Wind farms as suppliers of energy and mussels

The cultivation of mussels in Belgian offshore wind farms is both biologically and technically feasible, according to research carried out by our scientists and their partners within the Edulis project. The economic feasibility depends on solving technical challenges.

After two years of experimentation and research, scientists and private companies present the results of the research project ‘Edulis: offshore mussel culture in wind farms‘, which looked at the possibilities for mussel farming in offshore wind farms 30 to 50 km off the Belgian coast. Edulis is a collaboration between Ghent University, the Research Institute for Agriculture, Fisheries and Food (ILVO), RBINS/OD Nature and 5 private partners (Belwind, Brevisco, C-Power, Colruyt Group and DEME Group). The ambitious pilot project is largely financed by private funding and facilitated by Flemish and European funding.

Quality Mussels

The project has demonstrated that it is both biologically and technically possible to cultivate mussels in the Belgian offshore wind farms, which means that these can serve more than one purpose at a time. The experiments resulted in a tasty quality mussel that is well stocked and meets all food safety requirements. The yield is equivalent to that of hanging mussels from the Netherlands and Ireland, and the mussels grow faster than mussels from bottom cultivation (mussels ready for market in 15 months instead of 24 months).

Technical Challenges

The big challenge is designing installations that can withstand the sometimes extreme North Sea environment. Investing in robust, easy to maintain and safe systems, including vessels, is a must, according to the researchers, although this will push up overall production costs. In addition, it turned out that the sizing and organisation of the wind farms is not optimal for food production, which is logical as they were not designed for that purpose. The distance from the coast also poses a challenge to technical, practical and economic feasibility. When designing future wind farms, this should be taken into account in order to be able to combine both activities.

Economic Feasibility

“Edulis has given us a clear picture of the costs and benefits of mussel farming in the North Sea” says Margriet Drouillon, Senior Business Developer Aquaculture and Blue Life Sciences at Ghent University. “If we really want mussel farming on a commercial scale, we will have to put a lot of effort into developing knowledge about the economic feasibility of mussel farming in the wind farms. We will also explore other paths for multiple use of space at sea, with due attention to sustainable production”.

Three Additional Challenges for Aquaculture in the North Sea

Ghent University and the Research Institute for Agriculture, Fisheries and Food (ILVO) launched the ‘North Sea Aquaculture’ project in 2017, with Edulis and Value@Sea as subsidiary projects. They joined forces with their partners RBINS/OD Nature, Belwind, Brevisco, C-Power, Colruyt Group, DEME Group, Lobster Fish, and Sioen Industries. North Sea Aquaculture tackled three challenges:

  • Innovative shellfish and seaweed farming techniques;
  • Efficient use of space in the Belgian North Sea;
  • The development of a market for new regional marine products.

 

More info on Edulis:
Margriet Drouillon, UGent, 0484 13 95 39, margriet.drouillon@ugent.be

Leatherback turtle caught and released

On the 28th of October, the crew of the fishing vessel O190 Renilde experienced a shocking moment. Around 19:30 they encountered nothing less than a Leatherback turtle in their nets along the coast of Middelkerke/Ostend! The crew reacted quickly and was able to let the living animal return to the sea (see video © Kevin Van Thomme/crew O190).

Seventh Record

The Leatherback turtle typically inhabits open and warm seas, where they mainly feed on jellyfish. They don’t easily show up In coastal areas (unless to lay eggs, but that is excluded on our beaches). Jan Haelters of the Royal Belgian Institute of Natural Sciences provides interpretation: “Leatherback turtles are very rare in the Belgian part of the North Sea: until now, only three strandings (1988, 1998 and 2000) and three sightings (2018 and 2 in 2019) were recorded. Although the list only counts seven specimens, an increase is noticeable in recent years.”

© Kevin Van Thomme/bemanning O190

Also in the Netherlands

Remarkably, some Leatherback turtles were also seen in the Netherlands recently: one roamed the Eastern Scheldt from 22 to 24 September, while one swam along the North Sea coast of Scheveningen on 7 and 11 October. Comparison of the shape and size of the scars on the heads of the two animals, and of the ‘ribs’ on their back shields, shows that in Belgium and the Eastern Scheldt different individuals were involved. The Eastern Scheldt animal was washed ashore dead on 3 November near the Danish Ballum (article tvs).

