back! Well, we’re in Fremantle, Western Australia. The past two weeks have
flown by, and it feels strange that now it’s all over and we’ll be heading home
to our respective cities. Meeting new friends and learning new skills, I think
I can safely say we all had an amazing experience.
I’ve been to sea before, but this was my first time learning about plankton collection, identifying different climate events from microfossils, counting different birds and mammals, understanding CTD measurements… the list goes on! CAPSTAN has been a brilliant learning experience and if you’re thinking about applying for next year, definitely do!
I decided to work in the wet/dirty sediment lab because I felt like it might complement the work I’ve been doing at university. I’ve been looking at how changes in sediment provenance influence Neodymium, an isotope usually used to track changes in past ocean circulation. A lot of the age models used are derived from oxygen isotopes in foraminifera. Since we had Stephen onboard, our foram expert from Melbourne, it seemed like the perfect opportunity to learn as much as I could. I now know the importance of a certain species for identifying the last glacial maximum in sediment cores from the Southern Ocean, how changes in size and species distribution are influenced by temperature and light!
particular mini project while at sea involved sieving samples from the top and
bottom of the cores, separating the different fractions out to see how grain
size distribution varied down the canyon we were targeting. In these samples we
found a huge variety of forams – some look like popcorn, others look like
christmas baubles, and others were perfect spheres. The variety of forms within
such a small sample gave me a huge appreciation for just how diverse life is at
a microscopic scale.
The same could be said for in the plankton lab. The tiny jellyfish, starfish, copepods and various other little critters were fascinating, it was certainly a novel experience being able to see what I’m studying for a change!
From the science to dressing up as sea creatures and trivia, we had a great time. Maddie kept us all singing with showtunes, Sian’s whale calls (which may have something to do with the lack of cetaceans – sorry Sian!), movie nights, through to the excellent food and expert crew. A trip on the RV Investigator is one to remember.
To conduct the science needed to unravel the mysteries of the ocean and its influence on ecology and climate, you need to take operations up a notch. Some may think it’s simply a matter of dangling a few instruments over the side of a boat but let me tell you…RVInvestigator is no ordinary boat!
RV Investigator is a 93.9m long, 18.8m wide ship, powered by three diesel engines and two electric propulsion motors (Figure 1). Purpose built for CSIRO, RVInvestigator puts Australia at the forefront of ocean research globally, conducting oceanography, geoscience, atmospheric and marine science, from the Antarctic ice edge to the tropics. Along with a phenomenal team of engineers, navigational crew (Figure 2), technical crew and IT professionals, the ship’s impressive technical capabilities allow us to enhance our investigations to an advanced level.
The vessel is like a mesocosm of the world! It accommodates 40 scientists and support staff, and twenty crew. RV Investigator generates around nine megawatts of power, enough electricity to power a small suburb! It even completely biodegrades all sewerage onboard, so as not to contaminate the samples. Obviously, there is no room for error here, so engineers work around the clock to maintain the workings of the ship, keeping replacements for every part of the machinery. Engineers are also equipped with a workshop to repair engine parts or scientific units on the fly.
A brief overview of RVInvestigators ‘kit’ includes advanced sonar technology which emits acoustic signals in a 30 km wide beam in water depths to 11.5 km to reveal, in 3D, seafloor features such as deep-sea canyons and mountains. We used this swath data and ArcMap (GIS) software to create a high-resolution bathymetry map of a previously unmapped, deep sea canyon we traversed (Figure 3). A drop keel underneath the ship (Figure 4) can be raised or lowered into the water column. This allows water samples to be recovered without interference from the ship.
The ship is specifically designed to an international maritime classification called DNVSilent-R. This means RV Investigator is one of the quietest vessels in the world. Radiated ship noise interferes with acoustic signals, so by building a quiet ship, the performance of the equipment used to monitor the marine ecosystem, and map the seafloor is maximised. Roll stabilization also improves our use of scientific instruments, such as microscopes and balances, which can be tricky on a moving ship.
The logistics behind the location of sample sites and each sample collection is a strategic masterpiece and one aspect of our mission I was particularly in awe of. The Chief Scientist works in close collaboration with the Technical Operations Team, Integrated Ratings Crew and Master of the ship, to design each procedure in a way that ensures the safety of the crew and their scientific instruments, to meet the research objectives and to optimise sample quality. It really is a symbiotic relationship, in that each is part of the team that is integral to the other (Figures 5,6,8).
One of my highlights of the voyage was in the operational room on the internal communication system during deployment of the CTD unit (Figure 7). It was my job to request the CTD stops required to collect water samples remotely at different depths, up to the Integrated Ratings crew (IR crew) located in the ‘Cat House’. This area is where the winch and boom are managed, and where all the ships cameras are simultaneously viewed. This gives IR crew the ability to visualise the CTD going over the side, while viewing the winches below deck as it descends. Once the unit was in position at its lowest depth (it went down to 4500m), I fired the closing of each of the 24 sample bottles on the return journey with a single mouse click.
