Work Package 2
Organism Level Lead: Dr C. Hauton (SOTON/SOES)
The precipitation of calcium carbonate polymorphs by organic tissues represents a key process in the normal development and growth of multi-cellular marine organisms. WP2 determines how these complex multi-stage processes are affected by the physical and chemical conditions of the surrounding environment. Calcification processes are investigated at a higher level of biological organisation than addressed by WP1 and in organisms that demonstrate varying abilities to maintain control of their internal microenvironment.
Research Task 4: Environmental effects on the physiology of calcification in commercially important juvenile bivalves
Frauke Bagusche
Supervisors: Dr C. Hauton (SOTON), Dr S. Pouvreau (IFREMER)
Host: SOTON
Secondments to: UPS-IDES (with input from Prof Y. Dauphin, Prof J.P. Cuif and J. Nouet), IFREMER and the company “Cooperative Maritime L'Ecloserie Du Tinduff” (directed by J.P. Carval).
Variation in the calcification of larval bivalves has direct impacts on shell fixation at metamorphosis and subsequent indirect impacts on growth, susceptibility to predation by selective macrofaunal predators and mortality caused by impacts with fishing gear and in mechanical sorting processes. The Pacific oyster, Crassostrea gigas, represents an ideal, commercially important, model system. C. gigas shells are built of two different calcitic shell layers. A prismatic layer exists on the external side of the flat valve, whereas the main part of the shell is built by a foliated mineralized tissue. The prismatic and foliated crystal-like units are built by tiny crystallites (in the sub-micrometre range). The carbonate morphology in this species has also recently been shown to vary with life stage, from aragonite in larval stages to calcite in postlarvae. As the organic matrices are biochemically distinct between the different shell layers and the carbonate morphology differs during growth, it can be expected that variations in life condition may significantly influence the crystallization of nanometric units within each skeleton layer.
Light microscopy image
of C. gigas mantle.
(Photo: F.Bagusche)
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C. gigas – shell comparison
after treatment in high (right)
and low (left) seawater pH.
(Photo: F. Bagusche) |
Objectives: to investigate calcification at the biological organisational level of the whole organism and in species which exert control of their internal microenvironment.
Research Task 5: Effect of pH dynamics on coral recruitment and early colony growth
Marlene Wall
Supervisors: Dr C. Richter (AWI), Dr S. Khokiattiwong (PMBC)
Host: AWI
Secondments to: PMBC and NIOO-KNAW (input from Prof J. Middelburg).
There is growing evidence that increased CO2 and acidification of the surface ocean decrease coral calcification and, hence, the carbonate balance in coral reefs. While the long-term trends are already well established, the natural small-scale pH dynamics and their effects on reef organisms are still unexplored. Both internal and external factors such as the activity of the rich coelobite biota inhabiting coral reef framework crevices or very large amplitude internal waves may induce variations in reef waters of up to more than 0.4 pH units within metres and minutes, respectively.
Temperature variability recorded on west coast reefs in the Andaman Sea (Thailand) influenced by large amplitude internal waves. (Graphic: M. Wall)
Objectives: to assess the effects of small-scale large-amplitude oscillations in ocean pH and aragonite saturation state on coral recruitment and calcification, formation of primary corallites and early colony growth in the field and in the laboratory.
Research Task 6: Environmental and physiological controls of calcification in fish and cephalopods
Rommel Maneja
Supervisors: Dr U. Piatkowski and Dr C. Clemmesen (GEOMAR), Prof A. Geffen (UiB)
Hosts: GEOMAR (input from Prof A. Eisenhauer and Dr J. Fietzke) and UiB.
Secondments to: The fish hatchery “MerluNor AS” (input from Prof R. Salte).
Otoliths, scales and bones are calcified tissues found in fish, and statoliths and gladii are the calcified structures in cephalopods. Although evolutionary convergence may result in similarities in form and function, the physiological mechanisms for calcification can vary. Otolith growth is relatively well described through ultrastructure studies, but statolith and cephalopod hard structure biomineralisation is less well known. Research on otolith growth has been driven by interest in using primary or presumed daily increments to indicate age, especially in larval fish.
Otolith of juvenile cod (G. morhua).
(Photo: rmaneja)
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Statolith of cuttlefish S. officinalis
grown under 380 µatm CO2.
(Photo: rmaneja) |
Objectives: to investigate whether the growth of otoliths and statoliths - calcified tissues found in fish and cephalopods respectively - is regulated by similar mechanisms and how environmental and physiological control are functioning and interacting in both animal groups.
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