Although it would be hard to imagine, you couldn’t have seen a more excited group of adults than when a three-metre rectangular block of muddy sediment was pulled onto the ship. This surreal moment is when you realise you’ve fallen into the rabbit hole and entered a whole new world; the world of a sedimentologist.
This block of muddy sediment is a sediment core taken from
the bottom of the ocean and reveals a whole plethora of wonderful and strange
stories from Earth’s history. These stories relate to how our planet’s
environment, climate, and ocean currents have changed over time. What is truly
amazing is that we know so much about the long and dramatic history of our
planet despite the fact that we have not been part of that history for very
long. This amazement is humbling and is a reminder of the capabilities of the
human race, and the responsibilities we have as stewards of the planet.
Once the core is brought into the lab there is a flurry of activity to open the metal casing, which holds the sediment core, and to see what strange and mysterious tales from the ocean depths have been brought to the surface. With the casing removed heads are bent over to observe the colour, structure and composition of the sediments. Quick, sharp remarks are exchanged between the various parties involved before the processing of the core is started without delay. First, the core is logged which involves documenting the major characteristics of the core. This is important because these observations will underpin the majority of the interpretations which brings the whole story together. From here smear slides and small sediment samples are taken along the core to examine the changes which occur from top to bottom.
Hours will be spent analysing these slides and samples, with more sampling done along areas of interest until the sediment core looks less than pristine. Not to worry however since before the sediment core was scooped, poked and prodded an archive core was taken and stored in the fridge. This archive core is kept with all its structures and features intact as an original record for safekeeping.
There is a certain amount of chaos and untidiness in the lab which may be disconcerting to the casual viewer, but there is a method to the madness with great care being taken to systematically record and sample the sediment core. Furthermore, there are efforts to limit contamination across the core (i.e. avoid mixing sediment from one area of the core to another). In fact, it is quite liberating to be able to conduct science in a lab where things are more practical, and improvisation is encouraged. A day in a life of a sedimentologist will surely shake up the perception of the typical scientist in a lab coat conducting experiments in a clean and well organised laboratory.
It was somewhere between popping my first sea-sickness tablet and putting on the hi-vis vest to step on to RV Investigator that it finally sunk in – I was about to spend two weeks sailing across the Southern Ocean on a world-class research vessel. It was simultaneously daunting and indescribably exciting to be spending time on a ship managed by the CSIRO and Marine National Facility, sailing with leading experts from different fields of environmental science.
One of the main reasons I applied to CAPSTAN was to get a better understanding of how research vessels function at sea, and to help short circuit the “need job to get experience, need experience to get job” cycle. This experience was jump-started as soon as we switched to ship’s power and began steaming out of the harbour. We dived head-first into preparations for when we arrived on site, labelling sample bags for the sediment cores, prepping petri dishes for the plankton counts, and familiarising ourselves with the OPS room. This period was made that bit more challenging by the waves of tiredness brought on by the sea sickness tablets we were all taking, and the harsh discovery that my coffee addiction was making me seasick! But these little hurdles were promptly forgotten as we arrived on site at the canyons – where it was all systems go. Observing how the infinitely capable chief scientist Leah Moore made the big calls that shaped the rest of the fieldwork (and ultimately the data that we’d get from the trip) as new information came to light that affected our field plans, has given me more confidence to back my own opinions when making informed decisions in my PhD fieldwork.
The following two days operating around the clock sending CTDs (Conductivity, Temperature, and Depth water sampling device), Kasten Corers, and Bongo-net plankton tows down into the ocean’s depths was a stand-out period of the trip for me. The mentors’ passion for their chosen subject area was infectious and made learning new advanced techniques from foreign fields a breeze. Coming from a marine ecology background and seeing the excitement on everyone’s faces (…and hearing them spontaneously break into Christmas Carols) as they unpacked the second core taken from 2200 m that contained turbidites was fantastic – it was impossible not to get caught up in the flurry of excitement as well. Equally, it was awesome to share the trip’s cool biological discoveries with the geologists, and build the interdisciplinary understanding of the system we were working on as a collective.
Aside from the (literally) ground-breaking science we were conducting, I really couldn’t have asked for a better team of students and trainers to sail with. From the first night playing Rummy-O in Hobart, to venturing out at sunset to wave hello to our friends and family back home on the live feed camera, to high-intensity games of around-the-world-ping-pong, these guys have kept me smiling from ear to ear for the past 12 days!
The number of accomplished female scientists on board the ship has also been very inspiring. Chief Scientist Leah, quantitative ecologist Alice, microbiologist Lisa, oceanographer Veronica, and geochemist April, have all been great role models and mentors to me whilst at sea. Their amazing knowledge and skillsets, resilience, strength, senses of humour, unwavering positive attitudes and willingness to help at all hours of the day and night are just some of the attributes I hope to learn from them, and encompass in my future career too.
