Appendicularia (Tunicata) in an Antarctic Glacial Fjord–Chaotic Fjordic Structure Community or Good Indicators of Oceanic Water Masses?

Anna Panasiuk,Marcin Kalarus

doi:10.3390/d13120675

Abstract

Appendicularians are important but remain poorly studied groups of zooplankton in polar regions. The present research is based on samples collected in Admiralty Bay (King George Island) during a year-long period. Six larvacean species were noted, among which Fritillaria borealis and Oikopleura gaussica were found to be the most numerous, while the other species were relatively rare. Fritillaria borealis was a dominant part of the late summer (warm water) community, while O. gaussica had the highest presence in the winter (cold water) community. The abundance of appendicularians recorded in the bay was less numerous than that described by other authors. The most important factors influencing annual changes in the larvaceans in the bay was season, but only in the case of the two species. These facts were probably linked to the very dynamic changes in the abiotic conditions in the fjord, and the influx of specific masses of water.

Highlights

Appendicularians in some marine regions can be considered as one of the most important groups of epipelagic mesozooplankton immediately after copepods [1,2]
Appendicularians are a very important component of the mesozooplankton, they play an important role in the production of “sea snow”, and they can be an important link in the vertical carbon flux [59]
Larvaceans can play a crucial role in the diet of copepods, fish or jellyfish [60]

Summary

Introduction

Appendicularians in some marine regions can be considered as one of the most important groups of epipelagic mesozooplankton immediately after copepods [1,2] They play a different role in the marine food web [3], being an important group of marine pelagic filter feeders, especially in regard to very small organic particles [4,5]. Larvaceans are not well studied by using in situ collection methods, e.g., plankton nets or bottles [14] This is mainly due to their patchy distribution [15] and fragility, which makes them very difficult to identify [14,16] and leads to underestimations of their abundance and biomass [17,18]. Daponte and Esnal [21] validated the Antarctic species of the “Oikopleura gaussica group” in the regions near South Georgia and in the Bellingshausen

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Conclusion