Dinoflagellates as proxy indicators of marine environmental conditions in northern and southern high latitudes

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This proposal aims at studying several aspects of dinoflagellates and their cysts at various locations and timescales. Dinogflagellates are unicellular protists that are important primary producers in the World oceans. They produce a resting cyst as part of their life cycle in response to adverse conditions. The cyst is composed of a highly resistant polymer that allows them to be preserved intact for millions of years in the sediments. Dinoflagellates are notably responsible for harmful algal blooms, or "red tides", which cause chronic illness to humans, kill fish and marine mammals and cause the loss of millions of dollars in revenue to the Canadian aquaculture industry each year. They are also famous because they are easily transported in ballast tanks of ships and colonize new environments when the ballast tanks are emptied at the ship destination, often bringing toxic red tides in new areas. Despite that, their cysts constitute excellent paleo-indicators of sea surface conditions and they are used to quantitatively reconstruct sea surface conditions of the recent geological past. Here we present 7 projects that use dinoflagellates or their cysts as the main tool. One project aims at reconstructing the evolution of sea surface conditions in the Canadian Arctic, notably with respect to sea ice and primary productivity. The reconstruction focuses on the last 2000 years in order to understand how the primary productivity has changed in the recent geological past during warmer or colder climate conditions. The project also aims at looking at cysts of potentially toxic species that may have been transported in the Arctic by oceanic currents or by ship. Another projects aims at describing two new species discovered in Arctic surface sediments. A morphological description will be done, the cysts will be assigned a formal species name and their genetic code will be sequenced to help identifying them in the future. One project deals with the cysts of a toxic species in the Port of Halifax, Nova Scotia. Genetic sequencing of the cysts will be done to verify their toxicity and see if there is potential danger of toxic red tide in the area. A short sediment core will also be studied to find out if the cysts occur in that location naturally, or if they were transported from somewhere else by ships, therefore being considered as an invasive species. A similar study will take place in the Gulf of San Jorge in Argentina. There we will look at cysts in surface sediments to estimates the risks of toxic red tides, and look at short sediment cores to find out if anyone species present was transported there or if it occurs naturally. The next project consists of a highly innovative approach to study the cysts or the motile forms, or any other marine micro-organsims. We are using micro- and nano-CT-Scans, which use X rays to produce images to visualize the dinoflagellate. To our knowledge, this is the first time that such small organisms are successfully scanned with X rays. When perfected, the technique will allow observing dinoflagellates inside and out and from every angles without touching them, or any marine organism in plankton or sediment samples without having to use chemicals to process the samples and with the same precision as the most powerful microscope. And the scans produce very cool images too! Finally we will be studying the chemical composition of dinoflagellate cysts to try and find out what they are made of and why they are so resistant. If we are successful, we should be able to replicate this composition to create ultra-resistant nanomaterials. We are also planning to use the chemical composition of the cysts to find out about the environmental conditions in which they lived, therefore documenting past climates.