9 3 − 12 10 15 S, G 21.57 S, G 27.45 G 7.84 − S S − 39.22 29.41 S, A 74.51 Blažek et al.: Fishes of Niokolo Koba Copyright © Verlag Dr. Friedrich Pfeil 269 Table 2. (continued). family / species ‘Barbus’ niokoloensis Daget, 1959 ‘Barbus’ pobeguini Pellegrin, 1911 OS Dag Lev Pau + + N meth- % sites od freq MR1-4, TR1-6, TS1 11 S, A 50.98 MR1-3, TR2,4-6, OX3, 12 S 54.90 TS1-3, SP2 SP3 1 S 1.96 − − − − MR1-4, TR1,4-6, OX1,3 10 S, G 33.33 MR2-4, TR2,4, OX1, TS1 7 S, G 19.61 MR1-4, TR2,4,6, OX1,3 9 S, G 29.41 MR1-4, TR1,3-5, OX1 9 S, G, A 43.14 + + + + ‘Barbus’ salessei Pellegrin, 1908 ‘Barbus’ sublineatus Daget, 1954 Labeo coubie Rüppell, 1832 Labeo parvus Boulenger, 1902 Labeo senegalensis Valenciennes, 1842 Raiamas senegalensis (Steindachner, 1870) Bagridae Auchenoglanis occidentalis (Valenciennes, 1840) Claroteidae Chrysichthys johnelsi Daget, 1959 Chrysichthys maurus (Valenciennes, 1840) Chrysichthys walkeri Günther, 1899 Schilbeidae Parailia spiniserrata Svensson, 1933 Schilbe intermedius Rüppell, 1832 Schilbe mystus (Linnaeus, 1758) Amphilidae Amphilius rheophilus Daget, 1959 Clariidae Clarias anguillaris (Burchell, 1822) + UR + − + + + + + + + + + + + + + + + + + + + + + + + + MR1,3,4, TR4-6, OX1,3 − + − + − + + + − + + − − MR1,2, TR3,4 − − 4 − − − S, A 11.76 − − − + − + − + + − + + + − − TR2,4,5, OX1,3, TS1,2 − − 7 − − − S, G 23.53 − − − + + + − − + + + 11 S, G, A 25.49 Clarias buettikoferi Steindachner, 1894 Clarias macromystax Günther, 1864 Heterobranchus bidorsalis Geoffroy Saint-Hilaire, 1809 Heterobranchus longifilis Valenciennes, 1840 Malapteruridae Malapterurus electricus (Gmelin, 1789) Malapterurus occidentalis Norris, 2002 Mochokidae Synodontis annectens Boulenger, 1911 Synodontis batensoda Rüppell, 1832 Synodontis clarias (Linnaeus, 1758) Synodontis membranaceus (Geoffroy Saint-Hilaire, 1809) Synodontis nigrita Valenciennes, 1840 Synodontis ocellifer Boulenger, 1900 Synodontis schall (Bloch & Schneider, 1801) Syngnathidae Enneacampus ansorgii (Boulenger, 1910) Aplocheilidae Epiplatys bifasciatus (Steindachner, 1881) Epiplatys spilargyreius (Duméril, 1861) Micropanchax pfaffi (Daget, 1954) Nothobranchius kiyawensis Ahl, 1928 Poropanchax normani (Ahl, 1928) Scriptaphyosemion geryi (Lambert, 1958) Channidae Parachanna obscura (Günther, 1861) Cichlidae Hemichromis bimaculatus Gill, 1862 − − + + − + − + + − + + + MR1,2, OX1-3,5,6, TS1,2, SP1,2 + − − − MR2 + MR2-4, OX5 + − + + − + − − + − 1 − + + + + + + + LR + LR LR + + + + + + + + + + − TR4, OX1,3, TS1,2 + OX1 + TR4,6, OX3 + + MR2, TR2-4,6, OX1,3, TS1 MR1,2, TR4, OX3 + MR1,2, TR4 + + LR − + MR1,2, TR1 3 S 9.80 + + − + − + + LR + + + DN + + + + + + + + + + + + TR1,2,4,5, SP1,2 − − TS1,2 MR1-4, TR1,2,4-6, SP3 SP2 6 − − 2 10 1 S − − S S S 17.65 − − 3.92 29.41 3.92 − + + + − − − − + + + + MR1,3,4, TR1,4-6, OX3,6, TS1, SP2 11 S 29.41 Ichthyol. Explor. Freshwaters, Vol. 23, No. 3 + + sites of observation − MR2 8 S, G, A 21.57 − − − − − − − − 1 A 1.96 4 S, G, A 7.84 − A − 5.88 − − − 5 S, G 15.68 1 G 1.96 3 S, G 5.88 8 S, G, A 17.65 4 S, G, A 15.69 3 S, G, A 9.80 Copyright © Verlag Dr. Friedrich Pfeil 270 Table 2. (continued). family / species Hemichromis fasciatus Peters, 1857 Oreochromis niloticus (Linnaeus, 1758) Sarotherodon galilaeus (Linnaeus, 1758) Tilapia guineensis (Günther, 1862) Tilapia zillii (Gervais, 1848) Tylochromis intermedius (Boulenger, 1916) Tylochromis jentinki (Steindachner, 1894) Gobiidae Porogobius schlegelii (Günther, 1861) Eleotrididae Kribia kribensis (Boulenger, 1907) Anabantidae Ctenopoma kingsleyae Günther, 1896 Ctenopoma petherici Günther, 1864 OS Dag Lev Pau sites of observation N meth- % sites od freq MR1-4, TR1-6, OX1,3,6, TS1, 15 S, G, A 50.98 SP1 MR2, TR4, OX1,3, TS1 5 S, G, A 17.65 MR1-4, TR1-4, OX1,3 10 S, G, A 33.33 MR1-4, TR1-6, OX1-3, TS1,2 15 S, G, A 66.67 MR1,2,4, OX3, SP2 5 S, G 9.80 MR1-4 4 S, G 11.76 − − − − + + + + + + + + + − + + − + − + − + + + + + + + + − + + + LR − + MR1,2, TR3-5 5 S 9.80 − DN + + − − − − − + + + − TR1,2,4, OX1,3,6, TS1,2, SP1-3 − 11 + − rican fish species (Lévêque et al., 1991; Paugy et al., 2003; see Table 2) and, therefore, we discuss these species further using their correct identification. Three large species (Protopterus annectens, Parachanna obscura, Clarias buettikoferi) have possibly been missed in our sampling, as their numerical abundance is probably low. Further, Chrysichthys johnelsi and Amphilius rheophilus inhabit sections with rapid flow and Synodontis annectens is a nocturnal species; for them, our sampling was ineffective. Neolebias unifasciatus, Parailia spiniserrata and Kribia kribensis are also stream fishes for which our sampling may have been ineffective, particularly further from the shore. We failed to record two other species (Micropanchax pfaffi, Epiplatys spilargyreius). These fish are small cyprinodontiform species inhabiting stream and lake margins (Paugy et al., 2003), habitats for which our sampling by seine was most effective, as also confirmed by abundant catches of related cyprinodontiforms in permanent water bodies (main river channel, tributaries and spring pools; Table 2). It is possible that they occur in the NKNP, but at sites that we did not sample. Finally, ‘Barbus’ sublineatus, reported by Daget (1961), has a general coloration identical to that of ‘Barbus’ baudoni recorded by us. There is a clear distinction between the two species, however, in the length of both pairs of barbels, and Daget (1961) lists ‘B.’ baudoni as a species characteristic for the lower reach of the River Gambia. We paid particular attention to the distinction of all small ‘Barbus’ species and are + + − − S, G 25.49 confident that our identification is in accordance with Paugy et al. (2003). The most important disparate identification between our study and that of Daget (1961) is in the identity of the commonest Tilapia species. We determined this species (present in 68 % of sampled sites; one of the most abundant species in the NKNP) as Tilapia guineensis, while Daget (1961) reports Tilapia melanopleura Duméril, 1859 (currently a junior synonym of Tilapia zillii, though considered a distinct species in Daget (1961)) as the only Tilapia (sensu stricto) species from the NKNP. We collected T. zillii at several sites, including the main river, a large oxbow lake and a spring pool (Table 2), but its abundance was low compared to T. guineensis. Daget (1961) did not mention T. guineensis to occur in the Gambia Basin at all but clearly distinguished T. melanopleura as distinct from T. zillii (from the Niger). In contrast, Albaret et al. (2004), Vidy et al. (2004), Louca et al. (2008) and Louca et al. (2010) report T. guineensis to be a widespread species in the lower Gambia. Hence, we believe that T. zillii reported by Daget (1961) may actually be a mixture of both species, which are difficult to separate, especially as juveniles. It is therefore possible that T. guineensis was already present in NKNP habitats in the 1950s and it does not represent a case of recent range expansion. A further 14 species recorded uniquely by us were rare (Papyrocranus afer, Heterobranchus bidorsalis, Enneacampus ansorgii) or nocturnal mormyrids (Mormyrus rume, Petrocephalus bovei) and moBlažek et al.: Fishes of Niokolo Koba Copyright © Verlag Dr. Friedrich Pfeil 271 chokids (Synodontis batensoda, Synodontis membranaceus, Synodontis nigrita). Nothobranchius kiyawensis is an annual killifish that only inhabits temporary pools formed during the rainy season and survives most of the year in the form of eggs buried in dry sediment. Notably, we collected N. kiyawensis only in 2005, despite the 2004 collection being conducted in the same season, including the same sampling sites as in 2005, and being similarly exhaustive. This suggests that N. kiyawensis abundance may fluctuate greatly between years. Brycinus longipinnis is a species characteristic for the Guinean rather than Soudanian region and we only recorded it in a southern tributary of the Gambia (the River