Posts Tagged ‘phytoplankton’

UGA Skidaway Institute scientists study microbial chemical warfare

April 18, 2017

In the battlefield of the microbial ocean, scientists have known for some time that certain bacteria can exude chemicals that kill single-cell marine plants, known as phytoplankton. However, the identification of these chemical compounds and the reason why bacteria are producing these lethal compounds has been challenging.

Now, University of Georgia Skidaway Institute of Oceanography scientist Elizabeth Harvey is leading a team of researchers that has received a $904,200 grant from the National Science Foundation to fund a three-year study into the mechanisms that drive bacteria-phytoplankton dynamics.

Researcher Elizabeth Harvey examines a part of her phytoplankton collection.

Understanding these dynamics is important, as phytoplankton are essential contributors to all marine life. Phytoplankton form the base of the marine food chain, and, as plants, produce approximately half of the world’s oxygen.

“Bacteria that interact with phytoplankton and cause their mortality could potentially play a large role in influencing the abundance and distribution of phytoplankton in the world ocean,” Harvey said. “We are interested in understanding this process so we can better predict fisheries health and the general health of the ocean.”

This project is a continuation of research conducted by Harvey and co-team leader Kristen Whalen of Haverford College when they were post-doctoral fellows at Woods Hole Oceanographic Institution. They wanted to understand how one particular bacteria species impacted phytoplankton.

A microscopic view of a population of phytoplankton

“We added the bacteria to the phytoplankton and the phytoplankton died,” Harvey said. “So we became very interested in finding the mechanism that caused that mortality.”

They identified a particular compound, 2-heptyl-4-quinlone or HHQ, that was killing the phytoplankton. HHQ is well known in the medical field where it is associated with a bacterium that can cause lung infections, but it had not been seen before in the ocean. The team will conduct laboratory experiments to determine the environmental factors driving HHQ production in marine bacteria; establish a mechanism of how the chemical kills phytoplankton; and use field-based experiments to understand how HHQ influences the population dynamics of bacteria and phytoplankton.

“This project has the potential to significantly change our understanding of how bacteria and phytoplankton chemically communicate in the ocean.” Harvey said.
The project will also include a strong education component. The researchers will recruit undergraduate students, with an effort to target recruitment of traditionally under-represented groups, to participate in an intense summer learning experience with research, field-based exercises and some classroom work.

“The idea is for the students to return to their home institutions at the end of the summer, but to continue to work with us on this project,” Harvey said. “This will be a unique opportunity to offer students cross disciplinary training in ecology, chemistry, microbiology, physiology and oceanography.”

In addition to Harvey and Whalen, the research team includes David Rowley of the University of Rhode Island.

NOTE:  A complementary video with an interview with Dr. Harvey is available at http://www.skio.uga.edu/news/videos/

 

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Diving Deep Into Phytoplankton: How Tiny Ocean Organisms Help You Breathe — An Interview With GPB

March 21, 2017

You can hear Dr. Elizabeth Harvey’s interview with Georgia Public Broadcasting here.

“You may have learned in school that photosynthesis is how plants use sunlight to turn water into hydrogen and carbon dioxide, its food, and oxygen, which it releases into the air for all of us to breathe. But photosynthesis doesn’t just happen on land – it happens in the ocean.

Phytoplankton are tiny, single-celled algae basically, that live in the ocean,” explained Liz Harvey, Assistant Professor of Marine Science at University of Georgia’s Skidaway Institute of Oceanography, which is located on Skidaway Island. “They conduct photosynthesis just like land plants, trees and grass do, and they are prolific. They grow everywhere in the ocean.”

“There’s lots of different types of phytoplankton, they can do lots of different things,” Harvey continued. “But I think if you take one thing home, it’s that phytoplankton are important  as they produce about fifty percent of the oxygen that you breathe. Land plants produce about half and then phytoplankton produce about half. These tiny little microscopic organisms are actually very, very important for helping to sustain life on earth. “

Producing half of earth’s supply of oxygen is only half of this organism’s job.

