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This is the first blog report from the ongoing collaboration between ZMT and the University of Giessen. Collaboration started with the inauguration of the German Academic Research Service (DAAD) Center of Excellence in Marine Sciences (CEMarin) in October 2010 in Santa Marta, Colombia. Afterwards, two PhD students (Corvin Eidens and Elisa Bayraktarov) started their projects on coral reef functioning in the Colombian Caribbean. Since September, their work is supported by Julian Rau, an ISATEC master student from University of Bremen and ZMT.

All three projects deal with the coral communities and reefs in four bays located within Tayrona National Park, Southeast of Santa Marta. Main goal is to identify the key environmental parameters that control the functioning of these highly diverse locations. One of these factors may be the seasonal upwelling that usually occurs between December and April and transports cooler water from greater depths to the surface.

Elisa is mainly studying the water chemistry (temperature, pH, inorganic and organic nutrient, chlorophyll and oxygen availability as well as

turbidity), microbial processes (biological oxygen consumption of water column and sediments) and sedimentology (permeability, porosity, grain size, organic matter and carbonate content) in high spatial (8 stations) and temporal (monthly) resolution over a period of two years in total. She is also investigating coral bleaching patterns over space and time.

At the same time, Corvin is conducting supplementing studies at identical locations, thereby investigating benthic and pelagic community composition, primary production patterns, sediment-water coupling, coral-algae interactions and coral physiology.

Finally, Julian now starts to study succession and recruitment patterns on the seafloor and how this depends on the occurrence of pelagic and benthic herbivores, i.e. fishes and invertebrates that feed on algae. This will be a combination of descriptive and experimental studies.

All projects thereby are tightly interlinked, which offers the opportunity to generate comprehensive parallel datasets that enable us to understand functioning of these complex Caribbean coral reefs.


Bleaching monitoring
Air temperature 28°C, water temperature 24.5°C, wind speed 20 km/h, and raining

Today we had our last monitoring in the bay of Gayraca and finished the third coral bleaching campaign which had started in December last year. It was raining during the field trip, which was quite unusual, as it is currently major dry season. Normally rainfalls start end of April/ beginning of May for the Tayrona Park region.

This time, the researchers from the Colombian coral reef monitoring group “SIMAC”, Johanna Vega-Sequeda and Kelly Gómez-Campo, joined our field trip and helped with transect work. We found most of the corals in Gayraca bay in a very good shape. Corals that had experienced bleaching (less than 5 %) or were pale in December last year had already recovered. We also observed that the affected Colpophyllia natans colonies which we had marked last year had accomplish recovery at both sites of the bay or were still in the process of recovery at the sheltered site.

This was the last field trip of Elisa's project which had started in October 2010. We look back to an exciting time, plenty of new valuable experiences and challenges, great researchers that have collaborated with us during our investigations and a lot of new German-Colombian friendships! Thanks to all of you for a great time in Colombia!

04.03. - 08.03.13

After the last long term monitoring field trip in February, Elisa had a quite busy week in the lab. The filtered and frozen water samples that were collected in February had to be thawed in order to determine the concentrations of the inorganic nutrients nitrate, nitrite, soluble reactive phosphorus and ammonium. Therefore, reagents are added to the water samples which react with the dissolved nutrients to a color complex. In case of nitrate, a reduction of nitrate to nitrite has to be performed by a reducing cadmium column prior to reagent addition. The absorption of color complex can be measured by a spectrophotometer at a specific wavelength and gives the possibility to calculate the actual nutrient concentration after determination of a calibration curve by known nutrient standard solutions.

In addition, the dried sediment samples collected for the analysis of particulate organic carbon and nitrogen were homogenized by a manual porcelain mortar and stored in pre-combusted glass vials. These samples are now ready for their final analysis in the laboratories back home.

19.02. - 21.02.13

Air temperature 32°C, water temperature 25.2°C, and wind speed 45 km/h

This week we had the last monitoring for our long term project in Tayrona Park. Two years of field work and collection of data have passed in a flash.

Weather conditions were rough as usual during the season of strong winds and coastal upwelling. Interestingly water temperature was quite warm as compared to the same time period in the last couple of years. Minimal water temperature of values below 21°C was offset to the beginning of January this year while coldest temperatures have been usually detected for February during the last years.

This time, once again, we received help from the CEMarin student Juan Felipe who gave a hand in filling the 4 l plastic containers with water from 10 m depth. We additionally invited the INVEMAR researcher Raúl Navas to our field trips. Raúl is member of the Colombian coral reef monitoring group “SIMAC” and was particularly interested in the locations of our transects for benthic cover monitoring within the four bays. He had the idea to continue with data collection on benthic cover changes along the transects in the near future. After each sampling and subsequent removal of temperature loggers from the reef, we indicated the locations of the established transects and handed our underwater maps over to Raúl.

During our dives we met some interesting reef creatures such as the Spanish lobster trying not to pay too much attention to our activities and a green moray which was finishing its morning hygiene. We were not surprised that even during our final dives we met our well known gatecrasher – the lionfish.

