Arctic Diatoms - Diversity, Plankton Interactions and Poulation Dynamics

• Main Author: Tammilehto, Anna
• Format: Book
• Language: English
• Published: Natural History Museum of Denmark, Faculty of Science, University of Copenhagen 2015
• Subjects: Arctic; Greenland; Calanus finmarchicus; Climate change; Disko Bay; Phytoplankton
• Online Access: https://curis.ku.dk/portal/da/publications/arctic-diatoms--diversity-plankton-interactions-and-poulation-dynamics(9cbf5f0a-a8e0-48bf-b5a4-a7faabecee58).html; https://soeg.kb.dk/permalink/45KBDK_KGL/fbp0ps/alma99122611018305763

Oceans produce nearly half of the global net primary production annually. Most productive marine areas are found along coasts and, contrary to the terrestrial ecosystems, at high latitudes. In these areas most primary production is done by phytoplankton. In the Arctic, phytoplankton communities are often dominated by diatoms. They are single-celled, eukaryotic algae, which play an essential role in ocean carbon and silica cycles. Many species of the diatom genus Pseudo-nitzschia Peragallo produce a neurotoxin, domoic acid (DA), which can be transferred to higher levels in food webs causing amnesic shellfish poisoning (ASP). This thesis showed that three most abundant mesozooplankton species (Calanus finmarchicus, C. glacialis and C. hyperboreus and copepodite stages C3 and C4) in the study area (Disko Bay, western Greenland) feed upon toxic P. seriata and retain the toxin, and may therefore act as vectors for DA to higher levels in the arctic marine food web, posing a possible risk also to humans. DA production in P. seriata was, for the first time, found to be induced by chemical cues from C. finmarchicus, C. hyperboreus and copepodite stages C3 and C4, suggesting that DA may be related to defense against grazing. This thesis also quantified population genetic composition and changes of the diatom Fragilariopsis cylindrus spring bloom using microsatellite markers. Diatom-dominated spring blooms in the Arctic are the key event of the year, providing the food web with fundamental pulses of organic carbon. The bloom population of F. cylindrus was genetically highly diverse and the diversity was maintained throughout the bloom. Yet, initially the bloom was significantly different from the later bloom, and differentiation was relaxed during the bloom, indicating isolation by time. The results suggest that blooming behavior may be beneficial for F. cylindrus. High genetic diversity found in F. cylindrus coupled with high ecophysiological variability (i.e. variation among the strains and phenotypic plasticity) with regard to projected increase in temperature and decrease in pH due to climate change suggests that F. cylindrus has the ability to acclimate and adapt to these future changes.