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Aqaba, Jordan, 9.1.13 – 25.4.13

This is the start of an expedition that combines two projects of ZMTs Coral Reef Ecology Work Group (CORE): The DFG-funded project Carbon and Nitrogen fixation in Red Sea Coral Reefs in response to environmental change (CANCOR) and the ZMT-funded project Biological Interactions between Coral Reef engineers (BIOCORE). The work is carried out by the PhD students Vanessa Bednarz, Ulisse Cardini, and

Nanne van Hoytema (CANCOR) as well as PhD student Laura Rix and Dr. Malik Naumann (BIOCORE) under the supervision of Prof. Dr. Christian Wild. Both projects are combined wherever possible and carried out in close collaboration with our Jordanian partners from the MSS, particularly the station director Dr. Riyad Manasrah, Dr. Fuad al-Horani and Dr. Mamoon Alsraihdat.


Aqaba, air temperature 33 °C, water temperature 22 °C

Here we are with another post from the Aqaba crew. The time is flying by at the Marine Science Station (MSS) and, even if more than three weeks are still ahead, we feel our return to Bremen is getting closer. This, knowing how the German weather looks like at the moment, cannot make us happy, especially because of the nice and warm days we are experiencing in Aqaba. Also, a lot of tasks still need to be fulfilled before leaving.

We now successfully finished the manipulative experiment in which fragments of the hard coral Stylophora sp. were treated with increased inorganic nutrients and temperature and tested for differences in Carbon and Nitrogen fixation rates.

As we are moving into April, we are seeing the first signs of the spring bloom. Macroalgae are starting to show up all over the reef. We will continue to monitor this development in the coming weeks. The spring screening, which will give us the first results on the seasonal variability in Carbon and Nitrogen fixation rates among the key benthic organisms of the reef started earlier in the week with measurements of respiration by the genera Stylophora and Xenia.

While writing this post, two of us are collecting fragments of Pocillopora and turf algae which will also be incubated soon (Fig. 1). In the meantime, the ADCP (Acoustic Doppler Current Profiler) is logging in situ water movements, and the manta probes are deployed along the reef to test whether or not there is a gradient in turbidity, chlorophyll a, and other environmental variables due to the nearby presence of the port. Laura, for the BIOCORE project, successfully finished the sponge stable isotope labeling experiments with 13C and 15N enriched coral mucus and algal material to determine if Red Sea sponges consume coral and algal derived dissolved organic matter (Fig. 2). She is continuing to conduct sponge quadrat surveys and collect samples from sediment traps on the reef. Malik Naumann and Nanne van Hoytema performed a benthic survey along the entire Marine Park reef at 10 meters depth with video and photographs taken to gather with data on changes in benthic cover along the whole reef.

Last week, we presented our first results to the scientists of the MSS which was a good occasion to receive useful feedback for our work at the station (Fig. 3). We also hopped across the border to Eilat 10 km away on the other side of the Gulf of Aqaba to refresh our visa for the final weeks in Jordan. It allowed for a lovely day at the beach after which we are now good to go for the final weeks of work (Fig. 4).

Sunny greetings from Aqaba!

Ulisse collecting Pocillopora from the reef (Photo L. Rix)

Laura performing sponge labeling experiments (Photo M. Naumann)

Vanessa during our presentation to the MSS scientists (Photo M. Naumann)

The dense and colourful community of benthic filter feeders dwelling on the pillars of the container port


Aqaba, air temperature: 28 °C; water temperature: 21 °C

With regard to the above air and water temperature it may sound strange to readers from Germany and other regions north of here, but winter has indeed returned to Aqaba with strong northerly winds and a thin cloud cover. The past week has been the complete opposite with air temperatures as high as 35 °C and relatively high humidity. This sudden change to nearly summery conditions was caused by a temporary 180° turn in wind direction bringing in warmer air masses from the Arabian Peninsula and southern Red Sea. However, this change was not only detectable over water, but also under water by a significant increase in turbidity and thus decreasing visibility to sometimes less than 10 m (Fig.1).
Again, likely difficult to understand for our friends and colleagues in cold and momentarily snow-covered Bremen, we are actually pleased about this recent return to cooler winter conditions. This is mainly because we prefer constant winter temperatures for the cultivation and manipulation of reef organisms in our out- and indoor aquarium systems. There, the new manipulative experiment was finally started this week. It will investigate the single and combined effect of inorganic nutrient enrichment (i.e. ammonium and phosphate), and increasing seawater temperature on carbon and nitrogen fixation rates in the scleractinian coral Stylophora pistillata (Fig. 2).

