Description: Some studies have demonstrated that elevated CO2 concentrations in ocean waters negatively impact metabolism and development of marine fish. Particularly, early developmental stages are probably more susceptible to ocean acidification due to insufficient regulations of their acid-base balance. Transgenerational acclimation can be an important mechanism to mediate impacts of increased CO2 on marine species, yet very little is known about the potential of parental effects in teleosts. Therefore, transgenerational effects were investigated on life history in juvenile three-spined sticklebacks Gasterosteus aculeatus by acclimating parents (collected in April 2012, 55°03′N, 8°44′E) and offspring to ambient (~400 µatm) and elevated (~1,000 µatm) CO2 levels and measured parental fecundity as well as offspring survival, growth and otolith characteristics. Exposure to elevated CO2 concentrations led to an increase in clutch size in adults as well as increased juvenile survival and growth rates between 60 and 90 days post-hatch and enlarged otolith areas compared with fish from ambient CO2 concentrations. Moreover, transgenerational effects were observed in reduced survival and body size 30 days post-hatch as well as in enlarged otoliths at the end of the experiment, when fathers or both parents were acclimated to the high-CO2 environment. These results may suggest that elevated CO2 concentrations had rather positive effects on life-history traits of three-spined sticklebacks, but that parental acclimation can modify these effects without improving offspring fitness. Although the mechanistic basis of such transgenerational acclimation remains unclear, selective gradients within generations seem to determine the direction of transgenerational effects.

Description: Atlantic herring (Clupea harengus), an ecologically and economically important species in the northern hemisphere, shows pronounced seasonal migratory behaviour. To follow distinctive migration patterns over hundreds of kilometers between feeding, overwintering and spawning grounds, they are probably guided by orientation mechanisms. We tested whether juvenile spring-spawning Atlantic herring, caught in the western Baltic, use a sun compass for orientation just before they start leaving their hatching area. Fish were randomly divided into two groups, one of them clock-shifted 6 h backwards, to investigate whether they shift their orientation direction accordingly. Individual fish were placed in a circular bowl and their orientation was tested multiple times with the sun as a sole visual orientational cue. Our results show for the first time that juvenile Atlantic herring use a time-compensated sun compass during their migration. Their swimming direction was impaired, but still present, even when the sky was very cloudy, indicating additional orientation capabilities.

Description: The dissolution of anthropogenically emitted excess carbon dioxide lowers the pH of the world's ocean water. The larvae of mass spawning marine fishes may be particularly vulnerable to such ocean acidification (OA), yet the generality of earlier results is unclear. Here we show the detrimental effects of OA on the development of a commercially important fish species, the Atlantic herring (Clupea harengus). Larvae were reared at three levels of CO2: today (0.0385 kPa), end of next century (0.183 kPa), and a coastal upwelling scenario (0.426 kPa), under near-natural conditions in large outdoor tanks. Exposure to elevated CO2 levels resulted in stunted growth and development, decreased condition, and severe tissue damage in many organs, with the degree of damage increasing with CO2 concentration. This complements earlier studies of OA on Atlantic cod larvae that revealed similar organ damage but at increased growth rates and no effect on condition. # doi:10.1890/13-0297.1

Description: 2014-2019: Since September 2014, temperature, salinity, pH (only 2014-2015) and oxygen data were additionally logged in 10-minutes intervals at the GEOMAR pier (54°19'48.8N 10°08'59.6E) (AANDERAA oxygen sensor 3835 & SEABIRD SBE 37-SI MicroCAT CT(D)). The sensor system is mounted to a floating platform so that a continuous depth of 1 m is guaranteed at every time point. Oxygen data were corrected for salinity, temperature and depth following the manual for Aanderaa Optodes using the salinity and temperature measurements from the SEABIRD SBE 37-SI MicroCAT CT(D) sensor. pH was also corrected for salinity, temperature and depth following Martz et al. (2010). After cleaning and other re-boots of the sensor package, temperature, salinity and oxygen data tend to deviate from true values. Hence, 60 minutes of data after any re-boot (after sensor servicing with re-deployment, data download or power failure) were deleted. Furthermore, salinity data lower than 8 and pH data lower than 5 and larger than 10 were removed from the data set as these values were identified as outliers. On May 22nd 2018 as well as on May 26th (22:00) til 27th (15:00) 2019 oxygen data were identified as outliers and removed from the data set. The logged oxygen data were plotted against titration data (doi:10.1594/PANGAEA.930974) to check for drifts in the optode's data. But no drift pattern could be detected and the fit of the regression was very good R2adj. = 0.673, p 〈 0.001)

