Ancient plant DNA, macro- and microfossil studies of the lake sediments from the High Arctic lake Tenndammen, Svalbard

<p>Ancient DNA metabarcoding applied together with the investigations of the plant macro-remains, pollen, spores and non-pollen palynomorphs (NPP), open new perspectives and give better taxonomical resolution, allowing to obtain more precise and specific data on the local environment conditions and their changes. So far, only three multiproxy studies that involve both molecular and palaeobotanical/palynological methods are available for the high Arctic archipelago Svalbard. We intend to contribute filling this gap. Therefore, a field trip to Svalbard was undertaken in September, 2019, and three sediment cores were retrieved from the Tenndammen lake (N 78°06.118; E 15°02.024, 7 m asl) which is a small and shallow water body (ca 2.5 m depth). The lake is located in the valley of Colesdalen, a well-known Svalbard’s biodiversity hot spots and a home for about seven to ten thermophilic plant species.</p><p>To investigate the Holocene to modern vegetation history of this place, the 85cm core Te2019 was chosen, it was described for lithology, X-rayed, µXRF-scanned, line-scan photographed with high resolution and sampled for sedaDNA, pollen, spores and NPP studies as well as for studies on plant macrofossils. Ten 14C AMS dates were taken in order to establish an age-depth model. The DNA record contains around 100 taxa, most findings of those are supported by pollen studies (Asteraceae, <em>Betula</em>, Brassicaceae, <em>Salix, Saxifraga, Vaccinium</em>/Ericaceae) and by spores (<em>Equisetum</em> and Bryophyta). In addition, various fungi spores were identified. Investigations of plant macro-remains well support findings of the aquatic (i.e. Warnstorfia fluitans) and terrestrial mosses (e.g. <em>Aulacomnium</em> conf. <em>turgidum, Bryum</em> spp., <em>Distichium capillaceum, Calliergon richardsonii, Scorpidium cossonii, Sphagnum</em> spp., <em>Rhizomnium</em> spp.). Besides, fragments of <em>Salix</em> and <em>Betula</em> leaves and fruit parts, various leaf, stem tissues and flower fragments of <em>Saxifraga</em> species were found within the samples from the same depths with the correspondence to DNA records. Three DNA zones (SvDNA 1 – SvDNA3) and  one subzone within the earliest zone (SvDNA-1a – SvDNA-1b) were established. Relations between DNA, pollen and macrofossil zones were studied. This study is performed within the “Future ArcTic Ecosystems” (FATE) research program: Initiative for investigation on drivers of diversity and future scenarios from ethnoecology, contemporary ecology and ancient DNA.</p>

Seismoacoustic observations using molecular-electronic hydrophones on Sakhalin and the South Kuril Islands (Kunashir Island)

The article presents the main characteristics and studies spectral and recording capabilities of experimental samples of three types of molecular-electronic hydrophones with different sizes of electrochemical converting cells, which were installed in the central part of the south of Sakhalin Island and on Kunashir Island (southern part of the Kuril ridge) at the end of 2018. A hydrophone on a new technological basis (with an increased sensor sensitivity relative to previously conducted studies) was approved on Kunashir Island. Equipment of this type was used for observations on the territory of the Sakhalin region for the first time. As a result of continuous seismoacoustic observations on Kunashir Island, in seven cases out of 35 studied (from May 1, 2019 to February 29, 2020) earthquakes, a low-frequency anticipatory signal (LFAS) was detected, and all seven events had a depth of hypocenter of more than 80 km. In the area of the Central Sakhalin fault, in addition to the possibility of registering the LFAS, spectral features in the recording of waveforms were studied for different conditions of instrument installation. It is shown that the influence of such atmospheric factor as wind load significantly affects hydrophones located in a shallow water body and a shallow open borehole. It is shown that the influence of such atmospheric factor as wind load significantly affects hydrophones located in a shallow water body and a shallow open borehole. However, molecular-electronic hydrophones have demonstrated the ability to fully record seismic events regardless of the installation conditions of the equipment.

Phenology of Daphnia in a Northern Italy pond during the weather anomalous 2014

<p>This note reports a comparison between <em>Daphnia</em> phenology in the weather anomalous 2014 and a previous three years period (2011-2013), in a shallow water body of Northern Italy (Bodrio del pastore III) where we recorded <em>D. pulex. </em>In 2011-2013, <em>Daphnia</em> population showed 1-2 density peaks from mid spring to early summer, it declined in July-August and did not recover, from ephippia, until the following spring. The seasonal dynamics was probably related to the species thermal tolerance. Males and ephippial females appeared at the beginning of growth season according to a typical feature of <em>Daphnia</em> populations from temporary habitats. The presence of the <em>Chaoborus</em> larvae resulted in juvenile adaptive predator-avoidance cyclomorphosis. In 2014, in the study area, mean winter air temperature was much warmer than average recorded during the past three years while it was much colder than average in July and August. This reflected the relatively rainy and cloudy summer months: the winter and summer precipitations total was above the previous three years average. In 2014, <em>Daphnia</em> was found all over the year and showed a maximum peak of density in November. The general increase of <em>Daphnia</em> was related to a shift in <em>D. pulex</em> population phenology, seasonal growth started earlier and lasted longer, and to the occurrence of <em>D. longispina</em>. Both species were identified by genetic markers and phylogenetic analyses of <em>ND5</em> sequences placed isolates from the Bodrio del pastore III into the European <em>D. pulex </em>group. Both populations reproduced by cyclical parthenogenesis and showed cyclomorphosis. However, <em>D. pulex</em> produced more males and ephippial females than <em>D. longispina. </em>Their seasonal dynamics were quite different: <em>D. longispina</em> dominated in late summer while <em>D. pulex</em> showed the highest density in November. The presence of <em>D. pulex</em> in the Bodrio is important in the framework of conservation ecology especially because we have showed that it is native European strain instead of the invasive North American clone that replaced native <em>D. pulex </em>throughout Africa and was already recorded in Italy. We provide some indications and discuss how <em>Daphnia</em> phenology of shallow lakes of temperate areas may be susceptible to inter-annual variability in weather conditions.</p>