“Phytoplankton are eaten quite regularly and serve as food for other small organisms, which are then eaten by larger organisms which eventually lead up to fish, whales and sharks and all the really cool things that we think about when we think about the ocean,” Harvey said. “Although I would think phytoplankton are really cool too! So they serve a very important purpose to sustain the health and viability of fisheries. That’s another reason why we’re so concerned about what they’re doing, where they are, what types of phytoplankton are around – because they serve this purpose in supporting the larger fisheries as a whole.”

Tiny but voracious marine organism studied — video

February 8, 2017

Tiny but all-consuming marine organism focus of UGA Skidaway Institute study

February 8, 2017
Marc Frischer

Marc Frischer

Doliolids are tiny marine animals rarely seen by humans outside a research setting, yet they are key players in the marine ecosystem, particularly in the ocean’s highly productive tropical and subtropical continental margins, such as Georgia’s continental shelf. University of Georgia Skidaway Institute of Oceanography scientist Marc Frischer is leading a team of researchers investigating doliolids’ role as a predator in the marine food web.

Doliolids are small, barrel-shaped gelatinous organisms that can grow as large as ten millimeters, or about four tenths of an inch. They are not always present in large numbers, but when they bloom they can restructure the marine food web, consuming virtually all the algae and much of the smaller zooplankton.

A doliolid with a cluster of juvenile doliolids on its tail. Actual size is approximately three millimeters, or one eighth inch.

A doliolid with a cluster of juvenile doliolids on its tail. Actual size is approximately three millimeters, or one eighth inch.

“The goal of this particular study is to find out what the doliolids are eating quantitatively,” Frischer said. “This is so we can understand where they fit in the food web.”

Scientists know from laboratory experiments what doliolids are capable of eating, but they don’t know what they actually do eat in the wild. They are capable of eating organisms as small as bacteria all the way up to much larger organisms.

“What they are eating and how much are they eating from the smorgasbord that is available to them, that is the question,” Frischer said. “We are investigating how much of those different prey types they are really eating out there across the seasons.”

The project involves intensive field work, including 54 days of ship time on board UGA Skidaway Institute’s Research Vessel Savannah. During the cruises they conduct trawls using special plankton nets to collect the doliolids. They also collect water samples to understand the conditions where the doliolids thrive.

Graduate students Lauren Lamboley and Nick Castellane deploy a plankton net from the Research Vessel Savannah.

Graduate students Lauren Lamboley and Nick Castellane deploy a plankton net from the Research Vessel Savannah.

“We take the doliolids and the water samples back to the laboratory, and that is where the magic begins,” Tina Walters, Frischer’s laboratory manager said.

Because the animals are gelatinous and very delicate, the researchers cannot use classical microscopic techniques to dissect the animals and analyze their gut content. Instead they extract DNA from the animals’ gut and use sequence-based information to determine what the doliolid ate.

“We go through a process called quantitative PCR,” Walters said. “So even though we can’t see the prey in a doliolid’s gut, because the prey have unique DNA sequences, we can identify and quantify them using a molecular approach.”

The three-year project is funded by a $725,000 grant from the National Science Foundation and will run until February 2018. Frischer’s collaborator on the project is Deidre Gibson from Hampton University. Gibson received her Ph.D. from the University of Georgia in 2000, and did much of her graduate research at Skidaway Institute with Professor Gustav Paffenhöfer.  In addition to Walters, Savannah State University graduate student Lauren Lamboley is part of the team, along with a number of students at Hampton University. Several undergraduate research interns have also participated in the project, gaining hands-on research experience. Frischer is also working with the Institute for Interdisciplinary STEM Education at Georgia Southern University to engage K-12 teachers by inviting them to participate in the research cruises.

UGA Skidaway Institute team studies nutrient levels in Georgia’s coastal estuaries

June 6, 2016

How much of a nutrient load is too much for Georgia’s coastal rivers and estuaries? A research team from University of Georgia Skidaway Institute of Oceanography is helping Georgia’s Environmental Protection Division answer that question. Their primary focus is on the estuary at the mouth of the Ogeechee River, where the researchers are measuring nutrient concentrations and other water properties to determine how they change as they flow through the estuary.

