April 2018

Research cruise with the R/V Marion Dufresne to the Southern Ocean

I just came back from an exciting research cruise with the R/V Marion Dufresne to the Southern Ocean. This scientific cruise represented a major milestone for the MOBYDICK project (Marine Ecosystem Biodiversity and Dynamics of Carbon around Kerguelen: an integrated view), which aims at describing the links between marine biodiversity and carbon sequestration around the Kerguelen Islands. The biological carbon pump is an essential mechanism regulating the carbon balance on our planet, as it transports CO2 fixated through primary production by phytoplankton to the bottom of the ocean, where it is stored in the sediment. However, the efficiency of this carbon sink depends on species interactions on different trophic levels in the foodweb. The effects of differently structured foodwebs can be observed around the Kerguelen Islands, as there are areas with very different productivity. To investigate the relationship between oceanic biodiversity and functioning of the biological carbon pump, we used an end-to-end foodweb approach including bacteria, phytoplankton, zooplankton, jellyfish, salps, fish, seabirds and marine mammals.

​

​

​

​

​

​

​

 

 

 

 

On this cruise, I was in charge of a dilution experiment to estimate grazing rates of microzooplankton on phytoplankton. Additionally, I took samples to study infection of protists by eukaryotic parasites. This included isolation of single cells under the microscope, samples for fluorescence in-situ hybridization (FISH) and amplicon sequencing.

​

​

​

​

​

​

​

​

​

​

​

Our team of 37 scientists embarked on the R/V Marion Dufresne at the island of Reunion. After one week of transit, during which we set up the laboratories and tested the scientific equipment, we reached the Kerguelen Islands and started sampling. In total 62 rosette deployments with associated instruments such as CTD, 115 vertical tows of plankton nets and 52 pelagic trawls were carried out. Although the Southern Ocean, including the roaring 40th’s and the furious 50th’s, was relatively calm most of the time, we once had to deal with a cyclone. To be able to continue working, we took shelter in the Bay of Morbihan at the Kerguelen Islands. However, after a short reprieve we had to move on to our next sampling station despite 10m high waves.

​

​

​

​

​

​

​

​

​

 

 

 

Although most discoveries will happen during the next months in the laboratory, we were already able to observe many beautiful seabirds (penguins, albatrosses and petrels), deep sea fish and jellyfish in our trawls, and phytoplankton and zooplankton in our plankton nets. Even some wales paid us a visit, although they usually kept a safe distance to the boat so that we could only see their blows on the horizon.

This cruise represented an exciting experience for me and I really enjoyed collaborating with so many colleagues from different scientific fields. I cannot wait to start analyzing all the data that I collected and figure out how parasitism in protists affects carbon cycling in the Southern Ocean.

​

​

January 2018

A new position

After two years in Texas, I started now a new postdoctoral position at the Université du Littoral Côte d'Opal, Laboratoire d’Océanologie et de Géosciences in Northern France. I am very exciting about this opportunity, as I will get to know two new, fascinating ecosystems: the English Channel and the Southern Ocean. In both ecosystems, I will study the distribution and impact of protistan parasites on phytoplankton communities focusing especially on Phaeocystis blooms. Eukaryotic parasites belonging to the Marine Alveolates (MALV) seem to represent an important part of all phytoplankton communities, as their sequences are very abundant in all metabarcoding studies. During a cruise to the Kerguelen Islands (MOBY DICK), I will investigate the contribution of parasites to carbon export in the Southern Ocean. In the English Channel, I will study the impact of parasites on species succession through interactions with bloom forming species and their grazers.

​

​

September 2017

Hurricane Harvey

End of August, the Texan coast was hit by a hurricane of the category 4 named Harvey. A few days before it made landfall, students, PIs and staff at the Marine Science Institute started to prepare the labs and offices for the potentially devastating impact of this hurricane. Instruments were moved into cabinets and covered with plastic foil, chemicals were locked away and important equipment, such as freezers and incubators, was hooked up to the emergency generator. One day before landfall, the director of the Marine Science Institute and the mayor of Port Aransas recommended evacuation from the island.

With some colleagues, I evacuated to San Antonio, which is located 2.5 hours drive land inwards from the coast. From our safe hotel room, we observed the development and trajectory of the hurricane on the news. The north of Mustang Island, where Port Aransas and the Marine Science Institute are located, got basically hit by the eye of the hurricane. However, it took a few days before we got an idea about the scale of the damage, as it was not possible to enter the island due to blocked roads. Hurricane Harvey moved further to the west, but luckily turned around before it reached San Antonio, so we just received a bit of rain and moderate winds. Instead it hit Houston with unprecedented amounts of rainfall, which flooded the city for days.

Three days after the landfall of hurricane Harvey, we returned to Port Aransas to inspect the damage and start with cleaning up our lovely, little beach town and the Marine Science Institute. The majority of the houses in Port Aransas received severe damage.  Some houses got completely destroyed by the strong winds and the storm surge. Most houses had some water damage due to leaking roofs and windows.  Because of high temperatures and humidity, mold also infested most houses and apartments, as the air conditioning stopped working due to power outage. My own apartment had only minimal water damage, but is currently not inhabitable.

