Science Update

At yesterday's science meeting, Dr. Randie Bundy (WHOI) and Dr. Kristen Buck (USF) presented information about ligand (iron-binding compounds) analysis and a general overview of the results of Incubation 1 and 3. If these presentations would have occurred four weeks ago, I am not sure I would have understood the information, but yesterday, I followed along with no problem. It goes to show the amount of information that I have learned during my time aboard the RVIB Palmer (and the patience and expertise of the science team and crew when answering my daily onslaught of questions).

Ice Update

It rained last night. Not just a sprinkle or a mist, but rain. There were also occasional periods of snow yesterday, adding to the approximately 3 feet of snow that sits atop the ice. The warmer conditions are not helping the forward progress of the ship because of that slushy layer that slows us down and makes it difficult for the ship to break ice in a constant motion. Although the conditions are not helping, we did make progress (gaining about a half mile) in the last 12 hours. The process is slow, but we are making progress, and that is what matters.

Ice Diatoms

In a journal from mid-September titled Diatoms, Alexa Sterling (URI) introduced the term sea-ice diatoms. These are species of diatoms which attach themselves to floating sea ice using a type of mucus they produce. When the diatoms attach to the ice, the color of the ice changes from clear, light blue or white to a tan color. This is an indication that the ice is now home to millions of photosynthetic diatoms. You can see this brown coloration in the pictures of this journal, or in the first image of the 10-6-16 journal.

In the original research proposal, the science team requested the opportunity to sample ice. In the past few days, the science team expressed interest in collecting samples of sea ice from this area in order to analyze the ice (or water once it melts) and filter the water to collect biomass (biological material). We have seen this dirty ice throughout the research cruise. In our current location, we can see large amounts of this dirty ice as the ship creates a path and churns up the ice. It was decided that we might as well take advantage of our current situation and collect some of this sea ice.

The interest in sea-ice diatoms stems from the fact that this is the one area of the Antarctic marine ecosystem that is highly productive at this time of the year. These surface diatoms have received sunlight for longer periods of time than those that are currently deeper in the water column. This means, their biology and chemistry may be at a level similar to the incubation experiments that were conducted on the ship. Remember - the incubation experiments provide nutrients and light to the diatoms to analyze their productivity. Or, it could mean that the biology and chemistry are totally different because they are ice-bound versus moving through the mixed layer. Ice usually has slightly higher levels of iron, so there is also an interest in collecting ice and surface water samples to understand not only the types of diatoms, but how the chemistry affects their productivity, the presence of ligands, etc. It is amazing to think that these ice samples are capable of helping to answer many unknowns about the diatoms and ocean chemistry of this area.

Man Basket and Ice Ops

The best time to collect ice samples is when you are surrounded on all sides by ice, right? This was the logic behind the surface ice operations that occurred yesterday afternoon. The ice is too packed to launch the Zodiacs (small boats), so instead, the crew and the science team created a plan to use a piece of equipment called the man basket. I can only describe it as a cargo net wrapped around a circular base. The man basket was attached to the stern crane, the scientists and marine technician were attached to the man basket and away they went. This equipment was used instead of simply collecting ice from the side of the ship using a bucket or net. Samples from along the ship could be influenced (contaminated) by the metal hull. The use of the man basket allowed for the scientists to sample ice that did not come into contact with the ship.

Dr. Kristen Buck (USF), Dr. Bethany Jenkins (URI) and Marine Technician Jullie Jackson completed the operation in about 45 minutes. During that time, Dr. Buck and Dr. Jenkins collected large ice chunks along with surface water samples. MT Jullie Jackson directed the movement of the crane and ensured the safety of all three passengers. The images below tell the story of Surface Ice Ops.

Man basket deployment
The man basket was lifted off the main deck and lowered towards the 'clean' ice off the starboard side of the ship. This is the first time in four days that the ship stopped ice-breaking operations for a deck operation.

Bagging ice
Marine Technician Jullie Jackson (right) watches as Dr. Kristen Buck hands Dr. Bethany Jenkins a piece of diatom-filled ice.

Sea ice samples
Dr. Bethany Jenkins collects sea ice from the side of the man basket. Notice the discoloration of the ice in the area (especially to the right of Dr. Jenkins' gloved hand). The tan color is indicative of diatoms.