The nutrients are chemicals like nitrates and phosphates typically introduced into the rivers by agricultural runoff, storm water or sewage effluents, and the natural decay of organic matter in the river. When present in high concentrations, the nutrients act as fertilizer, promoting excessive growth of marine plants, especially microscopic marine plants called phytoplankton.

Researcher Kate Doyle lowers a sensor package into the water to measure salinity, temperature and depth.

Researcher Kate Doyle lowers a sensor package into the water to measure salinity, temperature and depth.

Elsewhere on the East Coast, excessive nutrients in estuaries have been linked to toxic algal blooms that can cause fish kills or shellfish closures. Death and decay of algal blooms by bacteria can drive oxygen concentrations down to levels that are unhealthy for other marine life. These are not presently known to be significant problems in Georgia’s waters, but scientists and regulators do not know what the thresholds are for developing water quality problems.

“The Georgia EPD wants to know how much nitrogen is coming down the river and whether it has any consequences when it gets to the estuary,” said UGA Skidaway Institute scientist William Savidge. “It doesn’t really matter if you have high nutrient concentrations if it is not having a harmful effect.”

The EPD is interested in these issues because they are mandated by the Environmental Protection Agency to set limits on nutrient levels for Georgia’s estuaries. Savidge describes the mandate as a difficult problem for several reasons.

“There is not any current and systematic information on nutrient conditions in most of the estuaries,” he said, “nor is there much information on the consequences of nutrient availability in the estuaries, and it’s those consequences that are the most important.”

They are currently mapping the biological and chemical properties of the Ogeechee River estuary each season to assess the nutrient changes throughout the year and to see what effects can be seen in the river and the estuary. Twice every quarter for the last year, the researchers have followed the incoming tide and sampled the river continuously as they moved upstream from the mouth of the estuary to fresh water. They used an onboard set of sensors to obtain continuous surface measurements of temperature, salinity, dissolved oxygen, chlorophyll (indicative of phytoplankton), turbidity and colored dissolved organic matter. In addition to the continuous surface measurements, the team stopped periodically and collected water samples from the bottom and throughout the water column. The product of each of these expeditions was a detailed map of conditions on the river, and when and where they are changing.

Researcher Lixin Zhu filters larger-volume surface water samples collected from the flow-through system to analyze for dissolved organic carbon.

Researcher Lixin Zhu filters larger-volume surface water samples collected from the flow-through system to analyze for dissolved organic carbon.

As they expected, Savidge and his team observed a wide range of conditions depending on the season. Nutrient inputs tend to be highest in the spring when agricultural fields are fertilized.

“Nutrient delivery is high in the spring, but we don’t have a high chlorophyll concentration in the Ogeechee River because, presumably, the nutrients are being washed off into the coastal ocean before any effect is noticed,” Savidge said

On the other hand, chlorophyll levels — which indicate phytoplankton population — are highest in the summer. Low summer river flow means water remains in the system longer. When combined with more sunlight and warmer temperatures, this slow flow this allows more time for the microscopic plants to grow.

In addition to sampling the Ogeechee River, the team is also conducting a smaller sampling project in the Altamaha River for comparison purposes.

Field work on the project will end in June, and Savidge expects to report the team’s findings to Georgia EPD by mid-summer.

“The Georgia EPD is going to have to balance the potential negative risks of nutrient loading versus the economic consequences of restricting nutrient additions,” Savidge said. “If, for example, most of the nutrient additions are agricultural, and that is creating problems downstream, the Georgia EPD may be forced by EPA to regulate nutrient additions, either by restricting how much fertilizer is placed on fields or mandating larger buffer zones around rivers and creeks.”

In addition to Savidge, the research team includes UGA Skidaway Institute scientists Jay Brandes and Aron Stubbins, research associate Kate Doyle and graduate student Lixin Zhu. UGA researchers Brock Woodson and Mandy Joye are also contributing.

