Sources & Sinks: A Tale of Coastal Biogeochemistry - BONUS COCOA
11.06.2018 21:38New COCOA publication!
A new study from BONUS COCOA is out:
(Institute for Baltic Sea Research Warnemuende) and co-workers wanted to know whether river plume and bottom boundary layer in
the coastal zone are potential hotspots for
nitrification, due to their favorable characteristics. Nitrification is a key process in the coastal nitrogen cycle:
the produced nitrate can either be substrate for primary production whereby
nitrogen stays in the coastal system, or for denitrification whereby nitrogen
is removed from the coastal system.
They found that neither river
plume nor BBL of the Vistula Estuary in the southern Baltic Sea are hotspots for
nitrification. Instead, short term changes such as sediment re-suspension during
a storm event or oxygenation of anoxic water can significantly enhance nitrification.
the full story here:
Bartl I, Liskow I, Schulz K, Umlauf L, Voss M (2018) River plume and bottom boundary layer – Hotspots for nitrification in a coastal bay? Estuarine, Coastal and Shelf Science 208:70-82. https://doi.org/10.1016/j.ecss.2018.04.023
22.02.2018 19:22Time to say goodbye and thanks
A big thank you to the project leaders Jacob Carstensen and Daniel Conley, all work package leaders and all other participants for super exciting 4 years!
27.11.2017 11:07New COCOA publication
Myself and co-workers measured the removal of riverine nitrate via the processes denitrification and anammox in the sandy and muddy sediments of the oligotrophic Öre Estuary at the Swedish coast of the Quark Strait, Northern Baltic Sea. Estuaries are generally assumed to be sinks of the land-derived, riverine load of nutrients and organic matter and thus hotspots of the "coastal filter". We found that the Öre Estuary gradually removes most of the riverine nitrate long after peak loading, after temporary "trapping" in phytoplankton biomass. Read the full story here:
Hellemann D, Tallberg P, Bartl I, Voss M, Hietanen S (2017) Denitrification in an oligotrophic estuary: a delayed sink for riverine nitrate. Marine Ecology Progress Series 583:63-80. http://www.int-res.com/articles/meps_oa/m583p063.pdf
06.11.2017 20:55New Dr. in COCOA!
....and hence is from now on Dr. Bartl!
During her PhD, supervised by Maren Voss, Ines sailed both stormy and calm waters of the southern and northern Baltic Sea and spent hours, days and nights in cold rooms, spiking water samples from the benthic boundary layer with nitrogen tracer, followed by filtering, filtering and...filtering.
21.09.2017 19:28New COCOA publications out!
and co-authors investigated the erodibility potential of coastal sediments and identified
regulating key factors of sediment resuspension. The study took place at the South-Western
Finnish Archipelago coast, which offers a divers habitat of different sediment
types. Measurements were done with a core based erosion device (EROMES) at the
Tväminne Zoological Station. The full
study and all interesting outcomes can be found here:
Pilditch AC, Harris R, Hietanen S, Pettersson H, Norkko A (2017) Sediment
properties, biota, and local habitat structure explain variation in the
erodibility of coastal sediments. Limnology and Oceanography, doi:10.1002/lno.10622.
and co-authors estimated the filter function of Baltic Sea coastal sediments for
the elements nitrogen (N) and phosphorus (P), i.e. they calculated how much N and
P is permanently removed from the coastal Baltic water column via benthic denitrification
and burial, respectively. For this, they compiled and analyzed published removal
rates of N and P from around the Baltic Sea coastline and could, for instance, identify
key environmental factors for the regulation of N and P in the coastal filter. For more on this and the main outcome (no spoiler here) please look at:
Asmala E, Carstensen J, Conley DJ, Slomp CP, Stadmark J, Voss M (2017) Efficiency of the coastal filter: Nitrogen and phosphorus removal in the Baltic Sea. Limnology and Oceanography.doi:10.1002/lno.10644
Excellent Baltic Sea must-reads for the long autumn evenings!
