Derivation of the clonal‐cell lines from Siberian sturgeon (Acipenser baerii) head‐kidney cell lines and its applicability to foreign gene expression and virus culture

This study was conducted to establish and characterize the clonal‐cell lines from Siberian sturgeon Acipenser baerii head‐kidney tissues and to evaluate its applicability as a research tool. From the culture of A. baerii head‐kidney derived cells, 10 cell lines were established first and then eight clonal‐cell lines were derived from clonal growth and colony expansion of two cell lines that showed significant high colony‐forming ability. All eight clonal‐cell lines were morphologically similar and grew stably under monolayer culture but their growth rates were significantly different. They possessed diploid DNA contents, expressed epithelial cell‐related genes and showed strong anchorage dependency to substrates. When a clonal‐cell line was transfected separately with three plasmid vectors including fluorescent reporter genes driven by cytomegalovirus, marine medaka Oryzias dancena β‐actin or A. baerii β‐actin promoter, the cell lines expressed fluorescent signals regardless of promoter types. The cells harbouring foreign genes could be expanded to stable cell lines under drug selection and then they additionally could form the extensively proliferating colonies at low‐density culture. Finally, the clonal‐cell lines showed the susceptibility to viral haemorrhagic septicaemia virus (VHSV). Collectively, the clonal‐cell lines from A. baerii head kidney were established and these cell lines will be able to provide an excellent in vitro system for various biological studies in this fish species.     

First evidence of spawning of eastern Baltic cod (Gadus morhua callarias) in the Belt Sea,the main spawning area of western Baltic cod (Gadus morhua L.)

Two cod stocks (western Baltic cod, WBC, and eastern Baltic cod, EBC) are managed in the Baltic Sea which is characterized by different main spawning areas and different main spawning periods. In this study we analyse the spatial and temporal occurrence of spawning individuals of both cod stocks in the main spawning grounds of the Baltic Sea based on eight microsatellite loci. Our results suggest that EBC (Gadus morhua callarias) has formed currently temporally stable, substantially homogeneous population not only in the Bornholm Sea (ICES SD: 25) but also in the Arkona Sea (ICES SD: 24). The presented analyses proved that EBC (G. m. callarias) can temporarily also spawn in the Belt Sea.     

RESTING CYST FORMATION OF EUTREPTIELLA GYMNASTICA (EUGLENOPHYCEAE) IN THE NORTHERN COASTAL BALTIC SEA1

Resting cyst formation of Eutreptiella gymnastica Throndsen was observed during a mesocosm experiment, where nutrient enrichment had induced almost a unialgal bloom. Cells and resting cysts of E. gymnastica were examined in scanning (SEM) and transmission electron microscopy (TEM) and light microscopy. Mature cysts were spherical, with a smooth thick mucilaginous cover that appeared layered when observed with the TEM. Intermediate forms were spherical and lacking flagella and a mucilaginous cover; the euglenoid pellicular striation and canal opening were easily visible. The volume of these intermediate spherical cells and mature cysts was estimated to have increased threefold compared to flagellated cells and contained many paramylon grains. When the cells were grazed by zooplankton, the paramylon grains passed the gut intact and were packed into fecal pellets. Intact undigested paramylon grains were observed in SEM after the breaking up of the pellets.     

Status and management of Atlantic sturgeon, Acipenser oxyrinchus, in North America

The Atlantic sturgeon, Acipenser oxyrinchus, consists of two subspecies distributed along the Atlantic coast of North America from Labrador to the east coast of Florida (Atlantic sturgeon subspecies – A. o. oxyrinchus) and along the Gulf of Mexico from Florida Bay, Florida to the mouth of the Mississippi River (Gulf sturgeon subspecies – A. o. desotoi). The species has been exploited throughout its range with landings peaking around the turn of the 20th century followed by drastic declines shortly thereafter. During recent years, landings in Canadian waters have increased substantially (approximately 129 metric tons in 1993) while in the United States landings are more controlled or prohibited (approximately 22–24 metric tons in 1993). Recently, the Atlantic States Marine Fisheries Commission developed a Fishery management plan for Atlantic sturgeon, and the United States Fish & Wildlife Service and Gulf States Marine Fisheries Commission drafted a Gulf Sturgeon Recovery/Management Plan. Fishery managers in Canada are in the process of establishing more stringent fishery regulations for sturgeon. Thus, the impact on populations due to harvesting should be substantially reduced. Current research focus includes: life history and population status studies, stock delineation, and development of culture and stock enhancement techniques. Implementation of the findings of such studies may be helpful in the restoration of depleted stocks.     

