Lake Tonga Research Articles

Water physicochemical quality as driver of spatial and temporal patterns of microbial community composition in lake ecosystems

This study aimed at monitoring and management of the surface water and potentially pathogenic microbes of Lake Tonga (Algeria) with respect to. It characterized the main bacterial diversity patterns of Lake Tonga and predicted from water physicochemical parameters and water quality index (WQI) the distribution of bacterial species and the main indicator groups of faecal water contamination. Water samples were taken monthly at three sampling sites of different water depths. Several physicochemical parameters were measured; of which some were included in computing WQI to characterize the water quality of the lake. Counting, isolation and bacterial identification methods were used to characterize the existing aerobic heterotrophic bacteria. The composition of the microbial community of the waterbody of Lake Tonga included an abundant culturable bacterial flora belonging to several bacterial families and whose specific richness varied between water depths of the sites sampled. Species richness of the bacteria identified phenotypically varied between 7 and 11 per sample. The site with shallow water was the richest in bacterial species, compared to moderate and deep waters. The redundancy analysis showed the main physicochemical drivers of the microbial community composition. Our findings showed that high WQI scores indicated the water quality deterioration which triggered the increase in total load of faecal indicator bacterial groups. This study identified in Lake Tonga an important culturable aerobic bacterial flora whose specific richness and distribution varied spatially following the effects of water physicochemical parameters. Lake Tonga needs an integrated management plan to mitigate human disturbances declining water quality.

Dual resistance to heavy metals and antibiotics of Aeromonas hydrophila isolated from Carassius carassius (Linnaeus, 1758) in Lake Tonga, Algeria

Aeromonas hydrophila, a bacterium with significant virulence potential, is the predominant pathogenic bacteria naturally infecting fish. This study aims to identify the antibiogram and heavy metal resistance pattern of Aeromonas hydrophila obtained from both Carassius carassius fish and their surrounding water environment in Lake Tonga, Algeria. A total of 59 strains of Aeromonas hydrophila were isolated from 168 Carassius carassius samples and 144 waters samples of Lake Tonga. All the strains were tested for resistance to 13 antibiotics and three types of heavy metals (Cobalt, copper and cadmium) using disk diffusion and two-fold agar dilution method, respectively. Clinical macroscopic examination of the fish was also carried out. More than 14% of the examined fishes showed the characteristic clinical signs. Drug screening showed high levels of resistance to β-lactam antibiotics, 100% of the strains were resistant to ampicillin followed by cefalotin (91.53%) and ticarcillin (88.14%). More than 40% of the strains exhibited resistance against gentamicin, amikacin and chloramphenicol. The multiple antibiotic resistance (MAR) indexing of A. hydrophila strains showed that all of them originated from high-risk sources. Among tested heavy metals, bacterial isolates exhibited resistant pattern of Co>Cu >Cd. A positive correlation was observed between antimicrobial resistance and metal tolerance (Odds Ratio>0.1). These resistant profiles could be useful information to avoid unnecessary use of chemical and antimicrobial products in the aquatic environment and to provide a novel approach to manage bacterial infection in fish.

An ecological survey of Laro-limicolae in Northeastern Algeria

We conducted an inventory and characterization of Laro-limicolae settlement at three Ramsar sites located in Eastern Numidia (Lake Tonga, Lake Oubeira and El Mellah lagoon) between 2014 and 2016. We identified 27 species belonging to six families, dominated by Scolopacidae (10 sp.) and Laridae (9 sp.) followed by Charadriidae (4 sp.), Recurvirostridae (2 sp.) and for Glareolidae and Haematopodidae families (1 sp.) Inventoried species exhibited different phenological status: resident (26%), wintering (44%), migratory breeders (19%) and wintering/breeding (11%). Population analysis showed the presence of protected species such as black-tailed godwit and Northern lapwing. Bird counts showed monthly variations in total abundance and richness, peaking during winter. Highest numbers were recorded in January and lowest numbers in August. Analysis of diversity and equitability indices indicated that maximum values (H’ = 3.01 and E = 0.94) were noted at El Mellah lagoon in November and at Lake Oubeira in June. Our study provides recent and unpublished data on a group of birds that are little-documented for North Africa, particularly for Algeria. Our findings open the way for further, more detailed work on the subject, and may serve to develop action plans for the management and conservation of these bird populations and their habitats.