The roof of one main building of the Marine Science Institute got ripped off, which caused severe leakage on all floors. Many instruments got destroyed, walls and floors need to be restored including in my lab and my former office. I was very lucky, as most of my experiments were finished and most data already analyzed. However, several colleagues lost many samples and equipment that is essential for their future experiments. Especially, many Master and PhD students, who are on a fixed time line, have currently no idea how to continue or finish their projects. The renovation of the Marine Science Institute will likely take several months.

Luckily, Texas A&M University in Corpus Christi offered office and lab space to scientist that won’t be able to work at the Marine Science Institute in the near future. Thus, several lab groups moved to Corpus Christi and, although we can’t replicate our old labs there, we will be able to slowly move forward with our science. Most classes taught by professors from MSI will be held there as well. I'm currently located at the Harte Research Institute and work both in Prof. Paul Zimba and Prof. Chris Bird’s labs, while I try to wrap up my project. Although the destruction by hurricane Harvey was a terrible experience, the evacuation to Texas A&M University offers opportunities for new collaborations and I’m really looking forward to working with scientists here, who are also studying phytoplankton and molecular ecology.

​

​

February 2017

First paper published from my postdoc project!

Over the last months at the Marine Science Institute at the University of Texas at Austin, I developed microsatellite markers for the dinoflagellate Gambierdiscus caribaeus. This dinoflagellate genus causes Ciguatera Fish Poisoning all over the world and represents, therefore, a severe threat to humans. However, the toxicity varies significantly between algal strains of the same species. Lately, the occurrence of Ciguatera is increasing due to environmental change and spreading of Gambierdiscus. Thus, it is important to investigate the connectivity between different outbreak sites and the intraspecific diversity in Gambierdiscus species. The newly developed microsatellite markers, which were just published in the Journal of Applied Phycology, will enable population genetic studies of Gambierdiscus caribaeus and help answering such questions.

 

​

 

​

​

 

 

 

 

 

 

October 2016

ICHA in Florianópolis, Brazil

Next week (8th to 15th October), I will travel to Brazil for the International Conference on Harmful Algae, which will take place this year in Florianópolis. I will talk about my current work regarding the temporal population structure of the dinoflagellate Gambierdicus caribeaus at the US Virgin Islands. This is the first time that I will present results from my postdoctoral research to an international audience. Additionally, I will meet several friends and former colleagues from Europe and, hopefully, I will get to know many more scientists working on harmful microalgae.

After the conference, I'm going to travel to Maringá to visit some friends, who I met a few years ago during field work at the Paraná river. They offered me the opportunity to give a seminar at the University of Maringá and I'm looking forward to discuss my past and current research with scientists and students there.

​

​

April 2016

Second Prodiversa paper published!

The population genetic study of a diatom spring bloom in the Baltic Sea by the Prodiversa Nordforsk network was accompanied by an investigation of the bacterial community associated with the phytoplankton. This study was just published in the journal Frontiers in Microbiology. We found that certain bacterial groups are strongly influenced by variables directly related to the phytoplankton bloom. Some taxa were strongly associated with phytoplankton biomass, diatom-dinoflagellate ratio and colored dissolved organic matter. Additionally, some groups were linked to specific populations of the diatom Skeletonema marinoi. I am amazed that intraspecific diversity in phytoplankton, which is often very hard to detect even with sensitive genetic markers, differentially impacts the bacterial community implicating genotype specific interactions among these two kingdoms.

​

 

 

 

 

​

 

 

 

 

 

 

 

 

February 2016

Prodiversa paper published!

The big population genetic study of the diatom spring bloom in the Baltic Sea by the Prodiversa Nordforsk network is published in the Journal of Biogeography. It was a lot of fun to cruise on a huge cargo ship from Helsinki to Travemünde while sampling the spring bloom and isolating thousands of diatom cells in an enormous group effort. Thanks so much to my Prodiversa colleagues for this great experience!

We found that the Baltic Sea spring diatom bloom displayed strong spatial structure driven by oceanographic connectivity and geographical distance. Additionally, environmental gradients like salinity and silica may select for specific populations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

September 2015

Postdoc position at the University of Texas at Austin

I just moved to Texas to work as postdoctoral researcher at the Marine Science Institute in Port Aransas. I am going to study the genetic population structure of toxic dinoflagellates. How fitting that a red tide just occured at the coast! https://www.utmsi.utexas.edu/blog/entry/red-tide-confirmed-in-the-port-aransas-area

 

 

May 2015

PhD defence

After four years of hard work, I defended my PhD thesis at Lund University. I am so grateful for the support of my supervisors Karin Rengefors, Torbjörn Säll and Anna Godhe. I would also like to thank Wim Vyverman, who was a great opponent during the defence and stimulated a very enjoyable discussion. Here, you can find the introduction (kappa) of my PhD thesis.