MAE: Marine aquaculture
One of the goals of Marine Animal Ecology is understanding how coral reefs respond to human-induced stressors. We culture corals and sponges to facilitate the research. Culture happens both in the lab and in the field.
Culture in the lab
A better understanding of how coral reefs function, in disturbed as well as in pristine areas, allows us to inform policy makers and reef managers about how to best manage these delicate ecosystems. To study coral reefs, we conduct field and laboratory experiments. For the laboratory experiments at Wageningen University we use live corals. To this end, we culture our own reef-building corals in the lab.
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As the city of Wageningen is located far away from the ocean, we require a dedicated lab to grow tropical corals. Since 2005, we have been gaining experience with handling and culturing these fragile animals. Currently, we have two coral labs, which are unique in the Netherlands. One focusses on asexual production of corals, which involves cutting branches off adult colonies and gluing these onto plastic slabs. These fragments will grow out into new colonies which can be used for experiments. In this lab, we also have a setup of 20 miniature aquaria for controlled experiments. The aquaria allow us to manipulate environmental factors such as temperature, pH and water quality to understand how corals respond to human-induced stressors.
Our second lab is dedicated to the sexual reproduction of corals. The species we use for this method of reproduction if the Golf ball coral (Favia fragum), which broods and releases larvae on a daily basis. These swimming larvae are also used for various experiments, to understand how corals respond to their environment during this sensitive life stage.
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Video courtesy: Dr. T. Wijgerde.
Culture in the field
Within the frame of the REEFolution Kenya project, Marine Animal Ecology is conducting experiments in the field (Wasini Channel, Southeast Kenya) on the mariculture of corals for the purpose of coral reef restoration. We monitor growth and survival of the cultured corals, which together determine productivity of the culture systems. Corals are grown from asexually produced coral fragments. After reaching a substantial size, cultured corals are outplanted on artificial reef structures and become fully integrated in the seascape after 3-4 years.
The mariculture studies include various aspects:
- Species: Different species may require different culture approaches. We currently have four coral species in culture.
- Starting size: Do smaller fragments grow faster than larger fragments? Does size influence surival? What size is optimal for maximal productivity?
- Season: What time of the year is best to start up cultures (initial survival) and when do corals grow fastest?
- Service: How often should divers service (i.e. clean them from fouling) the culture systems to enable maximal performance? How is this influenced by the presence of natural grazers?
- Location: Are there differences among locations and can we identify the factors that cause these differences (e.g. herbivory, corallivory, water quality, currents)?
- Culture methods: Do culture materials and culture structures affect coral performance?
In collaboration with the NGO Coralive, we are also testing the effectiveness of the Mineral Accretion Technique, in which mild electrical currents are led through the structures on which corals grow. The currents in turn accrete certain minerals which are thought to help corals grow more easily.
Techniques used & Implications
The marine aquaculture of corals contributes to eco-based circularity, but also allows for the rebuilding of reefs. Both of these things will result in reef resilience and will promote better conservation of ecosystems.
