Role of Ecohydrographical Barriers on the Spatio-Temporal Distribution of Chaetognath Community in the Gulf of Aqaba during Summer

Kusum Komal Karati,Reny P Devassy,Gopinath Vineetha,Ali M Al-Aidaroos,Mohsen M El-Sherbiny

doi:10.3390/w14050822

Abstract

The Gulf of Aqaba (GoA), positioned between the Sinai Peninsula and the Saudi Arabian coast is characterized by its uniquely high saline, oligotrophic waters, and seasonally stratified hydrography. Despite its geographical significance, information on its zooplankton ecology and biodiversity is still meager. Hence, the present study was aimed to investigate the detailed diversity and ecology of the dominant carnivorous zooplankton taxon chaetognath in the pelagic waters of the GoA during summer. Despite the known water flow exchange between the GoA and the Red Sea, only five chaetognath species were observed in GoA which is markedly less than the number earlier recorded in the Red Sea, indicating the role of high saline water mass as an ecophysiological boundary for the inhabitance of many epipelagic chaetognaths. Euryhaline, Serratosagitta pacifica formed the dominant species in both the surface water and the upper 200 m water column and was observed to be the most suitable representative of this high saline environment. Conspicuous diel variability in the distribution of the different growth stages of chaetognaths in the surface waters can be attributed to their varied susceptibility to visually oriented predators. The positive relation observed in the abundance of chaetognaths and their main prey, copepods, and their carbon and nitrogen contents indicated their significance in the pelagic trophic ecology of the GoA. The present study, providing the ecology of a major zooplankton taxon of this unique basin will be relevant for understanding the ecology and trophodynamics of the zooplankton community of the GoA.

Highlights

Chaetognath is a major carnivorous zooplankton taxon representing 8–27% of the zooplankton community of the Gulf of Aqaba [1]
The ecohydrography of Gulf of Aqaba (GoA) has helped in maintaining its distinct chaetognath community structure from its adjacent ocean basin, the Red Sea
Despite the limited sampling locations, the output generated from both the horizontal and vertical samplings along the diel scale at each location aided in filling the knowledge gap on the ecology of this important carnivorous zooplankton taxon of this less studied marginal sea

Summary

Introduction

Chaetognath is a major carnivorous zooplankton taxon representing 8–27% of the zooplankton community of the Gulf of Aqaba [1]. Copepods being their major prey, chaetognaths form a crucial trophic link between the primary consumers and the higher trophic levels in the pelagic realm [2–4]. The species-specific sensitivity of chaetognaths to the hydrographic attributes makes their distribution and community structure unique in the major ocean basins and their marginal seas [5,6]. Chaetognaths are known to exhibit normal diel vertical migration, which provides them with many adaptive benefits [10,11]. Along with their spatial distribution, assessment of the diel changes in their habitat is valuable for a detailed understanding of the ecology of any marine system [12,13]

Methods

Results

Discussion

Conclusion