This 2-week experiment requires continuous and most accurate monitoring of the treatment conditions, which is currently training the entire team well and extensively in inorganic nutrient analyses. After its completion the CANCOR team will carry on to measure carbon and nitrogen fixation of selected benthic reef organisms living on the reef at different depths and light availabilities. For that, we are at the moment collecting new specimens from different depths along the gradient.

The BIOCORE experiments to measure carbon budgets and nitrogen fixation of several abundant sponge species have been completed and the tracer experiments to investigate the role of coral mucus in sponge nutrition are now underway. During another sampling trip to the nearby container port terminal we were successful in finding additional specimens of the reef sponge Chondrilla sacciformis growing on the pillars resembling a dark forest underneath the container landing platform (Fig. 3). This cryptic sponge is also abundant on the reef, especially in reef caves and crevices, but from the port pillars it is much easier to sample without including parts of reef rock, which may affect our metabolic measurements. This is because reef rock is not only overgrown by the sponge, but is also colonized from the inside by endolithic organisms, such as algae, and bioeroding taxa, such as worms, snails and other sponges. During our sampling at the container terminal, we also were amazed by the diverse and colourful community of benthic filter feeders (e.g. sponges, ascidians and soft corals) completely covering the surface of the pillars (Fig. 4).

Actually, there is still more than one month to go in this expedition, however in our heads we are already preparing all important steps regarding logistics for the sample transport to Germany and the proper storage of our equipment over the very hot summer months here at the Marine Science Station (MSS). Now that we are again a group of five, after Malik’s return, we can coordinate and share these tasks easily within the team and with our Jordanian cooperation partners at the MSS, who are always giving their best to make our research stay as effective, successful and enjoyable as possible.

Low under water visibility during the period of warm southernly winds

The setup of the recently started manipulative experiment

Laura searching for cryptic sponges growing on the pillars beneath the Aqaba container port terminal

The Aqaba crew on the way back to Jordan after the day trip to Eilat (Photo V. Bednarz)


We are now halfway through our first Aqaba expedition. Winter is over and spring is now arriving bringing air temperatures of 25-32°C during the day, which gives us already a summer feeling. None of us wants to imagine how the real Jordanian summer of 45°C will feel during our second trip here in August!

After our incubation marathon during the first month we successfully finished our winter screening and have now data available for carbon and nitrogen fixation rates of 17 different benthic organisms and sediment cores (Fig. 1). After spending long days in front of our portable gas chromatograph injecting gas samples one by one we have almost analyzed all of them and detected nitrogen fixation activity by a whole range of different organisms. Before we start the spring screening end of March with these organisms again we will run a manipulative experiment with Stylophora sp. in the meantime. We set up 6 aquaria tanks (Fig. 2) for our different treatments with which we will study the effect of elevated single and combined nutrient concentrations (ammonium and phosphate), high temperature levels and the combination of both parameters on carbon and nitrogen fixation. The organisms were collected last week and have now some time to heal and acclimate to their new habitat. We are planning to start next week with the manipulation of the parameters, which will then in total run over a period of 3 weeks. In the meantime we have also been incubating four different species of sponges for respiration, photosynthesis and carbon uptake (Fig. 3).

Underwater: After we finished all the benthic transect work at our studied reef we went with a boat from the Marine Science Station to a more southern reef to do benthic surveys there in 1, 5, 10 and 20m water depth as well as benthic quadrats for sponge distribution (Fig. 4). The dive operator from the station took us one day on a dive with him right next to the container port. Even if the underwater structure has nothing to do with a coral reef we definitely discovered a new and suitable area for sponge collection. We have also deployed several different devices onto the reef that are continuously collecting data for us underwater. These range from high tech Manta probes that measure a variety of water parameters and the ADCP that measures water current velocity and direction to more low tech home-made sediment traps (Fig. 5). These devices provide information on changing environmental parameters for our seasonal reef-monitoring program.

After being here 2 months we have now settled into the Jordanian way of life and even our Arabic language skills are slowly improving. For the next couple of weeks our team of 4 will increase again to 5 as Malik will be arriving soon.

