Dorota Richter

Diversification of nitrogen sources in various tundra vegetation types in the high arctic

Low nitrogen availability in the high Arctic represents a major constraint for plant growth, which limits the tundra capacity for carbon retention and determines tundra vegetation types. The limited terrestrial nitrogen (N) pool in the tundra is augmented significantly by nesting seabirds, such as the planktivorous Little Auk (Alle alle). Therefore, N delivered by these birds may significantly influence the N cycling in the tundra locally and the carbon budget more globally. Moreover, should these birds experience substantial negative environmental pressure associated with climate change, this will adversely influence the tundra N-budget. Hence, assessment of bird-originated N-input to the tundra is important for understanding biological cycles in polar regions. This study analyzed the stable nitrogen composition of the three main N-sources in the High Arctic and in numerous plants that access different N-pools in ten tundra vegetation types in an experimental catchment in Hornsund (Svalbard). The percentage of the total tundra N-pool provided by birds, ranged from 0–21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment was built in 36% by birds, 38% by atmospheric deposition, and 26% by atmospheric N2-fixation. The stable nitrogen isotope mixing mass balance, in contrast to direct methods that measure actual deposition, indicates the ratio between the actual N-loads acquired by plants from different N-sources. Our results enhance our understanding of the importance of different N-sources in the Arctic tundra and the used methodological approach can be applied elsewhere.

Chalcone Synthase (CHS) Gene Suppression in Flax Leads to Changes in Wall Synthesis and Sensing Genes, Cell Wall Chemistry and Stem Morphology Parameters

The chalcone synthase (CHS) gene controls the first step in the flavonoid biosynthesis. In flax, CHS down-regulation resulted in tannin accumulation and reduction in lignin synthesis, but plant growth was not affected. This suggests that lignin content and thus cell wall characteristics might be modulated through CHS activity. This study investigated the possibility that CHS affects cell wall sensing as well as polymer content and arrangement. CHS-suppressed and thus lignin-reduced plants showed significant changes in expression of genes involved in both synthesis of components and cell wall sensing. This was accompanied by increased levels of cellulose and hemicellulose. CHS-reduced flax also showed significant changes in morphology and arrangement of the cell wall. The stem tissue layers were enlarged averagely twofold compared to the control, and the number of fiber cells more than doubled. The stem morphology changes were accompanied by reduction of the crystallinity index of the cell wall. CHS silencing induces a signal transduction cascade that leads to modification of plant metabolism in a wide range and thus cell wall structure.

Molecular, morphological and ultrastructural characteristics of Prasiola crispa (Lightfoot) Kützing (Chlorophyta) from Spitsbergen (Arctic)

It is commonly known that seabirds, along with cyanobacteria, play a key role in the enrichment of nutrient-poor polar terrestrial ecosystems. In habitats particularly enriched with nitrogen and phosphate ions, ornithogenic vegetation with Prasiola crispa and unique species composition develops. However, no studies have examined the potentially different impacts associated with seabirds on the morphological, ultrastructural and molecular diversity of P. crispa. For that purpose, the present study analyzed four populations from the Hornsund Fjord area (West Spitsbergen) collected in the vicinity of planktivorous or piscivorous colonies and individual nests of seabirds. The morphological variability of P. crispa was studied using fresh samples, and it was documented with light microscopy as well as transmission and scanning electron microscopy. Populations were investigated by molecular analyses based on rbcL and 18S rRNA sequences. The differences in features measured were subjected to statistical analysis. This study provides new data concerning the macro- and submicroscopic structure and molecular diversity of P. crispa with regard to differences in humidity and the quantity of biogenic nutrients deposited by seabirds. Molecular research provided the first data about P. crispa from Spitsbergen. Birds’ diet is relevant for the quantity and quality of the provided nutrients, especially nitrogen compounds (planktivorous species) and phosphorus (piscivorous birds). Climate changes influence the quantitative structure of the colony, clearly favoring piscivorous birds. This, in turn, causes changes in the environment and vegetation. The obtained data on the P. crispa population may be compared with potential changes in the future.

