have worked with Dr. Oliver Wurl before during Jocara Indian Ocean Quest,
taking air samples around the Indian Ocean for the study of persistant
organic pollutants (or
POPs). If you want to read more about this research and see the resulting
this voyage we are again working with Oliver, who now works for the Singapore-Delft
Water Alliance (SDWA) at the National University of Singapore. We will
collect water samples to study gel particles in the ocean.
are gel particles?
the deep ocean, marine snow is a continuous fall down of dead organisms
or their fragments, and faecal material from the upper layers of the
water column. Marine snow provides food to organisms habiting the deep
ocean, which is poor on own food sources.
The origin of marine snow lies in activities of algae within the productive
upper surface waters of the ocean. Consequently, the prevalence of marine
snow changes with seasonal fluctuations of the abundance of algae and
ocean currents. Thus marine snow is heavier in spring, and the reproductive
cycles of some deep-sea animals are synchronized to take advantage of
The clump- or string-like "snowflakes" are aggregates of dead
organism and faecal materials held together by a sugary mucus, transparent
exopolymer particles (TEPs). The sticky gel-like TEPs act like glue
among the other particles enhancing the formation of aggregations heavy
enough to sink into the darkness of the ocean. Natural sugar compounds
exuded as waste products by bacteria and algae are the original material
for the formation of TEP. TEPs are the most abundant form of marine
the box below is a write-up of the research project.
Particles in the Ocean
exopolymer particles (TEPs) are the most ubiquitous and abundant
gel particles in the oceans. TEPs are mainly formed by coagulation
of dissolved carbohydrates, which are released by phytoplankton
communities. Due to their surface-active nature and stickiness,
TEPs exhibit the characteristics of gel-particles. They have an
essential impact on the formation of aggregates as microhabitats
colonized by bacteria, which find rich substrates in the otherwise
poor water column (Fig.1). Therefore TEPs play a significant role
in the biogeochemical cycling of elements, such as nutrients and
trace metals. Their high abundance and stickiness enhance and even
facilitate the aggregation of solid, non-sticky particles and promote
therefore the sedimentation rate of particles. Due to the high carbon
content of TEPs, such sinking aggregates accelerate the carbon export
to the deep ocean and have an important role in the marine carbon
cycle and carbon sequestration. However recent studies suggested
that high TEP contents in diatom aggregates can lead to upward flux
through their buoyancy and can act as a vehicle in transporting
particle-reactive chemicals towards the surface of the ocean.
In this research project, water samples are collected during Jocara's
voyage to New Zealand and analyzed on TEP, carbohydrates and chlorophyll-a,
a proxy for the abundance of phytoplankton. TEPs collected on membrane
filters are stained with a blue dye to make them visible (Fig.1),
which is then dissolved in acid for quantitative colorimetric analysis.
The samples are drawn from Jocara’s modified seawater water
intake in the hull. The data will be used to further optimize a
mathematical model to estimate the production rates of TEP in the
oceans. The model consist data from different regions of the world,
but the data collected during Jocara's voyage are of particular
importance as oceanic data are rare, but essential for the verification
of the model. With the model, scientists may improve estimations
of the particle fluxes down to the deep ocean and therefore the
extent of carbon sequestration in sediments.
Figure 1: Stained TEPs and aggregations with solid particles
will be collecting 18 water samples along the route. On the map below
you can see the sample sites.