Community structure and Spatio-Temporal Distribution of Chaetognatha near Corals Reefs on Hurghada coast, Red Sea, Egypt

A Zooplankton survey was carried out between August 2015 and July 2016 along the Egyptian Red Sea coast of Hurghada to describe the species distribution of the arrow worms, Chaetognatha, in relation to the biological and physical factors. Monthly samples were collected by plankton nets of 350 and 500µm mesh size and 100cm mouth opening from four transects along the coast for one year. The average spatial and temporal variations, as well as diversity indices, were calculated. The correlation between Chaetognatha and physical parameters from one side and the biological factors from the other side was also investigated. A total of 17 species belonging to 3 genera and 3 families of the arrow worms were identified. The total abundance of Chaetognatha was 760 individuals/L, with an average of 126 individuals/L. The highest abundance of Chaetognatha was recorded in spring with a peak in April (378). The highest number of species was found in December (16 species). The most abundant species was Sagitta neodecipinens, with an average abundance of 159 individuals/L. Chaetognatha recorded a strong negative correlation with temperature and a strong positive correlation with pH and dissolved oxygen. They had a significant positive correlation with Copepods, Hydromedusa, and Tintinnids and a negative correlation with fish larvae.