Response of cyanobacteria and algae community from small water bodies to physicochemical parameters

The article presents the research into the taxonomic diversity of cyanobacteria and algae, as well as the relationships between these organisms and the habitat conditions of certain water ecosystems varying in origin and location (both rural and urban reservoirs in the Lower Silesia region — Poland). Another issue addressed in the paper is the influence of ecological conditions and the origins of the reservoirs on the structure of phytoplankton. The RDA enabled to identify the most important biological parameters (the biodiversity of cyanobacteria and algae described using the Shannon-Weaver Index) and the physicochemical properties of the studied basins. The results distinguished four groups of basins (I — artificial basins within urban areas; II — old river-beds within urban areas; III — ponds in rural areas; IV — an old river-bed in forest areas). This distinction shows major relevance of the reservoirs’ origins and their presence in the landscape. Additional PCA and RDA analyses of the studied basins have shown that the biological parameters are more efficient in diversifying the basins in respect of their origins than the physicochemical parameters.

Snapshot of micro-animals and associated biotic and abiotic environmental variables on the edge of the south-west Greenland ice sheet

Microinvertebrates play a role as top consumers on glaciers. In this study we tested what kind of cryoconite material the animals inhabit (mud vs granules) on the edge of the Greenland ice sheet (GrIS) in the south-west. We also tested the links between the densities of micro-fauna in cryoconite material and selected biotic (algae, cyanobacteria, bacterial abundances) and abiotic (water depth, pH, ion content, radionuclides) factors. We collected 33 cryoconite samples. Tardigrada and Rotifera were found in 18 and 61% of samples, respectively. Invertebrates in this study were considerably less frequent and less abundant in comparison with High Arctic glaciers. The highest density of tardigrades and rotifers constituted 53 and 118 ind./ml, respectively. Generalized linear models showed no relationship between the densities of fauna and biotic and abiotic factors. The densities of animals were significantly higher in granules than in mud. The difference in the densities of animals between granules and mud reflects a simple mechanistic removal of invertebrates from the sediment during its erosion by flushing which leads to mud formation. These processes may influence a random distribution of micro-fauna without clear ecological interactions with biotic and abiotic variables at the edge of the GrIS.

Analysis of changes in cyanobacterial and algal flora of selected water reservoirs in Wrocław between 1878 and 2010 (south-west Poland)

The paper includes the results of research carried out between 2006-2010 in the city of Wrocław (Poland). The water reservoirs selected for the analysis had previously described phycoflora and these studies were excellent comparative material for the today’s condition of their algoflora. The aim of this research was to conduct detailed studies of the current taxonomic composition of phycoflora in the chosen water reservoirs and to trace the changes which have taken place over time. The research determined the degree of similarity between the different communities in terms of the occurrence of common species and also the changes in their quantity. The study revealed 535 species of cyanobacteria and algae belonging to five phylas. The comparison of the composition of phycoflora from the studied ecosystems from previous years with the current results provided a model study showing the direction and pace of changes in the composition of the flora of cyanobacteria and algae in a given time. The species composition of cyanobacteria and algae in each year is adequate to the trophy of the studied water bodies. The processes in transforming communities of cyanobacteria and algae have led to the stabilization of the current status of the reservoirs as eutrophic.

The distribution of Salvinia natans (L.) All. in the Odra and the Oława River valleys in Wrocław area (Poland)

Abstract The data presented in this paper concern the occurrence of Salvinia natans (L.) All. in Wrocław area. Field research was conducted in the vegetation season (June-September) between 2013 and 2017 in water bodies (natural and artificial), in the main river beds of the Oława and the Odra Rivers and in the Odra canals in Wrocław. The study provided 32 S. natans locations in the city area. The studied species occurred in various plant communities accompanied by numerous species which were also under protection, increasing the ecological value of the habitats. Additionally, a stable S. natans site was confirmed by the study in a location where aquatic fern had previously been recorded in Wrocław. The research indicates numerous populations of the species along the Odra and the Oława and in many old river beds and artificial water bodies in Wrocław and the results confirm the visible trend of a growing number of S. natans sites in all of Poland.

Anabaena poulseniana J. Boye Petersen — a species new to Polish flora

Anabaena poulseniana J. Boye Petersen Bot. Iceland 2, 1923 (Cyanobacteria), a cyanobacteria species new to Polish flora, was noted during a study of phytoplankton in one of Wrocław’s clay pits. The species was noted in plankton samples among Cylindrospermopsis raciborskii (Wołoszyńska) Seenayya et Subba Raju (Cyanobacteria) and Mougeotia sp. (Chlorophyta) filaments. The green algae created a bloom characterized by vegetation mats floating on the water.The paper presents detailed characteristics for Anabaena poulseniana, and for the habitat and the ecological condition in the examined water reservoir during its presence. The paper also presents a comparison of morphological characteristics of A. poulseniana from Poland to the species from other geographical locations. The research will provide data on the morphology and ecology of the species. The species found during the study were documented in the form of original photos and illustrations.