Factors affecting biodiversity on hermit crab shells

This study explores the abundance, diversity and assemblage structure of epifauna on the shells used by two hermit crab species (Pagurus bernhardus and P. pubescens) in the Arctic (Svalbard and Northern Norway) and investigates the biotic and physical drivers of such patterns. Contrary to our expectations, we found that location (which reflects the variability in environmental conditions and the local species pool of potential colonizers) is a key determinant not only in the cold, ice-scoured, glacier-dominated Arctic shallows of Svalbard but also in boreal Norwegian fjords, where other factors were hypothesized to be more important. Depending on region, shell area and identity were of lesser magnitude, with larger and more irregular shells containing more diverse assemblages. Crab host species also played a role (P. pubescens-inhabited shells supported larger number of individuals and higher diversity than those of P. bernhardus) but this effect might be species or region specific. In this study, no effect of crab gender could be detected. The study indicated that epifaunal assemblages of hermit crab shells are influenced by complex set of factors that interact together to different degree at various locations

Validation of empirical and semi-analytical remote sensing algorithms for estimating absorption by Coloured Dissolved Organic Matter in the Baltic Sea from SeaWiFS and MODIS imagery

An extensive bio-optical data set obtained from field measurements was used to evaluate the performance of an empirical (Kowalczuket al. 2005) and two semi-analytical algorithms: Carder et al. (1999) and GSM01 (Maritorena et al. 2002) for estimating CDOMabsorption in the Baltic Sea. The data set includes coincident measurements of radiometric quantities and absorption coefficientsof CDOM made during 43 cruises between 2000 and 2008. In the first stage of the analysis, the accuracy of the empirical algorithmby Kowalczuk et al. (2005) was assessed using in situ measurements of remote sensing reflectance. Validation results improved whenmatching points located in Gulf of Gdańsk close to the Vistula River mouth were eliminated from the data set. The calculatederrors in the estimation of aCDOM(400) in the first phase of the analysis were Bias = -0.02, RMSE = 0.46 and R2 = 0.70.In the second stage, the empirical algorithm was tested on satellite data from SeaWiFS and MODIS imagery. The satellite data werecorrected atmospherically with the MUMM algorithm designed for turbid coastal and inland waters and implemented in the SeaDASsoftware. The results of the best case scenario for estimating the CDOM absorption coefficient aCDOM(400), based on SeaWiFSdata, were Bias = -0.02, RMSE = 0.23 and R2 = 0.40. The validation of the Kowalczuk et al. (2005) empirical algorithm applied toMODIS data led to a less accurate estimate of aCDOM(400): Bias = -0.03, RMSE = 0.19 and R2 = 0.29. This assessment of the accuracy of standard semi-analytical algorithms available in the SeaWiFS and MODIS imagery processing software revealed that both algorithms (GSM_01 and Carder) underestimate CDOM absorption in the Baltic Sea with mean systematic and random errors in excess of 70%. The paper presents examples of theapplication of the Kowalczuk et al. (2005) empirical algorithm for producing maps of the seasonal distribution of aCDOM(400) in the Baltic Sea between 2004 and 2008

Shallow-Water Scavengers of Polar Night and Day – An Arctic Time-Lapse Photography Study

Until recently, polar night constituted truly a “mare incognitum” of our times. Yet, the first records from this very little-explored period showcased a surprisingly rich and active ecosystem. This investigation aims to reveal the level of scavenger activity during both Arctic polar night and day. It compares the shallow-water scavenging fauna observed during two contrasting seasons (winter vs. summer) in a high Arctic fjord (Kongsfjorden, 79° N, Spitsbergen, Svalbard Archipelago). In each of January and July 2015, two different bait types – Atlantic cod (Gadus morhua) and a bird carcass (chicken meat) were deployed at a depth of 12 m. Fauna were monitored remotely using time-lapse cameras equipped with bait traps, with photographs taken every 15 min over a period of 4 days. Thirty taxa were recorded at baits, dominated by lysianassid amphipods (Onisimus sp. 88%, Anonyx sp. 2%, but only during winter), and buccinid gastropods (B. undatum 5%, B. glaciale 1%, Buccinum sp. 3%, in both seasons). In most cases, buccinids were the first animals to appear at bait. The total number of recorded taxa, mean species richness per sampling unit, total abundance and associations among taxa were higher, on average, in winter than in summer deployments, while Pielou’s evenness index showed the opposite pattern. Scavenger assemblages differed significantly between the two seasons and also in response to the two different bait types, with seasonal effects being strongest. Contrary to expectations, bait consumption rates differed very little between the two seasons, being slow in general and only slightly faster in summer (0.05 g of cod bait consumed in 1 min) compared to winter (0.04 g min–1), yielding novel insights into ecological interactions and functions in shallow marine ecosystems during Arctic polar nights