01.08.2017 22:23Equipment explained: part IV - the HAPS corer
This post might as well be entitled “Ode to HAPS”. For one thing, the HAPS corer is by far my favorite sediment sampler, clearly deserving of being sung about. For another thing, it already has been (cruise internally) sung about, showing that not only I have a personal affection for it, but that it is popular among several COCOA people (aka the HAPS gang).
So what is this HAPS sampler and what is so special about it?
The HAPS is a sediment corer for coarse sediments, i.e. sands. The tricky parts with sand sediments are that they are quite hard and sturdy, and that they have big pores, which impose only weak cohesive forces onto the pore water. This can result in water actually flowing through the pore space of sand (advective pore water flow), which has everyone experienced who ever saw a wave washing up a beach…and then disappearing into the sand under the own feet.
Pore water flow has huge implications for organic matter turnover, sediment biogeochemistry, and general elemental cycling- however, in terms of sampling, it means particularly one thing: how not to lose the pore water during core retrieval, if it´s so mobile? (In more plain words: pore water flow in sand is scientifically and ecologically really cool stuff, but it does add a challenging element to undisturbed sampling of sand sediments).
Luckily, there is the HAPS!
We wondered for years, what its name stands for (maybe “happy and prosperous sampling”?!), until getting the answer from the inventors themselves (Kanneworff & Nicolaisen 1973): apparently, “haps” is a Danish exclamation used when something is grasped very quickly. And that´s exactly what the HAPS does: after coring, a tight top lid keeps the sediment in the core, and during core retrieval, a super sharp, quick and tight shovel cuts immediately under the sediment core, so that pore waters are kept where they belong- in the sediment. However, never forget to use the core lid, otherwise also the super quick shovel does not help in holding any sample (*learned from experience*).
This sounds like basic sediment coring theory. Yet, the difference of the HAPS to e.g. the GEMAX corer is its weight, its stability and the speed of its closing mechanism.
Like the GEMAX (Equipment explained: part II - the GEMAX / GEMINI corer), HAPS is basically a gravity corer, i.e. it cuts into the sediment based on its own weight. But even if GEMAX does feel heavy when loading it onto the ship, it is too light to be able to cut into sand sediment. Plus, sands are usually located in high energy environments (too turbulent for finer particles to settle), where samplers need to be heavy to go down the water column and onto the sediment surface without being drifted away. The net weight of a HAPS corer is ~ 100 kg, which can be added up by additional 60 kg of lead weights, and a square bottom frame supports high stability at the sea floor. It is made out of stainless steel, including the core barrel and the closing shovel, which are both sharpened for uncompromising sediment penetration. If the weight of a fully loaded sampler should still be too light to penetrate the sediment, it can be equipped with a powerful vibrator unit. Insider tip: don´t drive it for too long, you might anchor yourself in the seafloor.
Undisturbed samples are easily to be seen in the clear water phase on top of the sediment, which during our sampling at the Finnish coast sometimes also included Saduria sp., having been surprised by the quick sampling (Killing in the name of).
Well, HAPS got its name for a reason.
04.07.2017 21:57An affair of the heart
And here it comes: my drawing turned out to be dominated by hearts. Hearts around N2. In relationship with a gas? Well, that does solve the problem of “plus avec” invitations via “take a breath of air”, but of course there was also a deeper meaning in using the symbols. Take a look at the drawing / bar-scribble, for better understanding re-coloured:
The 30 sec explanatory
talk went somewhere along the lines of....
“The Baltic Sea in northern Europe has too
many nutrients, mostly nitrate, which leads to algae blooms (--> green scribble) and oxygen
deficiency, so the sea is in bad ecological condition (--> sad smiley). The only way to remove
nitrogen from an aquatic ecosystem is via denitrification and anammox, which
results in N2 that goes into the air (--> that´s good *at least in a
eutrophic system* --> HEARTS). Estuaries are recognized as potential
hot spots of nitrogen removal and these are the 3 estuaries I looked at.“ FULL
STOP and a deep breath.
Don´t put me down on scientific spotless accuracy, but nevertheless, my piece of art & speech was convincing enough to score second place. Now I am proud owner of a new coffee cup.
The conference was rounded up by a hike in the national park Bic at the St. Lawrence Stream on World Ocean Day, strengthening our attachment to the biggest estuary of the world.