Currently, we have acquired a large data set on the major environmental parameters of water column and sediment surface from 8 locations in four bays. However, a large number of samples such as for chlorophyll a, particulate organic carbon and nitrogen still wait for their analyses in the laboratories back in Germany – there is still a lot of work to do!

15.01. - 17.01.13

Air temperature 30°C, water temperature 23.2°C, and wind speed 40 km/h

Currently, it is major dry season. We detected drastically decreased seawater temperature which is characteristic for coastal upwelling in the Tayrona National Natural Park. Wind speed reached record velocities of up to 40 km/h. However, we were able to reach our survey locations and sample all necessary environmental parameters, except for current dynamics by ADCP.

Underwater currents were exceptionally strong and it was difficult to hold diving position – for example during deployment of Clod Cards. Our team for the field trips in January consisted of Juan Felipe; Luis Alonso – a researcher from Invemar, and Elisa.

24.12. - 26.12.12

Air temperature 32°C, water temperature 26.2°C, and wind speed 20 km/h

The long term monitoring field trips in December were joined by an officer of the Tayrona National Natural Park (TNNP) authority. We were asked to give a hands-on introduction of our work and monitoring methods, and indicate the permanent transects at the sampling locations.

On Tuesday, we realized that the strong winds from the northeast started earlier this year than in the previous two years. This affected our field trip by large waves and strong currents. Consequently, due to security reasons, we were not able to sample the exposed site in Chengue Bay. Harsh weather conditions complicated also our second field trip on Thursday. However, we could complete the samplings without any losses. The internship student Javier carried the last monitoring on Lion fish abundance in the bays of TNNP.

08.12. - 14.12.12

Bleaching monitoring
Air temperature 33°C, water temperature 26.3°C, and wind speed 20 km/h

In the first two weeks of December, we started the third coral bleaching campaign for Gayraca Bay in the Tayrona National Natural Park. This time Elisa was accompanied by a team consisting of Prof. Valeria Pizarro and her student Vanessa Carillo. Once again the survey comprised a monitoring of the corals along permanent transects at the exposed and the sheltered site of the bay. Colpophyllia natans were identified to be the predominant bleaching species this year. Additionally to line transect monitoring, we surveyed photographically 10 previously marked C. natans coral colonies at the exposed site and compared them to 10 colonies of the same species at the sheltered site.

Preliminary results from line transects show that most of the corals in Gayraca Bay are doing quite well – bleached corals accounted for less than 5 % of the total coral cover. However, we will continue to monitor the bleached C. natans colonies during the following months.

13.11. - 15.11.12

Air temperature 31°C, water temperature 28.4°C, humidity 60 % and wind speed 10 km/h

We have enjoyed another two great field trips for our project on the long term monitoring of Tayrona Park bays. And this week, everything was perfect! The hurricane season is over and we had two beautiful, sunny days. The water was much clearer than during last month. A fisherman told us that on days with particularly clear water and a soft breeze, dolphins sometimes come closer to the bays to feed and play. And indeed, on Tuesday morning, when we were just arriving to Gayraca Bay, a school of dolphins approached and started a race with our boat. Of course they won without the slightest exertion.

During both field trip days, we could accomplish our sampling on time and without any problems. No troubles with weather and waves, no hurricanes, no changes in the time schedule – days like these are usually rare in the tropics!

On Thursday, after finishing our monitoring and preparations for the water & sediment respiration measurements on board, we decided to clean up our sampling locations in Gayraca a bit. The strong guys Juan Felipe and Carlos – a researcher from the Oceanography Group of Invemar who currently helps out with the deployment of ADCP in Gayraca Bay – rescued the two heavy buckets filled with cement which were once used as current meter docking stations. The 60 – 70 kg buckets, which were deployed at a depth of 10 m in February, were first fastened underwater with the rope of a surface buoy and later pulled by Juan Felipe and Carlos on board. Now we are looking for a recycling idea of the heavy buckets.

23.10. - 29.10.12

Air temperature 27°C, water temperature 29.5°C, humidity 90 % and wind speed 5 km/h

On her return from Germany to Santa Marta, Elisa realized that the main part of the rainy season has already taken place for Colombia. The streets of Santa Marta were filled with dirty water up to the knees and it was not a surprise to find the own rented apartment flooded in the evening after work.

Our field trips for the long term monitoring project in Tayrona Park were scheduled for the 23rd and 25th of October. On the 23rd, we visited the bays Cinto and Neguanje, stopping by in Gayraca to submerge the ADCP current meter at the exposed and insert the sediment falls and Clod Cards at both sites of the bay. The water was greenish and low visibility troubled our work. We measured a transparency of about 3 m Secchi depth for most of the sampling locations. Nevertheless, we could find and read out all temperature loggers and collect the remaining samples required for the monitoring.

On the way back to the laboratory, we suddenly realized that the wind was getting stronger and stronger – and this time it seemed to be unusually blowing from NW instead of NE. Later at night, strong rainfalls started without any warning. The waves seemed to increase with every passing minute. During the following day we received the information that the harbor of Santa Marta restricted the departure of every single boat in the region for the rest of the week due to severe bottom currents, dangerous waves and stormy conditions. The situation became critical for our planned field trip on the 25th. Later, after revising the web pages of the National Hurricane Center of the National Oceanic and Atmospheric Administration (NOAA), we became aware of the culprit responsible for the rough conditions of the Colombian coast: Most probably the stormy ocean and heavy rainfalls were a consequence of the formation of the tropical cyclone “Sandy” which was traveling toward Jamaica during this day and devastated the eastern coast of USA only some few days later.

