Observations on Palaeogeographical Evolution of Akrotiri Salt Lake, Lemesos, Cyprus

Akrotiri Salt Lake is located 5 km west of the city of Lemesos in the southernmost part of the island of Cyprus. The evolution of the Akrotiri Salt Lake is of great scientific interest, occurring during the Holocene when eustatic and isostatic movements combined with local active tectonics and climate change developed a unique geomorphological environment. The Salt Lake today is a closed lagoon, which is depicted in Venetian maps as being connected to the sea, provides evidence of the geological setting and landscape evolution of the area. In this study, for the first time, we investigated the development of the Akrotiri Salt Lake through a series of three cores which penetrated the Holocene sediment sequence. Sedimentological and micropaleontological analyses, as well as geochronological studies were performed on the deposited sediments, identifying the complexity of the evolution of the Salt Lake and the progressive change of the area from a maritime space to an open bay and finally to a closed salt lake.

Landscape Setting Drives the Microbial Eukaryotic Community Structure in Four Swedish Mountain Lakes over the Holocene

On the annual and interannual scales, lake microbial communities are known to be heavily influenced by environmental conditions both in the lake and in its terrestrial surroundings. However, the influence of landscape setting and environmental change on shaping these communities over a longer (millennial) timescale is rarely studied. Here, we applied an 18S metabarcoding approach to DNA preserved in Holocene sediment records from two pairs of co-located Swedish mountain lakes. Our data revealed that the microbial eukaryotic communities were strongly influenced by catchment characteristics rather than location. More precisely, the microbial communities from the two bedrock lakes were largely dominated by unclassified Alveolata, while the peatland lakes showed a more diverse microbial community, with Ciliophora, Chlorophyta and Chytrids among the more predominant groups. Furthermore, for the two bedrock-dominated lakes—where the oldest DNA samples are dated to only a few hundred years after the lake formation—certain Alveolata, Chlorophytes, Stramenopiles and Rhizaria taxa were found prevalent throughout all the sediment profiles. Our work highlights the importance of species sorting due to landscape setting and the persistence of microbial eukaryotic diversity over millennial timescales in shaping modern lake microbial communities.

Conservation Paleobiology as a Tool to Define Reference Conditions in Naturally Stressed Transitional Settings: Micropaleontological Insights from the Holocene of the Po Coastal Plain (Italy)

The key role of paralic environments as providers of ecosystem services, associated with their increasingly threatened state, led to the definition of international water management policies aimed to improve ecological quality status (EcoQs). Restoration actions rely on the definition of reference conditions, which is a particularly challenging task in naturally stressed transitional environments. In the present work, we apply the diversity index Exp(H’bc) on benthic foraminifer assemblages from two anthropogenically unimpacted transitional to coastal Holocene sediment successions of the Po coastal plain, in order to assess past EcoQs (PaleoEcoQs). Ostracod ecological groups provided detailed insights on naturally stressful paleoenvironmental conditions. We show that “poor” to “moderate” PaleoEcoQs are recorded by biological indicators at reference conditions under fluctuations of chemical-physical parameters and organic matter enrichment. We emphasize the importance of a site-specific paleobiological approach, as significant differences in diversity occur even on a short spatial scale. This study illustrates that early to mid-Holocene sediment successions resulted to be appropriate for conservation paleobiological purposes, providing a high-resolution paleoecological record under the influence of the Holocene sea-level rise in analogy with the present-day global change.