Thanks UQAR for organizing such an interesting symposium!
06.05.2017 11:01Equipment explained- part III: the t-brush
Last time in EE II you learned all about soft sediment coring with a GEMINI/GEMAX corer. Muddy soft sediments are generally sticky, often stinky, and sampling them will most likely make you look like a little piglet that enjoyed a decent roll in its favorite pit. That´s why we wrap us in orange rubber and simply accept the mud stains on everything uncovered, such as… the face.
A bucket full of black mud from the seafloor. Everything not in the bucket can be found on Anni and me, though the picture shows a rather clean state of us (pictures: Ines Bartl, IOW).
But what about the core sleeves that hold our samples, what degree of mud stain is acceptable there?
Very simple: none.
One of the most crucial points in getting reliable data are undisturbed and uncontaminated samples. When working with sediment, a fast track to destroy your sample directly onboard is to get sediments from deeper layers onto the top surface and the water overlying the surface, mixing totally different element compositions and concentrations.
This points a big finger to constant cleaning: fingers, top lids, sub sampling gear and the core sleeves. And with a sleeve diameter of 8-9 cm which tool would be better suited for that job than a t(oilet) brush?Clean core sleeves thanks to lots of water and a t(oilet) brush (picture: Franziska Thoms, IOW).
totally serious about this: a toilet brush is one of the essential key tools in
And so romantic in the sunset (picture: Franziska Thoms, IOW).
01.04.2017 17:56Equipment explained: part II - the GEMAX / GEMINI corer
Yet, with increasing water depth and subsequently decreasing light, sampling via diving becomes complicated. On the dark side of the sea floor we therefore use sediment corers operated from ships. As corers have no eyes, we work virtually blindfolded which can often feel like gambling (and thus holds a certain kick). Sediment maps are helpful for giving directions, especially in early planning phases; however, often they are extrapolated or outdated and when looking at the first sample coming on deck, you might find that the sediment type has changed over the years, e.g. due to a change of current regime or deposition environment.
Surprises for free, excitement guaranteed- that´s sediment coring!
retrieval of a sediment sample from the sea floor depends largely on the right
corer. Sediment types vary in sturdiness, resp. softness, e.g. comparing sturdy
sand sediment with soft mud sediment; consequently, you have special corers for
each type. If you have followed this blog for some time, you will have heard
about MUC, HAPS, GEMAX, GEMINI, BOX – over the last 3 years, we have had them
Today you will meet the GEMAX/GEMINI corer, which is according to an essay by Boris Winterhalter the “ultimate corer for soft sediment”. Do I need to say more?
The GEMAX /
GEMINI corers are twin gravity corers for soft sediments. They base on the
original Niemistö corer (Niemistö, 1974), which was highly successful with the
only offset of a too small sample size. By doubling the core barrels a twin
corer was born, self-evidently baptized GEMINI. Sample quality was further improved
by increasing the diameter of the core barrels, which created the GEMAX.
Today, both GEMINI and GEMAX are standard corers all along the Baltic Sea coast. They consist of a stainless steel housing which is fitted by acryl core liners with sharpened steel cutters at their ends; those, as the name says, are capable to cut through the sediment. In the end, the core liners will hold the sediment sample. Both corers might look alike, but do not underestimate their difference: even 1 cm variation in core diameter makes a huge difference when trying to fit in a wrong inner core liner. From experience I can say: no, they don´t fit and no, they also cannot be squeezed in. Acryl is a quite solid material.
The corer penetrates soft sediments vertically based on its own weight and the lowering speed of the winch. Upon upwards pull a closing mechanism is triggered that locks the sediment securely in the core liners, creating a nice sediment core of ~ 30-40 cm.
And action: Laetitia, Wytze and Mathias while retrieving the full core liners. Requirements here: be quick, put the plug tight and don´t be afraid of getting muddy (left). My house, my car, my....sediment core: happy mood while subsampling a fresh core (right). (pictures: Ines Bartl, IOW)
Some care needs to be taken for the core liners, which somehow have a tendency to roll over board. Your only solution if you want to have them back: diving- and the circle closes.
