Abundance, vertical distribution and feeding of chaetognaths in the upper 50 m layer of the eastern Aegean Sea

Abstract

The present study presents data on the abundance, vertical distribution and feeding of chaetognaths found in the 0–50 m column in a neritic area of the eastern Aegean Sea during July 2004. The abundance of total chaetognaths ranged between 7.76 and 35.92 ind m⁻³. The highest values were recorded in the uppermost 20 m and values decreased with depth. The chaetognath community comprised nine species with Sagitta enflata, Sagitta minima, Sagitta serratodentata and Sagitta setosa being numerically the most important. Copepods were the main prey for most chaetognath species, while S. minima showed a higher preference for cladocerans. An evident relation between the presence of food of chaetognaths and their horizontal and vertical distribution in the area of study was found. In the surface 0–50 m of this typical oligotrophic area of the eastern Mediterranean, the chaetognath species occupied different depth strata possibly in order to reduce the interspecific competition.

Keywords:

• chaetognaths
• abundance
• vertical distribution
• feeding
• Aegean Sea
• Mediterranean

Acknowledgements

We wish to thank the organization “Archipelagos” and also the captain and the crew of R/V “Penelope” for their help in the collection of the samples.