Seasonal abundance of parasitic Marine Alveolate Group II (MALV II) in an Arctic fjord, Svalbard

Abstract

During the last decade, knowledge has been building of the parasitic dinoflagellate group Marine Alveolate Group II (MALV II, within Syndiniales). While environmental cloning and sequencing approaches have indicated a high abundance of MALV II throughout the world’s oceans, relatively little is known about their seasonality and the significance of their role in the marine ecosystem. No studies to date have addressed either of these issues in Arctic waters. In this thesis, the relative abundance of MALV II rDNA was studied in Adventfjorden, Svalbard during spring 2012. Specific PCR primers were designed to the MALV II 18S V4 region and TaqMan PCR was used to quantify the relative abundances of MALV II 18S rDNA. 18S copy numbers rose from 400,000 – 500,000 copies / mL in February to a maximum of ~ 900,000 copies / mL in April, before a sudden crash to below 100,000 copies / mL after April 19th from which the population did not recover. The oceanographic conditions within Adventfjorden over the season explained the MALV II abundance pattern. Atlantic water incurred into the fjord immediately prior to the study and was replaced with Arctic water around April 19th. The MALV II populations detected in this study were probably transported into the fjord on the Atlantic currents. Attempts to determine a host species by comparing to phytoplankton and zooplankton abundances were unsuccessful. Further studies are required to investigate seasonality amongst MALV II in more Arctic water dominated systems and to determine host species.