Dinoflagellates

Event Date: 
Wednesday, July 29, 2015 - 18:15 - 18:30
Institution: 
Australian Institute of Marine Sciences
Title: 

Coral Reefs Go Viral: Unveiling the viruses associated with corals in a changing climate.

Abstract: 

Viruses are the most common biological agents in the global oceans, with numbers typically averaging ten billion per litre. The ability of viruses to infect all organisms indicates they most likely play a central role in marine ecosystems and have important consequences for the entire marine food web. Marine viruses influence many biogeochemical and ecological processes, including energy and nutrient cycling, host distribution and abundance, and horizontal gene transfer events. Research into viruses associated with coral reefs is a newly emerging field. Corals form an obligate symbiotic relationship with the dinoflagellate genus Symbiodinium, upon which the coral relies heavily for nutrition and calcification. Disruption of this symbiosis can lead to loss of the symbiotic algae from their host, resulting in coral bleaching and, if the symbiosis cannot re-establish, death of the coral colony. While a number of factors, including elevated reactive oxygen species production by Symbiodinium have been linked to coral bleaching, viral infection has not been methodically examined as a possible cause. Viruses that potentially target the algal symbiont, Symbiodinium sp., have been reported previously; therefore, we examined whether Symbiodinium in culture is host to a virus that switches to a lytic infection under stress, such as UV exposure or elevated temperature. Analysis of algal cultures, using techniques including flow cytometry and transmission electron microscopy, revealed prevalent viral activity, regardless of experimental conditions. This talk will present recent results and results allow for the development of molecular diagnostic probes for rapid detection of viruses in field samples, and will help monitor and assess the role of viruses in coral bleaching and holobiont functioning.

Event Date: 
Wednesday, March 27, 2013 - 19:15 - 20:00
Institution: 
Alfred Wegener Instute for Polar and Marine Research
Title: 

Alexandrium: Evolutionary and ecological insights into the most prominent toxigenic dinoflagellate

Abstract: 

Dinoflagellates are a major cause of harmful algal blooms, with consequences for coastal marine ecosystem functioning and services.  Representatives of Alexandrium tamarense species complex are of the most abundant and widespread toxigenic species, and produces paralytic shellfish poisoning toxins as well as allelochemical substances.  This species complex consists of four to five species. The debate of the separation of this complex into real species in long on going and here a concept for the divorce of this group will be proposed.  Problems with identification of a toxic member of this species complex in November 2012, which led to the accidental export of toxic mussels to Japan, has now led to severe restrictions on Australian shellfish exports to Japan for a year, and resulting losses of many million $. Furthermore, population genetic insight and adaptive strategies in species interaction processes will be presented. Allelochemical mediated intra-population facilitation, may explain at least partly the high genotypic and phenotypic diversity of Alexandrium populations. Consequently, multiple traits within a population potentially allow mutual facilitation, and may promote the success of microbial planktonic populations.

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