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Pogoda B.,University of Bremen | Pogoda B.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Institute for Marine Resources IMARE | And 2 more authors.

Aquaculture production plays an increasingly important role to meet the global demand for aquatic products and expands continuously. Most mariculture organisms are produced in coastal areas, where space is scarce and user conflicts exist. For extensive cultures farming off the coast at offshore sites could be a solution to eliminate these problems and facilitate further expansion of environmentally sustainable aquaculture. The aim of this study was to examine the biological adequacy of two candidate species for ostreiculture, the Pacific oyster Crassostrea gigas and the European flat oyster Ostrea edulis. Growth rates, condition and mortality in offshore environments were investigated by transferring oyster spat of both species to 4 different sites in 2004 and 2007. Samples were taken every six to eight weeks from April to October and length, width, height and dry mass were measured as well as the Condition Index (CI = dry mass meat. ?. 100/dry mass shell) was calculated. Results show that both oyster species grow successfully in a high-energy environment. Mean growth rates are similar to those measured in individuals from coastal habitats (wild banks and cultures) and the CI shows seasonal variation in both species. The survival rate for both species was >. 99% in 2007. However, in the previous trial in 2004 a high mortality rate was observed for O. edulis at one single site at the end of the experiment. Differences were observed in the increase of shell length and dry mass between sites and size classes. Taking these results into account site-selection criteria for different offshore locations are presented. We conclude that offshore cultivation of oysters will be successful if site-selection criteria are examined carefully when choosing a location for offshore aquaculture. © 2011 Elsevier B.V. Source

Weiss M.,Institute for Marine Resources IMARE | Heilmayer O.,German Aerospace Center | Brey T.,Alfred Wegener Institute for Polar and Marine Research | Lucassen M.,Alfred Wegener Institute for Polar and Marine Research | Portner H.-O.,Alfred Wegener Institute for Polar and Marine Research
Journal of Experimental Marine Biology and Ecology

Temperature changes during ENSO challenge the fauna of the Pacific South American coast. In many ectotherm benthic species pelagic larvae are the most important dispersal stage, which may, however, be particularly vulnerable to such environmental stress. Thermal limitation in aquatic ecotherms is hypothesized to be reflected first in the aerobic scope of an animal. Here we present results on whole animal oxygen consumption and on the activities of two metabolic key enzymes, citrate synthase (CS) and pyruvate kinase (PK)) of Cancer setosus zoeal larvae, acclimated to different temperatures. Larvae acclimated to cooler temperatures (12 and 16°C) were able to compensate for the temperature effect as reflected in elevated mass specific respiration rates (MSR) and enzyme activities. In contrast, warm acclimated larvae (20 and 22°C) seem to have reached their upper thermal limits, which is reflected in MSR decoupling from temperature and low Q10 values (Zoea I: 1.4; Zoea III: 1.02). Thermal deactivation of CS in vitro occurred close to habitat temperature (between 20 and 24°C), indicating instability of the enzyme close to in vivo thermal limits. The capacity of anaerobic metabolism, reflected by PK, was not influenced by temperature, but increased with instar, reflecting behavioral changes in larval life style. Functioning of the metabolic key enzyme CS was identified to be one possible key for larval limitation in temperature tolerance. © 2011. Source

Buck B.H.,Alfred Wegener Institute for Polar and Marine Research | Buck B.H.,Bremerhaven University of Applied Sciences | Bruggemann J.,Institute for Marine Resources IMARE | Hundt M.,University of Koblenz-Landau | And 4 more authors.
Journal of Applied Ichthyology

