Are you ready to have a closer look to my internship? Check out the three different experiments I performed working side by side with my IMBRSea colleague and dear flatmate, Anna Thomasdotter, and our great supervisor: Raquel Quintã.
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Number 1: experiment about allelopathic seaweed potential
The aim of this experiment was to find a species of seaweed that could have an allelopathic activity against G. catenatum survival.
We tested two different species (Ulva spp. and Asparagopsis armata) in two different conditions (fresh algae and algae's extract, with higher and lower [c]) and we set them in co-cultivation systems with healthy colonies of G. catenatum.
We collected two samples from each replicate at four different times (T0, at the beginning of the experiment, T2, after two days, T4, after four days and T6, after six days) and we carried out cell countings through Sedgwick-Rafter counting chamber to assess the survival rate G. catenatum cells.
Eventually, after analyzing through Excel the collected data, we could conclude that:
Ulva spp. was the least allelopathic seaweed among the ones tested;
Plocamium and Sphaerococcus (previously tested by our supervisor) were the most efficient in the allelopathic activity.
The systems where we set the fresh algae appeared to be more effective than the ones with algae's extract. Higher [c] showed better results than lower [c].
Number 2: experiment about the optimal growth conditions of seaweed for the hatchery phase of cultivation
The aim of this experiment was to assess the optimal growth conditions for the carpospores of Sphaerococcus and Plocamium: after collecting them in the field, we have put them in controlled conditions (climate chamber, 17°C) for the hatchery phase, where we investigated in which condition the spores would develop and attach to the ropes best. The hatchery phase is crucial before the transport and implementation of the ropes offshore.
For each of the two species, we set three different growing conditions: spools (directly attached to the ropes), spray (free-living and attaching to the ropes over time), and on slides.
Each replicate was placed in a becker, immersed in a solution of ionized water, enriched with nutrients and Germanium Dioxide (GeO2), used to counteract the growth of microalgae. Each becker was provided with an individual aeration system.
The weekly follow-up and monitoring included two main activities:
cleaning and changing the water of the beckers containing the samples;
checking the spores' development through the stereomicroscope and taking pictures of it, to assess their viability, density and size.
The experiment was still ongoing when we finished our Professional Practice, so I can't tell you confidence which condition had the best outcome.
stereomicroscope.MP4Number 3: experiment about the optimal growth conditions of Ulva spp. in earthen ponds
Here we find our beloved Ulva again! But this time, for a completely different use.
The aim of this experiment was to assess the best environmental conditions to grow this seaweed in the fish tanks where fish are normally farmed. The great potential application of this species is represented by its bioremediation abilities. For this reason it could be widely used and implemented in the aquaculture industry (in IMTA systems) to enhance the conditions of the ponds.
We had the chance to follow this experiment from the start to the end, being able to see the results in first person.
Me and Anna had to collect about 20kg of Ulva from the effluent pond of the EPPO station, clean it roughly and weigh it before the experiment setup.
But here comes the fun part: we had to design six floating cages where we would have placed Ulva and we had to implement an aeration system that would provide air (and therefore, movement) to the seaweed in three of the six cages. This way, we could compare the different conditions in terms of yield and energy costs.
Each cage was filled with 3kg of Ulva. The cages were set in the pond 1m from each other, alternating the air presence / absence conditions.
Daily monitoring
Daily monitoring
Every day, approximately at the same time, we had to collect the environmental parameters of the earthen pond where the cages were placed. We measured the water temperature, pH, salinity and oxygen saturation levels (% and ppm). Twice a week, we would also take water samples to filter and freeze for later chemical analyses to assess the nutrients (to better understand the N uptake performed by Ulva).
Weekly follow-up
Weekly follow-up
Every week, for three weeks, we had to assess the biomass gain or loss from each cage. We used to collect the seaweed from each cage, weigh it and evaluating Ulva's growth. We would put back in place the initial 3kg of each cage (so that we could see how environmental fluctuations would affect the growth) and we took the excess Ulva to the lab. Here, we would clean it and or set it to high temperatures (60° for three days minimum) to obtain the dry weight samples, or freeze it for later chemical analyses.
Results
Results
Every week, the results obtained were more and more clear. The difference in biomass between the two systems (air / no-air) was marked: in the cages where air was supplied, we recorded a weekly average of 1.3kg of increased Ulva's biomass, while in the cages without air, there was a weekly loss from the initial value due to the bleaching and dying of the algae.
Hence, nonetheless the greater energy costs used for the aeration systems are considerable, the yield obtained is remarkable compared to the no-air system.
This final outcome should be properly exposed and explained to the stakeholders of the aquaculture industry, that could easily implement Ulva's cultivation both as food supplement for the farmed fishes and, even more important, as added element in IMTA systems, improving the tanks' environmental conditions and representing a more sustainable form of aquaculture.
Collecting Ulva from each cage
Collecting Ulva from each cage
Cleaning Ulva's excess for dry weight and chemical analyses
Cleaning Ulva's excess for dry weight and chemical analyses
Daily measurement of environmental parameters
Daily measurement of environmental parameters
Ulva's comparison.movA comparison between the two systems (with air and without air). You can even notice the difference in Ulva's appearance: the one supplied with air looks green and healthy while the one without air looks bleached and dying.
Movement makes the difference!
Final considerations
I feel fully satisfied with my Professional Practice.
I gained a great knowledge on the topic of seaweed cultivation, both from a theoretical and practical point of view. By working on different experiments and distinct algal species, I learnt a lot about their ecology and physiology, both on a macro and microscale.
Working daily with our supervisor allowed me to learn different lab-related skills that were completely new to me. She gave me a good overview on how a research line should be properly carried out; her teaching method and the trust she gave me and Anna to work independently provided me a renewed confidence in my skills and my abilities.
The topic of seaweed cultivation still strongly fascinates me and I am sure that this industry will keep growing extensively in the next years. Research and funding on the different algal species - according to the geographic area considered - are still necessary.
After getting to know an actual working environment, observing the daily life of a seaweed researcher, as well as job shadowing different technicians and specialists of aquaculture industry, now I have a clearer idea of my future career aspirations. The research and entrepreneurship behind this field are surely the focal point for seaweed's success; as far as I am concerned, I would like to address my career more on outreach and scientific dissemination. Indeed, I think that there is the need of people able to explain and communicate properly all the bright sides of this industry to the main actors and stakeholders of the blue economy, promoting IMTA systems for a more sustainable aquaculture industry and engaging the seaweed cultivation on large scale for all its ecosystem services - desperately useful and needed in the environmental conditions we are experiencing in this era.
PP report_with pictures.pdfIn case this website didn't give you all the answers you were looking for, check out my Final Report and don't hesitate to contact me for any clarification.
Thank you for visiting my website and reading about my experience. I hope you enjoyed :)
gaia.ms.intonti@imbrsea.eu
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