The status of fish biodiversity in Ichkeul Lagoon, Tunisia

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<ul><li><p>This article was downloaded by: [University of Boras]On: 04 October 2014, At: 23:50Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK</p><p>Italian Journal of ZoologyPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/tizo20</p><p>The status of fish biodiversity in Ichkeul Lagoon,TunisiaBesma Chaouachi a &amp; Oum Kalthoum Ben Hassine aa Laboratoire de Biologie et Parasitologie marines, Facult des Sciences de Tunis , Tunis,1060, TunisiaPublished online: 28 Jan 2009.</p><p>To cite this article: Besma Chaouachi &amp; Oum Kalthoum Ben Hassine (1998) The status of fish biodiversity in Ichkeul Lagoon,Tunisia, Italian Journal of Zoology, 65:S1, 303-304, DOI: 10.1080/11250009809386837</p><p>To link to this article: http://dx.doi.org/10.1080/11250009809386837</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all the information (the Content) containedin the publications on our platform. However, Taylor &amp; Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor &amp; Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.</p><p>This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms &amp; Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions</p><p>http://www.tandfonline.com/loi/tizo20http://www.tandfonline.com/action/showCitFormats?doi=10.1080/11250009809386837http://dx.doi.org/10.1080/11250009809386837http://www.tandfonline.com/page/terms-and-conditionshttp://www.tandfonline.com/page/terms-and-conditions</p></li><li><p>Ital. J. Zool., 65, Suppb. 303-304 (1998)</p><p>The status of fish biodiversity inIchkeul Lagoon, Tunisia</p><p>BESMA CHAOUACHIOUM KALTHOUM BEN HASSINELaboratoire de Biologie et Parasitologie marines, Facult des Sciencesde Tunis, 1060, Tunis (Tunisia)</p><p>INTRODUCTION</p><p>Situated in northern Tunisia, Ichkeul Lagoon communi-cates with the Mediterranean Sea via Bizerta Lagoonwhich it is joined by Oued Tinja (Fig. 1). Ichkeul Lagoonhas a mean depth of about lm and covers an area ofabout 8900 ha (Ennabli &amp; Kallel, 1990). It is surroundedby many marshes chiefly found in the South and the Westof the Ichkeul Jebel. It has a mean salinity of 17.7%o anda mean temperature of 18.2 C. The Lagoon is suppliedby continentally derived surface water in winter and ma-rine water via intrusion from the Mediterranean Sea insummer. The alternation of physico-chemical characteris-tics (area, water level, salinity) is enhanced by variablemeteorology (i.e., wind, rain, and evaporation: Chaoua-chi, 1995, unpubl. data). These environmental features re-sult in a wide variability of habitat conditions within andbetween years. Presumably, these wide ranging condi-tions are related to the highly complex, species rich, andhighly endemic nature of the Ichkeul ecosystem.</p><p>However, the important hydrographie network associ-ated to Ichkeul Lagoon is subject to human interfer-ence, especially with regard to dam construction. Threedams are functional on Oueds Joumine, Ghezala andSejnane and three others are planned on Oueds Tine,Douimis and Melah. This dam construction may disturbthe ecosystemis hydrological characteristics and conse-quently undermine its biological diversity and richness(Ben Rejeb &amp; Kartas, 1988). For this reason, some futureprojects impacting the environment have been post-poned while an environmental impact study was madeto better understand the Ichkeul Lagoon ecosystem andto better define a strategy for its protection.