Present status of commercial stocks of sturgeons in the Caspian Sea basin

Catches for the last 25 years are analyzed for beluga Huso huso, stellate sturgeon A. stellatus and Russian sturgeon Acipenser gueldenstaedtii, which are the three commercially important species of sturgeons found in the Caspian Sea Basin. Population sizes for generations born between 1961 and 1970 are estimated, and found to depend on natural reproduction and the number of young fish stocked annually from sturgeon hatcheries located in the Volga River Delta. A ban on sea fishing from 1962 to 1991 positively impacted the number and total biomass of commercial stocks. Sturgeon growth rates depend on water levels in the Caspian Sea. In order to preserve Caspian Sea sturgeon populations, it will be necessary to coordinate efforts of all countries surrounding the Caspian Sea to achieve rational harvests, preserve juveniles, and produce at least 100 million juveniles annually from hatcheries.     

Copepod eggs survive a decade in the sediments of the Baltic Sea

Many planktonic calanoid copepod species have been proved to spend a part of their life cycle as benthic resting eggs. In addition to avoiding seasonally occurring unfavourable conditions resting stages may also be used as a long-term survival strategy. The aim of this study was to find out for how long eggs of calanoid copepods retain their viability in the sediments of the Baltic Sea. The occurrence of viable copepod eggs in sea bottom sediment was studied in Pojovik Bay, SW coast of Finland. Eggs were found throughout a 25 cm deep core but deeper than 20 cm they were very scarce. Eggs were incubated at 12 °C in order to check the viability, and their age was estimated by determining the sediment accumulation rate with ¹³⁷Cs-method. Viable eggs were estimated to be 10–13 yrs old, some possibly even 18–19 yrs. Most eggs in the top 8 cm were viable, their age being up to 7–8 yrs. Nauplii that hatched from the eggs belonged to Acartia bifilosa and Eurytemora affinis, A. bifilosa dominating the hatchers of the top sedment layers and E. affinis the deeper layers. Preliminary evidence is presented that E. affinis produces true diapause eggs in the Baltic Sea.     

High climate velocity and population fragmentation may constrain climate‐driven range shift of the key habitat former Fucus vesiculosus

Aim

The Baltic Sea forms a unique regional sea with its salinity gradient ranging from marine to nearly freshwater conditions. It is one of the most environmentally impacted brackish seas worldwide, and the low biodiversity makes it particularly sensitive to anthropogenic pressures including climate change. We applied a novel combination of models to predict the fate of one of the dominant foundation species in the Baltic Sea, the bladder wrack Fucus vesiculosus.

Location

The Baltic Sea.

Methods

We used a species distribution model to predict climate change‐induced displacement of F. vesiculosus and combined these projections with a biophysical model of dispersal and connectivity to explore whether the dispersal rate of locally adapted genotypes may match estimated climate velocities to recolonize the receding salinity gradient. In addition, we used a population dynamic model to assess possible effects of habitat fragmentation.

Results

The species distribution model showed that the habitat of F. vesiculosus is expected to dramatically shrink, mainly caused by the predicted reduction of salinity. In addition, the dispersal rate of locally adapted genotypes may not keep pace with estimated climate velocities rendering the recolonization of the receding salinity gradient more difficult. A simplistic model of population dynamics also indicated that the risk of local extinction may increase due to future habitat fragmentation.

Main conclusions

Results point to a significant risk of locally adapted genotypes being unable to shift their ranges sufficiently fast considering the restricted dispersal and long generation time. The worst scenario is that F. vesiculosus may disappear from large parts of the Baltic Sea before the end of this century with large effects on the biodiversity and ecosystem functioning. We finally discuss how to reduce this risk through conservation actions, including assisted colonization and assisted evolution.     