As students of the CAPSTAN voyage, we are spoilt with the level of expertise and state-of-the-art technology provided to us. It’s been a once in a lifetime experience that I will be forever grateful for.
By Mardi McNeil, Queensland University of Technology
Every marine science voyage has a research plan and specific aims and objectives that the science party wants to achieve. Months, or sometimes (usually) years, goes into planning the voyage and targeted survey site selection in order to achieve aims, test a hypothesis, or answer questions which will fill a knowledge gap in our understanding of the marine system we are studying. This is how science works!
The science objectives for our CAPSTAN voyage have been planned out by our Chief Scientist Dr Leah Moore, and the educational objectives by our CAPSTAN Director Dr April Abbott. On this research cruise we are targeting a submarine canyon system which connects the continental shelf margin off Portland Victoria, to the Otway Basin at 5,500 m water depth in the Southern Ocean. We are literally sailing across the abyss!
Our primary geological objective is the search for a cool-water carbonate turbidites, resulting from the funnelling of sediment down the submarine canyon until it is deposited in a submarine fan at the base of the canyon. Cool-water carbonate systems are not as well studied as their sub-tropical and tropical counterparts as there are fewer places in the world where they occur, and they’re typically in deeper water.
The term “Carbonates” refers to sediment grains which are comprised of calcium carbonate minerals, commonly calcite and aragonite. Over geological time these sediments lithify to form limestone rock. Most carbonate sediments are biogenic in origin, which means they are produced by biological organisms. The classic example is a coral reef, where the soft coral polyps precipitate their hard skeletons, and coralline algae produces the calcite cement which glues it all together, resulting in hard limestone.
In a cool-water carbonate
system there are definitely no reef building corals. In southern Australia, the
main carbonate producers are bryozoans and foraminifera. Bryozoans are
colonial, meaning hundreds to thousands of tiny animals called zooids, live
together in a colony and collectively produce a hard carbonate skeleton. This
skeleton can take many forms, like delicate fan-like nets, or robust upright
Foraminifera (or just “forams”) are single celled organisms similar to an amoeba, but they secrete a calcite “test”, or shell. Foram tests come in an almost endless variety of shapes and sizes, and can be benthic (bottom dwelling) or planktic, meaning they live freely in the water column. Forams have evolved rapidly throughout geological time (hundreds of millions of years), so geologists and micropalaeontologists use foram test shapes to determine the age of the sediments we are looking at. This helps us to quickly “date” our cores in the field, where we don’t have the capacity to use isotope mass-spectroscopy analysis to determine an absolute age. One reason we want to know the age of our cores is to determine whether the sediments we’re looking at were produced during a glacial cold period, or an inter-glacial warm period like today.
On this CAPSTAN voyage we have collected three cores from different water depths within the Portland Canyon, and one from the bottom of the canyon in the fan. We hope to capture evidence of glacial-interglacial cycles, and a cool-water carbonate turbidite system.
In geological speak, a turbidite is a characteristic sedimentary deposit which forms when sediment is transported down-slope in a fluidised (watery) plume under the influence of gravity. Because different sediment grains have different densities and shapes, they settle out of suspension in a characteristic way. The most dense sediments settle first, and the lighter less dense sediments are the last to fall out of suspension. This cycle repeats over and over every time there is a gravity driven turbid flow, resulting in a characteristic cyclical pattern of deposition which we call a turbidite.
Onboard RV Investigator we have now finished our coring and are working through sampling the cores at 10 cm intervals, looking at the sediments under the microscope to see what carbonate grains we have. Our preliminary results are in, and there is some excitement coming from the Sedimentology lab! We have picked up a glacial – interglacial cycle, and managed to estimate an oldest date based on a nanno-fossil called a coccolith, which we know from the geological record was abundant from about 80,000 years ago, so we now know that our cores cannot be older than 80,000 years.
So the big heroes of the Sedimentology Lab are the tiniest carbonate grains which allow us to read our cores like a history book, and interpret biological and physical processes through geological time. And it turns out that we have indeed, found our cool-water carbonate turbidites, and glacial-interglacial cycles. Science mission accomplished!
After what seemed liked forever, and exceeded excitement on Christmas morning, we finally had sediments to explore. Over the last two days we have deployed a total of four Kasten Corers and two sediment grabs from the shallow shelf to the deep marine environment within a Submarine canyon environment.