Barents Sea Cruise 5-1-13

May 1, 2013

Skidaway Institute scientists Marc Frischer and Jens Nejstgaard are participating in a research cruise in the Barents Sea, north of Norway. This is an account of the experience from Marc.

First day of the cruise.  Everyone is excited and anxious.  We were all on board the ship by 9:00am and busy scurrying around making final preparations, securing instruments & lab gear and setting up the various work stations.  The crew was exceedingly helpful and efficient.

The Marine Tech was delayed in Oslo (coming by plane) so we couldn’t leave until he arrived.  He made it around noon and we were underway at about 12:45pm.  We headed north through the fjords.  The scenery was fantastic.  Calm water, snow and fog covered mountains, sun and clouds.  Not too much wildlife present, some seabirds.  The captain (Tom Ole) predicted that we’d see a lot of life near the ice edge, perhaps even whales.  Next week they have a whale observing cruise scheduled in the same area that we are heading to now.

Heading out to sea

Heading out to sea

After discussions with Aud Larsen and Jens Nejstgaaard we decided that due to our late departure we would head to immediately to the polar front and ice edge to take full advantage of the night to steam.  Of course night doesn’t really feel like night since it only gets dim for a few hours this far north this time of year, but for some reason we still get tired.  We also decided to stop a various points along our course to characterize the water and plankton communities.  We are occupying a standard transect used by IMR (Norwegian Institute of Marine Research) called Fugløya – Bjørnøya and are lucky that the previous week (25 – 29 April 2013) this line had been run giving us a pretty good idea of what we’ll find this week.  The data from the previous week indicated that water conditions are not unusual and that we could expect to reach the polar front approximately 225 NM north of our first sea station after leaving the fjords.

Our goal is to locate water masses containing the algae Phaeocystis pouchetti in various stages of its bloom cycle so that we can study how it is eaten (or not) by other organisms and thereby contributes to the food web.  It’s a very interesting and mysterious algae because of its importance as a major blooming algae in high latitude waters and because whether it is eaten seems to be highly variable.  We suspect that at times it is readily eaten and at others it is not and that this is mainly due to its ability to dramatically alter its size, chemically defend itself from predation and its resistance to ubiquitous viruses.  Despite the fact that this algae is slimy and smelly, all of us who study it love it because it’s so interesting.  We call the  project “Phaeo Enigma” because there is so much we don’t understand about this organism.

We stopped around 3:30 pm (13:30 GMT) in the fjord to take a quick sample.  The water column profile was classic textbook fjord with a chla maximum at about 23 meters.  The water contained big colonies of the algae we are studying (Phaeocystis pouchetti), but we are sticking with our plan to head north.

Continuing north we finally made it to our first sea station at 70 30 N 20 00 E.  Again, it was a quick stop to look at the water.  As we expected we found classic Norwegian Coastal Current water.  Phaeocystis was present here too, though at lower concentrations that we found in the fjords.  After a quick 30 min stop we were back on our way.

Since there wasn’t much to do most for the remainder of the evening, most of us thought it was prudent to turn in early for the evening.  Soon enough we will all be very busy!

Barents Sea cruise

April 30, 2013

Skidaway Institute scientist Marc Frischer is beginning a research cruise in the Barents Sea. Here is the first of his reports.

The cruise starts! We’re on the hunt for the enigmatic but globally significant algae Phaeocystis. We head north to the ice shortly aboard the Norwegian Research Vessel Hakon Mosby. I’ll try to update as I can.

Marc Boat 4-30

 

A Day in the Life of a Citizen Scientist

June 21, 2012

Skidaway Institute volunteer scientist Nancy Tenenbaum recently travelled to Norway, to work with fellow Skidaway scientist Dr. Stella Berger. She described her experience in the form of a letter to her mentor, retired Savannah business leader and Skidaway Institute supporter,  Howard Morrison.       

Dear Howard,

Having had a few days to settle in here and wishing I could have packed you in my suitcase as well.  I am going to let you share the day with me through this letter.  I am in Espegrend, Norway, with a phytoplankton research project called Phytostress.  The word “stress” takes on a new meaning with this project. There are only a hand full of students and professors here to manage twelve mesocosms and three experiments.  In the course of the next two weeks I know I will need your encouragement and advise.