Fabrication of Plga/Hap and Plga/Phb/Hap Fibrous Nanocomposite Materials for Osseous Tissue Regeneration

The study presents the manufacturing of nanofibrous structures as osteoconductive, osteoinductive materials for osseous tissue regeneration. The fibrous structures were obtained by electrospinning of poly(l-lactide-coglicolide) (PLGA) with addition of hydroxyapatite (HAp) and of a blend of PLGA with polyhydroxybutyrate with HAp added. The polymers used in the experiment were synthesised by an innovative method with a zirconium catalyst. First, the optimal electrospinning process parameters were selected. For the characterisation of the obtained osseous tissue reconstruction materials, the physical, macroscopic, functional, mechanical and thermal properties as well as crystallinity index were studied. The study of the radiation sterilisation influence on average molar mass, thermal and mechanical properties was made in order to analyse the degradation effect

Hermit crabs (Pagurus spp.) at their northernmost range: distribution, abundance and shell use in the European Arctic

Hermit crabs are important components of Arctic benthic systems, yet baseline data on their densities and distribution patterns in this rapidly changing region are still scarce. Here we compile results of numerous research expeditions to Svalbard, the Barents Sea and northern Norway that were carried out from 1979 to 2011 by the Institute of Oceanology, Polish Academy of Sciences. The diversity of hermit crabs at the northern edge of their occurrence is very low; in Svalbard waters only one species (Pagurus pubescens) was detected. Another species (P. bernhardus), found in northern mainland Norway, north of the Arctic Circle, is likely to extend its distribution northward as the climate warms. Where the two species co-occur, competition between them probably accounts for the smaller sizes and poorer quality shells used by P. pubescens. The composition of the mollusc shells inhabited by these crabs differs between northern Norway and Svalbard, reflecting local mollusc species pools. Hermit crab densities were significantly higher than previously reported (max. mean 10 ind. m−2), suggesting their increasing level of dominance in benthic communities in the studied areas. The first to report the distribution of hermit crabs among habitats, this study showed that most individuals occurred at shallow depths (5–150 m), away from glacier termini and on hard bedrock rather than on soft substrata

Heterogeneous determinants of local unemployment in Poland

We identify determinants of large disparities in local unemployment rates in Poland using panel data on NUTS-4 level (poviats). We find that the disparities are linked to local demographics, education and sectoral employment composition rather than to local demand factors. However, the impact of determinants is not homogenous across poviats. Where unemployment is low or income per capita is high, unemployment does not depend on the late working-aged share in the population but does depend relatively stronger on the share of early working-aged. Where unemployment is high or income per capita is low, unemployment does not depend on education attainment and is relatively less responsive to investment fluctuations. Where small farms are present, they are partial absorbers of workers laid off due to investment fluctuations

Heterogeneous determinants of local unemployment in Poland

We identify determinants of large disparities in local unemployment rates in Poland using panel data on NUTS-4 level (poviats). We find that the disparities are linked to local demographics, education and sectoral employment composition rather than to local demand factors. However, the impact of determinants is not homogenous across poviats. Where unemployment is low or income per capita is high, unemployment does not depend on the late working-aged share in the population but does depend relatively stronger on the share of early working-aged. Where unemployment is high or income per capita is low, unemployment does not depend on education attainment and is relatively less responsive to investment fluctuations. Where small farms are present, they are partial absorbers of workers laid off due to investment fluctuations

Compositional differences of fluorescence dissolved organic matter in Arctic Ocean drift sea ice and surface waters north of Svalbard in spring.

