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Sultan Qaboos University (2018)

Macrophytes associated with the aquatic ecosystems in Al Hajar Mountain ranges of Northern Oman

Rajesh, Lakshmy.

Titre : Macrophytes associated with the aquatic ecosystems in Al Hajar Mountain ranges of Northern Oman

Auteur : Rajesh, Lakshmy.

Université de soutenance : Sultan Qaboos University

Grade : Doctor of Philosophy (PhD) in biology 2018

Résumé
The diversity of freshwater macrophytes in twenty six wedian (plural of wadi = seasonal river) of the northern Al Hajar Mountain range in Oman was studied for the first time. The number of species, their growth forms and frequency of occurrence were recorded. In all, 48 species belonging to 19 families and 38 genera were collected. Phragmites australis was the most dominant emergent followed by Typha domingensis. Among submerged macrophytes, Chara vulgaris had higher relative frequency followed by Potamogeton distinctus. Floristic diversity was estimated using four diversity indices. The Margalef’s richness index (D), ranged from 2.31-1.96 while the Shannon Weiner diversity index (H’) ranged from 2.42-2.26. The ranges of Pielou’s evenness (EH) and Berger-Parker dominance (d) were from 0.715-1.0 and 0.2-0.9 respectively. Principal Component Analysis (PCA) was used to evaluate the variability among the 26 study habitats based on species diversity measures. Species diversity of some habitats in different watersheds were similar while some in the same watershed were different. Beta diversity was calculated using Bray-Curtis similarity matrix and the results were ordinated using PCoA, a multivariate analysis. PCOA grouped similar habitats into four groups. TWINSPAN was used for vegetation classification which identified five indicator species ; Chara vulgaris, Pluchea arabica, Eleocharis geniculata, Cyperus laevigatus and Bacopa monnieri. Potamogeton distinctus has been reported for the first time in Oman and Arabian Peninsula through this study. Its identity was confirmed by DNA barcoding and the accession number has been submitted to National Centre of Biotechnology Information (NCBI) database. A total of 19 other macrophytes were also barcoded, and this is also the first effort for Oman. Special importance was given to Charophyta, the only non- spermatophyte included in this study. Morphology of thallus and oospores were studied in detail and with the help of SEM, and unique oospore characteristics described are helpful in species identification. The study recorded two species of charophytes, Chara vulgaris and Chara zeylanica in northern Oman aquatic habitats. A total of 15 water quality parameters were measured. Canonical Correspondence Analysis (CCA) indicated that temperature, water conductivity, anions like Cl-, NO3-, SO42- are the main water parameters that govern the distribution of macrophytes. Substrate soil analysis was done using XRF to find out the major ingredients influencing macrophytes. The mean concentration of six elements, Ca, Si, Fe, Al, Mg and K were higher (p<0.01). Ca, K and Fe played a major role in influencing macrophyte distribution. Agglomerative Hierarchical Cluster analysis was performed using all the major abiotic factors influencing macrophytes for respective sites and four major clusters were formed to group the sites. This study provides the muchneeded baseline data on the freshwater macrophytes of the wedian in northern Oman.

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