Read more about the Indigo V Expedition in these articles featured in the Sydney Morning Herald and the UNSW Newsroom
In the spirit of the Global Ocean Survey, and other major expeditions such as Tara Oceans,
Indigo V will leave Cape Town this May and over the course of six
months sail to Singapore, examining the microbes inhabiting some of the
most under-sampled waters on the globe. This will be an example of an
“Algal”roots oceanographic campaign, utilising inexpensive, flexible and
Proof of concept – open source, crowdsourced microbial oceanography
Oceanography has long been an extremely expensive discipline.
Oceanographic vessels generally cost in excess of $100,000 a day to
run. They are limited in their range and can only cover a few
collection points per cruise. Specialised scientific equipment only
adds to the mountainous costs. What is the best way to tackle this
‘bottleneck’ in data collection? Divide and conquer.
Thousands of private ocean going vessels are cruising around the
worlds oceans at any given time. By equipping these vessels with small
portable sampling devices, ‘fool-proof’ collection techniques and a
‘self-addressed-stamped-envelope’ to send in the samples, we will
transform the way data is collected around the worlds oceans. We aim to
prove that ‘bigger’ is not necessarily ‘better’ and the key to greater
understanding of the worlds oceans is to forge the way to easier and
cheaper data sampling methods.
Indigo V Expedition is the working prototype for this concept and is working as a blue-print for what we call ‘citizen science’. Every day there are thousands of manned vessels that cruise the
worlds oceans (see the map below) and, with the help of cruisers
world-wide we can to turn them into in situ marine microbe monitoring platforms, helping us all understand the world’s ocean in a holistic and comprehensive way.
Impact of shipping on ocean microbes.
Ships are constantly travelling the ocean, and as they sail they
leave behind traces of iron and other metals that are not always
abundant in seawater, especially in the tropics. These metals (or the
lack of them) are often limiting factors to the growth of ocean
microbes. During our leg from the Maldives to Phuket we sample in the
busiest shipping lane in the world (bright orange lines in the map
below). By comparing these samples to those taken just outside the
shipping lane we can identify how the deposition of iron impacts the
local microbial community. An recent re-analysis of data from the GOS showed
that while “the affinity of phosphate transporters is related to the
concentration of phosphate .. the occurrence of iron transporters is
connected to the amount of shipping, pollution, and iron-containing dust
(Patel et al 2010).
Diversity, distribution and activity of diazotrophs in the Indian Ocean
Nitrogen is one of the essential elements required for life, and is a key constituent of cellular proteins and nucleic acids, energy transfer compounds, photosynthetic pigments and bacterial cell walls (Karl et al., 2002). Consequently, nitrogen availability is considered a primary limiting factor for biological productivity particularly in oligotrophic marine environments (Galloway et al., 2004). Nitrogen plays a central role in ocean biogeochemistry, with nitrogen cycling believed to greatly influence the cycling of other critical elements including both carbon and phosphorous (Gruber, 2008).
Within the surface waters of the oceans N2 is the dominant form of nitrogen, and although present in abundance, the stability of the triple bond of N2 renders it unreactive and therefore biologically unavailable to marine primary producers (Karl et al., 2002). A diverse yet specific group of microorganisms (termed diazotrophs) have evolved the ability to tap in to this reservoir of dissolved N2 gas through biological nitrogen fixation. The activity of diazotrophs in oligotrophic marine environments is extremely important, providing an input of bioavailable fixed nitrogen to the oceanic nitrogen pool (Mahaffey et al., 2005).
While nitrogen fixation is predicted to be a significant process within the Indian Ocean (Luo et al., 2012) there is a severe lack of distribution and activity data for diazotrophs throughout this region. Conducting nitrogen fixation rate measurements within the Indian Ocean is of “high priority” (Luo et al., 2012) if we are to fully understand the significance of global marine nitrogen fixation. During Indigo V we will determine rates of nitrogen fixation in the surface waters of the Indian Ocean, along a transect between the Maldives and Thailand. In addition, we will determine the biogeochemical potential of microbial communities and characterise the diversity and relative abundance of diazotrophic microbes.
Indigo V provides the opportunity to undertake the most comprehensive study of nitrogen fixation activity and diazotroph community composition in the Indian Ocean to date; this will improve spatial coverage of nitrogen fixation rate measurements and diazotroph biomass in a critically under sampled region of the global ocean.
Galloway, J., Dentener, F., Capone, D., Boyer, E., Howarth, R. W.,
Seitzinger, S. P., Asner, G., et al. (2004). Nitrogen cycles: past,
present, and future. Biogeochemistry, 70, 153–226.
Gruber, N. (2008).
The marine nitrogen cycle: overview and challenges. Nitrogen in the
marine environment (pp. 1–50). Elsevier Inc.
Karl, D., Michaels, A.,
Bergman, B., Capone, D., Carpenter, E. J., Letelier, R. M., Lipschultz,
S., et al. (2002). Dinitrogen fixation in the world’s oceans.
Biogeochemistry, 57/58, 47–98.
Luo, Y.-W., Doney, S. C., Anderson, L.
a., Benavides, M., Berman-Frank, I., Bode, a., Bonnet, S., et al.
(2012). Database of diazotrophs in global ocean: abundance, biomass and
nitrogen fixation rates. Earth System Science Data, 4(1), 47–73.
C., Michaels, A. F., & Capone, D. G. (2005). The conundrum of
marine N2 fixation. American Journal of Science, 305, 546–595.
Patel PV, Gianoulis TA, Bjornson RD, Yip KY, Engelman DM, Gerstein MB
(2010) Analysis of membrane proteins in metagenomics: Networks of
correlated environmental features and protein families. Genome Biology
20 : 960-971