The current study aims to assess zooplankton diversity in Bahr Al-Najaf depression using diversity index, specimens were collected from five sites at Bahr Al-Najaf depression, Iraq during April 2017 to March 2018.
Forty-eight taxa of zooplankton were identified including 26 taxa to Copepoda, 17 taxa belonged to Rotifers and 5 taxa to Cladocera: Copepoda was the most dominant group (54.2%); Rotifera comprised (35.4%); Cladocera comprised (10.4%).
Relative abundance index of zooplankton showed Copepodite and nauplii of Harpacticoid, Hexarthra mira, Daphnia sp., Harpacticoid sp., and Copepodite and nauplii of Cyclops were more abundant. According to the constancy index, the Copepodite and nauplii of Harpacticoid, nauplii Cyclops, nauplii stage and Hexarthra mira can be considered as the most frequent; Shanon-Weiner diversity index values of zooplankton recorded less value 0.48 in August 2017 at site (5); while the higher value was recorded in April 2017 at site (2) was 2.42; the higher value of species richness index was recorded in April 2017 at site (2) which was (7.2), the higher value of species uniformity index was recorded in February at site (2) and March at site (1) (0.61).
The present study concluded that Copepoda was the most abundant of zooplankton with variations in zooplankton species (density and from month to another).