13-year population survey of the critically endangered European eel in the southern Mediterranean region (Algeria).

A 13-year biomonitoring survey was carried out on the European eel, Anguilla anguilla for the first time in North Africa (Algeria) where there is a serious lack of information on the species. The study targeted specimens populating the only four sites where the species is both potentially present and legally exploited (Lake Oubeira, Lake Tonga, Mellah lagoon and Mafragh estuary). A total of 1370 individuals were sampled ranging from 17 to 113 cm in length, 19 to 2642 g in weight and 0.7 months to 6.6 years old, age being estimated from otolith growth marks. Otolith interpretation and age estimation were generally unambiguous at all four sites. According to the EELREP silvering index, the highest proportion of silver females was captured in fresh water (46% in Lake Oubeira and 25% in Lake Tonga), whereas a third were present in brackish water (Mafragh and Mellah). The sex ratio was in favour of females, and silver males were found to mature early (mean length 40 ± 1 cm, mean weight 123 ± 28 g and mean age 2 ± 0.6 years). Growth differed at the four sites, and the growth rate was highest in Lake Oubeira and asymptotic length highest in Mellah lagoon. Metamorphosis from the yellow resident stage to the silver migrating stage occurred very early in the eels' continental life (between 3 and 4 years of age). Results highlight rapid growth in these Algerian sites, and earlier silvering than in eels living in European waters, suggesting different life-history traits of A. anguilla in North African waters, influenced by environmental conditions.

Avifauna diversity and phenology in a Ramsar site: Lake Tonga (Northeastern Algeria)

Between 2013 and 2016 we conducted an inventory and characterization of aquatic avifauna at Lake Tonga, a Ramsar site. We identified 61 species belonging to 17 families, dominated by Anatidae with 14 species. The inventoried species have different phenological status. Some are known for their regular wintering and some for their summer concentrations, while others are residents year round. Population analysis showed the presence of endangered species such as Oxyura leucocephala, Marmaronetta angustirostris and Aythya nyroca, that are protected by national and/or international laws. Bird counts showed monthly variations in total abundance and richness, peaking during winter. Peak numbers were recorded in February and January, reflecting gatherings to prepare for prenuptial migration. Analysis of diversity and equitability indices indicated that maximum values ​​were generally recorded during the pre– and post–nuptial passages (H’= 3.51 and E = 0.72). Our results reflect the importance of this wetland as a wintering site and nesting site for numerous waterbirds species.

The distribution and diversity of chewing lice (Phthiraptera) on the Common Moorhen Gallinula chloropus in Algeria

ABSTRACT Capsule The distribution and prevalence of chewing lice found on Common Moorhens Gallinula chloropus varied between seasons and peaked during the winter. There was also significant variation in how lice were distributed around the body regions of the hosts. Aims To identify the species of lice found on the Common Moorhen, evaluate the seasonal variation in their intensity of infestation and determine spatial distribution on the hosts. Methods Eighty-six Common Moorhens were captured, examined for lice, and released from December 2018 to February 2020 at Lake Tonga, Algeria. Lice were extracted, preserved in 70% ethanol, cleared, and mounted in Canada balsam for identification. The population mean intensity and prevalence of lice species were calculated for each season. Data were inspected using descriptive statistical tools, such as principal component analysis, to explore spatial dispersion on the body regions of the hosts. Results Five louse species were identified: Pseudomenopon pilosum, Rallicola minutus, Laemobothrion chloropodis, Fulicoffula sp, and Incidifrons gallinulae, with percentages of prevalence of 79.07%, 70.93%, 56.98%, 40.70%, and 23.26%, respectively. Their prevalence varied significantly across months, with a peak in the winter. Louse species were non-randomly distributed across the body regions of the hosts. Conclusion This study documents the distribution and diversity of chewing lice on the Common Moorhen for the first time in Algeria and establishes a baseline dataset for further monitoring studies.