Next time in equipment explained: why a toilet brush is an essential tool in sediment coring.
26.02.2017 14:11Equipment explained: part I – the scientific knitting needles
While writing up the materials & methods part of my work, I came to realize how often ordinary household items find a permanent place in the scientific tool box. So far, during field and lab work I have been using tooth picks, pressure cookers, flip-top beer bottles, knitting needles, toilet brushes and not to forget the number one all-purpose item, the bucket (water sampler, sample and waste container, water bath and chair all at once) – all for scientific purposes.
Yes, this is scientific equipment: flip-top beer bottles used for salinity sample storage (advantage: tight closing), a cup as support item, and two household pressure cookers used as autoclaves, e.g. for divers biogeochemical analysis.
In this new series you will get to know everything you ever wanted to know about our equipment – ALL our equipment.
Part 1: the scientific knitting needles
When measuring sediment denitrification, I add isotopically labeled nitrate (15NO3-) to intact sediment cores. This nitrate will be reduced by the denitrifying bacteria to as well labeled N2, from which the genuine denitrification rate can be calculated (a very rough and simplified description of the isotope pairing technique, Nielsen 1992). To stop the process after a certain incubation time, I carefully mix the sediment, create a sediment-water slurry and thus stop the anaerobic reaction by introducing oxygen.
Mixing a soft, muddy sediment is easy:
Mixing a coarse
sandy sediment is somewhat more challenging, as it is usually compact, sturdy
and thus utterly unwilling to be mixed:
That´s how the knitting needles found
their place in my sand work equipment: being similarly sturdy, sharpened
and slim, they proved to be the perfect tool for creating a careful sand-water
slurry. Beyond that, if you should have time off during your incubation waiting time...na, kidding. There´s no time off. Never :-)
Next time in "equipment explained": the Gemini / Gemax twin corer!
30.01.2017 11:264th annual BONUS COCOA meeting
Thus, the pressure to finish up is on, but luckily motivation and good mood as well. The necessity for synthesizing our work in mind, we used the 3 1/2 days of meeting very well with exchanging results from all involved disciplines and making plans on how to proceed in the time left. More details on the content and what magic has to do with science you can also read on the COCOA benthosphere blog: My great German adventure.
Thanks to the project coordinators Jacob and Daniel for the constructive meeting, and special thanks to Maren and her team for organizing and hosting it at the Institute for Baltic Sea Research (IOW) in Warnemuende. A direct view to the beach is always helpful when discussing matters on coastal ecosystems!
18.12.2016 22:26An enthusiastic roar for marine science communication
Held in the
Provincial Court on the Market Square right in the heart
of medieval Bruges, the
impressive venue arose slight considerations whether it might be appropriate to curtsy before a talk...
..and thanks to the chair decorations, also a significant number of lions attended the talks, cheering and roaring for each speaker.
An enthusiastic roar was well justified, thinking back to excellent talks and workshops, and overall passionate and motivated participants, discussing how to improve the communication of scientific results, which tools to use and why this is in general important. Picture right: VLIZ (Els Verhaeghe).
So why does science communication matter? Who should do it? And how?
It matters, because our scientific work will likely have only little impact on society and environment, if we do not tell about it- beyond the academic circles. This is particularly important in environmental sciences like ocean sciences, where our work is tightly linked to the effects of anthropogenic impacts such as climate change, eutrophication, acidification, over fishing. Explaining our aims and efforts to non-academics might lead to understanding, awareness and in the best case a change of behaviour towards the environment.
These communication efforts should not be seen disentangled from our pure scientific work as something that hopefully the public relations office can deal with, because there´s lab work to be done and a cruise to be prepared…
On the contrary, tell about your cruise preparation: what will you be doing, why the Arctic…and why in winter?! You can twitter, blog, produce videos, involve school children and have skype class room talks - there is a platform for everyone and equipment for everyone. It is totally fine to make a video with your mobile phone (Lisa D. Tossey: “Using the technology in your pocket for science storytelling in the digital age”). The main point is to get involved and spread your message, which may even increase your citation number (Line Reeh: "Boosting impact and citation- why talking to journalists might actually be a good idea").
