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Health categories of Caryophyllia huinayensis. Photographs of the lateral (a, c, e) and oral side (b, d, f) of C. huinayensis. Corals were divided into three health categories depending on the tissue coverage of their skeleton after one, three and six months. Health categories are defined as: 1) calyx fully (or partly) covered with tissue on the lateral and oral side (a, b), 2) only oral side of calyx fully (or partly) covered with tissue, lateral side not covered with tissue (c, d), 3) dead, bare skeleton without tissue or only tissue remains (e, f). Dead corals were excluded from respiration and calcification measurements.
Source publication
Cold-water corals (CWCs) are considered vulnerable to environmental changes. However, previous studies have focused on adult CWCs and mainly investigated the short-term effects of single stressors. So far, the effects of environmental changes on different CWC life stages are unknown, both for single and multiple stressors and over long time periods...
Contexts in source publication
Context 1
... a microscope adapter, Nikon Corporation) connected to a stereomicroscope (SteREO Discovery.V8, Carl Zeiss MicroImaging GmbH). We used the tissue covered surface area of the corals as proxy for their health status. Based on the lateral pictures, corals were classified into three health categories depending on the tissue coverage of their skeleton (Fig. 3) and survival rates were assessed monthly. The health categories were defined as: 1) calyx fully (or partly) covered with tissue on the lateral and oral side, 2) only oral side of calyx fully (or partly) covered with tissue, lateral side not covered with tissue, 3) dead, bare skeleton without tissue or only tissue remains. Dead corals ...
Context 2
... (R Core Team, 2021) and package rMR (Moulton, 2018). The slope of the respiration rates was analysed for 2 h intervals for late juveniles (six intervals over 12 h) and adults (three intervals over 6 h) and for 3 h intervals for early juveniles (six intervals over 18 h) and used to calculate the mean respiration rates over the whole time interval (Fig. S3). The script involved quality control steps and corrected for mean background respiration measured prior to the start of the incubations as well as for the incubation volume. Respiration rates were normalised to tissue covered surface area (mg O 2 cm 2 d 1 ...
Citations
... This will have a cascading effect on the availability of zooplankton. Consequently, the energy supply to CWCs will likely be more limited, potentially leading to reduced survival and calcification rates 25 . At the same time, the energetic demands of CWCs are expected to increase as environmental changes persist 12 . ...
The relationship between energy reserves of cold-water corals (CWCs) and their physiological performance remains largely unknown. In addition, it is poorly understood how the energy allocation to different metabolic processes might change with projected decreasing food supply to the deep sea in the future. This study explores the temporal and spatial variations of total energy reserves (proteins, carbohydrates and lipids) of the CWC Desmophyllum dianthus and their correlation with its calcification rate. We took advantage of distinct horizontal and vertical physico-chemical gradients in Comau Fjord (Chile) and examined the changes in energy reserves over one year in an in situ reciprocal transplantation experiment (20 m vs. 300 m and fjord head vs. mouth). Total energy reserves correlated positively with calcification rates. The fast-growing deep corals had higher and less variable energy reserves, while the slower-growing shallow corals showed pronounced seasonal changes in energy reserves. Novel deep corals (transplanted from shallow) were able to quickly increase both their calcification rates and energy reserves to similar levels as native deep corals. Our study shows the importance of energy reserves in sustaining CWC growth in spite of aragonite undersaturated conditions (deep corals) in the present, and potentially also future ocean.
... In the Mediterranean CWC Madrepora oculata only a small portion (1-3%) of the total metabolic energy is required for calcification and therefore the corals can maintain their calcification and thus their growth even under unfavourable conditions 50 . In addition, abundant feeding may help animals to compensate for stress 51,52 . Indeed, under low seawater pH, well-fed C. huinayensis juveniles increased their growth rates compared to those kept under low feeding conditions 51 . ...
... In addition, abundant feeding may help animals to compensate for stress 51,52 . Indeed, under low seawater pH, well-fed C. huinayensis juveniles increased their growth rates compared to those kept under low feeding conditions 51 . Similarly, Martínez-Dios et al. 52 detected a positive effect on net calcification rate and overall performance at a higher feeding frequency in D. dianthus kept in different pH environments. ...
... As natural survival rates for recruits are already low, this reduces success 9,30,76 . The impact and coral response to sediment load in the natural environment is influenced by additional factors, such as currents 45 and food supply 51,52,77,78 . Furthermore, the sediment-induced tissue regression suggests a deterioration or increasing influence on the coenosarc cover of the animals under T1 and T2 over time. ...
Chilean Patagonia is a hotspot of biodiversity, harbouring cold-water corals (CWCs) that populate steep walls and overhangs of fjords and channels. Through anthropogenic activities such as deforestation, roadworks, aquafarming and increased landslide frequency, sediment input increases in the fjord region. While the absence of CWCs on moderately steep slopes has been suggested to reflect high vulnerability to sedimentation, experimental evidence has been lacking. Here, we investigated the sensitivity of CWCs to sediment stress, using juvenile Caryophyllia (Caryophyllia) huinayensis as a model. A 12-week aquarium experiment was conducted with three sediment loads: the average natural sediment concentration in Comau Fjord, 100- and 1000-fold higher sediment levels, expected from gravel road use and coastal erosion. Changes in coral mass and calyx dimensions, polyp expansion, tissue retraction and respiration were measured. For CWCs exposed to two and three order of magnitude higher sediment concentrations, 32% and 80% of the animals experienced a decrease in tissue cover, respectively, along with a decrease in respiration rate of 34% and 66%. Under the highest concentration corals showed reduced polyp expansion and a significantly reduced growth of ~ 95% compared to corals at natural concentration. The results show that C.huinayensis is affected by high sediment loads. As human activities that increase sedimentation steadily intensify, coastal planners need to consider detrimental effects on CWCs.