With adrenaline kicking in, samples were prepared and while desperately waiting for samples to dry discussions where held proposing suggestive theories as to what secrets the mud will contain, consulting with the new bathymetry and causing a rave in the observations room.
Emotions were high with the excitement ongoing deployments and exploring the prepared samples and boy do we have some spectacular organisms and some outstanding structures.
My research will be looking at exploring a link to Last Glacial Maximum with shelf sediments. Without further ado, and with credit to the Ice Age, I present to you the sedimentology Mud song.
Mud, glorious mud…we’re anxious to dry it
Two cores a day, our favorite deployment!
Just picture a Turbidite, matching the
Where is Plankton City
you ask? In the mixed layer; the top most layer of the ocean surface where the water
column is largely uniform. How do I know where the mixed layer is? An amazing
instrument called a CTD.
The CTD is loaded with bottles that fill up with water at certain depths in the water column. Each bottle will fill at an individually nominated depth, allowing us to see water from all levels of the ocean. We get to sample the deep Antarctic water, the old oxygen depleted water and the nutrient rich mixed layer water all during one deployment!
Whilst sampling at the Bonney upwelling zone we were given the task of (hopefully) finding some plankton to identify, sort into size classes, and indicate biomass abundance. To do this, we used a bongo net to collect plankton from different points in the water column. These points were predetermined by analysing data from the CTD. We decided to always sample at 100m deep and one other depth depending on what we saw on the CTD profiles. We were looking for the point where the water column exhibits a sharp change in temperature and density; this is known as the mixed layer depth (bottom of the mixed layer). In basic terms, the water column goes from being mixed to more stratified the deeper you go. The mixed layer depth causes a barrier-type density difference, trapping nutrients above or below the boundary. If nutrients are brought into the mixed layer because of upwelling, the water above the mixed layer depth should be Plankton City; full of yummy nutrients allowing plankton growth.
The Bonney upwelling
zone is theoretically a ‘hotspot’ for plankton growth because of the nutrient
rich bottom water moving up the water column to the surface through a range of
mechanical processes. As we soon figured out, science and the ocean don’t care
how far you’ve come to see them; they just do their own thing. The upwelling
was not happening, in fact there was most likely downwelling occurring while we
were on site. The expected abundance of plankton was largely unknown. What
would we see? Would we see anything? Would we see lots?
The bongo net tows did not disappoint. Whilst we do not have the final results of biomass abundance or size class just yet, we do know that Plankton City is an exciting and diverse place. Each of the tow samples were passed through a sieve, separating the plankton into size classes: larger than 100 microns and smaller than 100 microns. Among the inhabitants of Plankton City were a couple of tiny juvenile squids, hundreds upon hundreds of copepods, the spiky tennis balls of the water column (otherwise known as radiolarians), a squishy sea star, and many more wild and wonderful things*. There were two specimens in particular that were voted ‘Plankton Cities Most Beautiful’; Mr Fabulous and The Sparkly Boy. This pair of bioluminescent pretty boys were the talk of the lab**. Mr Fabulous was voted Most Beautiful for his sparkling eyes; eyes that would make Mrs Fabulous swoon. The Sparkly Boy took this one step further, showing off his sparkles all over his body.
While on site we were
only able to do a handful of bongo net tows. We were able to see some pretty
amazing stuff from such a tiny sample size. Can you imagine what else we could
find down there? I don’t know about you, but Plankton City is certainly
somewhere I want to visit again.
*No squid, sea stars or sparkly boys were harmed in the making of this blog (we let them go back to Plankton City).
By Jessica Bolin, University of the Sunshine Coast
Time is flying by – it’s day six of CAPSTAN Voyage #2, and we’ve now had the chance to explore different fields of oceanographic research during our group rotations: hydrochemistry, birds and mammals, plankton, geophysics, and sedimentology. Because we all have diverse backgrounds and areas of research, we’ve started to decide what our favourite stations are. My favourite, so far, is hydrochemistry, because we get to work with the CTD!
stands for conductivity, temperature, and depth, and is one of the main pieces
of scientific equipment that oceanographers use, because it measures changes in
water properties throughout the water column. The CTD we’re using on board the RV Investigator holds 36 ‘Niskin’
bottles in a circular rosette frame, which is lowered from a huge boom on the
starboard side of the ship, into the depths below. Upon deployment, each
bottle’s plug is held open under tension by a spring-loaded metal hook. It’s an
impressive piece of gear – the frame is taller than me (1.8 m), and each bottle
can hold up to 12 L of seawater.