Pumping water
This pump was used to collect sea water samples from areas near the collected sea ice. The water was pumped from the water into the trace metal clean van on the main deck. It was then collected in clean bottles to store for analysis.

Surface water samples
In addition to the water pumped into the trace metal clean van, Dr. Kristen Buck collected water samples by dipping bottles into a hole in the surface ice. To help reduce contamination, Dr. Buck wears gloves as well as sleeves to cover the required float coats.

Ice chunks on deck
Although it is difficult to see in the picture, this large ice chunk is tan in color. This coloration indicates the presence of sea-ice diatoms. The ice chunks were wrapped in plastic prior to reaching the ship to ensure a 'clean' sample.

Author
Date
Weather Summary
Sunny with good visibility; rain (eek) overnight
Temperature
1.3C/34F
Wind Speed
15-20 knots
Wind Chill
-13C/8.6F

Comments

Vivian Tran

Hello Mrs. Pekarcik. About the sea-ice diatoms, are they similar to molecules in ice? I'm referring to if they are set into a specific pattern just like solid molecules?

Cara Pekarcik

Hi Savanna - sorry about the delay in response. I have sent your question to the diatom experts. I will post the answer an soon as it is
available.

On 2016-10-09 08:54, PolarTREC wrote:

Cara Pekarcik

I do not believe they form specific patterns, they may be clumped or spread out

On 2016-10-11 10:07, PolarTREC wrote:

Cara Pekarcik

Hi Savanna - This answer is from polar phytoplankton scientist Mattias Cape. Mattias is completing a post-doctoral position at Woods Hole
Oceanographic Institute.

That's a great question! To answer it it's worth thinking about ice
algae in their natural setting. Sea ice is an extremely diverse
environment where temperature, salinity, light, and nutrient levels can
change dramatically over very short distances, much more so than in the
surface ocean. Diatoms living in this environment (at the surface, at
the bottom, or within the ice in what are called brine channels) have
to
cope with extreme conditions - salinities ranging from that of
freshwater to five times that of seawater, for example. Sea ice does
transmit light to the ocean beneath, but the amount of light reaching
the ice-ocean interface is much less than found in the surface ocean
(especially when the sea ice is snow covered). Diatoms can to some
extent adapt to these conditions by changing their physiology - for
example, how much chlorophyll or other pigments each cell contains to
adapt to changing light conditions. However, the conditions are still
extreme.

With that in mind, and getting back to your questions, productivity of
diatoms in sea ice is on average much lower than that of diatoms in the
open ocean - ten to fifty times less in terms of daily primary
production. Primary production by ice algae over a year accounts for
about 10% of total primary production in the seasonally ice-covered
waters around Antarctica, the other 90% being primary production in
open
water once the ice melts. Keep in mind that these are averages -
productivity rates can be very high in pockets if sufficiently light
and
nutrients are present! Another thing to know is that there are actually
relatively few measurements of primary production in Antarctic sea ice,
especially year-round. As you can imagine it's a difficult place to
reach and work in.

The biggest factors affecting primary productivity in sea ice are
thought to be light during winter and early spring, and nutrients from
spring through the summer, although low temperatures and high
salinities
can also have important effects on diatom growth. Iron has been shown
to
be present in very high concentrations in sea ice - in fact it can act
as a source of iron to the ocean when the sea ice melts in the spring.
Therefore iron is not thought to play a big role in reducing rates of
primary production in sea ice diatoms as opposed to in the water
column.

On 2016-10-09 08:54, PolarTREC wrote:

Reina C, Block B

Hello again! I was extremely surprised that you guys only moved half a mile in twelve hours... typically how fast does the boat move? And it's great you're making use of time of the time you're semi-stuck in the slushy ice. How do you know that there are higher levels of iron in the ice? Why is this?

Cara Pekarcik

Hi Reina - the boat can typically move around 10 knots/hour (which is about 11-12mph) in open water.

Ice on the surface of the water generally shows higher levels of iron
in analysis. This is most likely because the surface ice may scrape
against rocks near land, or has a higher chance of accumulating
particles from the air.

On 2016-10-08 18:35, PolarTREC wrote:

Savanna Pitard

Hello, how much of a difference in productivity do you expect to see between the diatoms collected in the sea ice compared to the diatoms in the water column? Do you believe that higher iron concentrations on the sea ice is the driving force of this productivity difference?