Structure of waterbird assemblages in fragmented coastal wetlands of Northeastern AlgeriaAcronym: MCNB-Bouldjedri-Mayache-2020
This study was carried out from 2007-2017 on the ecological complex of the Jijel wetlands in the north-east of Algeria. Censuses were conducted during the twelve months of each year to study variation in richness and abundance of waterbird populations for each season. We used distance sampling (point count and transect methods). A total of sixty species (eleven orders and sixteen families) were recorded. The Anatidae and Scolopacidae families were the most numerous with thirteen species. The common coot (Fulica atra), and the Mallard (Anas platyrhynchos) were the most abundant and frequent species each year. About 70 % of the species recorded occur as migrants, passing between the western Palearctic and their winter quarters in North Africa. Phenologically, we found 15 % were breeders, and from the point of view conservation status, 56% were rare, 40 % were protected by Algerian regulations and 8 % were threatened species listed in the Red List of the International Union for Conservation of Nature (IUCN). Our results of ornithological monitoring in the wetlands in Algeria show that action is needed to address the consequences between birds, human activities, and climate change.
Fieldwork was conducted in Jijel eco-complex wetlands located in north-eastern of Algeria (36° 34'-36° 52'N, 5° 33'-6° 19' E), which are approximately 60 km2 in size. This natural wetland reserve comprises two major aquatic habitats that may vary in vegetation composition and structure, namely: (i) Beni-Belaid Lake (B-B.Lake) and (ii) El-Kennar Marsh (E-K.Marsh) (see map in fig. 1). This latter freshwater swamp is dominated by herbaceous rather than woody plant species. These mosaic hydrosystems are characterized by several types, mainly lakes, marshes, reservoirs, ponds, estuarine waters, and shallow seawater. Together, they form a complex ecosystem of wetlands.
For the transect survey, the perpendicular searching distances varied depending on the shape of the site, with 0.5 and 0.8 km in El-Kennar Marsh and Beni-Belaid Lake, respectively (i.e. depending on the size, and boundary location of the site). The vegetation type (emergent, submerged, grasses, shrubs, and trees) was determined by direct observation within the consistency of the point count stations. We also estimated the depth of the water in the shallow area from the length of the legs of shorebird species. Variability in observer error was minimized by measurements being performed by the same observer wherever possible throughout the study. Table 1 lists all the species included in the analyses.
The study of the avifauna ecology was approached by determining ecological indexes directly linked to the balance of populations (Shannon–Weaver, Frequency and Uniformity). The monthly mean number for species richness and the total number of individuals was calculated for the whole period. These values were then used to calculate the diversity of species for the two main sites, expressed by the alpha diversity (Hα) of Shannon–Weaver index (H′). This index was computed using the following mathematical formula (Shannon–Weaver, 1949): H’ = -∑ pi ln pi
where pi = (ni / N), N is the total population (individuals of all species), ni is the size of the population of species and S denotes the total number of species composing a population (specific richness).
Frequency index: Relative abundance (RA %)is computed by using the formula: RA (%) = ni / N × 100, where: ni is the number of individuals of species taken into account and N is the total number of individuals of all species.. Species relative abundance status (table 1) was estimated from the frequencies of sightings over 12 months and the categories were assigned according to the Pettingill (1969) scale: abundant (90-100 %), common (65-89 %), moderately common (31-64 %), uncommon (10-30 %) and rare (1-9 %).
Uniformity Index (Pielou index): this index measures the degree of numerical balance between species represented by the Equitability index (Evenness index). ‘E’ is calculated as the ratio:
E = H′obs / H′max between observed diversity H′obs and maximum diversity H′max = log2(S), S being the total number of species recorded during each month (Pielou, 1966). The equitability index ‘E’ makes it possible to assess the imbalances that the diversity index cannot detect; it varies from 0 to 1. When E < 0.5, this means that the individuals mostly tend to belong to a single species. When E > 0.5, it means that species have similar or balanced abundance, the same abundance occurs when the value is exactly one (Okpiliya, 2012).
For the entire study region, the mean (± standard deviation) was calculated for each ecological index (Shannon–Weaver diversity (H′), Equitability index (E), Abundance, Specific richness and Monthly population dynamics) based on all observations. The results were compared using analysis of variance (ANOVA), the choice of a parametric test analysis (two ways ANOVA) is supported by the Shapiro-Wilk test on the ANOVA residuals for the previous ecological index comparison which finds no indication that normality is violated. After this analysis, we used a Bartlett test on the ANOVA residual because the normality and homoscedasticity conditions were met: as the p-value was largely greater than 0.05, the assumption of homogeneity of the residual variances was therefore accepted. However, ANOVA led to the conclusion that there were differences between the means in some groups. Tukey’s (HSD) multiple comparison tests were used to compare the difference between each pair of monthly means. The choice of a non-parametric test (Friedman rank-sum test) analysis in the monthly abundance of shorebirds population is referred to that the condition of residual normality is violated (p= 0.001). These tests were performed using the statistical software R version 3•2•2 (R Core Team, 2015).
Correspondence analysis (CA) was applied (bi-plot species and dates) to the data collected from the entire e eco-complex. CA is a two-dimensional solution that is well-suited to describe the spatial and temporal gradients in composition occurrence, status and assembly of waterfowl found at this ecological site. This last statistical analysis was carried out using the ADE-4 software package.
Type of content
Includes: point occurrence data.
Bouldjedri, M., Mayache, B., 2020. Structure of waterbird assemblages in fragmented coastal wetlands of Northeastern Algeria. Museu de Ciències Naturals de Barcelona. Dataset/Occurrence:
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