Changed length-at-age of burbot, Lota lota, from an acidified estuary in the Gulf of Bothnia

Synopsis The burbot population off the River Kyrönjoki has suffered from acidification in its reproduction area, causing a reduction of the population throughout the 1980s. During the same period of time the mean length-at-age of burbot was found to increase, with a significant increase in length-at-age for age groups 3–8 from 1979 to 1993. The length-weight relationship however was not found to have changed during this same period. The decreasing burbot population was found to influence the changed length-at-age. An increase in potential prey species population was also documented during this period of increasing length-at-age. The increased lengths were associated to the changed availability of food caused by the simultaneous fluctuations in both burbot and potential prey species populations.     

Contribution of dendrochronology to understanding of wood procurement sources for panel paintings in the former Southern Netherlands from 1450 AD to 1650 AD

Since the middle of the 1980s, dendrochronological analyses of panel paintings produced in the former Netherlands have demonstrated the near-exclusive use of oak from the Baltic region. Further, as Hillam and Tyers [1995. Reliability and repeatability in dendrochronological analysis: tests using the Fletcher archive of panel-painting data. Archaeometry 37 (2), 395–405] did for English paintings analyzed by Fletcher, the objective of the present work was to determine whether it was possible to distinguish different Baltic typologies in the wood used for paintings in the ancient Southern Netherlands from 1450 AD to 1650 AD. In this study, it appeared that the same three “English” typologies (BALTIC1, BALTIC2 and BALTIC3) were also found in the Southern Netherlands, in proportions varying by period. The diversity of Baltic typologies in England was interpreted by Hillam and Tyers (1995) as reflecting changes in the procurement sources for wood.In addition to this diversification of Baltic typologies in the Southern Netherlands, a Western European provenance was identified for 16% of the wood used in Flemish panels. The research focused on determination of the provenance of these non-Baltic oaks, by comparison between wood from painting panels and site chronologies for all of Belgium, the northern half of France and southwest Germany. Such comparison yielded a network of good correlations between the panel ring series and site chronologies along the Franco-Belgian Meuse and the French Moselle River.Dendrochronological dates obtained for the Flemish panels in the corpus clarify the period during which diversification of Baltic sources intensified. The parallel between the very high proportion of BALTIC1 type woods in Flemish panels before 1565 AD, and its progressive decrease until complete disappearance in the 1620 AD, and quantitative data from the Sound Toll Records, among others, led to interpret the BALTIC1 typology as representing the enormous hinterland exploited by the Gdansk port, the principal place of export for wood until 1565 AD. This port then decreased in importance until its disappearance at the beginning of the 17th century. Oaks closest to BALTIC2 and BALTIC3 types reflect the percentage of exports lost to the Gdansk competitors.The period of increase in the use of oaks of BALTIC2 and BALTIC3 typologies also coincides with the appearance of the use of Meuse/Moselle oaks. Explanations for these changes are in relationship to the politico-economic and religious contexts, in particular the wars of religion starting in the 1560 AD that destabilized Europe, and the separation of Northern and Southern Netherlands in 1585 AD.     

Diving activity of migrating silver eel with and without Anguillicola crassus infection

Infection with the swim bladder nematode Anguillicola crassus has been hypothesised to threaten the spawning migration success of the endangered European eel (Anguilla anguilla). To examine this assumption, we compared the swimming behaviour of one Anguillicola crassus infested eel in the North Sea and three parasite‐free eels in the Baltic using data recovered from data storage tags attached to migrating silver eels. In both areas, eel activity was characterized by frequent diving behaviour throughout the water column during the night, with reduced activity during the day. Despite substantial damage of the swim bladder, the behaviour of the infested eel from the North Sea was within the same range of migrating and diving activity parameters as the three parasite‐free eels from the Baltic Sea. All eels had a similar frequency distribution of descent or ascent speeds and a similar average horizontal migration speed. The diving speeds and dive ranges exclude the possibility that the eels were in continuous hydrostatic equilibrium during their migrations and suggests therefore that the role of the swim bladder in vertical migration is likely to be more complex than currently thought. Our results suggest that eels infested by Anguillicola crassus are capable of diving in a similar manner to uninfested eels during the first stretch of their spawning migration.     

