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: 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: Cold-water corals (CWC) build complex, three-dimensional habitats for diverse communities of associated species. In spite of their importance, very little is known on their reproductive biology. In the Patagonian fjords of Chile, three caryophylliid CWC abound: Desmophyllum dianthus Es-per 1794 along with the recently described Caryophyllia huinayensis Cairns et al. 2005 and Tethocyathus endesa Cairns et al. 2005. This study reports first in situ and in vitro observations of the early life history of the latter two species along with in vitro growth data of juvenile C. huina-yensis. Both are brooding species with translucent tissues, which allowed us to detect and monitor larval development in the gastrovascular system of living specimens. In situ observations from summer 2017 showed between 15 and 25 milky white reproductive stages in the tentacle portion of the gastrovascular cavity of one adult specimen. Up to five younger, round stages were ob-served in groups in the tips of the tentacles. Small planulae of 1.13-1.28 mm length were observed in the tips of the tentacles or organized radially around the mouth. Observations from C. huina-yensis maintained (〉 1 yr) in an aquarium system showed that the 620 µm large orange planulae may swim with a velocity of 230 µm s-1 and thus may move from the tentacle tip to the mouth within less than a minute and thereafter reappear in the same or another tentacle in the similar time. After release larvae were found to be negatively buoyant, crawl along the substrate and settle between four and 16 days. Recently settled juveniles increased their basal disc diameter with a rate of 10 µm d-1. After 30 months of maintenance in the aquarium system (Temperature: 12.5 °C, Salinity 32, pH 8, argonite 〉1, feed with Artemia salina nauplii twice a week) recruits may gain 4.22 (+/-) 0.03 mm yr-1 in diameter and reach the mean size observed for adults in the field after three years. Research on the early life history of CWC is important to understand larval dispersal and connectivity of populations threatened by a changing climate and increasing eutrophication by expanding salmon farming operations.

Description: Cold-water corals play an important role as ecosystem engineers by providing the three-dimensional structural basis and habitat for a rich associated fauna. In southern Chile, the cold-water scleractinian Desmophyllum dianthus populates the steep walls of Comau Fjord. Where its principal energy source, the zooplankton, is less abundant in winter. This coral specie is often associated with filter-feeders, but the nature and possible trophic significance of this relationship remains enigmatic. Dense belts of the mussel Aulacomya atra and the brachiopod Magellania venosa thrive in the productive waters above and between D. dianthus, and both, visual observation and diver-operated push net samples revealed a rain of biodeposits (faeces and pseudofaeces) from these filter-feeders to the corals. This study aims to determine if the conversion by filter-feeders of microscopic plankton inaccessible to corals to macroscopic strings of faeces and pseudofaeces accessible to the corals’ tentacles may represent a new and so far overlooked trophic link channeling surface production to the corals. Preliminary in vitro experiments show that D. dianthus ingests biodeposits of the mussel Mytilus edulis, but only after the consumption of juvenile krill (Euphausia pacifica). This indicates that biodeposits of active filter feeders may play a role as a food supplement for corals. Follow-up experiments with biodeposits produced under natural conditions by the native filter-feeder community are expected to compound the evidence.

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.