THE SEASONAL SUCCESSION OF APPENDICULARIANS (TUNICATA, APPENDICULARIA) OFF PLYMOUTH

Earlier descriptions showed that the community of appendicularians off the British coast was mainly composed of Oikopleura dioica (Appendicu laria; Muller, 1846) and Fritillaria borealis (Appendicularia; Lohmann , 1896), rarely by Oikopleura fusiformis (Appendicularia; Fol, 1872) a nd Fritillaria pellucida (Appendicularia; Quoy & Gaimard, 1833) and ex ceptionally by Oikopleura longicauda (Appendicularia; Vogt, 1854). Bas ed on weekly samples collected during 1989 at a single station off the coast of Plymouth, we describe the first complete seasonal cycle of a ppendicularians in this area. The results suggest that rather than bei ng occasional visitors, O. fusiformis, F. pellucida and O. longicauda are consistently present and abundant from mid to late summer. Moreove r, the seasonal shifts in structure of the community of appendicularia ns in the area, as depicted by multivariate analysis, are consistent w ith those of the more southerly central Cantabrian coast (Spain). This suggests that they are viable populations rather than occasional expa triates from other areas.