Abstract
This study is considered to be the first on this sector of Tigris River after 2003, to evaluate the effect of Tharthar Arm on the composition and diversity of Copepoda in Tigris River. Six sampling sites were selected; two on the Tharthar Arm and four sites along the Tigris River, one before the confluence as a control site and the others downstream the confluence; thirty-five copepod taxa were recorded, 34 taxa in the Tigris River and 25 taxa in the Tharthar Arm. The highest density of Copepoda was 265584.2 Ind./m3 in the site 2 at Tharthar Arm lead to an increasing in Copepoda density in the Tigris River from 63878.2 Ind./m3 in site 1 before the confluence to 127198.3 Ind./m3 in site 4 immediately downstream the confluence. Also, the mean values of richness index and diversity index increased from 1.71 and 0.98 bit/Ind. in site 1 before the confluence to 2.08 and 1.00 bit/Ind. in site 4 below the confluence, respectively. Moreover, the highest similarity percentage was between sites 3 and 4 reached 87.83% while, the lowest percentage was between the sites 1 and 2 recorded 65.41%. For constancy index the highest value was 9 at the site 6 whereas the lowest value was 2 at site3.
Highlights
INRODUCTION River channel confluences play a major role in the dynamics of all fluvial systems and are ubiquitous, fundamental elements of natural drainage networks (Parsons et al, 2008; Sukhodolov et al, 2010)
Copepoda are used as live food for the early larval stages of many kinds of fishes in aquaculture throughout the world (Barroso et al, 2015) and they considered as the main food source for several planktophagous fishes and benthic invertebrates
The aim of this study is to investigate the effect of Tharthar Arm on the density and diversity of Copepoda in Tigris River, northern of Baghdad City during 2020
Summary
INRODUCTION River channel confluences play a major role in the dynamics of all fluvial systems and are ubiquitous, fundamental elements of natural drainage networks (Parsons et al, 2008; Sukhodolov et al, 2010). Copepods are found in a wide variety of aquatic environments, ranging from the benthic, littoral, and pelagic waters of lakes and oceans, to swamps, wetlands, marshes, large rivers, and temporary ponds (Reid and Williamson, 2010 ; Suárez-Morales et al, 2020). Most are omnivorous or herbivorous, consuming foods such as detritus, pollen, bacteria, and microalgae, but some groups (especially cyclopoids) are raptorial predators on other invertebrates such as protozoa, rotifers, nematodes, insect larvae; some large copepods can attack and eat small larval fish (Reid and Williamson, 2010; Suárez-Morales, 2015). Copepoda are used as live food for the early larval stages of many kinds of fishes in aquaculture throughout the world (Barroso et al, 2015) and they considered as the main food source for several planktophagous fishes and benthic invertebrates
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