English

Hanaa Hussein Mohammed,Malik Hassan Ali

doi:10.26842/binhm.7.2020.16.1.0083

English

Hanaa Hussein Mohammed, Malik Hassan Ali

Open Access

https://doi.org/10.26842/binhm.7.2020.16.1.0083

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Abstract

The aim of this paper is to present the first record of ctenophore species Pleurobrachia pileus (O. F. Muller, 1776) in the coral reef as was recently found in Iraqi marine waters. The specimens were collected from two sites, the first was in Khor Abdullah during May 2015, and the second site was located in the pelagic water of the coral reef area, near the Al-Basrah deep sea crude oil marine loading terminal. Three samples were collected at this site during May 2015, February and March 2018 which showed that P. pileus were present at a densities of 3.0, 2.2 and 0.55 ind./ m3 respectively. The species can affect on the abundance of other zooplankton community through predation. The results of examining the stomach contents revealed that they are important zooplanktivorous species; their diets comprised large number of zooplankton as well as egg and fish larvae. The calanoid copepods formed the highest percentage of the diet, reaching 47%, followed by cyclopoid copepods 30%, and then the fish larvae formed 20% of the diet. The current investigation showed that the density of zooplankton decreased significantly in the second site of all the groups, but the highest was in Calanoida group (324 ind./ m3) coincident with the presence of noticeable numbers of P. pileus (0.55-3.0 ind./ m3), in the same site compared to the density of Calanoida in the first site, which amounted to 991ind./ m3; as well, the increase was noticeable in relation to the rest of the other groups of zooplankton during the same period; such a state confirms the effect of predation by P. pileus on the zooplankton community. The study recommended that more attention should be given to investigate this group of zooplankton, and specific care should be exerted in preserving the specimens collected from the sea.

Highlights

Scientific reports have indicated the increase of the abundances and the instances blooms of the planktonic Ctenophores and the Hydromedusae in the marine ecosystems, especially in the enclosed seas and the semi-enclosed seas (Baltic Sea, Gulf of Mexico and Mediterranean sea) (Xian et al, 2005; Lynam et al, 2006; Ford and Link, 2014; Dehghan et al, 2017)
The expanding of this macrozooplankton is attributed to the combined impacts of many factors mainly, the climate change, eutrophication and overfishing (Fraser, 1970; Ford and Link, 2014). Their role in the food regime of the marine coastal waters became more understandable and noticeable throughout the results of many studies focusing on their role in the food chains in the marine ecosystems (Lynam et al, 2006; Pitt et al, 2008; Dehghan et al, 2017)
The aim of this study is to present the first record of this species in the unique coral reef (Palinurus Rock) which was recently discovered in 2012 in the Iraqi coastal waters (Pohl et al, 2014; Ahmed and Ali, 2017; Ali et al, 2017; Gutekunst et al, 2018) and lay light on its role in the ecosystem

Summary

Introduction

Scientific reports have indicated the increase of the abundances and the instances blooms of the planktonic Ctenophores and the Hydromedusae in the marine ecosystems, especially in the enclosed seas and the semi-enclosed seas (Baltic Sea, Gulf of Mexico and Mediterranean sea) (Xian et al, 2005; Lynam et al, 2006; Ford and Link, 2014; Dehghan et al, 2017). These comb jelly fish are made a preferred prey to many known predators such as other Ctenophora, fishes ( some commercial species such as Sunfish and Shads), whales and turtles (Purcell and Arai, 2001; Duryanabard, 2004; Pitt et al, 2008)

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