Rule #1 is “NEVER give up”. Howard Morrison

So, let the day begin.

7:00 AM

Taped to the window in my dorm room is a thick, black garbage bag to keep out the midnight sun.  Light at any hour after 10 pm is your worst enemy! Block it out at all costs. You might find it a bit challenging to navigate in my tiny dorm room. Most certainly it is not the spacious Civil War home, Lebanon Plantation, that you reside in. Through an open window in the kitchen field station birds sing incessantly. Fresh coffee waits patiently for the early riser made by Maria Segovia, the principal investigator of Phytostress. Norway has no version of half and half cream. Flotte,, heavy cream., is it. Putting a small amount in my coffee cup I think about the potential threat for artery clogging. Will I survive the day? On the wooden counter top a Norwegian breakfast of various cheese, lox, fruit muesli and a hardy multi-seed rye bread await.

View from the field station kitchen window.

 

Another view from the kitchen window

7:30 AM

You will need a jacket this morning as it is cool, about 11 degrees C (52 degrees F).  The fiord water sparkles in the sunlight.  On the hillside edelweiss, purple clover and yellow buttercups dance with the morning breeze. Compared to the weather when I was here in March, this is heaven.

Let me explain this project to you using an abstract provided by Maria Segovia, the principal investigator, for Phytostress:

Under the global change scenario around 40-50% of the CO2 emitted by anthropogenic activities is accumulated in the oceans causing acidification and increasing the availability of dissolved CO2 to primary producers (phytoplankton, algae, etc.). To understand the regulation of the carbon cycle it is basic to determine the interaction of the main factors controlling primary production in the ocean. The increase of UV radiation due to ozone loss can reduce the oceanic phytoplankton CO2 sinking capacity up to 2%. Concomitantly, the scarcity of micronutrients, such as iron, can affect the composition, functioning and growth of phytoplankton. However, although up to date there are several studies about the effect of UV on iron ocean speciation, there is none about the interaction between CO2, Fe (iron) and UV in phytoplankton, and the underlying mechanisms has not been elucidated yet. Equally, there is evidence of massive cell death phenomena in phytoplankton communities that can account for a great loss of biomass amount, altering diversity and hence affecting the carbon cycle. The proposed experiments, will lead us to a better understanding about the functions of marine phytoplankton as well as to determine how changes in CO2, UV and Fe availability control the fate of primary production in the ocean, regarding biomass and diversity loss.

In an introductory email before the research in May, Maria wrote that this mesocosm project is a dream come true for her.

8:45 AM

Howard, we are now at the dock.  I know how much you love to ride in boats.  Even though the ride to the raft will be quick it could be chilly. The swans that graced the fjord in March are gone.  Truthfully they were noisy, mean and not very white, like their counterparts in fairy tales.

Scientists and Ph.D. students, who are scheduled to sample water today, gather at the dock with sixteen, 25-liter carboys. Clothed in Healy Hansen immersion suits or only a life jacket they board small motorboats for the mesocosms.

You are now at the mesocosm raft.  Be careful on exiting the boat as the concrete raft moves with the current making its surface slippery. There are twelve covered mesocosms that are tethered to this raft.  A decoy hawk is mounted on a pole to scare off birds. It does absolutely no good! Birds actually seem attracted to it. Water is sampled by pumping H2O though a plastic meticulously washed tube into carboys. Full carboys of 25 liters are then loaded onto the boats, delivered to land and hauled up a hill using a flat wagon and human strength.

The mesocosm raft

THE MESOCOSMS

We are about to enter the lab when I spy a single wild yellow rose in full bloom. Immediately I am reminded of Antoine de Saint-Euprey’s story, The Little Prince. In this children’s book the rose is essential to the novel’s drama. Carefully tended by the prince, she is his motivation for leaving and returning to his planet. The rose in this book represents love, an invisible but essential emotion. If no passion exists to nourish life then the question presented is: can life survive? My passion extends to the invisible life of phytoplankton. They are in fact the unseen art forms. Simple, yet complex their balance in the food web is essential for life.

