Научная статья на тему 'Diversity assessment of vertebrate fauna in a wetland of hot hyperarid lands'

Diversity assessment of vertebrate fauna in a wetland of hot hyperarid lands Текст научной статьи по специальности «Биологические науки»

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Ключевые слова
ОЗЕРО АЯТА / AYATA LAKE / НИЗМЕННАЯ САХАРА / РЫБЫ / FISH / АМФИБИИ / AMPHIBIANS / РЕПТИЛИИ / REPTILES / ПТИЦЫ / BIRDS / МЛЕКОПИТАЮЩИЕ / MAMMALS / БИОЛОГИЧЕСКАЯ ВАРИАТИВНОСТЬ / АЛЖИР / ALGERIA / LOWER-SAHARA / BIODIVERSITY

Аннотация научной статьи по биологическим наукам, автор научной работы — Chenchouni H.

A great paradox arises when we talk about biodiversity in wetlands located at hot-hyperarid lands. Ayata Lake (155 ha) belongs to the complex of wetlands of Oued Righ Valley in Algerian Lower-Sahara. Surveys conducted between October 2009 and June 2010 has allowed assessing vertebrate diversity living in the lake and its surrounding areas. Several methods and techniques were used for sampling and censing each group of vertebrate (fish, amphibians, reptiles, birds and mammals). Inventories revealed the existence of 03 fish, 02 amphibians, 06 reptiles, 55 birds, and 07 mammals. Phenological types (winter or summer migrant, breeder, sedentary, occasional visitor) were attributed to birds then population dynamics were discussed. Birds used generally the waterbody in winter where migrants, mainly waterbirds, were abundant. We investigated for most inventoried species the specific habitats occurring in that respond to their behavioural and diet ecology. Biogeography status of vertebrate species revealed a desert affinity, which is represented mainly by Saharan and Saharo-sindian bio-models; except for birds which revealed dominance of Palaearctic biogeographical categories. This approach helped to highlight the biological resources of Ayata Lake and determine its actual ecological value. Furthermore, this study proposes some suggestions for management and conservation

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Текст научной работы на тему «Diversity assessment of vertebrate fauna in a wetland of hot hyperarid lands»

АРИДНЫЕ ЭКОСИСТЕМЫ, 2012, том 18, № 4 (53), с. 73-85

——— ОТРАСЛЕВЫЕ ПРОБЛЕМЫ ОСВОЕНИЯ ЗАСУШЛИВЫХ ЗЕМЕЛЬ ———

УДК 595.591.524

ОЦЕНКА РАЗНООБРАЗИЯ ПОЗВОНОЧНОЙ ФАУНЫ ЗАБОЛОЧЕННЫХ ЛАНДШАФТОВ ЭКСТРААРИДНЫХ ТЕРРИТОРИЙ

© 2012 г. Х. Ченхуни

Тебесский университет, отдел естественных наук, факультет точных и естественных наук Алжир, 12002 Тебесса. E-mail: chenchouni@yahoo.fr

Поступила 05.01.2012

Кажется парадоксальным говорить о биологическом разнообразии водно-болотных угодий гипераридных территорий. Озеро Аята (155 га) принадлежит к комплексу водно-болотных угодий долины Оуэд Рай в Нижней Сахаре в пределах Алжира. Исследования, проведенные в период с октября 2009 по июнь 2010 года позволили оценить разнообразие позвоночных, живущих в озере и его окрестностях. Фауна включает следующие группы животных: 3 вида рыб, 2 вида амфибий, 6 видов рептилий, 55 видов птиц и 7 видов млекопитающих. Птицы были отнесены к разным фенологическим типам: зимние или летние мигранты, гнездящиеся, оседлые, случайные), что позволило оценить динамику популяций. Чаще птицы приурочены к водоему зимой и наибольшая численность характерна для перелетных, преимущественно водоплавающих видов. Были изучены местообитания исследуемых видов, их пищевые и поведенческие особенности. Состав позвоночных озера Аята и его окрестностей имеет высокое сходство с фауной пустынь Сахарской и Сахаро-Синдской биотических областей, за исключением птиц, среди которых преобладают виды, относящиеся к Палеарктическому биотическому царству. Такой подход помог выделить биологические ресурсы озера Аята и определил его фактическую экологическую ценность. Кроме того, это исследование предлагает некоторые рекомендации по управлению биологическими ресурсами и сохранению биоразнообразия.

Ключевые слова: озеро Аята, низменная Сахара, рыбы, амфибии, рептилии, птицы, млекопитающие, биологическая вариативность, Алжир.