After days of hoping for better weather conditions, we finally could realize our second field trip to Chengue and Gayraca on Monday, the 29th of October. But not completely without losses: Unfortunately we found the deployed Clod Cards in the Bay of Gayraca completely dissolved as far more than 48 h have passed since they have been inserted. Also the water from the sediment falls was turbid and dark after six days and the filtered material was several mm thick on the filters. Due to logistic issues and overlapping field trips we also had to abandon the option to measure the current regime at the sheltered site of Gayraca. We can only hope that the season of high storm and hurricane incidence will be over soon.


Coral Spawning in Gayraca Bay

This week the Colombian professor, Valeria Pizarro, from the University Jorge Tadeo Lozano (UJTL) in Santa Marta invited volunteers to help out in her project on coral spawning observation, gamete collection and laboratory work. In total, seven volunteers (Elisa and Stefan from Germany volunteered) were part of the 12 people research group. The project “Rearing Montastraea faveolata larvae, embryos and recruits as a possible coral restoration strategy”, funded by the UJTL with collaboration of the Tayrona National Natural Park (TNNP), aims to raise coral embryos in the laboratory until the corals are juveniles and to transplant them back to the reef areas.

To accomplish this aim on September 6th the research group headed to Gayraca Bay, the area chosen to collect the gametes. Before sunset, at around 4:00 pm, we placed gamete traps above 15 M. faveolata colonies. These traps consisted of a conical mesh that maintained its vertical position due to a buoy. Traps were fixed to the bottom by tying ropes to rocks or nails. At the end of the conical mesh a plastic vial was placed for the gametes to be collected. Additionally, the areas containing gametes of all tagged colonies were measured. These measures along with the measurements done on the corals before spawning will be used to determine the fecundity of each colony.

Before the spawning event, that occurred between 21:40 and 22:10, all the volunteers and the research team set up the materials needed for the cross fertilization at “Playa del amor” where a field laboratory was installed for the day. We jumped into the water at 21:20 to observe the spawning, took the mentioned measurements and time of spawning and collected the gamete bundles after spawning was over. Coral gametes were collected in vials in the upper end of the traps and closed firmly with lids. Back in the field laboratory several filtration steps separated first zooplankton from gametes and then eggs from sperm, followed by a cross fertilization trial to avoid self-fertilization. After that the samples were transported back to the laboratory at the UJTL. On our way back we realized that the night was just magically perfect for a coral spawning to occur; the air was clear and the sea calm without a single breeze. Water temperature was 29°C.

In the laboratory all volunteering students helped Valeria with counting of thousands of perfectly rounded, viable eggs by stereomicroscopes until the late morning hours after a sleepless night. The quantity of fertile eggs was quite promising. At the end of counting all student volunteers were exhausted but happy about their hands on experience in coral reproduction.


Back in the lab we set up the material necessary for filtration and samples preservation after field trips. Within our measurements on respiration of Microphytobenthos community in sediment samples that we took from the first surface cm, we noticed repeatedly the difference between the exposed and the sheltered sites: Respiration was always higher in sediment samples from the sheltered sites of the bays which were also correlated with finer sediment. In contrast, at the exposed sites we found larger sand grains and less respiration. It seems that the increased turbulence at the exposed sites impedes settlement of finer sediment.

14.08. - 16.08.12

Air temperature 28°C, humidity 80 %, wind speed 10 km/h

The rainy season in Santa Marta arises with strong rainfalls and tropical storms which form hurricanes on their way over the Caribbean Sea. For our last field trips to Chengue, Gayraca, Neguanje and Cinto, we received some help from the German student Stefan who is currently doing an internship at the coral reef group of the Colombian host institute.

Thick clouds covered the sky and low visibility complicated our sampling. On our way back it started to rain heavily and we were relieved to have finished all measurements on board before the storm. Back at the institute we observed that there was at least someone enjoying the stormy weather – the pelicans on the trees around the institute were glad of heaving their freshwater bath.


Air temperature 31°C, water temperature 28°C, humidity 70 % and wind speed 20 km/h

The Oceanography Group of INVEMAR asked Elisa for help with a test deployment of the new Acoustic Doppler Current Profiler (ADCP). The equipment was obtained as a second current meter and replaced the old “Aquadopp” that has experienced some connection problems. The new ADCP is able to measure the current velocity and direction in all water layers above the sensor head as well as the wave heights. The test deployment of the ADCP was successful and the Oceanography Group motivates us to apply the new setup in our monitoring in Gayraca Bay.

