RV POSEIDON Cruise Report POS473 LORELEI II: LOphelia REef Lander Expedition and Investigation II, Tromsø – Bergen – Esbjerg, 15.08. – 31.08. – 04.09.2014

Form, Armin; Büscher, Janina; Hissmann, Karen; Flögel, Sascha; Wisshak, Max; Rüggeberg, Andres; Bannister, Raymond; Kutti, Tina; Stapp, Laura; Bennecke, Swaantje; Küter, Marie; Nachtigall, Kerstin; Schauer, Jürgen; Fenske, Martin

doi:10.3289/cr_pos_473

Cited by 3 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to compare the measured geochemical data to environmental data such as salinity and temperature, two landers were deployed in close proximity to the investigated reefs (Form et al, 2015). These landers were equipped with temperature, salinity and pH-sensors and recorded the environmental information for 14 months.…”

Section: Environmental Datamentioning

confidence: 99%

“…The landers were deployed on July 2 nd , 2013 (Trondheimsfjord) at a depth of 215m and July 4 th , 2013 (Sula Reef) at a depth of 315 m. Data in the Sula Reef was recorded every 30 minutes, in the Nord-Leksa Reef every 15 minutes resulting in 20123 and 37603 data points, respectively. This translates to a total recorded time of 419 days in the Sula Reef and 391 days in the Nord-Leksa Reef(Form et al, 2015).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Unraveling the potential of cold-water carbonates as geochemical archives for paleoceanographic reconstructions

Schleinkofer¹

View full text Add to dashboard Cite

Geochemical investigations on biogenic carbonates are commonly conducted to reconstruct the environmental conditions of the past. However, different carbonate producers incorporate elements to varying degrees, due to biological vital effects. Detecting and quantifying these effects is crucial to produce reliable reconstructions. These paleoreconstructions are of great importance to evaluate the consequences of our recent climate change and identify control mechanisms on the distribution of endangered species such as Desmophyllum pertusum. In chapter three we tested Mg/Ca, Sr/Ca and Na/Ca ratios on this species, among other coldwater scleractinians, to test if they provide reliable proxy information. The results reveal no apparent control of Mg/Ca or Sr/Ca ratios through seawater temperature, salinity or pH. Na/Ca ratios appear to be partly controlled by the seawater temperature, which is also true for other aragonitic organisms such as warm-water corals and the bivalve Mytilus edulis. However, a large variability complicates possible reconstructions by means of Na/Ca. In addition, we explore different models to explain the apparent temperature effect on Na/Ca ratios based on temperature sensitive Na and Ca pumping enzymes. The bivalve Acesta excavata is commonly found in cold-water coral reefs among the North Atlantic, together with D. pertusum. Multiple linear regression analysis, presented in chapter four, indicates that up to 79% of the elemental variability in Mg/Ca, Sr/Ca and Na/Ca is explainable with temperature and salinity as independent predictor variables. Vital effects, for instance growth rate effects, are evident and make paleoreconstructions not feasible. Furthermore, organic material embedded in the shell, as well as possible stress effects can drastically change the elemental composition. Removal of these organic matrices from bulk samples for LA-ICP-MS (laser ablation inductively coupled mass spectrometer) measurements by means of oxidative cleaning is not possible, but Na/Ca ratios decrease after this cleaning. This is presumably an effect of leaching and not caused by the removal of organic matrices. Interesting biogeochemical relations were found in the parasitic foraminifera H. sarcophaga. We report Mg/Ca, Sr/Ca, Na/Ca and Mn/Ca ratios measured in H. sarcophaga from two different host species (A. excavata and D. pertusum) in chapter five. Sr/Ca ratios are significantly higher in foraminifera that lived on D. pertusum. This could indicate that dissolved host material is utilized in shell calcification of H. sarcophaga, given the naturally higher strontium concentration in the aragonite of D. pertusum. Mn/Ca ratios are highest in foraminifera that lived on A. excavata but did not fully penetrate the host’s shell. Most likely, this represents a juvenile stadium of the foraminifera during which it feeds on the organic periostracum of the bivalve, which is enriched in Mn and Fe. The isotopic compositions are similarly affected, both δ18O and δ13C values are significantly lower in foraminifera that lived 23on D. pertusum compared to specimen that lived on A. excavata. Again, this might represent the uptake of dissolved host material or different pH regimes in the calcifying fluid of the hosts (bivalve < 8, coral > 8) that control the extent of hydration/hydroxylation reactions. Temperature reconstructions are possible using stable oxygen isotopes on this foraminifera species; however, the results are only reliable if the foraminifera lived on A. excavata. Samples of H. sarcophaga from D. pertusum would lead to overestimations of the seawater temperature due to the lower δ18O values. Apart from biological vital effects, storage and preservation methods can significantly change the geochemical composition of different marine biogenic carbonates. In chapter six this is presented on the example of ethanol preservation, a common technique to allow extended storage of biogenic samples. The investigation reveals a significant decrease of Mg/Ca and Na/Ca ratios even after only 45 days storage in ultrapure ethanol. Sr/Ca ratios on the other hand are not influenced. Besides temperature, salinity and pH further environmental parameters are important such as nutrient availability, especially for the distribution of cold-water corals. In chapter seven we extend the investigations on A. excavata by including the elemental ratios Ba/Ca, Mn/Ca and P/Ca. We expected P/Ca to be helpful in the otherwise difficult process of dentifying growth increments. Based on our observations we had to refute this theory. P/Ca ratios are not systematically enriched in the vicinity of growth lines. Instead, we found a regular sequence of peaks of Ba/Ca, P/Ca and Mn/Ca. This sequence as well as the peaks in general are potentially caused by equential blooms of different algae, diatoms and other planktonic organisms ...