DIVERSITY ASSESSMENT OF VERTEBRATE FAUNA IN A WETLAND OF HOT

HYPERARID LANDS

© 2012. H. Chenchouni

Department of Natural and Life Sciences, Faculty of Exact Sciences and Natural and Life Sciences,

University of Tebessa, Algeria 12002, Tebessa. E-mail: chenchouni@yahoo.fr

A great paradox arises when we talk about biodiversity in wetlands located at hot-hyperarid lands. Ayata Lake (155 ha) belongs to the complex of wetlands of Oued Righ Valley in Algerian Lower-Sahara. Surveys conducted between October 2009 and June 2010 has allowed assessing vertebrate diversity living in the lake and its surrounding areas. Several methods and techniques were used for sampling and censing each group of vertebrate (fish, amphibians, reptiles, birds and mammals). Inventories revealed the existence of 03 fish, 02 amphibians, 06 reptiles, 55 birds, and 07 mammals. Phenological types (winter or summer migrant, breeder, sedentary, occasional visitor) were attributed to birds then population dynamics were discussed. Birds used generally the waterbody in winter where migrants, mainly waterbirds, were abundant. We investigated for most inventoried species the specific

habitats occurring in that respond to their behavioural and diet ecology. Biogeography status of vertebrate species revealed a desert affinity, which is represented mainly by Saharan and Saharo-sindian bio-models; except for birds which revealed dominance of Palaearctic biogeographical categories. This approach helped to highlight the biological resources of Ayata Lake and determine its actual ecological value. Furthermore, this study proposes some suggestions for management and conservation.

Keywords: Ayata Lake, Lower-Sahara, fish, amphibians, reptiles, birds, mammals, biodiversity, Algeria.

The Sahara is the largest hot-desert in the world and occupies about 10% of the African Continent. Although species richness and endemism are low, some highly adapted species do survive with extraordinary adaptations (Le Houerou, 2001). The ecoregion includes the arid northern portion of the Sahara where rainfall occurs during the cooler winter, nourishing a variety of plants that rapidly flower before the hot-dry summer. Furthermore, the flora of the Northern-Sahara Desert is very poor considering the huge extent of the area (Ozenda, 1983).

North Africa has wetlands with rare typology and ecology in the world (Llewellyn, 2002). Algeria includes a multitude of wetlands of international importance where 50 sites are classified as Ramsar sites. However, very original and diverse aquatic habitats in the Sahara, which owns 80% of the country land area, still be little studied to assess their biological resources and ecological values. Besides, the special geographic position of the Lower-Sahara (Saharan low lands), its physical configuration and its original hydrogeology give it an important asset in wetlands, both in number and type (Chenchouni, Si Bachir, 2010). Considering the hyper-arid conditions, the fauna of the Lower-Sahara is richer than is generally believed (WWF, McGinley, 2007). Within the Lower-Sahara there are 04 species of fishes (Toumi, 2010), 04 amphibians, and around 32 species of reptiles (Le Berre, 1989; Mouane, 2010). There are also 80 species of resident and migrant birds, (Isenmann, Moali, 2000; Chenchouni, Si Bachir, 2010) and 19 species of mammal (Le Berre, 1990). Arthropods are also numerous in particular in wetlands and oases (Bekkari, Benzaoui, 1991; Bouzid, 2003). However, given the vast size of the region, the number of endemic species is very small as well as species richness is low.

Since, wetlands are rare-type-ecosystems in Sahara (Chenchouni, Si Bachir, 2010); we chose wetlands as a key-habitat model to assess and monitor wildlife biodiversity within general contexts of arid lands. Because the presence of water in these areas, which are subject to a harsh changing climate and tending toward desertification, makes water bodies attracting and concentrating the majority of animal species, both those that are aquatic as those that are not (Roshier et al., 2001).

Our current scientific understanding of vertebrate fauna community living in Algerian Lower-Sahara is poor. Thus, our knowledge of trends in fauna biodiversity in this area remains ill-known with regarding its ecological status. Indeed a huge lack in common understanding of aspects such as ecological impact and interactions and/or spatial and temporal distribution was found. Moreover, even the ephemeral habitats of the Sahara, which only develop following rainfall, are not highly threatened by human activities. The more persistent pressures are found in areas of permanent water (oases), or in areas where water comes close to the surface nearby urban (Marzluff, 2001; WWF, McGinley, 2007). Therefore outlining the ecological impacts of anthropic disturbances, such introductions of alien species, would provide reliable information more accessible for managers and conversationalists.

We were motivated to conduct this study because the wildlife of this biome should be further studied in this vast desert since species are rare, endemic or original. In addition, the fauna of wetland ecosystems is thus more appropriate to be studied and surveyed, as these environments are unique, original and rare in the arid Saharan territory.