19. - 21.06.12

Air temperature 31°C, water temperature 28°C, humidity 70 % and wind speed 15 km/h

At the beginning of June we introduced our new internship student Javier Alarcon. Javier is one of Valeria Pizarro´s students from the University Jorge Tadeo Lozano and is currently working on his BC thesis in Marine Biology. Colombian students have the possibility to choose between an ordinary BC thesis and a “professional internship” at an institute in order to achieve their BC degree. We offered Javier the activity of Lion fish monitoring in the Bays Chengue, Gayraca, Neguanje and Cinto from June until he finishes his internship in December 2012. He will also help with the field trip preparations, filtration work and samples preservation during the following months.
On 19th of June we went to the bays Chengue and Gayraca to conduct our sampling for the long term monitoring project and introduced Javier to the Lion fish survey showing him the marked buoys at the beginning and at the end of each transect of 50 m length. On 21st we visited the bays Cinto and Neguanje. On the way to Cinto, we stopped in Gayraca to recover the sediment falls and gypsum bodies which were deployed at each side of the bay around 48 h ago. Gypsum bodies or Clod Cards already show a clear difference between the exposed and sheltered site of Gayraca. We were also able to see a difference between gypsum dissolution during dry and rainy season which is an indicator for differences in water motion.


Air temperature 30°C, water temperature 27°C, humidity 85 % and wind speed 10 km/h

Today was the expedition to Gayraca, sheltered site, where we performed the last sampling for the succession and recruitment project. By this time, the experiment has covered periodical samplings during the whole dry season. As Julian has already left to Germany, we followed his exact instructions to collect tiles with algal growth from the setups with and without cage as well as from the cages which were open on both ends. Tile samples were brought back to the lab for further preservation which basically consisted of scratching off all algal material on the top side of each tile.
The whole underwater setup consisting of a total of 9 boxes was removed from the sea floor by lifting 3 at a time by fixing them to the rope of a surface buoy. We used the surface buoy to give signals to the boat driver indicating him when to lift the boxes.

12. - 20.04.12

Bleaching monitoring
Air temperature 30°C, water temperature 26°C, humidity 80 %, and wind speed 10 km/h

Weather conditions are changing around the area of Santa Marta and Tayrona Park. We observed that the wind has decreased since two weeks and the sky is more often covered with clouds. We are in the transition time between dry and rainy season in the Caribbean Colombia.

Our last field trips were dedicated to proceeding with the Bleaching Monitoring of corals in Gayraca Bay – we received some help from the Colombian coral reef monitoring group SIMAC (Sistema de Monitoreo de Arrecifes de Coral). This was our fourth monitoring campaign which focused this time on the recovery of corals after the minor bleaching in December 2011. In December we had observed that 6 % of the corals from the transects were bleached on the exposed site of Gayraca Bay, whereas at the sheltered site it was only 4 %. The content of pale corals was more pronounced at the sheltered site than at the exposed site. Additionally to transect work, we had marked 9 – 10 coral colonies of the species Siderastrea siderea, Colpophyllia natans and Diploria strigosa that showed some bleaching in December 2011 at the exposed and sheltered site of the bay. Our monitoring had revealed that the species most affected by bleaching was S. siderea at both sites of Gayraca but with more bleached colonies at the sheltered site in December 2011. Half of the C. natans colonies at the sheltered site were bleached whereas bleaching of this species was rather negligible at the exposed site. D. strigosa showed some bleaching for the sheltered and no bleaching for the exposed site in December 2011.

Luckily, almost all of the affected corals have recovered during the upwelling season from December 2011 to April 2012 as we observed during our last field trips. Only the coral S. siderea still showed some bleaching at the sheltered site with the occurrence of the coral sickness Dark Spot Disease.

It is now time to understand what caused the moderate-heavy bleaching in December 2010 with mostly Montastraea feveolata and M. franksii affected and how conditions have changed by December 2011 during which bleaching was observed to be rather negligible in the Bay of Gayraca.

20. - 31.03.12

Air temperature 31°C, water temperature 25°C

In order to quantify benthic primary production in Tayrona Park at the end of the upwelling season 2011/2012 we started out to Tayrona Park. This time, Till Deuß, a master student from JLU Giessen who studied and worked several months in the area completed our group. The 20th we mounted the equipment for our nearly two-week stay onto a pickup taxi and set off for Gayraca Bay with stopovers in Taganga, Mamatoco, and Bonda to get SCUBA tanks, blocks of ice, and pick up the cook and groceries. After three hours, we arrived at Gayraca Bay, loaded our equipment in a local fisherman’s boat and headed for the Playa del Amor.

At Playa del Amor we immediately set up our field lab and arranged everything for the coral sampling and fragmentation the next day. Data loggers were brought out to measure temperature and light intensities at the investigation sites in 10 m depth on the exposed and sheltered side of the bay. Johanna Vega, a researcher from Invemar, joined our group in the afternoon to help during the following busy days.
The next day, we dived first at the exposed site where the severe storms in December took all our coral samples. We collected specimens of the most abundant coral genera Diploria and Montastraea, brought them to the beach were Till immediately started fragmentation with a battery-operated rotary tool and glued them on ceramic tiles. In the afternoon, we also sampled corals at the sheltered site of the bay and samples were treated the same way as specimens from the exposed site.

