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: In the Arctic, the currently observed rising air temperature results in more frequent calving of icebergs. The latter derive from tidewater glaciers. Arctic macrozoobenthic soft-sediment communities are considerably disturbed by direct hits and sediment reallocation caused by iceberg scouring. With the aim to describe the primary succession of macrozoobenthic communities following these events, scientific divers installed 28 terracotta containers in the soft-sediment off Brandal (Kongsfjorden, Svalbard, Norway) at 20 m water depth in 2002. The containers were filled with a bentonite–sand mixture resembling the natural sediment. Samples were taken annually between 2003 and 2007. A shift from pioneering species (e.g. Cumacea: Lamprops fuscatus) towards more specialised taxa, as well as from surface detritivores towards subsurface detritivores was observed. This is typical for an ecological succession following the facilitation and inhibition succession model. Similarity between experimental and non-manipulated communities from 2003 was significantly highest after 3 years of succession. In the following years, similarity decreased, probably due to elevated temperatures, which prevented the fjord system from freezing. Some organisms, numerically important in the non-manipulated community (e.g. the polychaete Dipolydora quadrilobata) did not colonise the substrate during the experiment. This suggests that the community had not fully matured within the first 3 years. Later, the settlement was probably impeded by consequences of rising temperatures. This demonstrates the long-lasting effects of severe disturbances on Arctic macrozoobenthic communities. Furthermore, environmental changes, such as rising temperatures coupled with enhanced food availability due to an increasing frequency of sea-ice-free days per year, may have a stronger effect on succession than exposure time.

Description: Ascidians are abundant and well-represented members of worldwide benthic communities, including Antarctica and the Arctic. These organisms exhibit different reproductive patterns usually related to a latitudinal gradient, as do many marine invertebrate species. Reproductive seasonality varies from one or two annual peaks in cold and temperate water species to continuous reproduction throughout the year in warm water species. Styela rustica (Linnaeus 1767) and Halocynthia pyriformis (Rathke 1806) are solitary species with external fertilization and a wide distribution range, from the North Atlantic to the Arctic. The reproductive patterns of these two species were assessed for Arctic populations by year-round sampling and structural analysis of the gonads. Both species are hermaphrodites and showed marked seasonality in oocyte maturity and spawning; S. rustica peaked during the boreal summer and H. pyriformis in late spring. The two species also showed marked differences in mature oocyte sizes: H. pyriformis almost doubled those of S. rustica and, while spermatocytes of H. pyriformis were mature year-round, the maturity of male and female gametes was synchronized in S. rustica. The species thus showed an annual reproductive cycle coupled with a higher production period in the ecosystem, but also exhibited different strategies developed under the same environmental pressures.

Description: Donax species dominate the intertidal zone of coastal upwelling sandy beaches worldwide. The population dynamics of West African D. pulchellus and D. rugosus is still unknown. The population dynamics and ecology of surf clam Donax species, D. pulchellus and D. rugosus (Bivalvia: Donacidae), inhabiting two exposed sandy beaches of Ghana, were studied over 12 months period (August 2006 to July 2007). A total of 7,225 individuals of D. pulchellus, La beach and 2,452 individuals of D. rugosus, Chorko beach, were sampled. Two-way analysis of variance revealed a significant difference in the spatial and temporal distribution of the two species (p 〈 0.05). D. pulchellus attains first maturity at a mean length of 7.16 + 1.89 mm, and a maximum size of 11 mm while D. rugosus attains first maturity at a mean length of 20.94 + 6.98 mm, and a maximum size of 33.5 mm. Environmental factors namely, salinity, nitrate, and grain size modulate the growth in shell length of the two species. This book, provide new insight of Donax species as sedentary bivalves of sandy beach ecosystems. The book is useful for marine biologist, benthic ecologist, environmentalist, and chemical ecologist.

Description: In order to reveal the structure of the sparsely known deeper sublittoral hard bottom communities of glacial Kongsfjorden the macroepibenthos from six depth zones (30m - 200m) was analysed. A total 180 still images derived from six hours‘ video recorded at the Kongsfjordneset remotely operated vehicle station were assessed quantitatively. Overall 27 mainly suspension-feeding species/taxa were observed. Of these, two-thirds have an arcto-boreal distribution while the remainder are cosmopolitan. The overall mean epibenthos abundance was 33 ind. m-2 with maximum values at 150m depth (97.9 ind. m-2). The majority of the taxa inhabited the entire depth range. Encrusting red algae, an unidentified sponge and the sea anemone Urticina eques characterized the assemblage of the shallow zone. The sea anemones Hormathia spp. were important below 30m, the Serpulid polychaete Protula tubularia was characteristic for the community below 50m, and the demosponge Haliclona sp. was a key taxon between 100m and 200m depth. Cluster analysis and non-metrical multidimensional scaling based on abundance data showed differences between the assemblages along the bathymetric gradient, but only in the shallower depths in relation to the substratum surface incline. As surface and tidal current impacts attenuate with increasing depth, there is a gradual trend from robust key species towards more fragile ones (i.e. Protula tubularia), in line with the ‘Physical control hypothesis’.

Description: Increasing dissolution of anthropogenic-released carbon dioxide into the world’s oceans is causing ocean acidification (OA). OA is thought to negatively affect most marine-calcifying organisms, notably cold-water corals (CWC), which may be especially sensitive due to the deep and cold waters they normally thrive in. However, the impact of OA on CWC is difficult to predict. Recorded distributions of CWC are rarely linked to in situ water chemistry, and the boundaries of their distributions are not clearly defined. The fjord Comau in Chilean Patagonia features pronounced pH gradients, and up to 0.5 pH units have been recorded both vertically (at some sites within 50 m depth) and less distinct horizontally (from head to mouth). The cosmopolite coral Desmophyllum dianthus grows along the course of the fjord and of the entire pH range. It occurs in shallow depths (below 12 m, pH 8.1) as part of a deep-water emergence community, but also in 225 m depth at a pH of 7.4. Based on pH and totalalkalinity, data calculations of the associated carbonate chemistry revealed that this CWC thrives commonly close the aragonite (the orthogonal crystal form of calcium carbonate, the mineral structure of coral skeletons) saturation horizon and even below. This suggests a high adaptation potential of D. dianthus to adjust its calcification performance to conditions thermodynamically unfavourable for the precipitation of aragonite.

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.