Here, we assess vertebrate (fishes, amphibians, reptiles, birds, mammals) species diversity and explore how this knowledge can guide conservation efforts. It is important to remember that abiotic differences, human pressure and land use, invasive and anthropogenic species, disturb the study area (Ayata Lake, Lower-Sahara) differently in time and space. Our study provides the first data on fauna vertebrate diversity and provides important information for conservation scientists and land managers concerned with preserving wildlife of wetlands at arid-lands.

ОЦЕНКА РАЗНООБРАЗИЯ ПОЗВОНОЧНОЙ ФАУНЫ 75

Materials and metods

Study area. The Ayata Lake belongs to the complex of wetlands in Lower-Sahara. The site is located near the town of Sidi Amrane (Djamaa) at 150 km west of the wilaya (province) of El Oued (Souf). The lake is located on National Road No. 3 at about 6 km after Djamaa in direction to Touggourt city (fig. 1). The site has an area of about 155 ha, with an average altitude of 31 m. it is bounded by the following geographic coordinates: Longitude: 33°29'17" N and 33°29'48" N, Latitude: 05°59'10" E and 05°59'37" E. The soil has sandy texture and it is rich in limestone with more or less high concentration of salinity and low rate of organic matter (Chenchouni, Si Bachir, 2010). In addition, the water body of Ayata Lake is fed by surplus irrigation water flooding from a channel draining the agricultural area of palm groves of Chemora and Tamerna localities to the main channel of Oued Righ, which collects water from the Valley of Oued Righ and reject it into Chott Merouane then into Chott Malghir (Belhadj, Gasmi, 2005). According I. Toumi (2010), waters of the lake are characterized by a brackish quality and slightly alkaline pH, with rich rate of dissolved oxygen and low turbidity.

Рис. 1. Местоположение озера Аята на географической карте (долина вади Рай) с показателями вегетационных индексов. Затемненная область на карте Алжира - низменная чать пустыни Сахара. Fig. 1. Geographical location map of Ayata Lake (Valley of Oued Righ) with board-types of vegetation/landcover classes. The shaded region in the map of Algeria is the Lower-Sahara.

The climate is typically Saharan with the dry period extending throughout the year, with mean annual temperatures exceeding 25°C. Precipitations, mostly observed in winter (~2 months), are characterized by a great inter-annual and inter-monthly irregularity. The coldest month is January and the warmest month is July where temperatures rise often over 47°C (fig. 2). The area is also windy. Hot, dust-filled winds create dust devils which can make the temperatures seem even hotter.

The natural vegetation is represented by halophytes such as Salicornia fruticosa (Forssk.), Suaeda vermiculata (Forssk.), Arthrocnemum glaucum (Del.), Halocnemum strobilaceum (Pall.), Traganum nudatum (Del.), Anabasis articulata (Forssk.). Characteristic hydrophilic species such as Juncus maritimus (L.), Phragmites communis (Trin.) are present. Sparse spontaneous plantations of Limoniastrum guyonianum (Dur.), Tamarix gallica (L.), and Zygophyllum album (L.) are also recorded (fig. 1; Chenchouni, 2012).

Data collection.Field investigations were carried out during 2009-10 in order to determine the actual ecological value of Ayata Lake. This study was mainly based on field survey of vertebrates at the lake and at

its surrounding areas including halophytic and sparse vegetation landscapes, date palm groves (Phoenix dactylifera), and neighbouring urban. The vertebrate survey has two components: the first is a qualitative inventory for fish, amphibians, reptiles and mammals. The second includes quantitative data on both aquatic and not-aquatic bird populations.

Рис. 2. Климаграмма за 10-и летний период (1999-2008 гг.) для региона исследований. Fig. 2. Ombrothermic diagram of Bagnouls and Gaussen established from a 10-year period (19992008) applied for the study site.

Vertebrate species were inventoried then species richness (S) was assessed for each taxonomic class as the total number of species occurring along a given number of samples. Furthermore, we assigned the protection status for each species to assess its conservation degree according to contexts of the study area. Therefore, we based on animal species listed as protected in Algeria by the decree 83-509 issued on August 20th, 1983 for the national-scale protection. For the international level, we referred to the IUCN Red List (Vie et al., 2008).

