79 research outputs found

    Influence of Anthropogenic Climate Change on the Ecophysiology of the Cold Water Coral Lophelia pertusa = Einfluss des anthropogenen Klimawandels auf die Ökophysiologie der Kaltwasserkoralle Lophelia pertusa

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    Monographic work describing the cultivation of cold-water coral Lophelia pertusa in closed recirculating systems and climate change related short- and long-term experiments

    Cruise Report F.K. Littorina L07a-21

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    Dates of Cruise: 02.-06.08.2021 Areas of Research: Aquarium West Shore Port Calls: Grenå DK (03.08. - 05.08.2021, 2 nights) Institute: GEOMAR Helmholtz Centre for Ocean Research Kiel Acquisition of living marine organism for the institute’s own aquarium in the northern Kattegat

    Temperate carbonate cycling and water mass properties from intertidal to bathyal depths (Azores)

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    The rugged submarine topography of the Azores supports a diverse heterozoan association resulting in intense biotically-controlled carbonate-production and accumulation. In order to characterise this cold-water (C) factory a 2-year experiment was carried out in the southern Faial Channel to study the biodiversity of hardground communities and for budgeting carbonate production and degradation along a bathymetrical transect from the intertidal to bathyal 500 m depth. Seasonal temperatures peak in September (above a thermocline) and bottom in March (stratification diminishes) with a decrease in amplitude and absolute values with depth, and tidal-driven short-term fluctuations. Measured seawater stable isotope ratios and levels of dissolved nutrients decrease with depth, as do the calcium carbonate saturation states. The photosynthetic active radiation shows a base of the euphotic zone in ~70 m and a dysphotic limit in ~150 m depth. Bioerosion, being primarily a function of light availability for phototrophic endoliths and grazers feeding upon them, is ~10 times stronger on the illuminated upside versus the shaded underside of substrates in the photic zone, with maximum rates in the intertidal (−631 g/m2/yr). Rates rapidly decline towards deeper waters where bioerosion and carbonate accretion are slow and epibenthic/endolithic communities take years to mature. Accretion rates are highest in the lower euphotic zone (955 g/m2/yr), where the substrate is less prone to hydrodynamic force. Highest rates are found – inversely to bioerosion – on down-facing substrates, suggesting that bioerosion may be a key factor governing the preferential settlement and growth of calcareous epilithobionts on down-facing substrates. In context of a latitudinal gradient, the Azores carbonate cycling rates plot between known values from the cold-temperate Swedish Kosterfjord and the tropical Bahamas, with a total range of two orders in magnitude. Carbonate budget calculations for the bathymetrical transect yield a mean 266.9 kg of epilithic carbonate production, −54.6 kg of bioerosion, and 212.3 kg of annual net carbonate production per metre of coastline in the Azores C factory

    Interactive Effects of Ocean Acidification and Warming on Growth, Fitness and Survival of the Cold-Water Coral Lophelia pertusa under Different Food Availabilities

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    Cold-water corals are important bioengineers that provide structural habitat for a diverse species community. About 70% of the presently known scleractinian cold-water corals are expected to be exposed to corrosive waters by the end of this century due to ocean acidification. At the same time, the corals will experience a steady warming of their environment. Studies on the sensitivity of cold-water corals to climate change mainly concentrated on single stressors in short-term incubation approaches, thus not accounting for possible long-term acclimatisation and the interactive effects of multiple stressors. Besides, preceding studies did not test for possible compensatory effects of a change in food availability. In this study a multifactorial long-term experiment (6 months) was conducted with end-of-the-century scenarios of elevated pCO2 and temperature levels in order to examine the acclimatisation potential of the cosmopolitan cold-water coral Lophelia pertusa to future climate change related threats. For the first time multiple ocean change impacts including the role of the nutritional status were tested on L. pertusa with regard to growth, “fitness,” and survival. Our results show that while L. pertusa is capable of calcifying under elevated CO2 and temperature, its condition (fitness) is more strongly influenced by food availability rather than changes in seawater chemistry. Whereas growth rates increased at elevated temperature (+4°C), they decreased under elevated CO2 concentrations (~800 μatm). No difference in net growth was detected when corals were exposed to the combination of increased CO2 and temperature compared to ambient conditions. A 10-fold higher food supply stimulated growth under elevated temperature, which was not observed in the combined treatment. This indicates that increased food supply does not compensate for adverse effects of ocean acidification and underlines the importance of considering the nutritional status in studies investigating organism responses under environmental changes

