Spatial distribution of fifty ornamental fish species on coral reefs in the Red Sea and Gulf of Aden

Maroof Khalaf,Mohamed Abdallah

doi:10.3897/zookeys.367.5476

Abstract

The spatial distribution of 50 ornamental fish species from shallow water habitats on coral reefs were investigated using visual census techniques, between latitudes 11−29°N in the Red Sea, in Jordan, Egypt, Saudi Arabia, and Yemen, and in the adjacent Gulf of Aden in Djibouti. One hundred eighteen transects (each 100×5 m) were examined in 29 sites (3−8 sites per country). A total of 522,523 fish individuals were counted during this survey, with mean abundance of 4428.2 ± 87.26 individual per 500 m² transect. In terms of relative abundance (RA), the most abundant species were Blue green damselfish, Chromis viridis (RA=54.4%),followed bySea goldie, Pseudanthias squamipinnis (RA= 34.7), Whitetail dascyllus, Dascyllus aruanus (RA= 2.6%), Marginate dascyllus, Dascyllus marginatus (RA= 2.0),Red Sea eightline flasher Paracheilinus octotaenia (RA=1.0),andKlunzinger’s wrasse, Thalassoma rueppellii (0.7%). The highest number of species (S) per 500 m² transect was found on reefs at the latitude 20° in Saudi Arabia (S=21.8), and the lowest number of species was found at the latitude 15° in Djibouti (S=11.11). The highest mean abundance (8565.8) was found on reefs at latitude 20° in Saudi Arabia and the lowest mean abundance (230) was found on reefs at latitude 22°, also in Saudi Arabia. Whereas, the highest Shannon-Wiener Diversity Index was found in reefs at the latitude 22° (H`=2.4) and the lowest was found in reefs at the latitude 20° (H`=0.6). This study revealed marked differences in the structure of ornamental fish assemblages with latitudinal distribution. The data support the presence of two major biogeographic groups of fishes in the Red Sea and Gulf of Aden: the southern Red Sea and Gulf of Aden group and the group in the northern and central Red Sea. Strong correlations were found between live coral cover and the number of fish species, abundance and Shannon-Wiener Diversity indices, and the strength of these correlations varied among the reefs. A conclusion was done that environmental differences among the reefs and the habitats investigated were important components of abundance variations and species diversity of ornamental fish along latitudinal gradients in the Red Sea and the Gulf of Aden.

Highlights

Coral reefs are valuable and important ecosystems
A new and updated checklist of fishes of the Red Sea has recorded a total of 1078 species belonging to 154 families (Golani and Bogorodsky 2010)
A total of 50 fish species used for aquarium trade were investigated during the present study

Summary

Introduction

Coral reefs are valuable and important ecosystems. They are among the most productive and diverse of all-natural ecosystems, and they are often called «the tropical rain forests of the sea» (Bourilere and Harmelin 1989). Coral reefs have many functions, amongst which is the provision of a variety of habitats for a wealth of organisms. Fishes are a dominant group of coral reef fauna, in terms of both their biomass and diversity. They are the most visible and important mobile component in the coral reefs (Letourneur et al 1999). Destructive fishing, over-fishing, coral bleaching, tourism development and other stresses and activities threaten these valuable ecosystems

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