Fishes. Before proceeding to the identification, fish must be collected in good condition. It is therefore necessary to use adequate techniques of catch and fishing which allow survey of the fish community in the study area (Leveque et al., 1992; Leveque, Paugy, 2006). We investigated three different stations: (i) the drains that feed the lake, (ii) the channel of the outfall, and (iii) the reedbed and drains occupied by vegetation and with standing water. Furthermore, we used two methods of fishing where fish were trapped using a bottom gill net for small fish and with a dredge (gillnet pole) for the capture of attentive species. The caught fish were identified and classified systematically according to C. Leveque, D. Paugy and G.G. Teugels (1992), C. Leveque and D. Paugy (2006).

Amphibians and Reptiles. Since these two categories of animals are very difficult to capture due to the absence of suitable traps, we have simply used hunting at sight techniques for sampling them. Captured individuals were stored in vials filled with diluted formalin. For the identification and systematic classification, we referred to J. Bons and P. Geniez (1996) and H.H. Schleich, W. Kästle and K. Kabisch (1996).

Birds. Bimonthly censuses were conducted to study birds in their natural habitats. These censuses were starting in the early morning before dawn until the afternoon. Counts were made during the period between October 2009 and June 2010. A pair of binoculars was used to observe, identify and count bird species. To ensure that identification is accurate at the time of observation, we used a field guide (Heinzel et al., 2004).

The technique we followed during counts of waterbirds in Lake Ayata is described in the following steps: Waterfowl groups located at a distance of less than 200 m, and which do not exceed 200 individuals, were processed by a single counting. But if bird population size is more than 200 individuals or if the group is distant (>200 m) a quantitative estimate was considered. In this case, the visual field was divided into several bands, then the number of birds of a mid-band counts is reported as many times as bands. This method has a error margin of 5 to 10% (Lamotte, Bourliere, 1969) because a difference still exists between the number of birds detected by the observer and the number actually present (Tamisier, Dehorter, 1999). Besides the census of waterfowl, other species, found in the site and its surroundings, were also recorded. For each recorded bird species, we reported its complete classification (order, family and binomial name) and its English name according to B.L. Monroe and C.G. Sibley (1997).

Mammals. Since most mammals in Saharan regions have nocturnal activity and discrete behaviour (Le Berre, 1990), and due to lack in night observation equipment and adequate traps for their capture; we

drew on the method of direct observation in situ using a field guide that identifies some mammalian species from their presence indices, droppings, burrows and traces (Bang, Dahlstrom, 2004). Moreover, surveys within visitors of the lake and people from the town of Sidi Amrane (nearest urban area) were carried out to have details confirming the identification of some mammals that frequent neighbouring areas of the lake. In addition, vegetation clumps of Salicornia fruticosa, Tamarix gallica, Juncus maritimus and Phragmites communis were investigated in search of small mammals that use these forms of vegetation as refuge for their burrows (Le Berre, 1990). Taxonomic classification of inventoried mammal species follows that of T. Halternorth and H. Diller (1985).

Results

Inventories of vertebrate species of the lake consists of two parts. The first is a qualitative inventory of fishes, amphibians, reptiles and mammals. The second includes quantitative data on bird populations.

Fishes. Catches of fish allowed us to identify three different species: the mosquitofish (Gambusia affinis) and two Tilapia species: Peter's fish (Tilapia Zilli) characterized by a reddish colour and another species of the genus Tilapia (with a yellowish colour) not determined (table 1 A). These species belong to one class (Actinopterygii), two orders and two different families (table 2). Tilapias were caught in the flowing drains that feed the lake and in the outfall channel, but the mosquitofish were captured in drains with standing water.

Таблица 1. Систематический список видов позвоночных, зарегистрированных в районе Озере Аята. Условные обозначения: * - виды подлежащие охране в Алжире, " - виды подверженные угрозе уничтожения из красной книги IUCN, PT - фенологические типы для птиц, B - гнездящиеся виды птиц, OV - случайно встреченные виды, S - оседлые виды, SM - летние мигранты, WM - зимние мигранты. Table 1. Systematic list of vertebrate species recorded in Lake Ayata with their common English name (Species followed by (*) is protected in Algeria; and by (■) is cited as threatened species on IUCN's red list categories. Bird phenological types "PT": B - breeder, OV - occasional visitor, S - sedentary, SM -summer migrant, WM - winter migrant.

