Temporal and vertical distributions of three appendicularian species (Tunicata) in Conception Bay, Newfoundland

• Published in: Journal of Plankton Research
• Main Authors: Choe, Nami, Deibel, Don
• Format: Text
• Language: English
• Published: Oxford University Press 2008
• Subjects: ORIGINAL ARTICLES; Newfoundland
• Online Access: http://plankt.oxfordjournals.org/cgi/content/short/30/9/969; https://doi.org/10.1093/plankt/fbn064

Temporal and vertical distributions of the boreal appendicularian species Oikopleura vanhoeffeni, Fritillaria borealis and O. labradoriensis were observed in Conception Bay, Newfoundland, over a 1-year period in order to determine whether they share the same environmental niche. Total abundance of the three species together peaked after the spring maximum of chlorophyll a concentration, indicating that appendicularian abundance was generally related to the biomass of phytoplankton. The seasonal peak abundance of the three species did not overlap in time. The maximum abundance of O. vanhoeffeni occurred in May and June during the spring phytoplankton bloom, that of F. borealis occurred in July and August as upper mixed layer temperature increased and salinity decreased and that of O. labradoriensis occurred in October when salinity was at its annual minimum. Vertical distribution also differed among the species. Oikopleura vanhoeffeni occurred primarily below the surface layer and remained below the thermocline in summer. The vertical distribution of F. borealis was not correlated with the observed environmental variables, whereas O. labradoriensis occurred primarily at depths of minimum salinity. Each species displayed a distinct niche based on temperature and salinity. Oikopleura vanhoeffeni was a cryophile with a stenothermal and stenohaline niche, F. borealis was eurythermic and euryhaline and O. labradoriensis inhabited a mesothermal and mesohaline niche. These results indicate physical niche separation among these three sympatric, arcto-boreal appendicularian species and provide information from which future changes in their abundance and spatial distribution can be predicted given likely climatic variation.