Abstract
SUMMARY: Six chaetognath species were determined, all for the first time, in the inner waters between Reloncavi Fjord and Boca del Guafo, Chile. Sagitta tasmanica (85.3%) and Eukrohnia hamata (5.8%) were dominant. Sagitta minima was collected for the first time in the southern channel and fjord region. The largest chaetognath aggregations were found around the Desertores Islands, which create a geographic barrier between two microbasins (north and south) with different oceanographic characteristics. S. decipiens was distributed mostly in the surface layer (0-50 m), whereas E. hamata, S. chilensis, S. minima, and S. enflata were found in deeper waters (50-200 m). The vertical distribution of S. tasmanica was homogeneous; mature, egg-carrying individuals were found at greater depths than those without eggs.
Highlights
Chaetognaths, one of the most important and abundant zooplankton groups in the oceans, typically form dense aggregations in coastal zones (Casanova, 1999)
Chaetognaths exercise heavy selective predation on copepods; 10-30% of the copepod biomass is estimated to be transferred to chaetognaths (Alvariño, 1985; Stuart and Verheye, 1991)
Surface temperatures fluctuated between 11.5 and 13.7oC. They were higher in Reloncaví Gulf and Boca del Guafo and lower in Corcovado Gulf
Summary
Chaetognaths, one of the most important and abundant zooplankton groups in the oceans, typically form dense aggregations in coastal zones (Casanova, 1999). Chaetognaths play an important role in pelagic trophic levels. Preyed on mainly by fish, they are intermediaries for the energy flow between the lower and higher trophic levels (Bone et al, 1991). As their predatory impact depends on their abundance and on their biodiversity, the chaetognath species composition must be determined in order to understand their real
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