show abstract

Section: Environmental Datamentioning

confidence: 99%

mentioning

confidence: 99%

Unraveling the potential of cold-water carbonates as geochemical archives for paleoceanographic reconstructions

Schleinkofer¹

View full text Add to dashboard Cite

show abstract

Automated Activity Estimation of the Cold-Water Coral Lophelia pertusa by Multispectral Imaging and Computational Pixel Classification

Liu

Büscher

Köser

et al. 2021

Journal of Atmospheric and Oceanic Technology

View full text Add to dashboard Cite

The cold-water coral Lophelia pertusa builds up bioherms that sustain high biodiversity in the deep ocean worldwide. Photographic monitoring of the polyp activity represents a helpful tool to characterize the health status of the corals and to assess anthropogenic impacts on the microhabitat. Discriminating active polyps from skeletons of white Lophelia pertusa is usually time-consuming and error-prone due to their similarity in color in common RGB camera footage. Acquisition of finer resolved spectral information might increase the contrast between the segments of polyps and skeletons, and therefore could support automated classification and accurate activity estimation of polyps. For recording the needed footage, underwater multispectral imaging systems can be used, but they are often expensive and bulky. Here we present results of a new, light-weight, compact and low-cost deep-sea tunable LED-based underwater multispectral imaging system (TuLUMIS) with eight spectral channels. A brunch of healthy white Lophelia pertusa was observed under controlled conditions in a laboratory tank. Spectral reflectance signatures were extracted from pixels of polyps and skeletons of the observed coral. Results showed that the polyps can be better distinguished from the skeleton by analysis of the eight-dimensional spectral reflectance signatures compared to three-channel RGB data. During a 72-hour monitoring of the coral with a half-hour temporal resolution in the lab, the polyp activity was estimated based on the results of the multispectral pixel classification using a support vector machine (SVM) approach. The computational estimated polyp activity was consistent with that of the manual annotation, which yielded a correlation coefficient of 0.957.

show abstract

Tidal Dynamics Control on Cold-Water Coral Growth: A High-Resolution Multivariable Study on Eastern Atlantic Cold-Water Coral Sites

et al. 2020

View full text Add to dashboard Cite

Cold-water coral (CWC) communities form complex benthic ecosystems in a distinct part of the water column. The exact processes supporting CWC reef growth and changes with time are still partly unsolved. Besides local hydrographic conditions, noticeable interactions of tidal flow with topography have been reported for CWC sites. Recent studies have suggested a tidally driven hydraulic control of flow over topographic features as a driver for local overturning at cold-water coral sites. This mechanism proposed a link between surface productivity and coral growth depths and is a driver of resuspension of the bottom material. Only few studies have concentrated on how these processes vary with the health status and structure of the cold-water coral occurrences. In this study, we explore the processes over tidal cycles by analyzing in situ stratification, hydrography and velocity data which we then combine with local topography from seven Desmophyllum pertusum (previously Lophelia pertusa) dominated eastern Atlantic CWC sites, from the Arctic to the southern hemisphere. The "quality" of CWC sites varies from thriving to declining and dead reefs. We show that living and healthy corals are concentrated at sites, where local hydrodynamics create overturning and mixing which overcomes on a daily basis gravitational particle sinking and thus re-supply food to filterfeeding corals. We find a very wide range of local hydrographic and biogeochemical conditions at the sites which suggests they play only a secondary role for CWC health.

show abstract

RV POSEIDON Cruise Report POS473 LORELEI II: LOphelia REef Lander Expedition and Investigation II, Tromsø – Bergen – Esbjerg, 15.08. – 31.08. – 04.09.2014

Cited by 3 publications

References 0 publications

Unraveling the potential of cold-water carbonates as geochemical archives for paleoceanographic reconstructions

Unraveling the potential of cold-water carbonates as geochemical archives for paleoceanographic reconstructions

Automated Activity Estimation of the Cold-Water Coral Lophelia pertusa by Multispectral Imaging and Computational Pixel Classification

Tidal Dynamics Control on Cold-Water Coral Growth: A High-Resolution Multivariable Study on Eastern Atlantic Cold-Water Coral Sites

Contact Info

Product

Resources

About