Summary: The purpose of this study was to investigate the effectiveness of 11 different culture media for production of the free-living nematode Turbatrix aceti. Several other harvesting methods were tested in addition to mass production. A further focus was the investigation of amino acid alterations caused by the application of various media during the culture of T. aceti and two additional nematode species, Panagrellus redivivus and Caenorhabditis elegans. Finally, a cost analysis for the production of T. aceti was generated and its outcome compared to the production of conventional live feed organisms. Altogether 11 liquid culture media were tested for mass production of the nematode Turbatrix aceti using a minimum of effort in terms of labour and costs. Six harvesting methods, including filtration as well as active swimming of T. aceti were evaluated. Additional to the culture of T. aceti in four of the above-mentioned media, the nematodes P. redivivus and C. elegans were cultured on two different solid media. Cost analysis for the production of T. aceti includes those of the media, the equipment, as well as the labour costs for culture and harvest. An average density of approx. 30 × 106 ± 8.13 × 106 nematodes L-1 was achieved for T. aceti. The most efficient method (20 μm filtration) allowed harvesting 85.3 ± 2.7% of the nematodes from the medium without disturbing the particles. Lowest efficiency was achieved by combining sedimentation and filtration, accomplishing a harvest of 42.1 ± 5.8%. The amino acid profile of all three nematode species turned out to be both stable and very similar. Amino acid enrichment had little effect. The costs for producing one million T. aceti individuals ranged between 5.39 and 6.19 €, where labour costs accounted for 73 to 84% of the total production costs. In conclusion, T. aceti appears to be very robust, easy to handle, as well as cheaper to cultivate compared to other live-feed organisms. Therefore, its use in commercial aquaculture should be given future consideration. © 2014 Blackwell Verlag GmbH. Source

Pogoda B.,University of Bremen | Pogoda B.,Alfred Wegener Institute for Polar and Marine Research | Jungblut S.,University of Bremen | Buck B.H.,Alfred Wegener Institute for Polar and Marine Research | And 3 more authors.
Journal of Applied Ichthyology

The aim of this study was to determine the macro-parasitic infestation level of oysters from the southern German Bight focussing on copepods of the genus Mytilicola. Crassostrea gigas, Ostrea edulis and Mytilus edulis were collected at five locations: three nearshore sites in the eastern Wadden Sea and two offshore cultivation sites in the German Bight. To reveal seasonal variations one sampling site was investigated in winter and summer. At the nearshore sites, Mytilicola orientalis was regularly detected in C. gigas. Prevalences ranged between 32.3% and 45.1%, intensity between 3.0 ± 0.6 and 8.2 ± 1.5. Infestation rates of C. gigas within the southern German Bight decreased from west to east: Apparently, M. orientalis has started its range extension along the German coast with gradual retardation eastwards but generally followed the invasion route of its main host, the Pacific oyster. Interestingly, we detected not only M. intestinalis but also M. orientalis as an intestinal parasite in M. edulis, which has sofar not previously been described as host within this region. We conclude that M. orientalis is flexible in its host choice. Furthermore, in the eastern Wadden Sea infestation rates of oysters and mussels by copepods are similar. These results deviate from the patterns observed for the northern Wadden Sea in terms of infestation level and host specificity. No macro-parasites were found in oysters and mussels from the offshore sites. This absence can be considered as potentially beneficial for aquaculture activities in the open ocean in terms of stamina and physiological performance. © 2012 Blackwell Verlag, Berlin. Source

Brenner M.,Alfred Wegener Institute for Polar and Marine Research | Brenner M.,Institute for Marine Resources IMARE | Brenner M.,Jacobs University Bremen | Broeg K.,Alfred Wegener Institute for Polar and Marine Research | And 4 more authors.
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology

Blue mussels collected from suspended culture ropes and from three natural intertidal wild beds from different areas of the German Bight were tested for their ability to cope with hypoxic conditions. During the experiment mussels were exposed to air from 0 to 72. h. Mussels from all sampling sites displayed high tolerance to aerial exposure with moderate levels of mortality after 12 to 48. h of exposure. Lysosomal membrane stability (LMS), a biomarker of general stress, changed notably between minimum values after 12. h and maximum values after 24. h of aerial exposure in intertidal mussels. In contrast, labilization times of mussels from the hanging culture increased continuously up to 48. h of exposure. Intertidal mussels from the island of Heligoland exhibited significantly decreased membrane stability after 72. h of air exposure, correlating to higher mortality rates. Intertidal mussels, although adapted to daily aerial exposure in their natural environment, showed a similar pattern of mortality and lower LMS values during the experiment than mussels from the suspended culture site. The increase of LMS values of mussels under hypoxic conditions at the beginning of the experiment at all sites was tested for the influence of macro-autophagic processes using immune labelling techniques. With this approach it could be demonstrated that high LMS values significantly correlate with low autophagic activity. However, hypoxic conditions do not enhance autophagic processes during the early periods of aerial exposure. Only at the end of the experiment, high values for autophagy were measured in mussels from an intertidal site accompanied with high mortalities. The results indicate that autophagic processes are not involved in the early adaptive processes that enable the mussel to cope with periods of aerial exposure. © 2011 Elsevier Inc. Source

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