(A) Fishes (S=3)

Family Species English name

Poeciliidae Gambusia affinis (Girard, 1859) Mosquitofish

Cichlidae Tilapia zilli (Gervais, 1848) Peter's fish

Tilapia sp. Tilapia

(B) Amphibians (S=2)

Family Species English Name

Bufinidae Bufo viridis (Laurenti, 1768) Green Toad

Ranidae Rana saharica (Pallas, 1771) Laughing Frog

(C) Reptiles (S=6)

Family Species English Name

Geckonidae Tarentola deserti (Boulenger, 1891)* Desert Wall Gecko

Tarentola mauritanica (Linnaeus, 1758) Moorish Wall Gecko

Scincidae Chalcides ocellatus (Forskal, 1775) Oscillated Skink

Scincopus fasciatus (Peters, 1864) Peters' Banded Skink

Scincus scincus (Linnaeus, 1758) Sandfish

Viperidae Cerastes cerastes (Linnaeus, 1758) Saharan horned viper

(D) Birds (S=55)

Family Species English Name PT

Ardeidae Bubulcus ibis (Linnaeus, 1758) Cattle Egret WM

Egretta alba (Linnaeus, 1758) Great white heron OV

Egretta garzetta (Linnaeus, 1758) Little egret WM

Ardea cinerea (Linnaeus, 1758) Grey Heron WM

Ciconiidae Ciconia ciconia (Linnaeus, 1758) * White stork OV

Продолжение таблицы 1. Prolongation of table 1.

Family Species English Name PT

Phoenicopteridae Phoenicopterus roseus (Pallas, 1811) * Greater Flamingo WM

Anatidae Tadorna tadorna (Linnaeus, 1758) * Common Shelduck WM

Tadorna ferruginea (Pallas, 1764) * Ruddy shelduck SB

Anas penelope (Linnaeus, 1758) Eurasian Wigeon WM

Anas strepera (Linnaeus, 1758) Gadwall WM

Anas acuta (Linnaeus, 1758) Northern Pintail WM

Anas crecca (Linnaeus, 1758) Common Teal WM

Anas platyrhynchos (Linnaeus, 1758) Mallard WM

Anas clypeata (Linnaeus, 1758) Northern Shoveler WM

Marmaronetta angustirostris (Rei., 1853) *,B Marbled duck WM

Aythya ferina (Linnaeus, 1758) Pochard WM

Aythya nyroca (Guldenstâdt, 1770) ' Ferruginous Duck WM

Accipitridae Circus aeruginosus (Linnaeus, 1758) March harrier SB

Falconidae Falco biarmicus (Temminck, 1825) * Lanner Falcon SB

Rallidae Rallus aquaticus (Linnaeus, 1758) * Water Rail WM

Gallinula chloropus (Linnaeus, 1758) Common Moorhen SB

Fulica atra (Linnaeus, 1758) Common Coot WM

Recurvirostridae Himantopus himantopus (Linnaeus, 1758) * Black-winged stilt SB

Charadriidae Charadrius dubius (Scopoli, 1786) Little ringed plover WM

Charadrius hiaticula (Linnaeus, 1758) Common Ringed Plover WM

Charadrius alexandrinus (Linnaeus, 1758) Kentish plover SB

Scolopacidae Calidris minuta (Leisler, 1812) Little stint WM

Gallinago gallinago (Linnaeus, 1758) Common Snipe WM

Tringa erythropus (Pallas, 1764) Spotted redshank WM

Tringa nebularia (Gunnerus, 1767) Greenshank WM

Tringa ochropus (Linnaeus, 1758) Green sandpiper WM

Laridae Larus ridibundus (Linnaeus, 1766) Common Black-headed Gull WM

Columbidae Columba livia (Linnaeus, 1758) Rock Dove SB

Streptopelia decaocto (Frivaldszky, 1838) Eurasian Collared Dove SB

Streptopelia turtur (Linnaeus, 1758) European turtle-Dove SM

Streptopelia senegalensis (Linnaeus 1766) Laughing Dove SB

Meropidae Merops persicus (Pallas, 1773) Blue-cheeked Bee-eater WMB

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Upipidae Upupa epops (Linnaeus, 1758) * Hoopoe SB

Alaudidae Alaemon alaudipes (Desfontaines, 1789) Greater Hoopoe-Lark SB

Calandrella brachydactyla (Leisler, 1814) Short-toed Lark SB

Galerida cristata (Linnaeus, 1758) Crested Lark SB

Alauda arvensis (Linnaeus, 1758) Sky-Lark SB

Hirundinidae Delichon urbica (Linnaeus, 1758) Common House-Martin SM

Motacillidae Motacilla flava (Linnaeus, 1758) Yellow-Wagtail WM

Motacilla alba (Linnaeus, 1758) White-Wagtail WM

Muscicapidae Luscinia svecica (Linnaeus, 1758) Bluethroat WM

Muscicapidae Oenanthe deserti (Temminck, 1825) Desert Wheatear SB

Sylviidae Cisticola juncidis (Rafinesque, 1810) Zitting Cisticola SB

Phylloscopus sibilatrix (Bechstein, 1793) Wood Warbler WM

(D) Birds (S=55)

Family Species English Name PT

Phylloscopus collybita (Vieillot, 1817) Northern Chiffchaff WM

Laniidae Lanius meridionalis (Linnaeus, 1758) Great Grey Shrike SB

Lanius senator (Linnaeus, 1758) Woodchat Shrike SB

Ploceidae Passer domesticus (Linnaeus, 1758) House sparrow SB

Продолжение таблицы 1. Prolongation of table 1.