Social media platforms (twitter, facebook, instagram) and the visual aspect (video, photo, picture) are key aspects in modern science outreach. Left: good mood and probably some #CommOCEAN memory pictures. Right: Christopher Malapitan, visualizing the plenary talks. Pictures: VLIZ (Els Verhaeghe).
Some visualized talks of the first day, by Christopher Malapitan.
and supported by BONUS, I had submitted an abstract about my experiences in
running this science blog about the biogeochemistry work of the COCOA project,
and therefore tried to convince the participants of my session “Dealing with
the media” that blogging is a great tool for scientific outreach. Modern, fast,
easy, cheap, visual and with a wide-spreading impact- perfect for getting your
message out in today´s fast-running and internet-oriented world. My proposed
way of catching and keeping the audience: authenticity, collegiality and
parallel session “A blue public- getting the message out to a wide audience” Maija
Sirola from BONUS spoke about the engagement of scientist in communication and
outreach, e.g. also via the BONUS blogs. Pictures below left: me, right: Maija. VLIZ (Els Verhaeghe).
Thanks BONUS for the support, it was an inspiring conference with perfect organization, great people and the best conference bag you could wish for on St. Nikolaus Day!
Team BONUS Maija and me happy at CommOCEAN 2016 in Bruges, Belgium.
04.12.2016 21:25Three cheers for a motivation penguine
About two weeks ago, THE big moment was there: after 3 years, I finally took the last field samples of my PhD. Oooh, wooow...ahm, well. As so often in life, you don´t notice big moments when they are there. So also here, as we decided first some days later that I actually would have enough data. Thus, except for a beautiful sampling scenery in early Finnish snow, the last official sampling was rather unspectacular.
Early morning start, Gemax mud sampling, some light in the far distance and pore water sampling in ice and snow- sampling routine in winter conditions at the Finnish coast.
After all the fun on the water there remains the task of making sense of your data. And that´s exactly, what all of the BONUS COCOA PhD students are doing right now: writing manuscripts. Also the 3rd year of the COCOA project seemed to have passed on the fly, which means that us PhD students come closer and closer to the finish line (which has different time length still though, from several months to a year). The pre-christmas time is nearly famous for dedicated working towards manuscript submission- everyone wants to have them done before the holidays to not get distracted by excel, sigmaplot and ocean data view from drinking glöggi.
Thus, you won´t be surprised to find most of us these days hidden behind paper-piles and computer screens- no matter whether in Helsinki or Warnemuende:
Ines und Franziska (Institute for Baltic Sea Research, Warnemuende), fighting with nutrient dynamics in the rather dynamic Vistula estuary, Polish coast.
But is the prospect of drinking glöggi with a data unoccupied brain really the only motivation carrying us through the writing process? No, it´s not. Luckily there´s the motivation penguin (Ines), motivation cards (Franzi) and motivation t-shirts (me).
Fingers crossed for high motivation on the pre-christmas manuscript submission finish line!
07.11.2016 15:44Cold autumn, hot fingers
And indeed, the combination of decreasing air temperatures and first autumn storms had deepened the mixed surface layer in September, which developed into a completely mixed water column in October (with even slightly higher temperatures at the bottom than at the surface thanks to slightly higher salinity and thus higher density). The effect: bottom water temperatures of 9 - 11°C, which consequently also meant climate chamber working temperatures of 9 - 11°C! Yes!
As you can find a song for nearly every occasion (such as “muddy waters” & “dirty” for mud sediment sampling or “I just can´t get enough” for general sampling mania), this time it could have been “hot in here”. Only a brief joy, I am afraid, as the next sampling could likely feature “November (snow)rain”.
09.09.2016 16:40Cocktails in Bremen
Great talks on the coastal filter were given by Franziska, Mindaugas, Jacob, Elin, Peter, Alexey and me, and interesting posters were presented by Eero, Heather, Pirkko, Irma and Arturas:
Everyone survived their presentation and 4 days full of latest findings on estuaries and coastal seas around the world were rounded up by a dinner in fancy atmosphere:
Joining the next ECSA, we could have cocktails in Perth...^^ :-)