Howard, you often sign your emails with the quote: “Only those who can see the INVISIBLE can accomplish the IMPOSSIBLE!” Patrick Snow, Author, Creating Your Own Destiny

Armed with those words, I will take you into the lab hoping to have a productive day.

Actually the lab rooms are right out of Dr. Seuss!  Wacky and wonderful the equipment is dormant waiting for creative direction.  Machines hum and filtering systems wait expectantly. Life in the lab is a clandestine life unto itself.

We will need to double glove for this next task.  An elaborate washing protocol is the first order of duty.  Each sampling bottle must be washed with Deacon water, then immersed and soaked in HCl and finally rinsed five times with Milliq. H2O. As this involves a Fe (Iron) limitation experiment it becomes imperative to remove all possible traces of containment iron. This is a very time consuming process.

 

Ph.D students Charo, Armandoand and Candlera

The Espegrend Lab

10:30 AM

Dr. Stella Berger and I are on the microzooplankton team.  Microzooplankton can be defined as greater that 0.2-20 micrometers in size, which includes ciliates, dinoflagellates and diatoms. She is also working on a dilution experiment that she designed.

Dr. Stella Berger in command of the motorboat

Stella Berger with her dilution experiment

We return to the boat with Dr. Jose Fernandez from Malaga, to sample mesocosms numbers 1-6 and the fjord. Our samples are brought to our cold room. Part of every sample is then labeled and stored in covered boxes. Some are viewed as live slides in the inverted microscope. This is my favorite part of the day. Seeing the phytoplankton move and interact is just amazing. When I was here in March, I had the rare opportunity to meet and work with Andrei Sazchin. Dr. Sazchin is a Russian phytoplankton taxonomist.

Stella begins running her samples through a Flow Cam. Every cell is photographed and organized into libraries for later study. Each mesocosm sample involves a thirty-minute run process.

Flow Cam display of samples cell by cell

1:20 PM

I have a brief SKYPE conversation with my mentor and close friend, Sandra Nierzwicki-Bauer, Director of the Darrin Fresh Water Institute at Bolton Landing, Lake George, New York.

It does fact take a village of mentors to maintain the privilege of representing Skidaway Institute as a citizen scientist. Dr. Marc Frischer and Dr. Stella Berger are also instrumental in guiding me on scientific path.

2:30 PM

Lunch.  I am the only American here.  The Spanish lunch have a late, protracted lunch experience.  This long, heavy lunch is followed by lengthy scientific discussions in Spanish.

3:00 PM

Hope you are ready for a quick refreshing walk. The path by the fjord is a perfect place to reflect and regenerate. Bergen is a dichotomy. Look beneath the perfect postcard landscape and you will discover an ugly history of Nazi infiltration, which happened during WWII.

On the hillside adjoining the field station is the “castle.”  A Nazi once owned and lived in this forbidding residence. Inside, according to the locals, are memorabilia including swastikas that cover the walls.  Just looking upon it reminds me that six million Jews died as a result of Hitler.

Turning back to the water we are accosted by the smell of wild roses and rhododendron.  Seagulls cry. The sound of the water is soothing as it covers rocks and sand on a small beach.  Tiny islands with houses dot the fjord.  You can feel the ancient pulse of the land.  It emanates from the soil. Life despite its brief encounter with chaos and death has moved forward in a beautiful, peaceful way.

3:45 PM

Back in the lab we are ready to take the sample water for chlorophyll a (Chl a) is filtering in duplicate.  The lights are turned off and sunlight blocked by a makeshift shade as it excites the chlorophyll. A reading skewed by light will not be accurate. Once the water is filtered, the filter is put in a falcon tube, extracted with 90% acetone and then put in a covered box in a refrigerator where they stored for 6-24 hours.  The next day samples are measured by a fluorometer. This device measures parameters of fluorescence determining the amount of Chl a in the sample.

