Description: Knowledge on basic biological functions of organisms is essential to understand not only the role they play in the ecosystems but also to manage and protect their populations. The study of biological processes, such as growth, reproduction and physiology, which can be approached in situ or by collecting specimens and rearing them in aquaria, is particularly challenging for deep-sea organisms like cold-water corals. Field experimental work and monitoring of deep-sea populations is still a chimera. Only a handful of research institutes or companies has been able to install in situ marine observatories in the Mediterranean Sea or elsewhere, which facilitate a continuous monitoring of deep-sea ecosystems. Hence, today’s best way to obtain basic biological information on these organisms is (1) working with collected samples and analysing them post-mortem and / or (2) cultivating corals in aquaria in order to monitor biological processes and investigate coral behaviour and physiological responses under different experimental treatments. The first challenging aspect is the collection process, which implies the use of oceanographic research vessels in most occasions since these organisms inhabit areas between ca. 150 m to more than 1000 m depth, and specific sampling gears. The next challenge is the maintenance of the animals on board (in situations where cruises may take weeks) and their transport to home laboratories. Maintenance in the home laboratories is also extremely challenging since special conditions and set-ups are needed to conduct experimental studies to obtain information on the biological processes of these animals. The complexity of the natural environment from which the corals were collected cannot be exactly replicated within the laboratory setting; a fact which has led some researchers to question the validity of work and conclusions drawn from such undertakings. It is evident that aquaria experiments cannot perfectly reflect the real environmental and trophic conditions where these organisms occur, but: (1) in most cases we do not have the possibility to obtain equivalent in situ information and (2) even with limitations, they produce relevant information about the biological limits of the species, which is especially valuable when considering potential future climate change scenarios. This chapter includes many contributions from different authors and is envisioned as both to be a practical “handbook” for conducting cold-water coral aquaria work, whilst at the same time offering an overview on the cold-water coral research conducted in Mediterranean laboratories equipped with aquaria infrastructure. Experiences from Atlantic and Pacific laboratories with extensive experience with cold-water coral work have also contributed to this chapter, as their procedures are valuable to any researcher interested in conducting experimental work with cold-water corals in aquaria. It was impossible to include contributions from all laboratories in the world currently working experimentally with cold-water corals in the laboratory, but at the conclusion of the chapter we attempt, to our best of our knowledge, to supply a list of several laboratories with operational cold-water coral aquaria facilities.

Description: Benthic suspension feeders have developed a variety of feeding strategies and food availability has often proven to be a key factor explaining their occurrence and distribution. The feeding biology of coral species has been the target of an increasing number of studies, however most of them focus on Scleractinia and Octocorallia, while information for Antipatharia is very scarce. The present study focused on Antipathella wollastoni, a common habitat-forming antipatharian in the Azores Archipelago, forming dense black coral forests between 20 and 150 meters. The objective of the study was to investigate the food preferences of the target species upon availability of different isotopically enriched food substrates and determine its ability to capture zooplankton prey under different flow speeds. The species was able to utilize different food sources including live phytoplankton, live zooplankton and Dissolved Organic Matter (DOM), indicating the ability to exploit seasonally available food sources. However ingestion of zooplankton enhanced Carbon (C) and Nitrogen (N) incorporation in coral tissue and metabolic activity, highlighting the importance of zooplankton prey for vital physiological processes such as growth and reproduction. The species displayed a high capacity to capture zooplankton prey over different flow rates, however capture rates were higher under 4 cm s-1, highlighting the ability of A. wollastoni to exploit high quantities of shortly available prey.

Description: The majority of octocoral species are found in waters deeper than 50m where they create three-dimensional and highly heterogenous habitats known as coral gardens. The Azores Archipelago is an octocoral biodiversity hotspot and coral gardens are one of the most prominent deep-sea communities encountered regionally. Although food availability and flow have been recognized as key factors in determining the dynamics of suspension feeder communities, very little information exists on how flow affects the feeding capacity of deep octocoral species. The study focused on two common habitat-forming octocoral species in the Azores, Dentomuricea meteor and Viminella flagellum, aiming at determining their ability to capture zooplankton prey under variable flow velocities. The rotifer Branchionus plicatilis was used as prey, while three flow velocities were established in recirculating 13L flumes: 3 cm/s, 6 cm/s and 9 cm/s. Both species efficiently captured zooplankton prey. Capture rates were lower under 3 cm/s, however no difference was detected between 6 and 9 cm/s. Dentomuricea meteor reached higher capture rates per polyp than V.flagellum, possibly due to their differences in polyp size and density.

Description: Herein we report the respiration rates (O2 consumption) of the cold-water coral Viminella flagellum exposed to acute Cu concentrations. In a lab experiment, sixty nubbins of V. flagellum were distributed in six aquaria of 8 L (ten nubbins per aquarium) of each Cu solution (0 (control); 60; 150; 250; 450 and 600 μg/L) for 96 h. After this period, four nubbins from each Cu treatment, selected randomly, were incubated individually for 6 h in glass chambers filled with ca. 110 mL of 0.2 μm pre-filtered seawater, with the respective Cu dilutions (4 chambers per Cu concentration). The incubation period was set to 6 h to record changes in O2 consumption without exposing corals to oxygen levels below 80 % (air saturation, a.s.). During the incubation period, dissolved O2 (μmol/L) depletion rates were recorded every 30 min and corrected by the corresponding rates/variations in chambers without corals. Coral respiration rates were normalized to the coral surface area and time. Results are presented by µmol of O2 consumption per m2 per h.

Description: The study focuses on the early life stages of the species Dentomuricea aff. meteor, a common deep-sea octocoral in the Azores. The objective was to describe the embryo and larval development, survival and swimming behaviour of early life stages of the target species, under two temperature regimes, corresponding to the minimum and maximum temperatures in its natural environment during the spawning season (13°C and 15°C). Embryo and larval development were monitored closely and revealed faster developmental rates under 15°C. Survival counts were performed throughout embryo and larval development, but were not statistically different between temperatures. Moreover, swimming behaviour was assessed by means of video recordings, revealing a higher larval swimming speed at 15°C. Additional data on larval behaviour are provided, including settlement and metamorphosis rates which were low for both temperatures. Our results showcase how small temperature fluctuations can affect embryo and larval characteristics, potentially impacting larval dispersal and success.

Description: The antipatharian coral Antipathella wollastoni is commonly found in the Macaronesia (Cape Verde, Madeira, Canaries and the Azores Archipelago). In the Azores Archipelago the species forms dense populations and coral gardens on island slopes between 15-520 m water depth. Here, we present data from two experiments on the embryo and larval survival of A. wollastoni under two different seawater temperatures (21°C and 23­°C). Embryos were collected after spawning of mother colonies in aquaria. In the first experiment, we monitored the number of embryos for 24 h after spawning, while in the second experiment we monitored the number of embryos and planulae (larvae) for a total of 35 h.

Description: Includes data estimate of survival.

Description: Includes data on the embryo development of the species. Embryos/larvae were monitored (counted) and classified to developmental stages every 3-4 hours until the planula stage and every 2-3 days afterwards.

Description: Contains data on larval behaviour.

Description: Contains data on swimming velocity and behaviour.