SPREADING OF BRINE DISCHARGED INTO THE PUCK BAY (SOUTH BALTIC SEA): THEORETICAL STUDY VERSUS FIELD OBSERVATIONS

Increasing demands for gas storage capacity encouraged Polish Gas and Oil Company (PGNiG) to make use of salt deposits located in the north-eastern part of Poland, in the area bordering on the Gulf of Gdańsk (South Baltic Sea), and create underground gas stores. A complex of 10 chambers (250x106 m3) was designed to be built at a depth of 800-1600 m. The construction site is located about 4 km away from the sea coast. The drilling of boreholes and diluting of salt rock was proposed as a method of creating the chambers. Owing to ecological reasons, maximum discharge of brine is limited to 300 m3/h with the max. saturation of 250 kg/m3. The Puck Bay is a shallow water body with wind-driven currents and negligible tides. The main difficulty of the investment lay in the effective spreading of brine in the Puck Bay in accordance with all requirements that apply to regions protected by NATURA 2000. The most important restriction was the permitted excess salinity, defined as 0.5 PSU over the natural salinity in the Puck Bay. The location of brine discharge, number and diameters of nozzles, as well as consequences of brine discharge on the Puck Bay water, had been analyzed before the permission to install the system of diffusers was granted by the regional administration. The installation consists of a system of 16 heads spaced every 45 m, each of them equipped with 3 nozzles of 8 mm diameter.

Seasonal steady-state budgets of nutrients and stoichiometric calculations in an Eastern Mediterranean lagoon (Papas Lagoon-Greece)

The Papas Lagoon is an enclosed, small shallow water body in western Greece. The lagoon is naturally affected by eutrophication phenomena, but occasionally during the summer season, dystrophic crises occur, related to the decomposition of large beds of macroalgae. Physicochemical data collected monthly, from June 1998 to September 1999, were compiled and coupled with historical meteorological data, in order to construct seasonal water, salt and nutrients budgets using a single box single layer LOICZ model. Nutrients and other hydrochemical parameters exhibit great spatial and temporal variations. The non-conservative dissolved inorganic phosphorus flux (ΔDIP) is always positive, thus indicating that the system acts as a net source of DIP for the adjacent coastal waters. Higher values were estimated uring summer and autumn, probably due to organic matter mineralisation and release of DIP from surficial sediments in the reduced environment. In contrast to the ΔDIP, the non-conservative balance of dissolved inorganic nitrogen (ΔDIN) is negative for most of the year, except for the summer, indicating the dominance of DIN removal processes in the Papas Lagoon. The Ulva growth and decomposition processes seem likely to be of essential importance for the evaluation of the non-conservative DIN fluxes. During the investigated period the amount of organic carbon respired and mineralized is greater than that produced by gross photosynthesis and the Papas Lagoon is a net heterotrophic system. Losses of DIN via denitrification appear to dominate over its inputs through nitrogen fixation throughout the year.

Diurnal sediment resuspension and settling: impact on the coupled physical and biogeochemical dynamics of dissolved oxygen and carbon in a shallow water body

Small, shallow, inland water bodies are ubiquitous on the landscape and may be significant hotspots for biogeochemical transformations. However, the coupled physical and biogeochemical dynamics of these systems have received little attention compared with larger and deeper systems. Here, we examine the coupling between physical dynamics, sediment dynamics and oxygen–carbon dynamics in Mirror Lake, a small shallow pond in Storrs, CT, USA, using high frequency monitoring data and a simple coupled physical–biogeochemical model. The physical dynamics are characterised by a diurnal pattern of daytime thermal stratification and nighttime mixing. Observations show that the distribution of oxygen is tightly coupled with both the diurnal physical dynamics and photosynthesis–respiration reactions. Two 24-h periods in the summer of 2003 with similar meteorological conditions but distinctly different oxygen dynamics were simulated with a coupled physical–biogeochemical model. The model results suggest that the dynamics of sediment resuspension during nighttime convective overturn and subsequent settling during daytime stratification are critical in explaining the observed oxygen and dissolved inorganic carbon distributions. The diurnal dynamics provide a biogeochemical hot spot and hot moment by coupling meterologic forcing, resuspension of sediments, physical mixing and biological activity to hypoxia and anoxia in Mirror Lake.