Greetings from the Aqaba crew,

Vanessa, Laura, Nanne, and Ulisse (WG Coral Reef Ecology)

Nanne collecting sediment cores for the winter screening incubations (Photo Laura Rix)

CANCOR aquaria for manipulative experiments (Photo: Ulisse Cardini)

BIOCORE sponge incubation (Photo: Laura Rix)

Laura conducting sponge quadrat surveys (Photo: Vanessa Bednarz)

Sediment trap deployed on the reef (Photo: Laura Rix)


Aqaba, Jordan; air temperature night: 16 °C, day: 19 °C, water temperature: 22 °C

Today we sat at the dinner table and heard the waves rolling onto the shore. For many locations close to the shore-line like the Marine Science Station (MSS) this may seem absolutely natural. However, not for Aqaba, where usually the sea is calm as a bathtub. The storm out there is strong and actually not the first one we have experienced this week. This is my 8th visit to the subtropical Aqaba surrounded by the desert, but never in these many years has the weather been that cold, rough and unpredictable. These unforeseen weather conditions have an impact on our experimental work, which also takes place after sunset. At the moment, the CANCOR team is out there taking the final measurements of a respiration experiment. In fact a great share of our cultivation and experimental aquaria are outdoor setups, which in these days deserve special attention.

Although the weather has been quite difficult, our work has made great progress during the last week. Our missing equipment has arrived with the sea freight from Germany and we were finally able to build up our complete field laboratory in the MSS. After some minor difficulties at the start, the GC is now working like a charm. The first seasonal screening of benthic reef organisms for carbon and nitrogen fixation rates is well on the way, and the first samples from these experiments were analysed. For this, all dominant functional groups of benthic organisms and substrates have been sampled from the reef and incubated in time series experiments (Fig. 1). To measure nitrogen fixation via the acetylene reduction assay, we freshly produce acetylene from calcium carbide, a vivid chemical reaction that sometimes attracts an audience (Fig. 2). Also the stable isotope labelling experiment to produce labelled coral mucus has been finished successfully (Fig. 4). The coral mucus is now further processed to be used as a substrate in subsequent uptake experiments with reef sponges.

This week, the delicate sponges in our aquaria had a hard time. Due to a power outage, air bubbles were introduced to the water circulation, which were taken up and accumulated by the sponges. Most of the species we culture were affected by this, some even started to float. Also, the storm caused significant resuspension of sandy sediments in near shore waters, from were the aquariums are fuelled. Some of the resuspended sand was eventually pumped into the sponge aquaria, which however was obviously no problem for any of our sponges.

Underwater: After finishing the collection of the first round of benthic organisms for the screening and labelling experiments, we have now nearly completed all benthic transect surveys in the Northern part of the reef (Fig. 4). For the Southern part we will depend on boat transfer by the MSS staff, which is scheduled to start by the end of this or next week. We have deployed several Manta 2 multiparameter probes to monitor seawater chemistry and community metabolism at specific locations in the MSS reef. In addition, we have installed an accoustic Doppler current profiler (ADCP) to measure velocity and direction of the movement of water masses in the MSS reef (Fig. 5). Information on water movement inside and over the reef are esssential to calculate and model biogeochemical exchange processes between the benthic and pelagic reef compartments, as well as between reef and open ocean waters.
From tomorrow on the ZMT team will be reduced to 4 members, as Malik Naumann is leaving Aqaba to return to Bremen and takes with him a load of precious samples produced by the first round of experiments to be analysed at the ZMT and in other cooperating institutes. The weather forecast for Aqaba is not too positive, but we hope for the best and no rain.

Gas samples for ethylen analysis are taken at specific time intervals to test the incubated organisms for rates of nitrogen fixation. (Photo: M. Naumann)

Mushroom corals are fed with stable isotope enriched bicarbonate and nitrate to produce a label in the mucus released by these corals. (Photo M. Naumann)

Acetylen production from calcium carbide is a joint sunset activity. (Photo: M. Naumann)

The lionfish (Pterois spp.) is always a curious companion underwater, for example during transect works. (Photo: U. Cardini)

An accoustic Doppler current profiler (ADCP) was deployed for continuous measurements of water movements in the MSS reef. (Photo: M. Naumann)

18. - 21.1.13

Today’s blog entry features an outside-perspective of science author Bernhard Kegel written during his one-week stay at the Marine Science Station Aqaba:

Weekend is coming. The people of Jordan will elect a new parliament and except from the busy ZMT-researchers the Marine Science Station seems almost empty today. Some Jordanian families visit the aquarium, another one is inspecting the picnic area just in front of the Station and is now sitting around a table below one of the blue sun bleached corrugated metal roofs having lunch. No comparison to yesterday. “We allow the people to come in”, said the young Jordanian scientist, who picked me up in downtown Aqaba. Thirty or more small school or kindergarden kids conquered the area, running around and screaming and laughing like all kids in the world and turning the scientific station at least acoustically into a playground.

