Abstract: Littorinid snails are present in most coastal areas globally, playing a significant role in the ecology of intertidal communities. Laevilitorina is a marine gastropod genus distributed exclusively in the Southern Hemisphere, with 21 species reported from South America, the sub-Antarctic islands, Antarctica, New Zealand, Australia and Tasmania. Here, an updated database of 21 species generated from a combination of sources is presented: 1) new field sampling data; 2) published records; 3) the Global Biodiversity Information Facility (GBIF) and The Atlas of Living Australia (ALA), to provide a comprehensive description of the known geographic distribution of the genus and detailed occurrences for each of the 21 species. The database includes 813 records (occurrences), 53 from field sampling, 174 from the literature, 128 from GBIF, and 458 from ALA. West Antarctica had the highest species richness (8 species), followed by sub-Antarctic islands of New Zealand (4 species) and the south-east shelf of Australia (4 species). The provinces of Magellan, New Zealand South Island, and sub-Antarctic Islands of the Indian Ocean include two species each. This study specifically highlights reports of L. pygmaea and L. venusta, species that have been almost unrecorded since their description. Recent advances in molecular studies of L. caliginosa showed that this species does not correspond to a widely distributed taxon, but to multiple divergent lineages distributed throughout the Southern Ocean. Ongoing molecular and taxonomic studies are necessary for a better understanding of the diversity and biogeography of this genus.

Abstract:

Arctic coastal areas can experience higher erosion rates than temperate regions due to the combined influence of seasonal permafrost melt and extreme temperatures. In addition to these ordinary dynamics, high latitude coastal areas are even more affected by climate-induced changes such as increased weather hazards, rising temperatures or changes in river discharges and sediment supply.

The Svalbard region consists of an archipelago of Arctic islands and a rocky and sandy coastline chiseled by numerous fjords connected to glaciers and a complex hydrographic network. Highly sensitive and exposed to the impacts of climate change, this coastal area is a perfect witness to the environmental changes of our century.

The Svalbard Archipelago has recently become a key hotspot with an increasing number of studies, mainly focusing on glacier melt, temperature change or soil destabilization. The environmental, geographical, and geomorphological conditions of Svalbard make it extremely difficult to monitor coastal change on a large-scale. However, several studies, including Lim et al. (2020), Jaskolski et al. (2018), and Sisneros-Kidd et al. (2019), have highlighted the strong pressure of climate change, population, and human activities on the Svalbard coastal area.

This littoral is fully in line with our approach to apprehend the past, present, and expected consequences of climate change on the environment and populations.

In close collaboration with local researcher Maria Jensen from the University of Svalbard (UNIS) and other experts in France (Agnès Baltzer and Franck Garestier), we have explored the potential of the Copernicus Programme satellite images to produce key information on the past and recent dynamics of nearly 300 km of coastline on the archipelago. This is a major challenge, given the complexity of the environment and the meteorological and climatic conditions of the region, which limit the volume of usable spatial data (cloud cover and seasonal ice on the monitored sediments).

After a first phase of adapting the algorithms to our developments, we extracted the coastline over 25 years, as well as the evolution of the banks and the extent of the hydrographic network along several major fjords in Svalbard. Particular attention was given to Advenfjorden to improve our effort, due to the greater availability of data to validate our results. We experienced the bathymetric monitoring into the fjord. This information was one of the most complex challenge in terms of methodology and algorithm development regarding the environmental context, but it is also a crucial insight to consider the full climate change impact on coastal sediment dynamics. Finally, we extracted another coastal indicator to focus on changes in the deltaic areas, namely the pioneer vegetation coverage, which reveals the impact of warming on these highly dynamic regions.

For the first time, we present our new results issued from these investigations.