Family Species English Name PT

Corvidae Corvus ruficollis (Lesson, 1830) Brown-necked Raven SB

Corvus corax (Linnaeus, 1758) Common Raven SB

(E) Mammals (S=7)

Family Species English Name

Leparidae Lepus capensis (Linnaeus, 1758) Cape Hare

Gerbillidae Meriones shawi (Duvernoy, 1842) Shaw's Jird

Muridae Rattus rattus (Linnaeus, 1758) Black Rat

Mus spretus (Lataste, 1883) Small Rodent

Mus musculus (Linnaeus, 1758) House mouse

Canidae Fennecus zerda (Zimmermann, 1780)* Fennec fox

Suidae Sus scrofa (Linnaeus, 1758) Wild Boar

Amphibians and reptiles. The herpetofauna cebsed in the lake includes two species of amphibians and six species of reptiles (table 1 B and 1 C). The 08 surveyed species are divided into 2 classes, 3 orders, 5 families, 7 genera. Amphibians are represented by the order of Anura, which includes two different families: the family Bufonidae and Ranidae with one species for each family. Reptiles include two orders, Squamata and Ophidia. The Squamata are represented by families of Geckonidae and Scincidae with respectively two and three species. The Ophidian contain the Viperidae family with one species (Cerastes cerastes). All the species reported are not protected in Algeria (table 2).

Birds. A set of 16 bimonthly censuses allowed the inventory of 55 bird species frequenting the study area; among these 9 species are protected in Algeria (7 waterbirds). According to IUCN Red List criteria, the lake holds a "vulnerable" species that is the Marbled Duck (Marmaronetta angustirostris) and another has the status "Near Threatened" that is Ferruginous Duck (Aythya nyroca; table 1 D). The 55 bird species recorded are spread over 10 orders, 23 families and 37 genera. The Passeriformes order was best represented with 8 families and 17 species, followed by Anseriformes (one family and 11 species) and Charadriiformes (3 families and 9 species; table 2).

Both values of species richness (S=55) and bird abundance (N=4.084) have the same fluctuation shape (1-Way ANOVA: F=46.01; p<0.0001). These values reached their peak in winter (Dec-Feb) and decreased progressively from the end of wintering period (fig. 3).

Numbers of winter-migrants increased along winter to reach the peak in late December then experience a fast drop marking the end of wintering period where numbers of sedentary birds started to augment (fig. 4).

Wintering migrants followed by sedentary birds hold highest species richness values. Winter-migrants were more diverse during the rainy season which extended from early December and late February. Occasional visitors appeared almost in January with a single species. Summer migrants come by the end of winter with a single species, mainly during the months of March and April (fig. 5).

Mammals. Wild mammalian fauna of Lake Ayata includes seven species that are divided into 4 orders, 5 families and 6 genera. One species of mammals is protected in Algeria, it is the Fennec (Fennecus zerda; table 1 E). Mammals inventoried in the region is better represented by the order of rodents that holds four species belonging to two families. The remaining orders are represented by one species for each (table 2).

Discussion

Fish. Fishes recorded in Ayata Lake are widely distributed in north Algerian Sahara; they were reported in the valley of Oued Righ (Le Berre, 1989; Toumi, 2010) and also in Chott Ain El-Beida at Ouargla city (Bekkari and Benzaoui, 1991; Bouzid, 2003).

The spatial distribution of species reveals existence of a territoriality between species of the genus Tilapia that are living in flowing-deep waters and the mosquitofish that occur particularly in stagnant water of drains occupied by dense vegetation, usually of reeds (Phragmites communis). It should be noted that the abundance of fish in Lake Ayata attracts piscivorous waterbirds such as Great white heron (Egretta alba), the Little Egret (Egretta garzetta) and Grey Heron (Ardea cinerea). Indeed, the latter two species visit regularly

habitats where fish are in abundance.

Таблица 2. Распределение видов позвоночных животных Озера Аята (алжирская пустыня Сахара) по порядкам, семействам и родам. Table 2. Number and proportions of vertebrates species identified in Ayata Lake (Algerian Sahara) according to orders, families and genera.