The station is empty, but it isn’t quiet at all. The noise, the roar, of the ferry harbour is present all the time. One truck after the other is leaving the Queen Nefertini or the Amman and rolling over the bridge on to Jordanian ground. Announcements, so loud as if they were aimed to the people of Eilat on the other side of the northern Red Sea, were shouted every ten or fifteen minutes, sometimes mixed with the calls of the muezzin. The harbour delivers the acoustic environment of the five ZMT-scientists, who work hard to get their things going.

In a great moment a few minutes ago they unpacked the gas chromatograph, the GC, as they call it, one of these amazing high-tech-black boxes (actually it is turquoise), which can do things earlier generations of scientists could only dream of. To have this machine here in Aqaba is very special. Normally it is almost impossible to store and transport gas samples over a longer period of time without losing some of its contents. Now they have it here, right at the sea side, just a few meters apart from the reef and its organisms. It will enable the young researchers to do measurements, which have never been done before. Two of the researchers depend on the GC and I could feel their excitement, when they lifted it out of its containment, placed it on a table and connected it with the synthetic air cylinder.

I feel a strange inadequacy. Two hundred meters apart thousands of tons of steel are moved and this little machine here in the lab will measure ppb’s and ppm’s of diluted gases in the seawater helping to solve the riddle, what happens to the nitrogen when it passes through the body of tiny corals and their even tinier symbionts. I learned, corals are holobionts, like we are. One to two kilograms of our body weight are contributed by billions of microbes. In the coral holobiont algae fix carbon and bacteria fix nitrogen.

Silence is only under the water, when you are alone with the reef and the sounds of your breathing (if there wouldn’t be the harbour where they started to ram huge steel pillars into the sea ground. It hits the divers really hard. ). Yesterday and today the scientists collected the organisms they want to work with: corals, sponges, algae and jelly fish, representatives of the reef. Happy faces, when they carry them out of the water. The main actors enter the scientific stage. Biology is about organisms, everything else, even the expensive and sophisticated GC, is just a tool. Hopefully sea life will cooperate. You never know. Some of the sponges, a grey and very abundant species, don’t. Unwillingly transferred from the sea to the wet lab, they closed all their little openings and stay like this for hours. “They don’t look very happy”, Laura says.


When you “just” write about science, as I do, you normally think in terms of questions and answers, experiments and results. You forget about the long, long way in between and the many small problems scientists have to solve, before they can really start, especially in a place like this. At least half a year of planning, discussing, ordering and preparing ended when they flew to Aqaba with a lot of scientific luggage. And here a new period of preparations began. Leaking outflows need to be fixed, first with the wrong, then with the right silicon, a door handle broke, distilled water is missing, the sea water pumped into the aquariums is too warm. The grey sponges are dying in their artificial environment and need to be replaced by a different species, which hopefully do better. Yesterday the laboratory equipment, which came by ship, was delivered. Now, almost two weeks after their arrival, they start the first measurements.

When the GC and the gas cylinder were installed in the Benthos Lab it could not be switched on, because the plug didn’t work. So the whole equipment was moved to a different table. Then the display showed some strange values. In the evening everything was fine, but during the night they lost 15 bar of air out of the cylinder. The connection to the GC was leaking. You could hear it: Pffff … , probably a very nasty noise in the ears of Ulisse and Vanessa. Help came from Aqaba rather quickly, but still the peak of ethylene is not there where it’s supposed to be. Why? Polluted carrier gas? Different temperature? Emails were sent to Bremen and Hawaii, where the company, who built the GC, is situated. But it was weekend. Waiting, filled with a lot of other work. Then the answer came, with more or less new questions. At least they got their standard probes now with the laboratory equipment. New test measurements will start in the afternoon.

“It’s normal”, says Malik. OK, it may be normal, but you have to stay in good mood, you have to be optimistic. During lunch (bread, tomatoes, feta cheese presses as white worms out of little boxes) they talk about the sampling during the afternoon dives, who will do what, about the incubations, what should be done first and when. During dinner (original Spaghetti carbonara Jordanian style) they talk about the mucus production of their corals, during breakfast they discuss, if their oxygen measurements are salinity corrected. I wonder what they dream of during the nights.

Bernhard Kegel, “embedded writer” at the ZMT

The ferry port of Aqaba close-by the Marine Science Station

Vanessa, Nanne and Ulisse unpacking the GC

Vanessa and Ulisse when the GC produced its first result

Good-bye dinner with Bernhard Kegel at the Ali Baba restaurant


Aqaba, Jordan; air temperature night: 19 °C, day: 25 °C

Our first full week at the Marine Science Station (MSS) has been a pleasant and also quiet busy one. The weather has changed for the better and the air temperature is now steadily increasing. We have been warmly welcomed by the entire MSS staff after a long Jordanian holiday weekend and some of us met some old friends and collaborators. In the beginning of the week, which is Sunday in Jordan, we presented our planned research projects to the director and scientific staff of the MSS, followed by a lively discussion with the attending audience. On Thursday, unfortunately Christian Wild already had to return to Bremen. However, we are still a team of six, as Bernhard Kegel, a German science author, has joined us to spend one week in the field gathering impressions for one of his new books.