Due to problems with the coral glue, we were not able to return the corals the same day, so we temporally stored them in a little cave next to the beach. We also had time to do benthic surveys at the exposed site of the bay.
The following day, we returned the fragments and read out the data logger. Furthermore, we sampled rubble overgrown with algal turfs and macroalgae. After the dive we performed our first incubations at the beach with the turf samples.
A boat from INVEMAR visited us for lunch that day and Johanna took the chance and returned with the boat to Santa Marta in the afternoon after helping us a lot the last days. Before she headed for Santa Marta, we used the time to conduct the benthic surveys at the sheltered site.
On Friday morning, Julian arrived at the Playa del Amor after conducting lionfish surveys in the bays of Cinto, Neguanje, Gayraca and Chengue and his sampling of the succession and recruitment experiment the previous days. Straight ahead, we went diving to obtain the coral samples from the sheltered site that were fragmented during the first field trip to Gayraca in April 2010 and survived the stormy weather in Dec. 2011. We hurried to clean them in order to conduct the incubations that day. Luckily, together with the help of Julian we were able to conduct coral incubations and at the same time incubations of macroalgae. After the dark incubations we put the fragments in the same cave which we used for the newly fragmented samples. After conduction of all planned coral incubations, the coral fragments were not returned to their original habitat, but were transferred to a newly established coral nursery in Gayraca Bay. These corals will now be used for a joint venture coral restoration program between Universidad Tadeo Lozano, the National Park Authority, and a local dive centre.

The next days, when the weather permitted, we sampled other dominant benthic primary producers, namely crustose coralline algae and sand-inhabiting microphytobenthos, and performed their incubations. One week after returning the newly fragmented corals, we got the samples, performed the incubation experiments and afterwards incorporated them into the coral nursery.

After 12 days of being at this marvellous place, we had to return back to civilisation, but not without planting a little mangrove tree at the Playa del Amor.

16. - 20.02.12

Air temperature 30°C, water temperature 23.7°C, wind speed 25 km/h

Based on our experience, it seems that one very important ecosystem controlling factor is the underwater current in the bays of the Tayrona Park. The hydrodynamics in the bays are enhanced during the season of Trade Winds or dry season. As a consequence, also the differences in currents between the exposed and sheltered site of the bays are much more pronounced. We wanted to know more about the underwater current regime.

First experiments with Clod Cards, simultaneously deployed for 48 h at a depth of 10 m at the exposed and sheltered site of the Bay of Gayraca have already provided highly significant results; there is no doubt that the currents at the exposed site were stronger than those at the sheltered site! At least we can state this from observations for the months of January and February… We will keep track on this behavior and include Clod Cards in our monthly routine sampling work for the Bay of Gayraca.

Talking about this interesting current behavior and the first results with Clod Cards, we were still wondering whether other and more accurate ways of underwater current determination were available. Our questions and preliminary data raised interest in the Oceanography Group of the Colombian Institute Invemar. We were informed that the group has an Acoustic Doppler Velocimeter (ADV) of the type “Aquadopp”. The Aquadopp is a current meter which uses the physics of the Optical Doppler Effect of moving particles in the water column to calculate velocity and direction of underwater currents. Therefore the sensor measures the Doppler shift occurring, when sound pulses are transmitted and received after reflection on small particles within the water column.

We decided to make a first attempt to measure the currents with the ADV technique. Our team consisted of Martha Bastidas, group leader of the Invemar Oceanography; David Morales, Geologist; Maura Maruri, internship student and helping diver; the CEMarin student Juan Felipe; Julian and Elisa. The Aquadopp from the company Nortek looks like a 60 cm long cylinder having its three sensors in the upper or “head” part. Deployed at a certain depth, it can measure the water current velocity in a single volume above the sensor´s head. In order to achieve a secure deployment of the sensor at our sampling locations, we constructed an Aquadopp-docking-station consisting in a bucket filled with heavy cement in which a PVC tube with the sensor dimensions was inserted. On the 16.02 we deployed the first docking station at the Bay of Gayraca, the exposed site.

Afterwards the Aquadopp was inserted by divers into the station and measurements of the current characteristics allowed during the time of 10 a.m. to 3 p.m. On the 20.02 we deployed a second docking station on the sheltered site and subsequently measured the current dynamics from 9 a.m. to 2 p.m. Even if simultaneous measurements in the exposed and sheltered site are not possible with only one Aquadopp, there is still the possibility to compare the hydrodynamics if the current regime is recorded during equal tidal phases. We are looking forward to the detailed data analysis with Martha´s help which will show us whether measurements with the current meter were successful!


In the last week of January we conducted the first lion fish surveys. Counting and size estimation of individuals was done at 10m depth along transects (3x50m at the sheltered side, 3x50m at the exposed side) in the bays of Chengue, Gayraca, Neguanje and Cinto. Transects are the same as the ones used for the benthic survey conducted by Corvin. With a width of each transect of 5m, an area of 6000m2 in total is surveyed every month. Size estimation can be done quite precisely by means of a scale (5cm-steps) indicated on a white metal stick. Due to its fearless nature one can measure the lionfish under water quite smoothly.