Filtering for chlorophyll a

 

Fluorometer

5:00 PM

We are back at a hood with an exhaust fan. After we have double gloved, each bottle will be immersed in hydrochloric acid for two hours.

6:00 PM

At some point every day it is good protocol update a lab notebook with general thoughts and data for the day.

7:00 PM

Stella has just finished running the last sample in the Flow Cam.  Slides from the inverted microscope used during the day are carefully washed.

7:30 PM

Dr. Jose’ Fernandez, Armando Olmo and I are on cooking duty tonight for 16 hungry people. You can pour the wine Howard to keep us happy while we cook. Tonight we will prepare paella. a traditional Spanish dish. This is a secret recipe of Jose’s grandmother.  I am chopping vegetables and hoping to learn the recipe for this famous meal. What I did manage to get from Jose’ is that the rice must absorb the flavors of the meat and vegetables. Timing apparently is everything.  So thanks to Jose the paella was delicious and a great success.

10:00 PM

The scientist and students sit down for dinner at a long narrow wooden table which seats at least 25. Most of the conversation is in Spanish.  Some students go back to the lab after dinner to finish up.

11:30 PM

Howard, there is something about the Norwegian blue hour that is pure magic.

The blue hour, not quite at sunset, floods the landscape with a purplish blue hue.  Maria’s two children are still running around with abundant energy. Laughing, and singing they are so undeterred by the hour.  I on the other hand am jet lagged and exhausted.  From my room I hear Maria’s husband calling his son Rodrigo to come inside.

Midnight sun

 

Sunset at the mesocosm raft. Photo by Maria Segovia.

Thanks for sharing the day with me!

Good night from the land of the midnight sun.

With love,

Nancy Tenenbaum –Citizen Scientist, Skidaway Institute of Oceanography

Skidaway Institute researchers published in international journal

June 14, 2012

Skidaway Institute of Oceanography scientists Jens Nejstgaard and Stella Berger are part of a 21-member, international team of researchers whose paper was recently published in the Journal of Experimental Marine Biology and Ecology.

The object of the research was to observe the effects of different light levels on the behavior of microscopic marine organisms. The team focused their efforts at a group of organisms called mixotrophs. Those are single-cell plankton that exhibit the characteristics of both animals (heterotrophs) and plants (autotrophs). They feed on other organisms, but they also can grow through photosynthesis, just like algae and other plants.

“Most higher organisms are either plants or animals, and we have therefore traditionally sorted most organisms in to these two groups, or fields of science: botany or zoology,” said Nejstgaard. “However, as our understanding of the smallest sized life on earth, single celled organisms is rapidly growing it appears that a large part of the life on Earth may be mixotrophs. This opens new focus of seeing, and investigating our ecosystems.”

The international team with Stella Berger (back row, center, with sunglasses) and Jens Nejstgaard (far right) conducting experiment with specially designed mesocosms, using neural (grey) optical films to simulate light levels on different depth’s down to 50 m in the Eastern Mediterranean.

Nejstgaard, Berger and their colleagues, collected natural water containing plankton and other organisms from the Eastern Mediterranean Sea near Crete and transported it to a into specially-designed tanks on land, called mesocosms, at the Hellenic Centre for Marine Research.  In the 30-cubic-feet mesocosms they adjusted light levels to simulate differences in ocean depths down to approximately 150 feet.

The researchers found the mixotrophs do react to different levels of light. In general, the organisms tended towards plant behavior in brighter light and animal behavior at lower light levels. However, they also found that response is very complex, and the entire team of  scientists that worked on the mesocosms are presently analyzing a large amount of data to clarify many of the ecosystem interactions in this complex system.

Skidaway scientist working on international research team

June 8, 2012

Skidaway Institute scientist Stella Berger is spending time in Norway, as part of an interesting project involving an international team of researchers. They are looking at the relationship among carbon dioxide, iron and ultra violet radiation as they relate to the production of phytoplankton in the ocean.  You can read more about it at the team’s blog http://phytostress.wordpress.com/.