    Effects of ocean acidification and global warming on reef bioerosion—lessons from a clionaid sponge

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    Coral reefs are under threat, exerted by a number of interacting effects inherent to the present climate change, including ocean acidification and global warming. Bioerosion drives reef degradation by recycling carbonate skeletal material and is an important but understudied factor in this context. Twelve different combinations of pCO2 and temperature were applied to elucidate the consequences of ocean acidification and global warming on the physiological response and bioerosion rates of the zooxanthellate sponge Cliona orientalis—one of the most abundant and effective bioeroders on the Great Barrier Reef, Australia. Our results confirm a significant amplification of the sponges’ bioerosion capacity with increasing pCO2, which is expressed by more carbonate being chemically dissolved by etching. The health of the sponges and their photosymbionts was not affected by changes in pCO2, in contrast to temperature, which had significant negative impacts at higher levels. However, we could not conclusively explain the relationship between temperature and bioerosion rates, which were slightly reduced at both colder as well as warmer temperatures than ambient. The present findings on the effects of ocean acidification on chemical bioerosion, however, will have significant implications for predicting future reef carbonate budgets, as sponges often contribute the lion’s share of internal bioerosion on coral reefs

    Ocean Acidification Accelerates Reef Bioerosion

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    In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process – biologically induced carbonate dissolution via bioerosion – has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia’s Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges’ bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation

    RV POSEIDON Cruise Report POS420 COWACSS Biological observation and sampling of cold-water corals to investigate impacts on climate change

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    Trondheim – (Kristiansund) – Kiel 08. – (25.) – 30.09.201

    Phenotypic plasticity of coralline algae in a High CO2world

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    It is important to understand how marine calcifying organisms may acclimatize to ocean acidification to assess their survival over the coming century. We cultured the cold water coralline algae, Lithothamnion glaciale, under elevated pCO2 (408, 566, 770, and 1024 μatm) for 10 months. The results show that the cell (inter and intra) wall thickness is maintained, but there is a reduction in growth rate (linear extension) at all elevated pCO2. Furthermore a decrease in Mg content at the two highest CO2 treatments was observed. Comparison between our data and that at 3 months from the same long-term experiment shows that the acclimation differs over time since at 3 months, the samples cultured under high pCO2 showed a reduction in the cell (inter and intra) wall thickness but a maintained growth rate. This suggests a reallocation of the energy budget between 3 and 10 months and highlights the high degree plasticity that is present. This might provide a selective advantage in future high CO2 world

    Discovery of symbiotic nitrogen fixation and chemoautotrophy in cold-water corals

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    Cold-water corals (CWC) are widely distributed around the world forming extensive reefs at par with tropical coral reefs. They are hotspots of biodiversity and organic matter processing in the world’s deep oceans. Living in the dark they lack photosynthetic symbionts and are therefore considered to depend entirely on the limited flux of organic resources from the surface ocean. While symbiotic relations in tropical corals are known to be key to their survival in oligotrophic conditions, the full metabolic capacity of CWC has yet to be revealed. Here we report isotope tracer evidence for efficient nitrogen recycling, including nitrogen assimilation, regeneration, nitrification and denitrification. Moreover, we also discovered chemoautotrophy and nitrogen fixation in CWC and transfer of fixed nitrogen and inorganic carbon into bulk coral tissue and tissue compounds (fatty acids and amino acids). This unrecognized yet versatile metabolic machinery of CWC conserves precious limiting resources and provides access to new nitrogen and organic carbon resources that may be essential for CWC to survive in the resource-depleted dark ocean
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