Ecologically, the Nature Reserve of Tonga Lake (northeastern Algeria) is very important for water... more 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.
Physico-chemical and bacteriological quality assessment of surface water at Lake Tonga in Algeria, May 2020
Maintaining standard water quality of aquatic ecosystems requires continuous monitoring of water ... more 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 and bacterial parameters were measured (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, total heterotrophic bacteria, total coliforms, faecal coliforms and faecal Streptococci). Physicochemical analysis of Tonga Lake water revealed a slightly alkaline environment pH (6.5<pH<8.5), electrical conductivity<1500μS/cm, turbidity>7.02 NTU, dry residues<2000mg/L, suspended solid materials (11.8mg/L, <30mg/L), dissolved oxygen<5mg/L, phosphates >5mg/L, BOD5<5mg/L, nitrates<50mg/L, nitrite >0.1mg/L, and NH4+>0.5mg/L, Ca<200mg/L, Mg<150mg/L, Cl>500mg/L, K>20mg/L and sulfates<200mg/L. In addition, microbiological results indicated the presence of different groups of fecal bacteria with an average of 32.3×10³ CFU/100mL for total heterotrophic bacteria, 24×10³ CFU/100mL for total and faecal coliforms, and 37×10³ CFU/100mL for faecal Streptococci. Tonga Lake is in a eutrophication state and further severe ecosystem degradations may occur if appropriate management measures are not taken in short term.
Ecologically, the Nature Reserve of Tonga Lake (northeastern Algeria) is very important for water... more 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.
Physico-chemical and bacteriological quality assessment of surface water at Lake Tonga in Algeria, May 2020
Maintaining standard water quality of aquatic ecosystems requires continuous monitoring of water ... more 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 and bacterial parameters were measured (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, total heterotrophic bacteria, total coliforms, faecal coliforms and faecal Streptococci). Physicochemical analysis of Tonga Lake water revealed a slightly alkaline environment pH (6.5<pH<8.5), electrical conductivity<1500μS/cm, turbidity>7.02 NTU, dry residues<2000mg/L, suspended solid materials (11.8mg/L, <30mg/L), dissolved oxygen<5mg/L, phosphates >5mg/L, BOD5<5mg/L, nitrates<50mg/L, nitrite >0.1mg/L, and NH4+>0.5mg/L, Ca<200mg/L, Mg<150mg/L, Cl>500mg/L, K>20mg/L and sulfates<200mg/L. In addition, microbiological results indicated the presence of different groups of fecal bacteria with an average of 32.3×10³ CFU/100mL for total heterotrophic bacteria, 24×10³ CFU/100mL for total and faecal coliforms, and 37×10³ CFU/100mL for faecal Streptococci. Tonga Lake is in a eutrophication state and further severe ecosystem degradations may occur if appropriate management measures are not taken in short term.
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