Physical oceanography

Event Date: 
Wednesday, May 27, 2015 - 18:15 - 18:30
Institution: 
University of Western Sydney & Macquarie University
Title: 

Structure, diel functional cycling and viral ecological filtering in the microbiome of a pristine coral atoll in the Indian Ocean

Abstract: 

Given the role of microbes as both indicators and drivers of ecosystem health, establishing baselines in pristine environments is crucial to predicting the response of marine habitats to environmental change.  Here we describe a survey of microbial community composition and metatranscriptomic gene expression across the Indian Ocean, encompassing the first samples from the pristine Salomon Atoll in the Chagos Archipeligo.  We observed strong patterns in beta-diversty  which reflected  Longhurst biogeographical  provinces established  using primary productivity and thermohaline properties of ocean currents.  Samples from within Salomon Atoll showed a highly unique community which was remarkably different even from adjacent samples despite constant water exchange.  This pattern was driven by the dominance of the photosynthetic cyanobacterium Synechococcus within the lagoon, the diel activity of which was responsible for driving shifts in the transcriptional profile of samples.  Inside the lagoon, increases in the expression of genes related to photosynthesis and nutrient cycling associated with the bottom-up control of bacterial populations, however the expression of viral proteins increased five-fold within the lagoon during the day, indicating a concomitant top-down control of bacterial dynamics byphage.  Indeed, genome recruitment against Synechococcus reference genomes suggested  viruses  provide  an  ecological filter for determining the diversity patterns in this system. This study also represented a proof of concept for  using a ‘citizen oceanography’ approach utilzing tools that may easily be adapted to deployment on any ocean going yacht, greatly expanding the scale and outreach of marine microbiology studies. 
 

Event Date: 
Wednesday, February 29, 2012 - 15:15 - 15:45
Institution: 
CSIRO Tasmania
Title: 

Towards a biological Argo float.

Abstract: 

Humans have long known about the physical attributes of the ocean – waves, tides, currents and temperatures. Since the 1800’s, deliberate measurements of depth, temperature and velocity have helped to build a low- resolution picture of the dynamic ocean. Argo is an international, collaborative program started in 2000 in which 3000 depth-profiling floats are deployed worldwide. These floats surface routinely and transmit salinity, temperature and depth data via satellite to data handling stations from where it is available to the global research community within 24 hours. Argo data have revolutionised physical oceanography and climate science.

Marine microbial ecology, in particular, how microbial community composition interacts with biogeochemical function in the ocean, is at the low-resolution phase of its history. With deep sequencing, we have the ability to take individual high-resolution samples but we do not yet have the global coverage required to make the connections between the bio and the geochemical.

We have a long-term goal of developing the microbiological equivalent of the Argo float. This requires a lot of hardware and “software” development. Hardware that can automatically sample, filter and process seawater and “software”, the genomic-based assays of microbial community structure that can be automated and miniaturised to work within the hardware. I will describe the development and rationale behind some of our array-based assays that might satisfy these criteria.

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