Comparison of the Leatherback turtle heads from Belgium (right, © Kevin Van Thomme) and the Eastern Scheldt (left, © Wageningen Marine Research)

Impressive Noctiluca (Sea Sparkle) bloom in the North Sea

On 15 August, striking orange spots and strings were observed in the Belgian part of the North Sea near the Buitenratel sandbank, that were reported to the Coast Guard as a possible pollution. After inspection by various services, it became clear that this was an unseen bloom of the single-celled plankton species ‘Sea Sparkle’. The warm and calm weather of the past few days is probably an important explanatory factor. The rotting mass could possibly lead to oxygen deficiency and fish mortality. It is also possible that the remains will be washed ashore on Belgian beaches during the next week.

Noctiluca bloom Buitenratel sandbank, 15 August 2020, documented from surveillance aircraft RBINS (© RBINS/MUMM)

In the morning of Saturday 15 August, the Belgian Coastguard Centre (MRCC – Maritime Rescue and Coordination Centre) received a report of a striking orange patch at sea, containing some dead birds. A sailor had noticed this at the ‘Buitenratel’ sandbank, one of the sandbanks in the ‘Vlaamse Banken’ complex. This sandbank is situated about 16 to 20 km from the shore of the Belgian West Coast, near the border with the French waters. The striking report raised eyebrows at the Coast Guard, because the reported colour did not match the typical colours of mineral oil, and because the dead birds may have hinted to a chemical product. However, an extensive natural algal bloom was also a possibility.

Control on Land, at Sea and in the Air

Following the report, the Shipping Police sent a patrol vessel to the Buitenratel. They found the reported patch and took some samples. Dead birds were no longer spotted. A rescue helicopter from the Coxyde air base also flew over the area, and the surveillance aircraft of the RBINS (MUMM, Royal Belgian Institute of Natural Sciences) was called upon to scan the wider sea areas off the Belgian coast for any further pollution. Both aircraft made images of the orangeish, kilometre-long patches and streaks.

Noctiluca bloom Buitenratel sandbank, 15 August 2020, documented from NH90 helicopter (© Geronimo/Rodrigo Vissers)

All the sailing and flying units involved came to the same conclusion: the patch probably indicated a large natural bloom, albeit on a very large scale. The sample taken by the Shipping Police was taken to the RBINS biological laboratories in Ostend where it could soon be confirmed that it was indeed a Noctiluca bloom.

Video: 2020_08_15 Noctiluca Buitenratel (c) Geronimo_Rodrigo Vissers NL

Sea Sparkle

The dinoflagellate Noctiluca scintillans or Sea Sparkle is a relatively large single-celled micro-algae (0.5 – 1 mm, so visible to the naked eye) that occurs in most seas of the world and belongs to the plankton. It looks like a gelatinous pellet with a tail (flagel), which catches food. In high concentrations – called blooms – Noctiluca forms highly visible orange-red spots that can occur in spring and summer. In case of turbulence, Sea Sparkle produces a bluish light that creates fairytale effects in the dark (‘lighting up’ of the sea). This bioluminescence is caused by luciferin, a pigment, and luciferase, an enzyme, when they come into contact with oxygen.

Samples of Noctiluca scintillans bloom at the Buitenratel sandbank, 15 August 2020, sample taken by Shipping Police (© RBINS/Francis Kerckhof)
Microscopic image of Noctiluca scintillans bloom at the Buitenratel sandbank, 15 August 2020, sample taken by Shipping Police (© RBINS/Francis Kerckhof)

Current Conditions

The high concentrations of Sea Sparkle that have now been observed are probably due to the very warm and calm weather of the past few days. The sampled Noctiluca was also already partly rotting, a process that consumes oxygen. Although it is essentially a harmless organism, mass extinction and rotting can locally lead to oxygen deficiency. At higher temperatures, less oxygen dissolves in water anyway, and the absence of strong winds and waves means that there was also little mixing that brought extra oxygen into the water. The resulting low oxygen tension due to the various phenomena can lead to the death of fish and other aquatic organisms, although under normal circumstances this is very unlikely in open sea conditions.

Modelling simulations by the RBINS, taking into account currents, meteorological conditions and the physical properties of the floating Noctiluca spots, illustrate that the remains of these spots could potentially wash ashore on Belgian beaches in the course of the next week.

In recent decades there has been a relative increase in the dinoflagellate community in the Belgian part of the North Sea. This increase could be related to the warming of the sea water (+ 1.6 ° C over the last thirty years). Noctiluca scintillans may also show an upward trend. In addition, blooms from other single-celled plankton organisms can also be expected, including some potentially dangerous species.

Noctiluca bloom Buitenratel sandbank, 15 August 2020, documented from surveillance aircraft RBINS (© RBINS/MUMM)

 

Noctiluca bloom Buitenratel sandbank, 15 August 2020, documented from surveillance aircraft RBINS (© RBINS/MUMM)