We counted 24 individuals, leading to 40 ind./hectare. The average size of 27cm shows that individuals detected were mainly quite big adults. Information given by interviewed fishermen and other lion fish hunters suggest that fishing pressure is highest in Gayraca. However, Gayraca was the bay with most lion fish detected (16 ind.).

The second sampling of the succession and recruitment project was conducted successfully in another fieldtrip to Gayraca also in the last week of January. Photos taken show great differences in algae species between tiles within cages and without cages. Latter ones are mainly covered by turf algae and crustose coralline algae while cage-tiles show cover of more different species of fleshy algae as well as more dense vegetation.

Tiles that were brought out last month and collected at this field trip show only very little fouling and there were no striking differences between cage- and no-cage-tiles. In the second week of February another photo sampling was conducted. The analysis of the photos is still in progress, but especially the photos of the cage-tiles suggest an interesting development of the succession of the fouling organisms.


Air temperature 33°C; water temperature 23°C; wind speed > 25 km/h

Yesterday, we returned from the third of our field trips in January to the Tayrona National Park. On the 19th we sampled water, sediment and the main physicochemical data in the bays Cinto and Neguanje and in Gayraca and Chengue on the 21st. This time we could deploy in every location four fragments from a dead Acropora cervicornis coral colony that will provide information on the dynamics of colonization by algae and bioerosion during the months of the current dry season.

We decided to choose Gayraca as representative bay to quantify exposure to water currents by the technique of Clod cards (gypsum bodies stuck on acrylic plates by contact cement and fixed on structures of the reef). Clods cards use the physics of gypsum dissolution during a certain time which strongly depends on the current conditions at the site of deployment. This time we had the opportunity to return to Gayraca two days later and to sample the Clod cards. As expected, much more gypsum was removed from the Clod cards on the exposed compared to the sheltered side.

In both sides of Gayraca, additionally to our routine sampling, we also deployed three sediment traps at a water depth of 10 m in an approximate distance of 10 m from each other. The sediment traps are used to retain sediment and organic material sunk down to the sea bottom during a determined time. In our case, the time of exposure was 48 hours. A curious Lion fish observed our actions without knowing that it will be one of our main protagonists for the coming months…


Our last one-day expedition to the Bay of Gayraca was on the 27th of December 2011 since the strong winds forbade us to go on the 23rd of December, the original date. After a quite bumpy boat-trip over the sea, that was in parts strongly swayed by the wind, we started the sampling of the succession and recruitment experiment on the sheltered site of the bay. We took photos of each terracotta tile that showed already nice cover by different algae. These photos are used for analysis of the percentaged cover of each algae group.

The predominant alga was expectedly turf, but we also found crustose coralline algae and other red algae growing on the tiles. Besides taking photos and cleaning the cages from algae, we took samples of one tile of each of the nine boxes for later analysis of carbon and nitrogen content of the algae material. Furthermore, each tile we sampled was replaced by a new tile. In a month, one “new” plus one “old” tile is sampled from each box for the aforementioned purposes of analysis. All sampled tiles are also examined for recruits of invertebrate organisms.

After the second dive at the sheltered site and the sampling for Elisas project (taking water and sediment samples), we went for our third dive - this time at the exposed site of the bay. What we found down there was a disaster! The strong currents and turbulences produced by the strength of the trade winds of the last days destroyed all cages and boxes and washed everything almost traceless from the reef. Solely some of the ropes we used for tying the setup to adjacent rocks, indicated the sites of destruction. All nine boxes, including all tiles and all six cages were gone. And so is one important component of this experiment, i.e. the comparison between the sheltered and the exposed site.

Under these continuing environmental circumstances, we decided not to rebuild and reinstall everything but we still continue sampling the sheltered site. Additionaly, we go about a new project: In the next three months we will estimate the abundance of lionfish in this area, more precisely at the sheltered and exposed site of the four bays of Chengue, Gayraca, Neguanje and Cinto. The surveys will be conducted along three 50m transects at each location once a month.

Lionfish is an invasive species in the Caribbean Sea and the first time it was detected in this area was two years ago. There are some efforts to try to reduce the population by selective hunt for the “pez león”, because this fish propagates quickly and feeds almost unselectively on reef fish. Interviews with the “hunters” shall help assessing the biomass of lionfish removed by hunting. The first surveys will take place in the third week of January.


Air temperature 30°C, water temperature 23°C, humidity 75%

The weather conditions worsened at the end of the second December week. Strong winds reached record velocities. Every early morning we started our day with the hope to be able to leave the harbor of Santa Marta with one of the small boats. Finally, we could reach the bays Cinto and Neguanje sheltered on 15.12, Neguanje exposed and Chengue on 21.12, and Gayraca on the 27.12. Luckily we received some help from the CEMarin student Juan Felipe; Julian joined the field trip to the Bay of Gayraca and provided his helping assistance during the field trip and back in the lab.

Unfortunately, in some of the bays, sampling at the exposed sides was not possible due to dangerous conditions for diving. The waves were hitting too strong the rocky shore making any diving attempt impossible. Nevertheless, for the locations that were possible to be sampled, we introduced the incubation of sands for the measurement of microphytobenthos respiration and took additional sediment samples for porosity, grain size distribution, chlorophyll-, C/N- and carbonate content.