After the two-day whirlwind of being on station passed, we got stuck into analysis and writing as we steamed towards Fremantle and returned to a more regular schedule (I’ve never been happier to wake up at 5:30am!). Seminars and skill development workshops have continued, as well as the odd tour or two. However, even after a number of tours of the restricted zones of the ship, it maintains a feeling of discovery in the air. Whether that might be for finding another hidden gem like this little buddha painted somewhere secret on the ship, mapping an unnamed seamount, or identifying an unknown hotspot of biological activity, only time will tell.
Now onto planning my next seafaring research voyage!
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.
Today is the last day of the CAPSTAN research voyage IN2019_T01. My excitement is palpable as CAPSTAN has surpassed my expectations. The training provided in multidisciplines ranging from geology, geophysics, oceanography and microbiology will definitely act as a milestone for stepping into a future marine scientist. Time passes so quickly, I spent almost 12 days in the ocean and during these days I observed nature very closely, clear water, blue sky, sea birds and micro organisms with in the ocean.
This year’s training cruise was targeted on the canyon system on the eastern edge of the Bight Basin, near the outer continental shelf just southeast of Portland, Victoria. This region is unique due to the presence of cool water carbonate turbidite deposits. Such carbonate systems can only be formed with minimal terrestrial input. I was enthusiastic to see these carbonate systems as my masters research project is also related to the carbonates but they are formed in warm and temperate environment.
Carbonate involves limestone and dolomite (rocks) that consists of mineral calcium carbonate (CaCo3) and dolomite CaMg(Co3)2 respectively. The organisms that live with in the water are zooplanktons (animals) and phytoplanktons (plants). They are made up of calcium carbonate and after their death they accumulated with in the water and after cementation and compaction, limestone is formed. It is important to understand carbonates because they can tell us about sea level changes, paleoceanography, paleoclimates, and marine ecosystems. They also holds around 50% of the oil and gas reserves.
A submarine canyon is a steep sided valley that extends from continental shelf to the sea bed. The turbidity currents carry material from the continental shelf passes through the canyon with an immense speed and may deposited with in the canyon and deep ocean floor. There can be many driving forces behind these turbidity deposits. These can be triggered by earthquake, gravity flows and tectonic forces. Due to density contrast between the sediments, the coarser ones will deposit first and finer will remain in suspension and deposited at the end.
Our chief scientist, Dr. Leah Moore selected specific depths for coring after looking at the bathymetry (geophysical) data. The bathymetry data uses acoustic (sound) waves to determine the geomorphological features of the ocean floor. The RV Investigator is equipped with the Kongsberg EM122 multibeam echosounders to retrieve high quality bathymetry maps. The cores were retrieved at 1700m, 2200m, 3700m and 4700m depths. I was working in the sedimentology lab to find out the variations in percentage of the fossils present in the top and bottom of each core. I was exposed to using the microscope to identify different foraminifera.
Another exciting thing was CTD as it was new for me. CTD stands for conductivity, temperature and depth. It consists of a carousel that has 36 niskin bottles with sensors at the bottom. In the operations room, a fluorescence curve that shows the chlorophyll activity with in the ocean and helps to decide the locations for samples. These bottles were closed at designated depths while coming back to surface. The polystyrene cups that were decorated by the students were sent down with the CTD to demonstrate the pressure affect. These polystyrene cups became very small in size after coming back from the ocean. Due to this small experiment, it is very easy to understand that pressure increases with depth.
On the very last day, we had a lot of fun. Our CAPSTAN director, Dr. April Abbott arranged a quiz to entertain all the participants and crew members. Everyone was in a different costume except me to relish those last moments. Our trainer, Stephen is a great geologist but his sense of humour was also amazing. I am obliged to be a part of this exciting opportunity as it not only increased my knowledge related to marine science but also helped me to thick critically, improved my confidence and science communication skills.
Due to the nature of the support
offered by the CSIRO Marine National Facility to the CAPSTAN Program, our story
takes place on a transit leg of the RV Investigator. This means that it was already sailing from
Hobart to Fremantle for its next major voyage. For this reason, our Chief
Scientist, Dr Leah Moore, had to design a 48-hour sampling program that lay
along the route through that part of the Southern Ocean.
Fortunately, the southern
Australian coast offers many unique and varied locations for such an
investigation, so Dr. Moore chose to look a little more closely at an area off
the south-western coast of Victoria, near Portland. This region is unique due
to the low terrestrial sediment input that occurs, so material moving in the submarine
canyons that cut across the continental slope is dominated by pelagic sediment
(of oceanic origin), some in the form of fluidised flow deposits (cold water carbonate
turbidites). The planktonic fossils in these sediments can also be used to help
recreate past climatic conditions.