Nest site selection and breeding ecology of the Ferruginous Duck (Aythya nyroca) in Algeria

Ecologically, the Nature Reserve of Tonga Lake (northeastern Algeria) is very important for waterbirds. This study investigates breeding biology of an emblematic species of this region: The Ferruginous Duck (Aythya nyroca), a duck ranked globally 'Near Threatened' on the IUCN Red List. This study aimed to determine wetland environmental variables influencing nest site selection and breeding success of the species. Over two successive breeding seasons (2016 and 2017), the effects of habitat characteristics and nest traits on breeding parameters of 50 nests constructed on alder carr of the lake and offshore floating vegetation islets in the center of the waterbody were analyzed using generalized linear models (GLM). Clutch size averaged 9.8 ± 0.7 eggs (range: 2–26 eggs) with 66% hatching success. Desertion of the nest (i.e. nest abandonment by the parents during the period of egg-laying and/or incubation) was the main cause for breeding failure (18% of total nests). Clutch size was positively related to nest surface and nest depth, but it decreased with the increase in the distance of nest on the vegetation platform to water. GLM revealed that breeding success was positively associated with late clutches; with a negative effect of conspecific nest density on clutch size and breeding success. Nest-site choice is resulted from interspecific competition and/or is affected by the reduced number of favorable nesting sites. Nine nests (18%) were parasitized by the same species of which 67% were central nests. Only 2% of the nests studied were parasitized by Oxyura leucocephala nesting at the site. Possible explanations of nest site selection of Aythya nyroca in the study area are discussed. Variations in selection pressures may explain the relationships between the choice and characteristics of nest site in the Ferruginous duck at Lake Tonga.

Comparative study of the energy reserves of two populations of eels Anguilla anguilla (L. 1758) fished in the El Mellah Lagoon and Lake Tonga in northeastern Algeria

Comparative study of the energy reserves of two populations of eels Anguilla anguilla (L. 1758) fished in the El Mellah Lagoon and Lake Tonga in northeastern Algeria

Antioxidant Activity and Phenolic Content of Extracts of Wild Algerian Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes).

Mushrooms can be employed as functional foods or medicines for the prevention and treatment of several chronic diseases, since they are rich sources of bioactive metabolites. Nonetheless, the therapeutic value of Algerian mushrooms remains largely unexplored. To date, there are no published studies concerning the different medicinal properties of endemic Ganoderma lucidum in Algeria. This study aimed to compare the antioxidant potential of an endemic specimen collected in the Lake Tonga Forest of El Kala National Park in Northeast Algeria with findings from other countries. To this end, phenolic and flavonoid contents were determined using three solvents of increasing polarity (chloroform, ethyl acetate, and butanol). The mushroom specimen was identified as G. lucidum based on strong molecular evidence using internal transcribed spacer, large subunit, and small subunit sequences. Our study showed that ethyl acetate extract contained higher total phenolic content (171.1 ± 1.06 μg gallic acid equivalents/mg and 102.5 ± 0.69 μg pyrocatechol equivalents/mg extract) and total flavonoid content (25.48 ± 0.13 μg quercetin equivalents/mg and 40.45 ± 0.83 μg rutin equivalents/mg extract) than the other mushroom extracts (chloroform and butanolic). The ethyl acetate extract also showed good antioxidant activity in DPPH (28.51 ± 0.24 μg/mL), ABTS·+ (10.06 ± 0.13 μg/mL), galvinoxyl radical (15.46 ± 0.48 μg/mL), reducing power (22.74 ± 0.30 μg/mL), cupric reducing antioxidant capacity (21.36 ± 0.04 μg/mL), and phenanthroline (12.87 ± 0.26 μg/mL) assays. These results suggest that G. lucidum could be used as a source of strong natural antioxidants for the food and pharmaceutical industries.

