ALBERT

Description: The steep walls of Chilean fjords are biodiversity hotspots and characterized by high precipitation rates, high river run-off and natural landslides with an inherent high sediment input. These sedimentation rates are likely to increase in the future due to expanding salmonid farming and coastal road construction. Caryophyllia huinayensis, is a Scleractinia, solitary cold-water coral (CWC) growing on steep slopes and overhanging portions of the fjord walls, which may indicate a sensitivity to sedimentation. However, actual data on the susceptibility to sediment of this CWC species is lacking. Furthermore, there is a deficit of information on juvenile CWC dealing with sedimentation stress, which is why this is the first study on this topic. The aim of this work was to investigate whether increased sediment concentrations affect the overall performance of juvenile specimens of C. huinayesis, measuring over three-months the coral growth, behaviour and respiration rates. The study consists of an ex-situ experiment which included three different treatments: i) the control treatment: with the current natural sediment concentration of Comau Fjord, ii) a 100-fold sediment concentration and iii) a 1000-fold sediment concentration than the control. The most remarkable result demonstrates that corals under the highest sediment concentrations display a significant decreased polyp activity (60 % lower) hence affecting pray capture thus nutrition, leading to a significant reduced growth rate (natural 0.14 ± 0.09 mg d-1; 100-fold: 0.09 ± 0.07 mg d-1; 1000-fold concentration: 0.003 ± 0.009 mg d-1). Furthermore, polyps partly retracted their tissue with increasing sediment load. The results show that all these effects seem to be lower for corals facing vertical downwards than for individuum’s growing horizontally. Another important result reveals that long-time exposed (13 weeks) juveniles significantly decrease their oxygen consumption which is directly related to increasing sediment load. Whereas newly exposed individuals (24 h) showed no significant change in their respiration rate under the influence of increased sedimentation load. The results of this experiment contribute to a better understanding of the abilities of CWC recruits to cope with anthropogenic impacts. This information is fundamental as the viability of the juveniles is indispensable for future coral populations and the so called ‘Cold-Water Stony Coral Forests‘. Consequently, management plans for the fjord need to consider the harmful effects of increased sedimentation on threatened CWC’s.

Description: The table shows respiration data, dry mass, and ash-free dry mass (AFDM) of juvenile Caryophyllia (Caryophyllia) huinayensis individuals exposed to a natural, a 100-, and 1000-times increased sediment concentration. Corals after a 12-week exposure experiment towards the three sediment concentrations ("long-term") and corals exposed to the natural and highest concentration only for the respiration experiment ("short-term"), were studied for respiration for 24 hours. Mean oxygen consumption rate of C. huinayensis was determined by closed-chamber respirometry. The values have been corrected for the volume of the incubation vessels, the background respiration and the AFDM of the animals and calculated to mg O2/AFDM/day.

Description: The table shows the calyx diameters of the juvenile Caryophyllia (Caryophyllia) huinayensis measured in ImageJ (Version 1.53), separated according to exposed sediment concentration at the beginning of the 12-week sediment exposure experiment (week 0), in the middle (week 6) and at the end (week 12). Corals were exposed to three concentrations, a natural (0.0042 ml/l) and a 100-fold and a 1000-fold increased sediment concentration.

Description: The table shows the nutrient concentration of the incubation beakers for juvenile Caryophyllia (Caryophyllia) huinayensis exposed to three sediment concentrations. A natural, a 100-fold and a 1000-fold increased sediment concentration. Recorded were the nitrate, nitrite, phosphate and ammonium values from pooled water samples of five experimental beakers and separated by sediment concentration (two measurements per sediment concentration). Samples were measured weekly over the experimental period of three months via photometer (NOVA 60, Spectroquant, Darmstadt, Germany).

Description: The table shows the polyp behaviour of juvenile Caryophyllia (Caryophyllia) huinayensis during a 12-week sediment exposure experiment. Corals were exposed to a natural (0.0042 ml/l), a 100-fold and a 1000-fold increased sediment concentration and observed three times a week, two hours after feeding start and once a week without feeding, by illuminating only the targeted coral briefly with a spotlight torch. Polyp extension was categorized into three groups: A = polyp fully extended (polyp fully visible, 100 %), B = polyp partly extended (polyp partly visible, 50 %) and C = polyp fully retracted (polyp tentacles not visible, 0 %).

Description: This dataset contains date, mean salinity, temperature, pH and oxygen values of the artificial sea water within 340 ml glass beakers (n=10), which were used as incubation vessels for juvenile Caryophyllia (Caryophyllia) huinayensis, specified according to the exposed sediment concentration: a natural (0.0042 ml/l), a 100-fold and a 1000-fold sediment concentration.

Description: Treatment water contained a natural, 100- or 1000-fold increased sediment concentration in the experimental vessels (340 ml glass beakers) of the corals C. huinayensis, to which they were exposed during the periods between water changes (2-3 d). Using a turbidimeter (2100Qis, Hach Lange GmbH, Düsseldorf, Germany), the turbidity of the treatment water was measured every day and twice a day when a water change took place (just before and after the water change). The mean values from the bulk samples (ten vessels per concentration; bulk sample of water from five vessels of one concentration = one sample; per concentration = two samples) were calculated and are shown in the table, as well as the standard deviation.

Description: The mass of horizontal and vertical downwards oriented juvenile Caryophyllia (Caryophyllia) huinayensis was determined during a 12-week sediment experiment. Corals were exposed to a natural (0.0042 ml/l), a 100-fold and a 1000-fold sediment concentration. The mass of the individual corals was measured at the beginning (week 0), in the middle (week 6) and at the end (week 12) of the experiment. The mass of the individuals was determined using the buoyant weight method (Davies, 1989) and by calculating the skeletal mass in air after Jokiel et al. (1978). From this, the increase in mg per day and year for the individuals were determined.

Description: The images show individuals of juvenile Caryophyllia (Caryophyllia) huinayensis in the zenithal view (calyx) at the beginning (week 0), in the middle (week 6) and at the end (after 12 weeks) of a sediment exposure experiment with a natural, a 100-fold and a 1000-fold increased sediment concentration, as well as from the lateral view after 6 and 12 weeks. Pictures were taken using a stereomicroscope (LEICA MZ 16, Leica Microsystems GmbH, Wetzlar, Germany) and the software Leica Acquire 3.4.1. Build 9072 © 2006- 2013 (Leica Microsystems GmbH, Wetzlar, Germany).

Description: The aim of this work was to investigate whether increased sediment concentrations affect the physiological performance of juvenile specimens of the cold-water coral Caryophyllia (Caryophyllia) huinayesis by measuring growth, behaviour and respiration rates of the corals over a period of three months. The study consists of an in vitro experiment which included three different treatments: i) the control with the current natural sediment concentration of Chilean Comau Fjord, ii) a 100-fold sediment concentration of the control, and iii) a 1000-fold sediment concentration of the control. Coral recruits were taken from the aquarium facilities of the Alfred-Wegener-Institute (Bremerhaven, Germany). These were offspring of adults of C. huinayensis collected by scientific SCUBA divers in 2015 from Comau Fjord, which have successfully acclimatized and reproduced in the laboratory aquaria (see Laudien et al., 2018, 2019, 2021). Growth was measured with the buoyant weight technique and via the increase in calyx diameter using images. Behaviour, i.e. the expansion of the polyps, was visually observed four times a week. Pictures were taken of the lateral view of the corals to see if the animals retracted their tissue. Oxygen consumption was determined for 24 h in corals from the three-month experiment and in corals newly exposed to the natural and 1000-fold sediment concentration.