The other interesting phenomenon
that occurs in this region from a biological point of view is the Bonney
Upwelling, which is the largest and most predictable along the Great Australian
Bight. The upwelling of cold nutrient-rich deep ocean water is episodically
active along the coast from Portland, Victoria through to Robe, South
Australia. The continental shelf narrows to approximately 20 km here and the upwelling
water is funnelled up the underwater canyons onto the shelf, where it fuels
phytoplankton (microscopic plants) and plankton (microscopic animals) blooms,
which in turn feed whales, seals and birdlife.
The plan going into the voyage was to map two canyons (maybe three if there was enough time), collect sediment cores, bathymetry, oceanographic and biological data within the Bonney Upwelling area (Figure 1).
And, of course, the best laid plans… so once on board with access to higher resolution geophysics data Dr. Moore decided to modify our station locations. The easternmost canyon was not going to be suitable to place the cores at the depths originally planned as it was much steeper than expected. The adjacent canyon was an interesting Y-shape and much broader enhancing the opportunity to place cores, with an increased chance of finding the turbidites we were looking for. In addition, consultation of satellite, meteorological, and Argo float data indicated that the Bonney Upwelling was not active, so an alternative plan was required and quickly (Figure 2).
To maximise the time on station and to try to get as many cores collected as possible (its safer to collect them in daylight) the biological and oceanographic data were collected in the early hours before dawn or in the late afternoon to evening. Overnight we mapped the sea floor at high resolution to assist with the AusSeaBed Project (http://marine.ga.gov.au/). The final voyage map reflects the waypoints for ship navigation and station locations along the canyon (Figure 3).
As a teaching voyage it was an
amazing opportunity to see how decisions were made and why (this explanation
came after we left the stations due to time constraints) and how to adjust on
the fly to changing conditions and circumstances while still ensuring project
objectives and data quality were not compromised. As a result, all the
equipment we deployed on this scientific voyage generated high quality data and
a complete suite of samples, which rarely happens at sea. It was also great for
our Chief Scientist to then sit down and talk us through all the decisions she had
made and why, and convey that to us. The
best laid plans…
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
A very important part of research as a scientist is being able to communicate what you have worked on to a wider audience. The general public have varied knowledge and levels of understanding of science so the simpler, clearer, and more engaging the message, the better. The message can be communicated through blogs, documentaries, podcasts, even art. There has always been an ‘us versus them’ mentality between the arts and the sciences. But at the best of times they come together for a common purpose. From the beautiful natural history illustrations of animal specimens, to Attenborough’s documentaries enthralling young and old with sublime cinematography, it’s all a unification of the two disciplines.
learning so much during my CAPSTAN voyage, about so much fantastic science from
entirely different disciplines that I had no prior knowledge of. Something that
took me by surprise was the use of a fascinating piece of oceanography
equipment to create miniature works of art. The CTD (Conductivity, Temperature,
Depth) is a carousel that holds 36 bottles and is lowered to the oceans depths.
On the way back up to the surface, bottles are closed at particular points to
obtain samples from different depths of the ocean. While all of this fantastic
ocean water sampling is happening, a mesh bag of polystyrene cups that have
been decorated are accompanying the CTD down into the oceans depths and back up
again. The magic trick is that the polystyrene cups, that are for the most-part
made of air, experience the extreme pressure of the oceans depths and the air
is squeezed right out of them. What a fantastic way to demonstrate the immense
pressure of the oceans depths than with little pieces of art.
The “D” in CTD stands for “Depth” but is more of a representation of hydrostatic pressure, the pressure of the water above (and around). So the deeper into the water, the greater the increase of pressure. The CTD and the polystyrene cups can withstand a lot more pressure than we possibly could, which is evident in the air that is lost from the cups at such great depths and amounts of pressure. I decorated three cups; drawing the phytoplankton that would be sampled in the CTD bottles, the CTD itself, and my personal experiences on RV Investigator.
Phytoplankton are plant and algae that occur in a variety of beautiful shapes ranging in size from a few mm to the very tiniest most microscopic. Phytoplankton is extremely important in our oceans as it is the very first link in the food web, providing food for many animals. They are also an important part of the carbon cycle, storing carbon and producing around 70% of the worlds oxygen. So as you might imagine, measuring and collecting quantities and types of phytoplankton in our oceans is very important in monitoring ecosystem health locally and globally.
Phytoplankton appears again on my CTD cup. For that cup I drew the CTD carousel that holds the sampling bottles, and drew the sampling bottles representing the different measurements taken by the CTD; oxygen, conductivity (salinity), temperature, current velocities, nitrate, fluorescence (light), and pressure/depth. Generally people aren’t going to know what all of these things are, so my illustrations attempt to convey these in a more approachable way. For example conductivity/salinity is represented as a salt shaker. Even with my science background, I don’t fully understand the ins and outs of all of the measurements and hydrochemistry involved with the CTD, but I hope I’ve presented it in a way that bridges the gap for most people. It’s not so easy to draw on a polystyrene cup, so these aren’t absolute masterpieces, but I hope they’re a good form of communicating some of the science from onboard RV Investigator!
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).