The Excised Embryo Culture Method for Controlled Seedling Growth of the Sweet Fern, Comptonia peregrina, of the Family Myricaceae

Sweet fern, Comptonia peregrina (L.) Coult. according to Fernald (1950), in older literature often referred to as Myrica asplenifolia L. or Comptonia asplenifolia (L.) Ait., is the only species in this genus. It is a low branching, stoloniferous shrub up to a meter and a half tall, with linear-lanceolate leaves that are regularly and deeply pinnatifid giving a fern-like appearance, though it is not at all related to the ferns. It has a characteristic sweet resinous scent. The plants are monoecious or dioecious, flowers are in catkins; staminate catkins are slender and cylindrical; pistillate catkins become a spherical bur-like fruit. Because the shrub spreads by rhizomes, it forms clonal colonies. The family, Myricaceae, includes but two genera according to Fernald (1950): Myrica and Comptonia. The closest relative of Comptonia, Myrica Gale, is also abundant in this area, especially in swamps north of Lake Superior. Fernald ( 1950) gave the range of Comptonia peregrina as extending from Cape Breton Island, Nova Scotia westward to Manitoba in Canada, and southward and westward in the United States to Virginia, northern Indiana, northeastern Illinois, and Minnesota. Fernald (1950) listed also variety asplenifolia being distinguishable mainly by the smaller stature and more minute hairiness or glabrous condition

Maintenance of Genetic Diversity: Challenges for Management of Marine Diversity

There are three general classes of threat to biodiversity at the gene level: 1) extinction, which result in complete and irreversible loss of genes; 2) hybridization, which may cause re-arrangement of co-adapted genes and loss of adaptability to local conditions, and 3) reduction of genetic variability within populations. While extinction avoidance is a fundamental management objective and hybridization can usually be dismissed in marine populations, the reduction of genetic variability within populations is a plausible threat and can occur in two ways. First, a decrease in population size may result in inbreeding. Normally, marine fish have very large population sizes, and commercial extinction is likely to occur long before populations are reduced to the level required for losses of genetic diversity due to inbreeding. However, when populations are very severely over-fished to small numbers, concerns associated with small population sizes and disruptions of migration between populations may become prominent. In particular, undetected populations within management units may be fished to this level before the situation is properly evaluated and remedied. Second, a reduction of genetic variability within populations may occur in a directed way, due to, e.g., selective fishing. Fishing is expected to generate selection on life history traits such as age and size at maturation; changes in life history traits influence the dynamics of fish populations, energy flows in the ecosystem, and ultimately, sustainable yield. We discuss management objectives designed to ameliorate genetic complications associated with small population size and fisheries-induced selection, and outline a management approach that may be useful when developing advice for maintaining genetic diversity

Optical quality assurance of GEM foils

An analysis software was developed for the high aspect ratio optical scanning system in the Detec- tor Laboratory of the University of Helsinki and the Helsinki Institute of Physics. The system is used e.g. in the quality assurance of the GEM-TPC detectors being developed for the beam diagnostics system of the SuperFRS at future FAIR facility. The software was tested by analyzing five CERN standard GEM foils scanned with the optical scanning system. The measurement uncertainty of the diameter of the GEM holes and the pitch of the hole pattern was found to be 0.5 {\mu}m and 0.3 {\mu}m, respectively. The software design and the performance are discussed. The correlation between the GEM hole size distribution and the corresponding gain variation was studied by comparing them against a detailed gain mapping of a foil and a set of six lower precision control measurements. It can be seen that a qualitative estimation of the behavior of the local variation in gain across the GEM foil can be made based on the measured sizes of the outer and inner holes.Comment: 12 pages, 29 figure

Trophic ecology of blue whiting in the Barents Sea

Blue whiting (Micromesistius poutassou) are distributed throughout the North Atlantic, including the Norwegian and Barents Seas. In recent years, both abundance and distribution of blue whiting in the Barents Sea have increased dramatically. Therefore, to evaluate the trophic impact of this increase, we analysed the diet of the species. In all, 54 prey species or taxa were identified, the main prey being krill. However, the diet varied geographically and ontogenetically: the proportion of fish in the diet was higher in large blue whiting and in the north of the range. Blue whiting overlap geographically with other pelagic species at the edge of their distribution in the Barents Sea, with juvenile herring in the south, with polar cod in the north, and with capelin in the northeast. The overlap in diet between blue whiting and these other pelagic species ranged from 6 to 86% and was greatest with capelin in areas where both species feed on hyperiids and krill. The importance of blue whiting as prey for predatory fish was highest in the areas of greatest abundance, but overall, blue whiting were seemingly unimportant as prey of piscivorous fish in the Barents Sea

Habitat filtering determines spatial variation of macroinvertebrate community traits in northern headwater streams