The setup of our work places has progressed rapidly during the last few days. While we are still waiting for a large part of our equipment to be delivered to the MSS via sea freight, the field laboratories and aquaria facilities are nearly completed. Outdoor cultivation aquaria and incubation setups for benthic reef organisms have been constructed and a large indoor aquarium setup for reef sponges has been installed (see picture). And, most fortunately, our precious portable gas chromatograph has been setup up in the lab and is running a test phase now.

Below the water surface, we have continued the benthic transect studies to characterize the community composition of the MSS reef. We successfully sampled the first three genera of scleractinian corals and several specimens of the upside-down jellyfish Cassiopeia to be investigated by CANCOR. For BIOCORE we collected Fungia mushroom corals and specimens of at least four species of reef sponges, now being cultivated in the respective aquarium systems in- and outdoors. In addition, we extended the environmental monitoring program by deployments of light and temperature loggers and by taking water samples for organic and inorganic nutrient analyses.

During the next few days we expect to receive our missing equipment to finalize the field laboratory to be fully operational and are planning to conduct the first physiological experiments on carbon and nitrogen fixation as well as coral isotope labelling.

The ZMT team meeting the scientific staff of the Marine Science Station Aqaba

One of the two indoor sponge cultivation system with sponges in the lower two aquaria

The portable gas chromatograph was set up in one of the MSS laboratories

The first coral colonies are prepared for the acclimatization period


Aqaba, Jordan; air temperature night: 5 °C, day: 15 °C

We started the underwater work with an orientation dive to show all the new CORE members the MSS fringing reef. This revealed that hard coral cover obviously went down since our last visit and clearly more soft corals now occur. We will confirm these first observations by quantitative benthic surveys in the next couple of days. In addition, the environmental monitoring commenced with the in-situ deployment of our multiparameter loggers that are able to simultaneously measure and record important water parameters such as temperature, pH, oxygen concentration, turbidity and chlorophyll concentration.

Above the water, we now started to set up our outdoor aquaria for the maintenance of several reef organisms (including corals, sponges, and algae).
Unfortunately, we were still not able to set up our precious gas chromatograph in the indoor laboratories, because the station - after the two days exceptional winter holidays - is now again closed because of the regular weekend that already starts on Friday in Arab countries.

The air temperature is still chilly, but in the water it is warmer than expected with still 22 °C, so we now try to spend as much time there as possible;-).

The CANCOR-BIOCORE team under water

Nannes setup to measure biological oxygen demmand

Vanessa doing benthic transect surveys

Construction of outdoor maintainance aquaria in progress


Aqaba, Jordan; air temperature night: 3 °C, day: 14 °C

Because of a heavy snow storm in Amman (the airport area looked like a Swiss skiing resort; see picture) with pronounced delay, we arrived not yesterday evening as planned, but only early this morning at 2 am at the Marine Science Station (MSS) in Aqaba, Jordan. The temperature was so cold that it was impossible to believe that we are going to do research in a typical tropical ecosystem such as a coral reef during the next 14 weeks.

However, after sleeping a bit, we were welcomed by a blue sky and lots of sun, a sharp contrast to the grey weeks in Bremen before. The Red Sea looked like a peaceful lake with no waves, and we were excited by the turquoise, clear water and by going diving soon. We then visited the town of Aqaba (10 km North of us) to buy the stuff required for our living at the station. This was not that easy, because most of the shops were closed due to the winterly conditions in Jordan.

After return to the station, we inspected the new wet laboratories of the station and started to unpack our equipment, including a brand new portable gas chromatograph (see picture) that will hopefully allow us to directly measure nitrogen fixation rates of different coral reef organisms.

We will regularly report at this place about our experiences, observations and first findings over the entire expedition period until April 25th. Best greetings from the cold Red Sea!

Prof. Christian Wild, Dr. Malik Naumann, Vanessa Bednarz, Laura Rix, Ulisse Cardini, Nanne van Hoytema, WG Coral Reef Ecology (CORE)

View at Amman airport area from the window of our plane waiting for take off

The beach in front of the MSS with a view to the Israelian Red Sea coast

The main mosque of Aqaba

The Combined CANCOR-BIOCORE team caressing the portable unpacked gas chromatograph