Koulountou, a Guinean tributary), where the species was abundant. Daget (1961) did not sample the Koulountou and hence could not have recorded its presence within the NKNP. Similarly, ‘Barbus’ salessei is a Guinean species that we recorded outside the boundary of the NKNP, in a stream at high altitude near the Guinean border (Fig. 2). ‘Barbus’ salessei was a common species at this site and, indeed, Daget (1961) listed this species as typical for the upper reaches of the Gambia Basin. Distichodus rostratus is a large species of which we only collected 12 individuals in gill nets placed across two oxbow lakes and one main river site. Finally, a gobiid, Porogobius schlegelii, was found in the main river and in one tributary, though in small numbers. Daget (1961) actually reports 11 of these 14 species as being present in the lower reaches of the Gambia River Basin (Table 2). The last of these species (Heterobranchus bidorsalis) is certainly a new record for the NKNP, though it has been reported from the Gambia Basin in recent compendia on West African fishes (Lévêque et al., 1991; Paugy et al., 2003) and its occurrence in the middle Gambia is not unexpected. In conclusion, therefore, we consider most differences in species lists reported by us and by Daget (1960, 1961) as representing a sampling (presence or absence of rare species) and taxonomic (misidentification, recognition of new species) artefacts rather than a consequence of species turnover. A final comprehensive list of fishes reliably recorded in the NKNP (taken as a representative set of middle Gambia Basin habitats) includes 73 species as a conservative figure. This estimate excludes ‘Barbus’ salessei (from the upper Gambia Basin) and Ctenopoma kingslaye (a likely misidentification), and treats Tylochromis intermedius and Ichthyol. Explor. Freshwaters, Vol. 23, No. 3 T. jentinki as a single species. As such, only native species are presently found in the middle Gambia Basin. It is also notable that the River Gambia is unique in the absence of the Nile perch Lates niloticus, a large predatory species found in all other West African basins (Paugy et al., 2003). Highest species richness was observed in the main river (41 species at Simenti, 45 species in total), followed by large, typically permanent, oxbow lakes (38 species in Mare de Simenti, 31 species at Mare de Wouring, 44 species in total for all 6 oxbow lakes combined), and tributaries (41 species at Passage Koba on the River Niokolo Koba, 43 species in total). There are likely to be objective differences between sites and habitat types that are mirrored in the species richness estimates presented in Table 1. Sampling intensity, however, is certainly responsible for part of the between-site variation, sites with the highest estimated species richness being investigated more intensively, across all years, and with the widest variety of sampling methods. Marked differences were observed in species richness among oxbow lakes (Table 1), differences being related to the degree of lake desiccation, with oxbows at a later stage only being inhabited by species adapted to low oxygen conditions (e. g. Heterotis niloticus, Gymnarchus niloticus, Ctenopoma petherici, Clarias anguillaris, Heterobranchus spp.). There appears to have been a recent shift to almost annual desiccation of many large oxbow lakes that previously supported relatively species rich fish communities. This is probably due to the high abundance of scrub resulting from the highly invasive, non-native giant sensitive plant Mimosa pigra, a wetland species from the Neotropics. In the absence of elephants (eliminated by poaching), it is not consumed by local herbivores, resulting in an increased surface evaporation rate and the obstruction of large parts of the water surface. Acknowledgments We thank the staff of the Niokolo Koba National Park in Tambacounda and the Direction des Parcs Nationaux in Dakar, for issuing permits and facilitating the study. Amadou Demba Ndiaye, Sheh Djigo and Alioune Badara Gueye provided invaluable help in the field. Financial support came from Czech Science Foundation (P505/12/G112) and Masaryk University. Copyright © Verlag Dr. Friedrich Pfeil 272 Literature cited Albaret, J. J., M. Simier, F. S. Darboe, J. M. Ecoutin, J. Raffray & L. T. De Morais. 