Although our knowledge of the spatial distribution of stream organisms has been increasing rapidly in the last decades, there is still little consensus about trait-based variability of macroinvertebrate communities within and between catchments in near-pristine systems. Our aim was to examine the taxonomic and trait based stability vs. variability of stream macroinvertebrates in three high-latitude catchments in Finland. The collected taxa were assigned to unique trait combinations (UTCs) using biological traits. We found that only a single or a highly limited number of taxa formed a single UTC, suggesting a low degree of redundancy. Our analyses revealed significant differences in the environmental conditions of the streams among the three catchments. Linear models, rarefaction curves and beta-diversity measures showed that the catchments differed in both alpha and beta diversity. Taxon- and trait-based multivariate analyses also indicated that the three catchments were significantly different in terms of macroinvertebrate communities. All these findings suggest that habitat filtering, i.e., environmental differences among catchments, determines the variability of macroinvertebrate communities, thereby contributing to the significant biological differences among the catchments. The main implications of our study is that the sensitivity of trait-based analyses to natural environmental variation should be carefully incorporated in the assessment of environmental degradation, and that further studies are needed for a deeper understanding of trait-based community patterns across near-pristine streams

Report on the Diet of the Blue Whiting in the Barents Sea in the Summer 2005 and in the Winters of 2002 and 2006

We analyzed stomach content of blue whiting in the Barents Sea in February-March 2002 and 2006, and in August-September 2005. Krill was the most important prey for blue whiting in the Barents Sea, and constituted about 90% of diet in winter and 50% in summer. Blue whiting also fed on amphipods and fish, including blue whiting. Copepods, an important group of prey for blue whiting in the Norwegian Sea, was unimportant in the diet in the Barents Sea. NORSK SAMMENDRAG: Vi undersøkte dietten til kolmule i Barentshavet i februar-mars 2002 og 2006, og i august og september 2005. Krill var det viktigste byttet til kolmula i Barentshavet, og utgjorde ca 90% av diett om vinteren og ca 50% om sommeren. Kolmula spiste også amfipoder og fisk, inkludert kolmule. Hoppekreps som er viktig for kolmula i Norskehavet, utgjorde en ubetydelig andel av dietten

The Intrinsic Size of Sagittarius A* from 0.35 cm to 6 cm

We present new high-resolution observations of Sagittarius A* at wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration with the Pie Town Very Long Baseline Array antenna. We use the measured sizes to calibrate the interstellar scattering law and find that the major axis size of the scattering law is smaller by ~6% than previous estimates. Using the new scattering law, we are able to determine the intrinsic size of Sgr A* at wavelengths from 0.35 cm to 6 cm using existing results from the VLBA. The new law increases the intrinsic size at 0.7 cm by ~20% and <5% at 0.35 cm. The intrinsic size is 13^{+7}_{-3} Schwarzschild radii at 0.35 cm and is proportional to lambda^gamma, where gamma is in the range 1.3 to 1.7.Comment: ApJL, in pres

Reaction norm analysis reveals rapid shifts toward delayed maturation in harvested Lake Erie yellow perch (Perca flavescens )

Harvested marine fish stocks often show a rapid and substantial decline in the age and size at maturation. Such changes can arise from multiple processes including fisheries‐induced evolution, phenotypic plasticity, and responses to environmental factors other than harvest. The relative importance of these processes could differ systematically between marine and freshwater systems. We tested for temporal shifts in the mean and within‐cohort variability of age‐ and size‐based maturation probabilities of female yellow perch (Perca flavescens Mitchill) from four management units (MUs) in Lake Erie. Lake Erie yellow perch have been commercially harvested for more than a century, and age and size at maturation have varied since sampling began in the 1980s. Our analysis compared probabilistic maturation reaction norms (PMRNs) for cohorts when abundance was lower and harvest higher (1993–1998) to cohorts when abundance was higher and harvest lower (2005–2010). PMRNs have been used in previous studies to detect signs of evolutionary change in response to harvest. Maturation size threshold increased between the early and late cohorts, and the increases were statistically significant for the youngest age in the western MU1 and for older ages in the eastern MU3. Maturation envelope widths, a measure of the variability in maturation among individuals in a cohort, also increased between early and late cohorts in the western MUs where harvest was highest. The highest rates of change in size at maturation for a given age were as large or larger than rates reported for harvested marine fishes where declines in age and size at maturation have been observed. Contrary to the general observation of earlier maturation evolving in harvested stocks, female yellow perch in Lake Erie may be rapidly evolving delayed maturation since harvest was relaxed in the late 1990s, providing a rare example of possible evolutionary recovery

Evolution of age and length at maturation of Alaskan salmon under size-selective harvest

-Spatial and temporal trends and variation in life-history traits, including age and length at maturation, can be influenced by environmental and anthropogenic processes, including size-selective exploitation. Spawning adults in many wild Alaskan sockeye salmon populations have become shorter at a given age over the past half-century, but their age composition has not changed. These fish have been exploited by a gillnet fishery since the late 1800s that has tended to remove the larger fish. Using a rare, long-term dataset, we estimated probabilistic maturation reaction norms (PMRNs) for males and females in nine populations in two basins and correlated these changes with fishery size selection and intensity to determine whether such selection contributed to microevolutionary changes in maturation length. PMRN midpoints decreased in six of nine populations for both sexes, consistent with the harvest. These results support the hypothesis that environmental changes in the ocean (likely from competition) combined with adaptive microevolution (decreased PMRNs) have produced the observed life-history patterns. PMRNs did not decrease in all populations, and we documented differences in magnitude and consistency of size selection and exploitation rates among populations. Incorporating evolutionary considerations and tracking further changes in life-history traits can support continued sustainable exploitation and productivity in these and other exploited natural resources