</p><p>Despite interest in this ecosystem, no complete inven-tory or assessment of the ichthyofauna of the Lagoonhas been conducted. Thus it was necessary and appro-priate to do an ichthyologycal survey in this Lagoon</p><p>ABSTRACT</p><p>In Ichkeul Lagoon there are 24 fish species belonging to 15families. These fish were obtained from the commercial fishingfleet and from scientific collections made during experimental,fishery independent sampling. Most species are of marine originsand enter the Lagoon to feed. Among residential forms, there aretwo species of freshwater fishes (Barbus callensis and Aphaniusfasciatus). However, future plans to modify the water flow consti-tute problems for the Parc National de lIchkeul. Disturbance inthe hydrological regime will inevitably have some repercussionson the fish biology and their population dynamics. The closing ofthe lock, installed on the Oued Tinja, may compromise the enter-ing of migratory fish which will result in a total halt to fishing ac-tivity.</p><p>KEY WORDS: Fish assemblages - Ichkeul Lagoon - Tunisia.</p><p>MATERIALS AND METHODS</p><p>Fishes from Ichkeul Lagoon were collected from 1992 to 1994.These fish were obtained from fishery dependent sampling activi-ties of the Office National des Pches (ONP) and from scientific,</p><p>i</p><p>3rj/ ICHKEUL LAGOON</p><p>J Z ^ )i ? J BrZERT* LAGOON /</p><p>A /</p><p>MEDITERRANEAN SEA</p><p> ^ \</p><p>i 7&gt;</p><p>y 1</p><p>(Received 28 August 1997 - Accepted 14 April 1998) Fig. 1 - Ichkeul Ecosystem.</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f B</p><p>oras</p><p>] at</p><p> 23:</p><p>50 0</p><p>4 O</p><p>ctob</p><p>er 2</p><p>014 </p></li><li><p>304 B. CHAOUACHI, O. K. BEN HASSINE</p><p>fishery independent experimental fishing efforts by the authors.The 'bordigue', a fixed fishing device, was the principal methodof capture conducted in Oued Tinja. Additional fishes were ob-tained from the 'capechade' operated by Italian fishermen in di-verse Lagoon zones (essentially near the Jebel) and trammel netsoccasionally used by fishermen. Experimental fishing was con-ducted in different portions of the Lagoon to verify the presenceof fish species suspected to be present Ichkeul Lagoon. The useof diverse capture methods allowed us to increase the sampledspecies number in the Lagoon (Chaouachi, 1995, unpubl. data).</p><p>RESULTS AND DISCUSSION</p><p>Fish species can be divided in three groups based ontheir occurrence in the lake.</p><p>Residential widespread species</p><p>These species spend the totality of their life cycle(birth, growth, and reproduction, etc.) in the Lagoonand are, therefore, constantly subjected to the extremevariations in environmental conditions found in the La-goon. They are characterised by early sexual maturityand a weak specific diversity. These fish have littlecommercial value and they are represented by the fami-lies: Syngnathidae (Syngnathus abastef), Gobiidae (Gob-ius niger, Zosterisessor ophiocephalus and Pomatoschistusmicrops), Blenniidae (JLipophryspavo), Clupeidae (Alosa</p><p>fallax algeriensis), Engraulidae (Engraulis encrasicolus),Atherinidae (.Atherina boyeri), and Cyprinodontidae(Aphaniusfasciatus).</p><p>Residential localized species</p><p>These fish are restricted to freshwater portions of theLagoon. They disappear from the saltiest Lagoon sectorlocated in the proximity of Oued Tinja. This group isrepresented by two species: Barbus callensis (Cypri-nidae) and Gambusia affinis (Poecilidae).</p><p>Marine visitor species</p><p>These fishes are subject to the hydroclimatic andtrophic constraints at the origin of migratory tropismwhich causes these juvenile species to penetrate in theIchkeul Lagoon during spring, to seek more favourableenvironment conditions for their development. Thesespecies generally reproduce in the sea. These reproduc-tive migrations generally occur from the end of summerto the beginning of winter. These fishes are the mostimportant quantitatively and economically. They arerepresented by the Anguillidae (Anguilla anguilld), theMugilidae (Mugil cephalus, Liza ramada, L. saliens andL. auratd), the Soleidae (Solea aegyptiaca, S. senegalen-sis and S. vulgaris), the Moronidae (Dicentrarcbuslabrax), the Sparidae (Spams aurata and Lithognathusmormyrus), the Belonidae (Belone belone gracilis), theAtherinidae (A. boyeri, migratory population), and theHemiramphidae (Hyporamphus picarti).