The Composition and Diversity Indices of the Fish Assemblage in the Tidal Mudflats of the Shatt Al-Arab Estuary in the Northwest Arabian Gulf

Abstract

Ten thousand four hundred and thirty-five fish were collected from January 2021 to February 2022, belonging to 71 species distributed across 39 families and 20 orders. The study included the tidal zone of the Shatt al-Arab estuary in the northwest of the Arabian Gulf. Two methods used to collection the fishes; fixed gill nets and trowel nets. Various diversity indices, relative abundance, and richness were assessed. Several biodiversity indices were used to assess the area biologically and ecologically which Species diversity for Shannon and Simpson, species richness for Margalef and Menhinick, dominance for Berger-Parker, species similarity for Jaccard, numerical similarity for Bray – Curtis, and evenness for Peilou index. Nematalosa nasus had the highest relative abundance, which was recorded at 24.53%. However, the lowest relative abundance was observed for 20 species, with a value of 0.01% with only one individual. The Carangiformes had the highest percentage of 18.31% and the lowest percentage of 1.41 % for many orders only, with one species recorded. The Margalef index had its highest value on June 5.24 and its lowest on December 1.24. The Menhinick index had its highest value of 1.53 in October and its lowest value of 0.71 in November. The Shannon Index reached a peak of 2.69 in January 2021, and fell to 0.98 in September. The Simpson index recorded the highest value of 0.92 in January 2021 and the lowest value of 0.37 in September. The Peilou index reached its highest value of 0.965 in December, while its lowest value was 0.294 in September. The Jaccard index had its highest value of 0.667 between January 2021 and March, while its lowest value was 0.079 between December, June, and July. The highest value for the Bray-Curtis index occurred between July and August, reaching 0.644. In contrast, the lowest value observed was 0.005 between July and December.

Keywords

• Diversity
• Dominance
• Evenness
• Occurrence
• Richness
• Similarity