target site is a submarine canyon near Portland, Victoria, and we’re dropping
the CTD at various sections along the canyon to further understand the circulation
and other physical processes occurring within. As the CTD descends through the
water column, sensors attached to the bottom of the frame sample the water’s
properties, including temperature, oxygen, and conductivity; the latter which
is used to calculate salinity. The data are pinged back to the ship’s operations
room, where we all watch the vertical profiles of these parameters developing
the CTD has nearly reached the bottom and starts ascending to the surface, each
bottle is remotely ‘fired’ by an observer in the operations room at regular depth
intervals. ‘Firing’ a bottle relays a signal to the CTD to release the hook on
the target bottle’s plug, closing the bottle and trapping the water at that
depth inside. After we have fired every bottle, the CTD is carefully retrieved
by the crew and prepped for subsampling on deck… and the real fun begins!
each bottle, we’ll take three subsamples of water for further testing: one to
test for nutrients, one for salinity, and one for dissolved oxygen, whilst also
recording water temperature. From these subsamples, we can calculate the
density of the seawater, which is a primary driving force for major ocean
currents. It blows my mind to think that the water we’re working with has come
from up to 2200 m within a submarine canyon, which in turn, has travelled along
ocean currents all over the world!
It is safe to say that I’ve developed a new-found love for physical oceanography and all things ocean currents. The ocean is inherently dynamic, and constantly changes in real-time. Teasing apart the mechanisms underpinning the circulation within our site is both challenging and fascinating. Once we start processing and analysing our data, we’ll hopefully be able to pick up the signature of the Flinders Current that flows west along the Great Australian Bight, and perhaps internal waves from within the canyon. Also, with a bit of luck, *fingers crossed* we can pick up the signature of a deep-water ocean current, that Veronica Tamsitt – our token physical oceanographer on board – recently discovered in the Bight, and collect some much needed data to ground-truth the current’s existence. In short, we are discovering SUPER exciting stuff this voyage, so stay tuned!
For many of us this is our first long voyage at sea, and our first time aboard a research vessel. After arriving onboard on Sunday afternoon, and spending a pleasant and rather relaxed evening, unpacking and getting settled in on the ship, we ventured off on Monday morning. We woke early hoping to hear the sounds of the ship’s emergency siren, but not because we wish to sink in the Derwent River before we have left, but because it is a sign of our time starting on the ship, and one of the many safety inductions we would have ahead of us.
One of the many things on the ship that we all had to get used to, now that we are on board, is finding our way around! The doors, passageways and staircases all begin to look the same, and it can be rather easy to get lost! One area that people always know the location of is the dining mess area, (but this could just be because of the amazing food and ice-cream fridge!) and the lounge area, which is always nice to relax in when there is some downtime. We have currently started our 12-hour shift rotations, where half of the student cohort is working from 2am-2pm, and the other half 2pm-2am. For some it was a great shock to the body clock, and for others it fitted in well with the poor sleep patterns of young academics!
We sometimes still get a bit lost on our way to the labs, but we sure won’t in the next few days! We are currently on our way to our first station, or data collection point. Until we reach this point we are having safety demonstrations, tours around the ship and labs, and starting our shifts. Once we arrive onsite at 700 am, data collection will begin, and not only will the labs become full with rich data to observe and understand, but also our brains will become very full from the next 24-48 hours of data heavy work!
In trying to get a hang of my sea legs, I’ve been exploring the ship trying to find the lesser known areas (that aren’t off limits!) and discover more of what is onboard. Although we haven’t been able to view land for a large majority of the time we have been at sea, it hasn’t been a scary or isolating feeling. This could be due to the ship being approximately 100 metres long and feeling like its own city out on the sea.
From the moment we left Hobart, the ship
has been collecting bathymetry data and mapping the seafloor, which is very
exciting as only 5% of the total seafloor has been mapped!
As the sun rose on Wednesday morning, it was the beginning of an exciting day ahead (and a sleep in for some), as it was day one of two of operations. Operation days are the times in which we deploy equipment into the ocean. This equipment includes:
CTD (a device that measures conductivity, temperature and depth of the ocean, as well as collecting seawater samples)
Before getting to station and while we have been acclimatising to ship life, we have been decorating Styrofoam cups to send down with the CTD, so we can have a hard analogue of the amount of pressure in the ocean. The cups were placed in an onion bag and sent down at the first station, attached to the CTD. With a smile and a swipe of a sharpie, they were on their way to 1700 m below sea level.
The rest of Wednesday was a packed day, where we had our first sediment core (from 1700 m) arrive into the lab, and analysis began! We took the time to carefully log the core, drawing and writing comments about what we saw in the mud/sediment before we began to sample it. Wednesday evening lead into the deployment of the Smith Mac grab, just as the sun was setting over the sea, and seals were millings around the ship. Before we knew it, the popcorn and beanbags were out to view the live stream video from the camera that was placed down into the ocean.
Ending the day in the operations lab, seeing the seafloor bathymetry progress, the promise of a new exciting day of science lies ahead!