We assessed the qualitative composition of fluorescent dissolved organic matter (FDOM) in Arctic Ocean surface water and in sea ice north of the Svalbard Archipelago (in the Sophia Basin, the Yermak Plateau and the north Spitsbergen shelf) in May and June 2015, during the “TRANSSIZ” expedition (Transitions in the Arctic Seasonal Sea Ice Zone). Samples collected in open lead waters (OW), under-ice waters (UIW) and from the sea ice (ICE) were analyzed by fluorescence spectroscopy and subsequently by multivariate statistical methods using Parallel Factor Analysis (PARAFAC). Statistical analyses of all measured DOM fluorescence excitation and emission matrices (EEMs) enabled four components to be identified and validated. The spectral characteristics of the first component C1 (λEx/λEm 282(270)/335) corresponded to those of tryptophan. The spectral properties of the other three components corresponded to those of humic-like substances: components two (C2 − λEx/λEm 315(252)/395) and three (C3 − λEx/λEm 357(258)/446) corresponded to humic-like substances of marine origin, whereas component four (C4 − λEx/λEm 261(399)/492) resembled terrestrial humic-like substances. Changes in FDOM composition were recorded in OW, in contrast to UIW and sea ice. In the OW the sum of fluorescence intensities of humic-like components (C2, C3 and C4) was two times higher than the fluorescence intensity of protein-like component (C1). Component C2 exhibited the highest fluorescence intensity. In the UIW and particularly in the sea ice the fluorescence intensity of the protein-like component, IC1, was the highest. The IC1 in the sea ice increased toward the sea ice bottom, reaching maximum values at the sea ice-water interface. The calculated spectral indices (SUVA(254) and HIX) and ratios of fluorescence intensities of protein-like to humic-like components, Ip/Ih, suggested that FDOM in water and sea ice was predominantly autochthonous, characterized by low molecular weight organic compounds and low aromatic ring saturation. Enrichment factors Dc, calculated from salinity-normalized values of the optical DOM properties and dissolved organic carbon concentrations, indicated the significant fractionation of FDOM in the sea ice relative to the parent open waters. The humic-like terrestrial component C4 was enriched the least, whereas the protein-like component C1 was enriched the most. A statistically significant (p < 0.0001) and relatively strong (R = 63) correlation between IC1 and the total chlorophyll a concentration Tchla was found in the sea ice, which suggests that sympagic algal communities were producers of the protein-like FDOM fraction

Leaf photosynthetic capacity, trunk wood structure and stem xylem sap flow in 700-years old Quercus robur L.: a pilot study upon oak ‘Bartek’, a natural monument in Poland

Physiological studies of long-lived trees are particularly important at this time, especially in light of the need for trees to adapt to global climate change. The results of the present studies were obtained on an approximately 700-year-old Quercus robur L. – the ‘Bartek’ oak. The tree has to adapt to changing climatic conditions, starting from the transition between the Medieval Warm Period and the Little Ice Age, up to the present time of rapid global climate change. Tomograph imaging showed decay of the tree trunk interior and revealed that undamaged wood forms a thin layer around the trunk perimeter. Two series of experiments were carried out to assess the physiological state of the tree. The first concerned measurements related to photosynthetic capacity: chlorophyll a fluorescence, gas exchange (CO2 assimilation, transpiration), stomatal conductance and leaf water potential. The second series concerned xylem sap flow velocity and anatomical studies of stem wood. Photosynthetic capacity was within the limits reported for young healthy trees. The diurnal pattern of velocity of xylem sap flow was also typical for young vigorous trees and flow velocity correlated positively with solar radiation and negatively with air relative humidity. Anatomical observations of the outermost wood showed relatively narrow annuals rings with large diameter earlywood vessels. The results indicate that the veteran tree does not show signs of water stress probably due to a good balance of water flow and that leaf area of the canopy needs only the current ring of wood to feed transpiration of the canopy

Bioactive oligomers from natural polyhydroxyalkanoates and their synthetic analogues

Contemporary reports on the bioactive oligomers derived from natural aliphatic (co)polyesters (PHA) and their synthetic analogues, formed through anionic ring-opening polymerization (ROP) of β-substituted β-lactones are presented. Synthetic routes for such oligomers, developed mostly by Polish authors, are discussed. The described approaches enable design of novel biodegradable and bioactive oligomers for diverse applications in medicine, cosmetic industry and agrochemistry. Abstrakt: Przedstawiono przegląd aktualnych wyników badań dotyczących bioaktywnych oligomerów otrzymywanych z naturalnych alifatycznych (ko)poliestrów (PHA) oraz ich syntetycznych analogów, uzyskanych na drodze anionowej polimeryzacji z otwarciem pierścienia (ROP) β-podstawionych β-laktonów. Omówiono ścieżki syntezy tych oligomerów opracowane głównie przez polskich badaczy. Zaprezentowane metody umożliwiają projektowanie nowych biodegradowalnych a zarazem bioaktywnych oligomerów dla różnorodnych zastosowań w medycynie, przemyśle kosmetyczny i agrochemii