Description: 2005-2019 CTD (48M, Sea & Sun Technology GmbH, Trappenkamp, Germany) measurements and water samples at the surface (0 m depth), at 7 m and 18 m depth were taken biweekly between 2005 and 2019 at the “Wittlingskuhle” a bit off the GEOMAR pier in the Inner Kiel Fjord (N 54°19.69, E 10°09.06). The oxygen concentration of these water samples was measured by the Winkler- iodometric titration method (Winkler 1888) in mg/L and are converted to oxygen-saturation values by correcting for temperature, salinity and pressure.

Description: This dataset is part of a dataset collection. Please read the documentation in Kiel fjord carbonate chemistry data between 2015 (February) and 2016 (January) doi:10.1594/PANGAEA.876551 for details on sampling, measurement and data processing.

Description: The stable production of high quality fry in marine aquaculture is still hampered by unpredictable mortality caused by infectious diseases during larval rearing. Consequently, the development of new biocontrol agents is crucial for a viable aquaculture industry. The bacterial energy storage compound poly-ß-hydroxybutyrate (PHB) has been shown to exhibit beneficial properties on aquatic organisms such as enhanced survival, growth, disease resistance and a controlling effect on the gastrointestinal microbiota. However, the effect of PHB on the developing immune system of fish larvae has so far not been investigated. In the present study, the effect of feeding PHB-enriched Artemia nauplii on survival, growth and immune response in European sea bass (Dicentrarchus labrax) post-larvae was examined. Amorphous PHB was administered to 28 days old sea bass larvae over a period of 10 days. The survival and growth performance were monitored and the expression of 29 genes involved in immunity, growth, metabolism and stress-response was measured. While the expression of the insulin-like growth factor 1 (igf1), an indicator of relative growth, was upregulated in response to feeding PHB, the larval survival and growth performance remained unaffected. After 10 days of PHB treatment, the expression of the antimicrobial peptides dicentracin (dic) and hepcidin (hep) as well as mhc class IIa and mhc class IIb was elevated in the PHB fed larvae. This indicates that PHB is capable of stimulating the immune system of fish early life stages, which may be the cause of the increased resistance to diseases and robustness observed in previous studies.

Description: The reliable production of marine fish larvae is one of the major bottlenecks in aquaculture due to high mortalities mainly caused by infectious diseases. To evaluate if the compound poly-ß-hydroxybutyrate (PHB) might be a suitable immunoprophylactic measure in fish larviculture, its capacity to improve immunity and performance in European sea bass (Dicentrarchus labrax) yolk-sac larvae was explored. Dietary PHB was applied from mouth opening onwards to stimulate the developing larval immune system at the earliest possible point in time. Larval survival, growth, microbiota composition, gene expression profiles and disease resistance were assessed. PHB administration improved larval survival and, furthermore, altered the larva-associated microbiota composition. The bacterial challenge test using pathogenic Vibrio anguillarum revealed that the larval disease resistance was not influenced by PHB. The expression profiles of 26 genes involved e.g. in the immune response showed that PHB affected the expression of the antimicrobial peptides ferritin (fer) and dicentracin (dic), however, the response to PHB was inconsistent and weaker than previously demonstrated for sea bass post-larvae. Hence, the present study highlights the need for more research focusing on the immunostimulation of different early developmental stages for gaining a more comprehensive picture and advancing a sustainable production of high quality fry.