Techniques Used in Coral Research

Study the biology of key bioengineering cold-water coral species

Study the biology of key bioengineering cold-water coral species Cold-water corals and important bioengineering species that enhance biological and functional diversity at the deep seafloor. Yet, there is limited information on their fundamental biology such as early life development, physiology, reproduction, feeding, and growth rates. Using aquaria-based experiments at the DeepSeaLab, we have studied fundamental aspects of the biology and ecophysiology of key habitat- forming octocorals in the Azores. Our research has focused on their reproductive biology and seasonality, larval development, as well as food preferences and metabolism. These studies provide essential insights into the reproductive potential and dispersal capabilities of larval stages, as well as their metabolic strategies. The findings have significant implications for understanding the ecology of these corals and their crucial roles in carbon and nitrogen cycling in the deep sea.

Climate change and cumulative stressors

The deep ocean is increasingly under threat from multiple human activities, including fishing, oil and gas exploration, and prospective deep-sea mining. This human exploitation of ocean resources is happening in parallel with climate change in the oceans. Many areas of the deep seafloor are already becoming warmer, more acidic, less oxygenated, and with altered food inputs. Investigating the cumulative impacts of climate and human activities on cold-water corals is particularly pressing because of their low resilience to disturbance. We have been performing a series of aquaria-based experiments on different coral taxa (scleractinians, octocorals, antipatharians) to understand how the cumulative and potentially synergistic effects of these climate and human-made stressors may lead to loss of biodiversity, ecosystem functioning, and the provision of goods and services by deep-sea ecosystems.

Deep-sea mining

While it has not taken place yet, the commercial exploitation of deep-sea mineral resources is considered one of the most pressing human threats to deep-sea ecosystems. We have been dedicated to understanding the effects of toxic sediment plumes produced during mining activities for polymetallic sulphides (PMS) on cold-water corals. We conducted a series of experimental studies exposing cold-water corals to suspended polymetallic sulphide particles. Our findings show that even low concentrations of these particles, or metals like copper released during mining, caused coral death within a short period (13-27 days). Additionally, these studies revealed delayed mortality in corals exposed to low concentrations of copper in seawater, suggesting that some coral species may not recover from the effects of PMS mining plumes. The results highlight the significant adverse impacts that mining can have on deep-sea ecosystems, and have been presented at the International Seabed Authority’s (ISA) Council meetings. We are continuing to work to develop environmental indicators of ecosystem health and thresholds for serious harm (e.g., metal toxicity or turbidity) as policy instruments for the environmental management and regulation of deep-sea mining.

Ecological Restoration

In some cases, conservation measures alone are insufficient to reverse the degradation of marine ecosystems, particularly in deep-sea ecosystems formed by cold-water corals characterized by slow growth, long longevity, and low fertility. In such situations, direct human intervention through ecological restoration is necessary to support ecosystem recovery. To address this, our team has been developing tools and techniques for the assisted regeneration, or active restoration, of coral gardens that may be impacted by human activities (e.g., seafloor mining, fishing). One methodology we have tested involves recovering corals accidentally captured during fishing, rehabilitating them at the DeepSeaLab, and then replanting them back on the seabed. The results indicate that this transplantation technique is successful, but they also show that the survival of transplanted corals depends on the coral species. Therefore, it is crucial to combine coral replanting with protection in marine protected areas to allow for the natural recovery of other corals. We are continuing this work with the goal of demonstrating that the involvement of professional fishermen in the recovery of accidentally captured corals and their subsequent replanting at sea could provide a low-cost alternative to traditional restoration actions. This initiative also helps raise awareness among local communities about the importance of protecting these vital ecosystems.