Summer plankton of high mountain Lake Dzhulukul (Altai, Russia) in August 2020

The summer phytoplankton composition of high mountain Lake Dzhulukul located in Altai Mountainsat the source of Chulyshman River was studied in August 2020. Under the electron microscopic examination of thephytoplankton samples algae from four taxa groups – Chrysophyta, Bacillariophyta, Chlorophyta and Euglenophyta wererevealed, that has been supplemented the list of algae for the lake. Stomatocysts of chrysophycean algae various in shapeand structure have been revealed firstly for the lake algaflora.

Hydroclimate reconstruction of Western Iberia over the last 3600 years - insights from lipid biomarker and specific isotope signal

<p>Located between the temperate and arid climates of Europe and North Africa, Iberia is one of the most climatic vulnerable regions of Europe with more severe and longstanding extreme climate events being expected in this region. The Iberian climate, mainly in winter, is modulated by the North Atlantic Oscillation (NAO). Persistent positive (negative) NAO phases, can lead to significant changes in the North Atlantic westerly wind-belts, resulting in strengthened (weakened) winter precipitation in Western Iberia.</p><p>The Iberian Central System mountain range constitutes one of the biggest physical barriers to the moist air masses coming from the Atlantic Ocean. Usually, under low anthropic influence, the high mountain lake ecosystems have sensitive responses to climate and environmental changes, which makes lake sediments a pristine record for paleo reconstructions.</p><p>The increasing number of studies on Iberian high lakes depicted a wide spectrum of spatiotemporal variability in climate and environmental conditions for the last few millennia. However, the paucity of archives from the western region hampers the understanding of the effect of major climate forcings on different climate periods.</p><p>In this sense, to assess the past hydroclimatic patterns over western Iberia, we study upper 120 cm sediments of a 5 m core retrieved from a high mountain lake in central Portugal (Lake Peixão, Serra da Estrela). The age and depth model provides a robust chronology of the last 3600 years based on four <sup>14</sup>C AMS dating on pollen concentrates and <sup>137</sup>Cs and <sup>210</sup>Pb profiles.</p><p>Here we present the preliminary results on sedimentary lipid biomarker (leaf wax <em>n</em>-alkane) and compound-specific hydrogen isotope (δD<sub>wax</sub>) analysis performed at centennial time scale resolution. <em>n</em>-Alkane characterization, based on diverse indices (e.g., ACL, CPI, Paq, relative percentages, etc.), shows a clear higher plant signal, with a strong odd-over-even carbon predominance of long-chain <em>n</em>-alkanes, and predominance of the C<sub>31</sub> homologue. Principal component analysis (PCA) applied to the odd <em>n</em>-alkanes (C<sub>17</sub> – C<sub>35</sub>) concentrations reduced the data dimensionality into two principal components (PC). The PC1 mostly represents total <em>n</em>-alkane concentrations. PC2 has a positive correlation with Paq, C<sub>27</sub>, and δD signals, while a high negative correlation with ACL. Another important feature of the PC2 signal is its parallelism with NAO index reconstructions.</p><p>Our new data show a sensitive response from the lake catchment vegetation to hydroclimatic variability and allow the reconstruction of climatic phases occurring in this region based on plant waxes from Lake Peixão.</p><p>Acknowledgments</p><p>The financial support for this work was possible through the following FCT project: HOLMODRIVE—<em>North Atlantic Atmospheric Patterns Influence on Western Iberia Climate</em>: From the Late Glacial to the Present (PTDC/CTA-GEO/29029/2017).</p>

The unusual isolation of carnobacteria in eyes of healthy salmonids in high-mountain lakes

Carnobacteria are common bacteria in cold and temperate environments; they are also reported during fish mortality events. In a previous study, carnobacteria were isolated from the eyes of healthy wild salmonids from a high-mountain lake. To better understand these findings, salmonids were captured from three high-mountain lakes (Lower and Upper Balma Lake, Rouen Lake; northwest Italy) during August 2019 and subjected to bacteriological and histological examination. Although all were healthy, 8.7% (Lower Balma Lake), 24% (Upper Balma Lake), and 32.6% (Rouen Lake) were positive for carnobacteria colonization of the eyes. A Trojan-horse effect was hypothesized to explain carnobacteria isolation in the eye. This immune-escaping macrophage-mediated mechanism has been identified in other Gram-positive bacteria. Biochemical, molecular, and phylogenetic analysis were carried out on isolated bacteria (Carnobacterium maltaromaticum and C. divergens). Based on previous references for carnobacteria isolated from fish, C. maltaromaticum strains were tested for the pisA precursor gene of the bacteriocin piscicolin 126. Carnobacterium maltaromaticum strains were found to display genotypic heterogeneity and a low percentage of pisA positive amplification. Features of geomorphology, geographic isolation, and microbiota common to the three lakes are thought to be possibly related to our findings. Moreover, terrestrial insects collected from the lake shoreline and the stomach contents were screened for the presence of carnobacteria. The salmonids in these high-mountain environments feed mainly on terrestrial insects, which are considered possible vectors for carnobacteria that might catabolize the exoskeleton chitin. All insects tested negative for carnobacteria, but as a small number of samples were analyzed, their role as possible vectors of infection cannot be excluded. Further studies are needed to corroborate our research hypothesis.

Feeding preferences in aquatic invertebrates associated to Egeria densa in a tropical high-mountain lake

Introduction: The benthic fauna of the littoral zone in lakes is important in transferring energy to other trophic levels, habitat coupling, and helping to keep habitat stability. The study of this type of interactions in lentic systems is priority, since functional aspects about biological communities are unknown. Objective: Describing the trophic relations of aquatic invertebrates of the littoral zone in a tropical high mountain lake by characterizing gut content and stable isotope analysis of δ13C and δ15N. Methods: Samples of benthic invertebrates were collected in the littoral zone of the Lago de Tota where Egeria densa was present using a handheld net method. Samples were processed in the laboratory, organisms were identified, counted and weighed. Gut contents and δ13C and δ15N stable isotopes analysis were performed as well. Results: Records of the trophic relations of aquatic invertebrates, which live in the littoral in high mountain lentic ecosystem in the Neotropics are shown. The analysis of gut contents distinguished seven food items, microphytes and MOPF were the most frequent, and through the stable isotopes analysis (δ15N) we identified four trophic levels, among resources (macrophytes and POM), and consumers (detritivores, herbivores, and predators). The two upper trophic levels concentrated greater diversity and biomass. Conclusion: Most of the organisms studied were linked to omnivorous habits, evidenced in a wide spectrum of food items in their diet. The δ15N values show an enrichment, which occurs due to the effects of the tendency towards eutrophication of the system or due to unknown values of protozoa and bacteria that plays a fundamental role in the diet of these organisms, besides the δ13C values reported in organisms consumes, allows us to suggest an affinity with native resources of the littoral zone.

Nupela eremica sp. nov. (Bacillariophyta, Naviculaceae) from a páramo lake in the Colombian Andes

A new species, Nupela eremica sp. nov. is described from a high mountain lake located in the Eastern Range of Colombian Andes. The new taxon was studied from sediment and epiphyton samples and under light and scanning electron microscope. Comparison with morphologically similar taxa is showed. N. giluwensis, N. carolina, N. gomphosphenioides, N. encyonopsis, N. incerta, N. neglecta, N. tenuicephala, and N. exilissima show morphometric values overlapping those of Nupela eremica sp. nov. The combination of valve size and outline is unique and justifies the erection of this new species.