Complete distribution of the genus Laevilitorina (Littorinimorpha: Littorinidae) in the Southern Hemisphere: remarks and natural history

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

Trophic ecology of two co-existing Sub-Antarctic limpets of the genus Nacella: spatio-temporal variation in food availability and diet composition of Nacella magellanica and N. deaurata

Interactions between algae and herbivores can be affected by various factors, such as seasonality and habitat structure. Among herbivores inhabiting marine systems, species of the order Patellogastropoda are considered key organisms in many rocky coasts of the world. Nacella species are one of the most dominant macro-herbivores on the rocky shores of the sub-Antarctic ecoregion of Magellan. However, the importance of its key role must be associated with its trophic ecology. The objective of this work was to evaluate spatial and temporal variabilities in the dietary composition of two intertidal Nacella species, considering grazing on macro- (macroalgae) and microscopic (periphyton) food. The composition of periphyton and the availability of macroalgae in the winter and summer seasons were examined at two localities of the Magellanic province, alongside the gut contents of N. magellanica and N. deaurata. The dietary composition differed between the two Nacella species, as well as between seasons and locations. The differences observed in the diet of the two species of Nacella may be mainly due to their respective distributions in the intertidal zone. Both species presented a generalist strategy of grazing, which is relationed to the seasonality of micro- and macroalgae availability and to the variability of the assemblages between the localities. This research was the first to perform a detailed study of the diet of intertidal Nacella species

Revealing the hidden biodiversity of Antarctic and the Magellanic Sub-Antarctic Ecoregion: A comprehensive study of aquatic invertebrates from the BASE Project

Antarctica, its outlying archipelagoes and the Magellanic Subantarctic (MSA) ecoregion are amongst the last true wilderness areas remaining on the planet. Therefore, the publication, citation and peer review of their biodiversity data are essential. The new Millennium Institute Biodiversity of Antarctic and Subantarctic Ecosystems (BASE), a Chilean scientific initiative funded by the National Agency of Research and Innovation, contributes 770 new records of aquatic invertebrates as a point of reference for present-day biodiversity research at these latitudes.The occurrence dataset presented here has never been released before and is the result of the systematic recording of occurrences of several taxa across the Antarctic, Subantarctic and Magellanic Subantarctic ecoregions. We collected data from marine and freshwater invertebrates across numerous samplings from 2008 to 2023. From the 770 occurrences, we identified 160 taxa, 125 at species level and 35 at the genus level. The database has been registered in the Global Biodiversity Information Facility (GBIF). The publication of this data paper was funded by the Belgian Science Policy Office (BELSPO, contract n°FR/36/AN1/AntaBIS) in the Framework of EU-Lifewatch as a contribution to the SCAR Antarctic biodiversity portal (biodiversity.aq

Evaluating the effects of ocean warming and freshening on the physiological energetics and transcriptomic response of the Antarctic limpet Nacella concinna

In the Southern Ocean, warming and freshening are expected to be prominent signals of climate change and the reduced ability of Antarctic marine organisms to cope with changing environmental conditions could challenge their future survival. The Antarctic limpet Nacella concinna is a macroinvertebrate of rocky ecosystems, which occurs in high densities in the shallow subtidal zone. Subtidal individuals were exposed to a combination of temperatures (1, 4, 8, 11, 14 °C) and salinities (20 and 30 psu) for a 60-day period. A drastic increment in mortality was observed with seawater warming, showing that N. concinna is highly stenothermal, with limited ability to survive at temperatures warmer than 4 °C, although there was some degree of acclimation at 4 °C and ambient salinity (30 psu). This study confirmed the stenohaline characteristic of this species, with mortality reaching 50% and lower scope for growth at low salinity (20 psu) even at the control temperature (1 °C). At the sub-cellular level, limpets' low tolerance to out-of range salinity is illustrated by the activation of cell remodelling processes whereas the down-regulation of chaperones proteins and plasma membrane ATPase suggest that under the combination of warming and freshening N. concinna experiences a severe level of stress and devote much of its energy to somatic maintenance and survival. The drastic effect observed can be explained by its subtidal origin, an environment with more stable conditions. The surviving individuals at 1 °C and lowered salinity (20 psu) were either more tolerant or showing signs of acclimation after 60 days, but the combination of warming and freshening have a greater combined stress. Projections of climate change for end of the century for this part of the Antarctic can, therefore, result in a significant diminution of the subtidal population of N. concinna, affecting ecological interactions and diversity of the food web

Genetic footprints of Quaternary glacial cycles over the patterns of population diversity and structure in three Nacella (Patellogastropoda: Nacellidae) species across the Magellan province in southern South America

Quaternary glaciations severely altered landscape/seascape at high latitudes and had major consequences on species geographicalranges, population sizes, genetic differentiation, and speciation rates. The Magellan province in southern South America,constitutes an interesting area to evaluate the effect of glaciations over near-shore marine benthic organisms. Existing data haveshowed clear signatures of population genetic bottlenecks during glacial maxima followed by recent recolonizations and expansionsduring the interglacial.Here, we present new population-based analyses in species of the patellogastropod genus Nacella (N. deaurata, N. magellanica, andN. mytilina). The species N. magellanica and N. deaurata inhabit rocky ecosystems while N. mytilina lives closely associated tokelps. The analyzed species exhibit narrow bathymetric ranges and consequently should have been severely affected by recurrentglacial cycles. We performed phylogeographic and demographic analyses in Nacella species including different localities across theirrespective distributions in the Magellan province including the Falkland/Malvinas Islands (F/M).Genetic analyses showed that all Nacella species exhibited low levels of genetic diversity, the presence of single dominant broadlydistributed haplotypes, lack of correlation between geographical and genetic distance, and recent demographic growths which areevidence supporting rapid postglacial expansions. Such results may have been facilitated by larval and/or rafting-mediateddispersal following the Cape Horn Current System. The three species showed strong and significant differentiation between F/Mand southern Pacific margin (SPM) populations including localities across the Strait of Magellan and Cape Horn. Haplotypegenealogies and mismatch analyses recognized older and more complex demographic histories in the F/M than in South America.Different glaciological histories between SPM and F/M may be responsible of the marked phylogeographic structure in the analyzedspecies of Nacella. Alternatively, as previously proposed, the F/M represent a glacial refugium for Nacella species (sink area), aswell as a secondary contact zone where endemic haplotypes are found together with recently arrived South American ones.Historical and contemporary processes, contrasting glacial histories between the analyzed areas, as well as life history traits ofthe analyzed organisms are main factors explaining current phylogeographic patterns of shallow Magellan marine benthicorganisms.Fil: Gonzalez Wevar, Claudio A.. Universidad Austral de Chile; ChileFil: de Aranzamendi, Maria Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Segovia, Nicolás I.. Universidad Austral de Chile; ChileFil: Rosenfeld, Sebastian. Universidad Austral de Chile; ChileFil: Maturana, Claudia S.. Universidad Austral de Chile; ChileFil: Rios Molina, Cristián. Universidad Austral de Chile; ChileFil: Brickle, Paul. University of Aberdeen; Reino UnidoFil: Gardenal, Cristina Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Bastida, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Poulin, Elie. Universidad Austral de Chile; Chil