2004. Fish diversity and distribution in the Gambia Estuary, West Africa, in relation to environmental variables. Aquatic Living Resources, 17: 35-46. Darboe, F. S. 2002. Fish species abundance and distribution in the Gambia estuary. UNU – Fisheries Training Programme Final Project. Daget, J. 1959. Description des trois poissons nouveaux de la Gambie: Barbus niokoloensis, n. sp., Chrysichthys johnelsi, n. sp. et Amphilius rheophilus, n. sp. 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World Wildlife Fund, Zeist, 42 pp. Received 13 September 2011 Revised 22 May 2012 Accepted 3 October 2012 Blažek et al.: Fishes of Niokolo Koba Ichthyological Exploration of Freshwaters An international journal for field-orientated ichthyology INSTRUCTIONS TO CONTRIBUTORS Warning Prospective authors should read carefully the following instructions and follow them when submitting a manuscript. Doing so significantly hastens publication and saves money and efforts. Manuscripts which do not satisfy the instructions below may be rejected at the Editor’s discretion and will not be returned. Submission of manuscripts The original manuscript should be sent to the Editor, Maurice Kottelat, by e-mail (mkottelat@dplanet.ch). 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There will be no page charges and no charges for justified colour illustrations. Ichthyological Exploration of Freshwaters An international journal for field-orientated ichthyology Volume 23 • Number 3 • November 2012 CONTENTS Conway, Kevin W., Richard L. Mayden, Jiwan Shrestha and David R. Edds: Redescription of the Nepalese endemic torrent minnow Psilorhynchus pseudecheneis with comments on P. homaloptera (Teleostei: Psilorhynchidae) ............................................................................. 193 Costa, Wilson J. E. M.: Two new species of Melanorivulus from the Caiapós hill, upper Araguaia river basin, Brazil (Cyprinodontiformes: Rivulidae) ........................................... 211 Turan, Davut, Maurice Kottelat and Semih Engin: The trouts of the Mediterranean drainages of southern Anatolia, Turkey, with description of three new species (Teleostei: Salmonidae) .............................................................................................................................................. 219 Kottelat, Maurice and Craig Leisher: Fishes from Phuong Hoang cave, northern Vietnam, with description of a new species of loach (Teleostei: Nemacheilidae)............................. 237 Kullander, Sven O.: Description of Danio flagrans, and redescription of D. choprae, two closely related species from the Ayeyarwaddy River drainage in northern Myanmar (Teleostei: Cyprinidae) ............................................................................................................... 245 Blažek, Radim, Markéta Ondracková, Barbora Bímová Vošlajerová, Lukáš Vetešník, Ivona Petrášová and Martin Reichard: Fish diversity in the Niokolo Koba National Park, middle Gambia River basin, Senegal....................................................................................... 263 Banyankimbona, Gaspard, Emmanuel Vreven, Gaspard Ntakimazi and Jos Snoeks: The riverine fishes of Burundi (East Central Africa): an annotated checklist .......................... 273 Cover photograph Danio flagrans (photograph by Ralf Britz) Sven O. Kullander (this volume pp. 245-262) Articles appearing in this journal are indexed in: AQUATIC SCIENCES and FISHERIES ABSTRACTS BIOLIS - BIOLOGISCHE LITERATUR INFORMATION SENCKENBERG CAMBRIDGE SCIENTIFIC ABSTRACTS CURRENT CONTENTS/AGRICULTURE, BIOLOGY & ENVIRONMENTAL SCIENCES and SCIE FISHLIT ZOOLOGICAL RECORD View publication stats