Species

Classes Orders Families Genera Number %

Cyprinodontiformes 1 1 1 33.3

Pisces Perciformes 1 1 2 66.7

Total 2 2 3 100

Amphibia Anoura 2 2 2 25

& Squamata 2 4 5 62.5

Reptila Ophidia 1 1 1 12.5

Total 5 7 8 100

Ciconiiformes 2 4 5 9.1

Phoenicopteriformes 1 1 1 1.8

Anseriformes 1 4 11 20

Falconiformes 2 2 2 3.6

Aves Gruiformes 1 3 3 5.5

Charadriiformes 3 5 9 16

Lariformes 1 1 1 1.8

Columbiformes 1 2 4 7.3

Coraciiformes 2 2 2 3.6

Passeriformes 8 13 17 31

Total 22 37 55 100

Lagomorpha 1 1 1 14

Mammalia Rodenta 2 3 4 57

Carnivora 1 1 1 14

Artiodactyla 1 1 1 14

Total 5 6 7 100

The introduction of fish species has sometimes been justified by the creation of new aquatic habitats (Gozlan et al., 2010). Besides, the introduction of some fish species has been performed to fight against disease vectors (Gozlan, 2008). As well, some species such as Gambusia affinis was and still be used in different regions of Africa, in Algerian Sahara particularly, to control the mosquitoes that transmit malaria (Hammadi et al., 2009). Accordingly, decline in population of native species and disturbance in ecological nets are common results when Mosquitofishs are introduced as a biological controlling agent in freshwaters (Hamer et al., 2002). It is to note that Gambusia affinis has become naturalized all over studied Saharan sites, affecting therefore aquatic ecosystems and will probably exercising heavy predation on endemic small fishes (Chaibi et al., 2012).

Amphibians and reptiles. The batrachofauna of Lake Ayata, which was represented by two species of the genera Bufo and Rana, is common in Saharan humid environments (Bekkari, Benzaoui, 1991; Bouzid, 2003; Mouane, 2010). Similarly, the herpetofauna recorded in the lake indicates a clear desert affinity, especially with the presence of characteristic species like Tarentola deserti, Tarentola mauritanica, Scincopus fasciatus, Cerastes cerastes that have Saharan or Saharo-sindian in biogeographical origins (Mouane, 2010). Indeed, several authors have noted these pecies in different regions in the northern Algerian Sahara: in the Valley of Oued Righ and Souf (Le Berre, 1989), in Ouargla (Bekkari, Benzaoui, 1991; Bouzid, 2003), and in Erg Oriental (Souf and Touggourt; Mouane, 2010). On the other hand, most of censed species are invertebrate feeders except Cerastes cerastes which (family of Viperidae) is carnivorous and venomous.

The abundance of reptile species and rarity amphibians can learn about the richness of reptiles in arid regions. This difference in richness can be also justified as a better acclimatization and adaptation of reptiles

to conditions of aridity that reign in deserts. Moreover, the occurrence of amphibians is closely linked to the existence of humid habitats and the presence of water in, which is considered as scarce resource in xeric lands (Dayton, Fitzgerald, 2006; Mouane, 2010). Moreover, H.-A. Blain, S. Bailon and G. Cuenca-Bescos (2008) emphasize on variations in the quantitative and qualitative composition of herpetofaunal successions (in amphibians and squamate reptiles) can be used recognize climatic and environmental changes. There is only one endemic species at the lake i.e. Tarentola deserti which is endemic at Sahara scale (Schleich et al., 1996).

Рис. 3. Изменения богатства и обилия видов птиц во времени на озере Аята (столбики ±1SE): непрерывная кривая представляет модель регрессии обилия видов и прерывистая кривая - регрессию богатства видов. Fig. 3. The temporal variations in species richness and abundance of birds at Ayata Lake (bars ±1SE). Continuous curve represents the polynomial regression model fitted to abundance data, and discontinuous curve is polynomial regression of species richness data.

Рис. 4. Изменения обилия птиц по фенологическим типам во времени (вертикальная линия -стандартное отклонение - SD). Fig. 4. Temporal variation of bird phenological guild abundances (vertical line = SD).

Birds. All birds censed in this study have been already described for Algeria in the literature. The recorded avifauna is almost the seventh of birds in Algeria (406 species listed by Isennman, Moali, 2000). It

also includes almost half of the orders described in the country (Ledant et al., 1981). Families reported in the Lake represent 40% of all known families in Algeria. The Lake holds over one-fifth of genera reported nationally (Ledant et al., 1981; Isenmann, Moali, 2000). In addition, species richness recorded in Lake Ayata is quite similar compared to some wetlands in Northeast Algeria (Van Dijk, Ledant, 1983; Bouzid, 2003; Belhadj and Gasmi, 2005) and to other Algerian IBA wetlands (Fishpool, Evans, 2001; Samraoui, Samraoui, 2008).