In some of the bays we deployed sediment traps to investigate the deposition of organic matter to the sediment and also gypsum clod cards to measure the relative turbulence – but were not able to collect these on time because of the complicated climatic conditions and daily rescheduled field trips. At the same time, the water temperature had decreased to 23°C within only few days – the consequence of strong Trade Winds and Coastal Upwelling.

Back in the lab, the samples needed to be processed as soon as possible, demanding the filtration of over 70 L seawater for particulate organic matter-, chlorophyll- and nutrient analysis. Sediments were prepared for porosity and grain size distribution measurements, some of them frozen or dried for further analysis.


Santa Marta

On the 18.12.11 the strong Trade Winds from the Northeast increased dramatically reaching velocities of more than 30 km/h wind speed. No wonder why these winds from December to April each year are called “La Brisa Loca” or the “Crazy Breeze” by the local people. Compared to 2010, we felt that the winds were much stronger in 2011. When the waves reached heights of more than 4 m, we could not realize our planned field trips to the bays Chengue, Gayraca, Neguanje and Cinto on the scheduled dates. The field trips were further postponed towards Christmas.

During this time of the year, Santa Marta showcases itself from its illuminating side; every square and larger street is decorated for Christmas by lucent crystal trees, glowing Christmas baubles, blazing shapes of animals and other shiny Christmas ornaments. Even being so far away from home, in our thoughts and hearts we are with our families and friends in Germany and wish you all a Merry Christmas and a Happy New Year 2012!

07.12.- 13.12.11

In December 2011 we realized two field trips to the Bay of Gayraca to monitor possible coral bleaching like the moderate – heavy bleaching in December 2010. We first visited the sheltered side of Gayraca and were positively surprised that most of the corals looked quite healthy. Not even the usually strongly affected Montastraea faveolata showed visible bleaching. Only some Colpophyllia natans, Diploria strigosa and Siderastrea siderea colonies showed some signs of coral bleaching. We marked 10 of each mentioned species at water depths from 6 to 12 m, took pictures and established underwater maps in order to be able to find the marked corals again in April 2012.

To get an overall picture about the corals at a water depth of 10 m, we monitored 3 x 50 m transects and noted the state of every coral underneath the transect line. We proceeded with the corresponding bleaching monitoring also on the exposed side of the bay where we hardly could find any bleached corals. Also at this side of the bay we marked colonies of the mentioned species enabling the comparison with those at the sheltered side.

Even if the year 2011 had a strong La Niña index, which usually corresponds with stronger precipitation than usual accompanied by increased probability for tropical storms, the corals of the Tayrona Park were in a good shape. Nevertheless, we will look for bleaching in the coming up field trips – probably some species may bleach later than others. We do not want to miss the start of such events.

15.11.- 04.12.11

Santa Marta, air temperature: 29 °C, water temperature: 25 °C, humidity: 79 %

We (Julian and Corvin) spent almost three weeks at the remote Playa del Amor located in Garayca Bay, in the middle of the marvelous Tayrona National Park. With the help of Carmen and her sister Magaly, who cooked for us and helped us with logistics (food-gathering, boat trips etc.) we lived in an almost all-inclusive beach resort. Furthermore we could use some almost dry storage space in the only building at this beach, built up by a now 82-year old, one-eyed fisherman named Victor.

After the establishment of the field laboratory directly at the beach, we took coral fragments for primary production measurements from two study sites at the exposed and sheltered part of the bay to shore. These fragments were produced during the last field campaign in April 2011 at which time post-upwelling primary production was measured. After the post-upwelling measurements the coral fragments were transported back to their environment at 10m depth. Before the incubation experiments could take place, the fragments were cleaned thoroughly to measure only oxygen production and consumption of the corals.

On Saturday, 17.11., Prof. Dr. Valeria Pizarro, together with a colleague, came to the bay in order to help put up the experimental setup of the succession and recruitment study. For this, at both the exposed and sheltered part of the bay, more than 160 tiles fixed on 9 containers were deployed. These experimental units were fixed on the substratum and cages were put up around them to test the effect of herbivory. With the help of Valeria Pizarro, her colleague and another CEMarin student, we could deploy all experimental units in one day.

The following days, we could not continue our work, due to a tropical storm in the region. Even worse, the powerful current damaged some of the installed units of the succession and recruitment investigation. Moreover, the currents washed away one container with coral fragments which were about to be measured the next day. To reestablish the succession and recruitment setup, we ordered new hardware to substitute the damaged units. Because of logistic reasons, we were not able to install the containers before November 22nd.

By that time, we were lucky to have some sunny days to finish the incubation measurements of the coral fragments. After returning the corals to 10 m depth at both sites, we collected specimens of dominant groups of primary producers, namely calcareous coralline algae, turf algae, macroalgae, and sand-inhabiting microphytobenthos. Due to the weather conditions, we could not conduct light incubation measurements so we took a day off and used the time to set off to the neighboring bay. We wandered through the spider-infested coastal dry forest to reach the mangroves at Chengue Bay which grow in proximity to huge cactus trees. After a short walk we left the mangroves and reached a superb beach in front of an extensive seagrass bed. At the beach we met a wealthy couple who brought us back to our base with their boat, offering us ice-cold beer and a freshwater shower, which we thankfully enjoyed. They really knew what we missed the most!

