| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4534852 | Deep Sea Research Part I: Oceanographic Research Papers | 2011 | 12 Pages |
The influence of a thick layer of oxygen-depleted water (<0.2 ml l−1) on the abundance and distribution of chaetognaths was investigated in the northeastern Arabian Sea (NEAS), a natural oxygen-deficient system in the global ocean. The species and maturity stage-wise distribution of this group were studied at five discrete depths down to 1000 m. A total of 22 species belonging to four genera were observed, and the genus Sagitta dominated, representing 60% (500–1000 m) to 89% (Mixed layer depth) of the total chaetognath population. Based on their vertical distribution limits, four groups were recognised, as follows: I: species abundant in surface water with a maximum distribution limit up to 300 m; II: species confined mainly to deeper waters (>500 m); III: species present throughout the water column (0–1000 m); and IV: species present in most layers, but with a preference for a specific depth stratum. A positive correlation (P<0.01) was observed in the abundance of chaetognaths and their main prey copepods, emphasising the strong trophic relationship between these groups. It was found that the intensely oxygen-deficient waters of the NEAS play a crucial role in the vertical distribution and abundance of chaetognath species of all four genera. This report presents information on the maturity stages and ontogenetic migration of this important planktonic group in relation to the oxygen-depleted water in the study region for the first time. The results obtained are also important for understanding the biological processes associated with a major oxygen minimum zone (OMZ) in the global ocean.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Eastern Arabian Sea is one of the prominent oxygen deficient systems in global ocean. ► Impact of oxygen depleted water in vertical distribution of chaetognath was studied. ► Life stage information relative to OMZ is an important addition to this. ► Their vertical migration was restricted by species specific sensitivity to this water. ► Vertical distribution of the species of all 4 genera varied based on thickness of OMZ.