Ecology of Avian Settlements in Lake Tonga (Northern Algeria)

Lake Tonga is an integral reserve within the El-Kala National Park, Biosphere Reserve and Ramsar site. This study consists in determining the diversity and phenology status of waterbirds in this reserve over an entire annual cycle (2017–2018). The census was carried out from fixed observation points. Of the 35 species recorded, wintering birds dominate with 12 species (34 %), followed by breeding sedentary species with 11 species (32 %). The breeding water bird populations are dominated by the common coot Fulica atra, (with a maximum of 6,033 birds) followed by the Anatidae, Herons and Grebes. Lake Tonga is a breeding area for several avian species and a recruitment site for a multitude species bird during the wintering period. Three Anatidae nest at Lake Tonga: the white-headed duck Oxyura leucocephala, the ferruginous duck Aythya nyroca and the mallard Anas platyrhynchos.

Physico-chemical and bacteriological quality assessment of surface water at Lake Tonga in Algeria

Maintaining standard water quality of aquatic ecosystems requires continuous monitoring of water physicochemical and bacteriological characteristics. This study aimed at assessing water physicochemical and microbiological proprieties of Lake Tonga (northeastern Algeria). Water samples were collected monthly (January–June) from three different stations at different depths. Several physicochemical parameters (pH, electrical conductivity, turbidity, hardness, biological oxygen demand (BOD5), concentrations of suspended solid materials, dry residuals, dissolved oxygen, phosphate, nitrites, nitrates, ammonium, calcium, magnesium, chloride, potassium and sulfur dioxide) and bacterial group sdensity (total heterotrophic bacteria, total coliforms, faecal coliforms and faecal Streptococci) were measured. Physicochemical analysis of Tonga Lake water revealed a slightly alkaline environment pH (6.5 < pH < 8.5), electrical conductivity < 1500 μS/cm, turbidity > 7.02 NTU, dry residues < 2000 mg/L, suspended solid materials (11.8 mg/L, < 30 mg/L), dissolved oxygen < 5 mg/L, phosphates > 5 mg/L, BOD5 < 5 mg/L, nitrate < 50 mg/L, nitrite > 0.1 mg/L, and NH4+ > 0.5 mg/L, Ca2+ < 200 mg/L, Mg2+ < 150 mg/L, Cl–> 500 mg/L, K+ > 20 mg/L and sulfates < 200 mg/L. In addition, microbiological results indicated the presence of different groups of faecal bacteria with an average of 32.3 × 10³ CFU/100 mL for total heterotrophic bacteria, 24 × 10³ CFU/100 mL for total and faecal coliforms, and 37 × 10³ CFU/100 mL for faecal Streptococci. Tonga Lake is currently in an eutrophication state and further severe ecosystem degradations may occur if the appropriate management measures are not taken in short term.

The breeding ecology of Mallard Anas platyrhynchos at Lake Tonga, north-eastern Algeria

The breeding ecology of Mallard Anas platyrhynchos was investigated at Lake Tonga, north-eastern Algeria, which is at the southern edge of the species’ range in the Western Palearctic. Breeding was mainly carried out in stumps of alder carr (Alnus glutinosa) that border the northern limit of the lake. The breeding season was relatively short, spanning two months. Laying occurred mainly in April but continued until end of May. The average clutch size was 8.4 ± 1.9 eggs (N = 19 clutches) with 10 eggs being the modal clutch. The overall nesting success was 54% (N = 29 clutches), whereas predation accounted for most nest failure (76%). As often happens in arid climates and instable habitats, breeding outcome was significantly and negatively related to egg-laying date with precocious nests conferring better survival to eggs. In contrast, nest predation was positively associated with a deferred laying date. Seven cases of interspecific brood parasitism were recorded, all involving the Mallard and the Ferruginous Duck Aythya nyroca, with both species acting as either a host or a parasite. Nests in dense vegetation were more likely to harbour this interspecific interaction.