</p><p>The Ichkeul Lagoon residential fish assemblage has alow species diversity and have a high biomass withinthe system. The species which do not have commercial</p><p>value are represented by the Atherinidae A. boyeri, theCyprinodontidae, Aphanius fasciatus, and the GobiidaePomatoschistus microps.</p><p>The main species exploited in the Lagoon are: twospecies of Mugilidae (JA. cephalus and L. ramada), eel(A. anguilld), sea bass CD. labrax), sole (5. vulgaris),anchovy (E. encrasicolus), and barbel {B. callensis). Thefishery production is directly influenced by the currentdirection, the water level and the salinity variations. Theexchange intensity with the sea conditions regulates thein and out movements of fish.</p><p>The main fish species we have found in Ichkeul La-goon are also present in the Lagoons of Bizerta, Ghar ElMelh, Tunis and El Biban. Sea bass, seabream and soleare all migratory are found in all five Tunisian Lagoons.</p><p> The four mullet species collected from the Ichkeul La-goon were also captured in the other Lagoons except L.ramada which was absent from El Biban Lagoon. How-ever, Ichkeul Lagoon differs from the other Tunisian La-goons by the presence of B. callensis. This speciesseems to remain in Ichkeul Lagoon as long as the salin-ity is less than 2O%o (Kraiem, 1986).</p><p>The identification of the fish populations present inIchkeul Lagoon contributes to the characterization of theIchkeul ecosystem which is a relatively pristine and com-plex environment. In the iclikeul Lagoon the ichtyofaunaconsists of 24 species belonging to 15 families. However,future plans to modify the water flow constitute prob-lems for the Pare National de Ichkeul. Indeed, some dis-turbance in the hydrological regime will inevitably havesome repercussions on the fish biology and their popula-tion dynamics. The quasi-permanent closing of the lock,installed on the Oued Tinja, may lead to the extinction ofmigratory fish; the absence of the latter means a totalhalt to fishing activity. Unfortunately, the managementprogram for this lock is not yet clearly defined and, inspite of the diverse research programs, many necessarytasks remain , in particular, those tasks concerning thequalitative and quantitative features of the ecosystem.Besides, it is interesting in the context of an urgent pro-gram to determine the time and the duration of recruit-ment of the main species found in the Lagoon. These re-sults, which must be interpreted according to environ-mental conditions, will allow management of the locksystem. Furthermore, this will allow, us to determine theecosystem balance which must be maintained.</p><p>REFERENCES</p><p>Ben Rejeb A., Kartas F., 1988 - Effets des perturbations hy-drologiques et climatiques sur la production halieutique du lacIchkeul (Tunisie). Rapp. Comra. int. Mer Mdit., 31: 281.</p><p>Chaouachi B., 1995 - Contribution l'tude de l'cosystmeIchkeul: conditions du milieu et peuplements ichtyiques. DEA,Univ. Tunis II, 282 pp.</p><p>Ennabli M., Kallel M. R., 1990 - Caractrisation hydrologique ethydrogologique du bassin du lac Ichkeul. Agence Nationalede Protection de l'Environnement. Tunis, 94 pp.</p><p>Kraiem M. M., 1986 - Influence de la salinit sur la prsence desbarbeaux Barbus callensis Valenciennes, 1842 (Poissons,Cyprinidae) dans le lac Ichkeul (Tunisie Septentrionale). Bull.Inst. natn. Sci. tech. Oceanogr. Pche Salammb, 13: 89-94.</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f B</p><p>oras</p><p>] at</p><p> 23:</p><p>50 0</p><p>4 O</p><p>ctob</p><p>er 2</p><p>014 </p></li></ul>

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