Because of the weather we conducted the last incubations on December 2nd. The following day, the first data of the succession and recruitment study were obtained by means of digital photography. That day, all equipment was packed so we could leave the beautiful beach of love, heading back to civilization December 4th.

Despite the climatic conditions, we were able to conduct all planned measurements, looking forward to set up our field station in Gayraca at the end of March 2012 to quantify post-upwelling primary production in the bay. In the meantime, Julian will monitor the succession and recruitment experiment every second week and sampling tiles from both sites of the bay each month.


Santa Marta, air temperature: 33 °C, water temperature: 29 °C, humidity: 70 %

After a rainy night, this morning at 6 am the sky is clear and sunny. We (Corvin, Julian and Christian) start our trip to Tayrona National Park with loading our equipment on a pick up taxi. After a 2 h drive we arrive at the entrance of the National Park. From there it is another hour over rough streets to Gayraca Bay. From there, we transfer our entire luggage on a little boat which brings us to the remote Playa del Amor, where we will stay for the next 2 weeks.

We immediately start to build up our camp and field laboratory. Our first dives at the exposed side of Gayraca Bay reveal that all our coral fragments from the last campaign survived and have grown quite a bit. We also identify some appropriate places for the deployment of the herbivory exclosure experiments. Gayraca Bay harbours exceptional coral reefs for the Caribbean as indicated by high densities of the nowadays rare elkhorn coral Acropora palmata and lots of fish diversity as well as abundance. Everything is now prepared for the start of the incubation experiments tomorrow.

Meanwhile Elisa proceeds with the organisational work of her monthly field trips to the four bays Chengue, Gayraca, Neguanje and Cinto which are scheduled for Friday the 18th and Monday the 21st for the month of November. In the last three months, another PhD student from the Center of Excellence in Marine Science helped with the field trips during Elisa´s journey to Germany. The task of the next two field trips will be to continue with data collection on the main biotic and abiotic parameters of the water column. Also, our temperature loggers which were deployed last year will be checked, read out and replaced if necessary. New data collection methods to investigate how the biogeochemistry of sediments is influenced by the different seasonality will be established and sampling methods tested and improved.

Some weeks ago we received the information that the year 2011 will likely be dominated by the La Niña phase of the El Niño Southern Oscillation which usually coincides with a decreased water temperature (not linked to coastal upwelling) and strong precipitation. In fall 2010, Colombia was influenced first by an El Niño phase increasing the seawater temperatures for several weeks above the maximal summer seawater temperature average followed by a strong La Niña phase - Colombia experienced the worst rainy season in history, hurting the poorest and most vulnerable people. The heavy rains, high levels of poverty, internal displacement and inadequate infrastructure have converted the floods into a major disaster and humanitarian emergency. Over two million people were affected by the heavy rainfalls.

From an ecological point of view, after the strong rainy season in fall 2010, the first moderate-heavy coral bleaching event of the last 30 years was observed by Valeria Pizarro for the Tayrona National Park. We decided to monitor this bleaching event in the bay of Gayraca on both sides of the bay. The western and the eastern side of each bay of the Park differ especially in the current conditions due to exposition to strong winds coming from the northeast (December to April, upwelling) but also in coral appearance, content of benthic invertebrates and fish which could be a result of the differences in exposition degree.

Also this year we expect the corals to bleach rather due to drastic changes in salinity and strong inflow of sediment-rich freshwater than due to increased seawater temperature. The next bleaching monitoring is planned for mid of December. This time we want to mark the dominating corals in water depths between 3 and 12 m and monitor the state of bleaching before upwelling, during and after the upwelling phenomenon. Thereby, we hope to answer the question if bleaching is mitigated by coastal upwelling and if the corals at the current- and wave exposed side of the bay bleach less and recover better than the ones at the sheltered side of the bay.


Santa Marta, Colombia; air temperature: 32 °C, water temperature: 28 °C, humidity: 90 %

After two days of intensive discussion and exchange of first data among all team members and the Colombian partners, today the last preparations for the field campaigns are completed. Tomorrow morning, a 14 days research expedition into the National Park will start with the main goal to begin the succession and recruitment experiments along with the intense work required for the development of a pre-upwelling primary production budget for the exemplary Gayraca Bay.

Because there are neither buildings nor electricity at the selected study site, the team is prepared to sleep on the beach in hammocks and to use a gas cooking device to prepare the food. Unfortunately, it has rained a lot the last days so that also mosquito repellent is essential. Let’s hope for the best…

This blog will now be continued by the students as soon as they are back from the National Park.

Corvin Eidens, Elisa Bayraktarov, Julian Rau, WG Coral Reef Ecology

Prof. Dr. Christian Wild (ZMT and University of Bremen)
Prof. Dr. Thomas Wilke (JLU Giessen)
Prof. Dr. Valeria Pizarro (Universidad Tadeo Lozano, Bogota and Santa Marta).