Рис. 5. Изменения видового богатства птиц по фенологическим типам во времени. Fig. 5. Temporal variation of species richness applied for bird phenological guilds.

Since the search for food is the main reason of bird migrations (Blondel, 1979), the monitored successions in phenological guilds give an indication on the dynamics of food supplies in both quantitative and qualitative varieties. Indeed, A. Tamisier and O. Dehorter (1999) claim that bird diet determines phenological character including sedentary or migratory traits.

Basically, dynamics of phenological guilds follow that in Western Palearctic, although wintering is much earlier and ends earlier than what is known in Eurasian and coastal North African regions (Thorup et al., 2007). Indeed, winter-migrants are being replaced after the end wintering-period by sedentary species, which were present throughout the study period but with their numbers are increasing significantly during the breeding season. The predominance of winter-migratory birds, in particular Anatidae, reflects the importance of this wetland for hosting waterbirds especially on wet habitats located in hot-hyperaridlands where water is a very scarce resource (Roshier et al., 2001; Chenchouni, Si Bachir, 2010).

Moreover, the presence of certain endemic species to North African Sahara (such as Merops persicus, Alaemon alaudipes and Oenanthe deserti) in the lake provide information on avifauna biogeography trends. It should be noted North Sahara including Lake Ayata is considered as transitional region between the Palaearctic and Afrotropical because it includes, besides birds of these two ecoregions, species that are not defined by Voous' faunal type classification (Voous, 1960).

Mammals. The recorded Mammals are characterized by a dominance of the order Rodentia, which includes two different families: the family Gerbillidae with a species and family Muridae with three species. Even though desert ecosystems are known to be qualified as healthy biotopes, the presence of certain species belonging to the category of rodents such as Rattus rattus, Mus spretus, Mus musculus, ... as well as other species like Sus scrofa, demonstrates that these natural hyper-arid habitats are anthropologically influenced, which inducing the introduction of invasive species (Loope et al., 1988). Moreover, these species, in majority, have an omnivorous diet, which facilitates their adaptation to hostile environmental conditions of the region. Moreover, these mammals have a diet composed by as well plants and animals, but they feed generally on different parts of plants, digging up roots and tubers, and eat fallen seeds. They may therefore, in case of outbreak and absence of natural predators, become harmful to natural vegetation. However, they

also can cause significant damage to nearby crops, especially crops underlying date palm. Indeed, other studies (Bekkari, Benzaoui, 1991; Bouzid, 2003) revealed the existence of invasive mammalian species in the vicinities of wetlands nearby oases and urban areas in the Lower-Sahara.

The Fennec (Fennecus zerda) is an endemic species for north Sahara desert (Le Berre, 1990; Cusin, 1996) which is protected in Algeria in order to sustain its vital ecological role this species plays in Saharan ecosystems (Incorvaia, 2005). Since Fennec feeds on a diverse range of animal prey (vertebrate and invertebrate) but also plant parts (Khechekhouche et al., 2011). These authors state also that the fennec's diet is dominated in terms of species by insects and dates (fruits of Phoenix dactylifera); however, in terms of biomass vertebrates (rodents, birds and lizards) are most abundant, which gives it the status of a carnivorous-predator. Unfortunately, this species has declined greatly throughout its distribution area at the Sahara Desert (WWF, McGinley, 2007).

It is noteworthy that study site could hold a further diverse mammalian fauna, particularly rare species and those with nocturnal and/or discrete behaviour as well as species using the site for brief visits. Therefore, this inventory should be enriched by additional investigations that would reveal the existence of other species, particularly if appropriate sampling techniques could be applied.

Conclusion and perspective

This study provides the first qualitative inventory of vertebrate fauna of Ayata Lake, which would be the most exhaustive and accurate. All species identified and recorded in this study have been already described for Algeria in the literature. Although this inventory remains far from being the most exhaustive, given the short period during which the study was conducted; our results suggest that knowing species composition as well understanding their temporal dynamics could be relevant to identify and to outline future conservation decisions.

Finally, it is important to emphasize the presence in the Lake Ayata of several protected species in Algeria and internationally, which also deserve more attention to carry out specific studies. The site is particularly important in hosting an abundant avian population, despite its small area, including wintering Anatidae which include also Marbled Duck (VU) and Ferruginous Duck (NT). The mere presence of all these protected and rare species suggests a direction of researches to conservation studies to guide policy makers and managers to mitigate deterioration and threatening factors.

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