The sculpture and morphology of postcranial dermal armor plates and associated bones in gasterosteiforms and syngnathiforms inhabiting Estonian coastal waters

Lees, J., Märss, T., Wilson, M. V. H., Saat, T. and ?pilev, H. 2011. The sculpture and morphology of postcranial dermal armor plates and associated bones in gasterosteiforms and syngnathiforms inhabiting Estonian coastal waters. ―Acta Zoologica (Stockholm) 93 : 422–435. Five fish species inhabiting Estonian coastal waters (Gasterosteus aculeatus L., Pungitius pungitius (L.), and Spinachia spinachia (L.) of the order Gasterosteiformes and Syngnathus typhle L. and Nerophis ophidion (L.) of the order Syngnathiformes) are described on the basis of the sculpture and morphology of their postcranial dermal armor plates, as revealed and illustrated by SEM images. This study shows that the shapes of these superficial skeletal elements vary by species as well as by their position on the body, whereas the sculpture on the bones is taxon specific. The detailed features allow the identification of isolated fossil and subfossil remains and show promise for future systematics studies.     

A remarkable new genus of Cretaceous dustywings (Neuroptera： Coniopterygidae)in amber from northern Myanmar

A new dustywing genus and species,namely Cretaconiopteryx grandis gen.& sp.nov.,from the mid-Cretaceous amber of Myanmar is herein described in the lacewing family Coniopterygidae.The new genus is distinguished from all other dustywing species by the combination of following morphological features:relatively large body-size,comparatively rich crossvenation,origin of RP+MA near wing base in both fore-and hindwing,forewing RA and RP terminally fused into a loop,and proximally zig-zagged forewing CuP.A new subfamily,Cretaconiopteryginae subfam,nov.,is erected based on this spectacular new genus.The new subfamily might represent the basalmost lineage of known coniopterygids.     

Long-term changes in the phytobenthos of the southern Åland Islands,northern Baltic Sea

Marine macrophytes and -algae have undergone major changes in abundance and species composition over the last decades, primarily due to eutrophication. However, comparable studies conducted in the mid 20th century are rare, but potentially valuable for enabling insight into changes in the benthic communities from the early onset of the eutrophication of the Baltic Sea. In the present study, the submerged phytobenthic community in the exposed southern archipelago of the Åland Islands was examined in 2018 and compared with surveys conducted in 1956 and 1993, respectively. The aim was to analyze long-term changes in the phytobenthic community in relation to the general large-scale anthropogenic drivers since the 1950s. Between 1956 and 1993, a decrease in the total number of species/taxa, an increase of filamentous algae coverage and a decrease in the depth range of Fucus vesiculosus was observed. These changes in the phytobenthic community continued between 1993 and 2018, suggesting no changes in the previously described negative trends. Between 1956 and 2018, a general shift in the distribution of phytobenthic functional groups, (grouped according to morphology and type of algae; green, brown and red) occurred, with increased coverage of filamentous brown and green algae, and decline in red algae coverage. The depth range of F. vesiculosus also decreased by >50% between 1956 and 2018. The results support findings that the eutrophication of the northern Baltic Sea is still at a high level, which slows down or prevents the recovery of offshore phytobenthic communities, despite the progress seen in other areas. Thus, the likely main drivers behind the changes are the direct and indirect effects of eutrophication in combination with warmer water, i.e. an effect of climate change.     

A new species of winged fruits of Podopterus (Caryophyllales,Polygonaceae) from the Miocene amber,Chiapas, Mexico

In Chiapas, southern Mexico, there are Miocene amber deposits containing high diversity of biological inclusions of plants, fungi, crustaceans, and vertebrates. Here I describe a new species of Podopterus (Polygonaceae), P. mijangosae n. sp. based on well-preserved fruit fossils collected from the Los Pocitos mine, Chiapas. The fruit specimens are characterized by obovate shape, emarginate apex, cuneate base with three thin wings, and the endocarp being pubescent or tomentose. The wings are thin and translucent with entire to undulate margin, pubescent hairs, and fine fusiform-reticulate venation. This new record of Podopterus represents the second fossil record to the southernmost in North America, and further supports the idea that several genera that grow in Mexico today were present in the area since the Miocene.