ALBERT

Description: In the last few decades and in the near future CO2-induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g. brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences for biomineral formation remain poorly understood. Only a few studies have addressed the impact of ocean acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789). These were grown in the natural environment as well as in controlled culturing experiments under different pH conditions (ranging from 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy. Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low-pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2 source in the culture set-up. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

Description: Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.

Description: Two scleractinian cold-water corals, Desmophyllum dianthus and Caryophyllia huinayensis are abundant on hard substrate, below 18 m depth, throughout the entire fjord Comau in Northern Patagonia, Chile. At “X-Huinay” (42º 23.276’ S, 72º 27.657’ W) on the western side of the central fjord, a recent mass mortality of D. dianthus occurred, while C. huinayensis survived. H2S seeps here support the formation of filamentous chemosynthetic bacterial mats. At this site, sulfide concentrations of up to 100 higher than normal ambient water values have been measured.

Description: Scleractinian corals (or stony corals) are important habitat forming organisms. Their characteristic growth creates three dimensional structures that provide shelter, settlement substrate and habitat to a diversity of organisms. This also holds true for cold water corals (CWC), but current knowledge is limited with only two decades of research. Caryophyllia huinayensis (Carins et al. 2005) is a small solitary scleractinian coral, which can serve as a model organism for the study of metabolism of CWC. This stony coral is commonly found in association with the larger scleractinian coral Desmophyllum dianthus in the Chilean Fjord Region, even in diving depths. As to quantify the basic physiological parameter ‘respiration’, specimens of the whole size range were collected at two stations and acclimatised to in vitro condition. Oxygen microoptodes (based on the dynamic fluorescence quenching principle), a four channel optode array, an intermittent flow system, and online data registration were used to measure the metabolic activity of Caryophyllia huinayensis during in vitro respiration experiments. This species showed oxygen consumption rates, ranging from 0.01mg/l up to 1.61mg/l. The overall metabolic rates are compared with those of other scleractinian corals.

Description: The energy budget is one key to the understanding of an ecosystem and may be determined by its carbon fluxes. The aim of the study was and still is to quantify the carbon flux between newly established arctic hard bottom communities and their pelagial in-situ. A complex setup was constructed to establish a functional in-situ method for hard bottom communities. We used artificial panels, installed in arctic Kongsfjorden at 20 m depth. The panels were colonized by hard bottom organisms over the last decade. These panels were transferred in-situ into benthic chambers. The latter were connected via Tygon-tubes to a multiprobe array (CTD, Seabird 19 V2 plus) allowing measurement of O2-concentrations. A newly designed 16-way valve was used to measure several panels over a period of 72 h in a day and night rhythm.

Description: The cold-water hydrocoral Errina antarctica provides habitat for numerous macroepibenthic species. Gaining knowledge about the highly diverse communities associated with E. antarctica is crucial for efficient protection of the ecosystems, which are strongly threatened by aquaculture and other human activities. This investigation for the first time provides information on quantitative composition of benthic communities associated with E. antarctica. Structure of macroepibenthic community associated with E. antarctica in three bathymetric zones (Zone 1: 10-20 m; Zone 2: 20-30 m; Zone 3: 30-40 m) from four diving sites in the Chilean fjord region is described by analyzing 260 images extracted from videos recorded via ROV. Community compositions were investigated based on abundances using multivariate statistical methods (SIMPER, ANOSIM, MDS). Ecological indices (S, H´, d, J´) were calculated. Distribution of differently sized E. antarctica-colonies (small [diameter 〈 10 cm], medium [10 cm 〈 diameter 〈 20 cm], large [20 cm 〈 diameter]) was investigated and set into context with analysis of community structure. No significant influence of depth on the investigated community was detected. Differences between the four diving sites seem to overlay bathymetric effects. Annelids (mainly genus spirorbis) dominate all bathymetric zones, in line with former investigations. ANOSIM indicated poor distinctness between bathymetric zones (GR=0.062). The MDS-plot showed no grouping of bathymetric zones. Low values of ecological indices in Zone 1 are explained by distribution of E. antarctica-colonies. Abundances of colonies of all sizes decreases with depth, portion of small colonies is highest in Zone 1.