Population Structure and Morphometrics of the European Pond Turtle (&lt;i&gt;Emys orbicularis&lt;/i&gt; (Linnaeus, 1758)) at Lake Tonga, Algeria

A total of 100 specimens of Emys orbicularis were collected and marked at Lake Tonga (northeastern of Algeria) during 3 consecutive years (2013, 2014, 2015). Most of the turtles inhabit a canal where they remain throughout the whole activity season (March to October) and where they overwinter as well. Carapace Length (CL) and body weight (BW) were measured for each individual of E. orbicularis . The size of the turtles of our population was more similar to those of northern European populations than to the Mediterranean populations; females were significantly larger than the Spanish and Italian populations. The population size was calculated as 108.50 and the density as 8.63 turtles/ha. From 6.52 to 12.77% of the population were juveniles. The adult sex ratio was slightly in favor of males (males:females = 1.12, P &lt; 0.005).

Study of the physicochemical parameters of water and phytoplankton in Lake Tonga (wetland of the national park of El Kala, North East of Algeria)

Study of the physicochemical parameters of water and phytoplankton in Lake Tonga (wetland of the national park of El Kala, North East of Algeria)

Distribution and breeding ecology of the Ferruginous Duck Aythya nyroca in Algeria

We conducted a survey of the distribution of Ferruginous Duck Aythya nyroca across Algeria and analysed the influence of nest-site characteristics on nesting success at a Ramsar site, Lake Tonga. The species was found to occupy different wetlands (freshwater lakes, brackish marshes and salt lakes) across three major climatic belts (subhumid coastal strip, semi-arid Hauts Plateaux and arid Sahara). Mean clutch size of successful nests was 13.3 ± 6.0 eggs (N = 26) with a hatching rate of 74% for successful clutches. Nesting success was recorded for 44% of nests with clutch desertion (72.7%) accounting for the majority of failed clutches. Egg size of the study population, which breeds at the southern limit of the species’ range, was significantly smaller than that of its northerly counterparts. Clutch size was negatively related to egg size and positively associated with depth of water below the nest, suggesting that older, more experienced or high-quality birds monopolised the safest sites. Successful clutches were significantly associated with tall vegetation, suggesting that when nesting is carried out mainly on offshore floating islets, protection against aerial predators and heat stress determine nesting outcome. Conspecific brood parasitism was significantly and positively associated with deferred egg-laying and smaller egg size, suggesting an age-dependent mechanism.

Sitting ducks: diet of wintering wildfowl in Lake Tonga, northeast Algeria

Dietary studies of five species of Anatidae (Gadwall Anas strepera, Shoveler Anas clypeata, Pochard Aythya ferina, Ferruginous Duck Aythya nyroca, and White-headed Duck Oxyura leucocephala) were carried out at Lake Tonga, northeast Algeria, from December 2011 to March 2012. Diet analysis of all five wintering species indicated a heavy reliance on seeds, which included a wide variety of aquatic plants, such as Myriophyllum spicatum, Ceratophyllum demersum, Sparganium erectum, Scirpus lacustris and Potamogeton pectinatus. Noteworthy is the paucity of ingested macroinvertebrates. Despite dietary overlap, the type, abundance and frequency of food consumed clearly indicated differences in resource use among the ducks. Incidentally, the study also highlighted the high vulnerability of threatened ducks to poaching (harvesting and disturbance) in a protected area. We discuss the implications of these findings for the management and conservation of wintering wildfowl and their North African habitats.