Genetic variation in photosynthetic performance and tolerance to osmotic stress (desiccation,freezing, hyposalinity) in the rocky littoral foundation species Fucus vesiculosus (Fucales,Phaeophyceae)

Genetic diversity may play an analogous role to species diversity, as it can contribute to ecosystem function and stability, and provision of ecosystem services. In the Baltic Sea, perennial algal beds are often comprised of only Fucus vesiculosus and the amount of genetic variation in fitness‐related traits (i.e., the ability of the alga to photosynthesize or withstand stress) will thus determine the alga's local persistence in a changing environment. To study genetic variation in the crucial traits behind persistence we grew replicate vegetative branches that came from the same genotype in common gardens. We quantified osmotic stress tolerance and recovery responses by exposing branches to desiccation, freezing, and hyposalinity regimens. Our results show that genetic variation among genotypes was apparent for some photosynthetic parameters (maximal electron transport rate, saturation irradiance for electron transport, nonphotochemical quenching) and growth. Algae tolerated freezing (1,440 min at ?2.5°C) and hyposalinity (1,560 min at 2.5) well, but did not recover from desiccation (70 min at 12°C, causing ~94% water loss). Furthermore, we found very little if any evidence on genetic variation in tolerance to these stressors. Our results suggest that low salinity and cold winters in the northern marginal populations selected for hyposalinity and freezing tolerant genotypes, possibly eroding genetic variation in tolerance, but that tolerance to harsh desiccation has been lost, likely due to relaxed selection. The overall availability of genetic variation in fitness related traits might be supportive for F. vesiculosus during adaptation to gradual changes of its environment.     

The associations between chronotype,a healthy diet and obesity

Unhealthy diet has been associated with obesity. Evening type has been associated with unhealthier food and nutrient intake that could predict a higher risk of obesity among them as compared to morning type. However, thus far no study has examined the interrelationships between chronotype, a healthy diet and obesity. We examined whether a healthy diet mediates the association between chronotype and obesity and whether chronotype modifies the association between a healthy and obesity. The National FINRISK 2007 Study included 4421 subjects aged 25–74 years. Diet was assessed using a validated food frequency questionnaire. Baltic Sea diet score (BSDS), including nine dietary components, was used as a measure of adherence to a healthy Nordic diet. Weight, height, body fat percentage and waist circumference were measured, and body mass index values were calculated. Chronotype was assessed using a shortened version of Horne and Östberg’s morningness–eveningness questionnaire (MEQ). The sum score calculated from MEQ was either used as a continuous variable or divided into tertiles of which the lowest tertile demonstrated evening preference and the highest tertile demonstrated morning preference. A series of regression analyses were conducted to determine whether the BSDS mediates the association between chronotype and obesity. Likelihood ratio test was used to determine whether chronotype modifies the association between the BSDS and the obesity measures. After testing the interaction, chronotype-stratified analysis for the association between the BSDS and obesity measures was determined by linear regression. Generally, the evening types had lower adherence to the BSDS and were more often smokers (men), physically inactive and had lower perceived health than the other chronotypes (p < 0.05). The poorer health behavior of this group, however, was not manifested in their obesity measures, and no evidence that the BSDS would mediate the association between chronotype and obesity was found (p > 0.05). No evidence that chronotype would modify the association between the BSDS and obesity was found either (p > 0.05).     

Tetracycline marks visible in Baltic cod Gadus morhua otoliths stored for 40 years

Baltic cod Gadus morhua otoliths marked with oxytetracycline (OTC) in 1974–1975 had been sectioned and the sections stored in paper envelopes at room temperature in dry, dark conditions. After 40 years of storage, the historic OTC marks were still clearly visible showing that OTC is suitable for long‐term chemical marking of otoliths. They were, however, noticeably paler than marks in recently recaptured and archived Baltic G. morhua otoliths, chemically tagged with tetracycline at similar dosage to the historic otoliths.