First data on the population of the European pond turtle Emys orbicularis at Lake Tonga, El Kala National Park, Algeria

AbstractThe North African distribution of

Comparing habitat preferences of a set of waterbird species wintering in coastal wetlands of North Africa: implication for management

AbstractEvery year, the Coastal wetlands of North Africa support an important wintering waterbird population of many Palearctic and sub-Saharan species of various contrasting habitat requirements. In this study, we describe the habitat use by24 water-obligate species wintering in a coastal wetland of the Northeastern Algeria (the wetland of Lake Tonga), highlighting thereby the ecological mechanisms that support their coexistence and their resources partitioning. The analysis of resource exploitation (Relative frequency, Feinsinger niche breadth, Pianka niche overlap and Ivlev’s electivity indexes) showed that waterbird species inhabiting the lake wetland have several similarities in using the different habitat categories, which lead us to cluster them into 5 guilds (G1: one rails, two grebes and eight ducks; G2: five wading species and one gull; G3: three herons; G4: cormorants, mallards, and on gull; finally, G5: only one species Cattle egret (Bubulcus ibis).Almost all the species were specialists in resource utilization patterns (narrow niche breadths, both under 0.3) and therefore, vulnerable to fluctuations in resources, particularly the feeding habitats. Mean niche overlaps for all the pairs of species ranged from 0.05 to 0.68. The overall pattern in the community was higher niche overlaps between the species of a particular guild than those between other species. According to Ivlev’s electivity index, we found that only three microhabitats from seven were the most important for the discussed species, open water body was the most attractive, followed by meadows, muddy areas and floating- leafed vegetation. Similarities on habitat requirements derived from our region can provide important and optimal wetland management at multi-species assemblage level for this wetland and similar area around the African coast.

Nesting ecology of Ferruginous Duck Aythya nyroca in north-eastern Algeria

The status of waterbirds breeding in protected areas in North Africa needs constant monitoring because of a naturally fluctuating environment and permissive attitudes towards illegal activities likely to negatively affect population dynamics of threatened species. We present the results of a study conducted at a protected site, Lake Tonga, north-eastern Algeria, on a breeding population of Ferruginous Duck Aythya nyroca, a Near-Threatened duck subjected to considerable pressure from egg-pilfering and illegal hunting. Two distinct habitats within the lake were used by Ferruginous Duck: an Alder carr (Alnus glutinosa) and floating islets across the lake. The mean clutch size was 9.51±1.84 eggs (N = 51 clutches) with hatching rate of 80.7% for successful clutches. Breeding success was low (37%) with predation (33%) and clutch desertion (17%) accounting for the majority of failed nests. The probabilities of nest failure and nest desertion increased with a delayed onset of egg laying. Predation was not significantly associated with egg laying date and vegetation cover, but late breeders nesting in dense vegetation seemed to suffer less predation. Conspecific brood parasitism was positively associated with nest size, whereas interspecific brood parasitism was marginally associated with water depth. We discuss different hypotheses concerning nest desertion, and argue that illegal hunting and disturbance may best explain why birds desert their nests.

Factors affecting nesting success in the Great-crested Grebe Podiceps cristatus at Lake Tonga, north-east Algeria

The breeding ecology of the Great-crested Grebe Podiceps cristatus was investigated over four consecutive years (2009-2012) at Lake Tonga, north-east Algeria. In all four years, the egg-laying period was relatively short, spanning two months (end of March to end of May), and bimodal. Nests were mainly located in Phragmites australis, over water of substantial depth (178 ± 43 cm, N=209), far from the shore and in habitat with low vegetation cover (12.37 ± 7.67%, N=209). The overall clutch size was 3.73 ± 0.92 eggs (N=127) and it decreased marginally over time. The overall nesting success was 70.4% (N=209), with nest failure caused mainly by predation (65%) and flooding (23%). Breeding outcome was significantly and positively related to nest size, with bigger nests conferring better survival to eggs and young probably through affording better protection during spells of adverse weather. However, the benefits of bigger nests may be confounded by the age or intrinsic quality of birds. The location of nests in P. australis, rather than other vegetation types, increased nesting success marginally but significantly. Two cases of interspecific mixed clutches involving the Great-crested Grebe were recorded.