| Abstract | The unsaturated karst represents a transitional zone connecting the land surface to the water table of the underlying saturated zone through percolating water and small perched aquifers. It constitutes a significant groundwater reservoir and hosts a high
biodiversity of specialized and endemic species. Whereas investigating this ecotone can shed light on the invertebrate diversity of the whole karst system, ecological studies in the unsaturated karst have been hampered by access, mapping, and sampling challenges. We studied the unsaturated zone of 52 caves in the Lessinian Massif (NE-Italy), which is dominated by carbonate rocks interspersed with spot areas composed mainly of igneous rocks. Our aim was to understand which ecological and historical factors may have shaped the distribution of the groundwater crustacean copepods at a regional spatial scale in the Lessinian unsaturated karst. We collected 33 species belonging to the orders Harpacticoida and Cyclopoida. Species richness estimators and related species accumulation curves suggest an exhaustive sampling effort. A hydrologic analysis performed in a Geographic Information System environment divided the study area in three distinct drainage basins: Eastern Lessini, Lessinian Core, and Western Lessini. Regression analyses indicated that richness of non-stygobitic copepods (i.e., surface-water species which exploit groundwater
for different purposes) was mainly driven by inter-basin differences. Richness of stygobitic copepods (i.e., obligate groundwater dwellers) was instead strongly related to lithological features and responded negatively to surface thermal variability. Next,
we used a kernel density estimation to spatially explore diversity patterns in the area.
The highest density of stygobitic harpacticoids was identified in the Eastern Lessinian basin, which is lithologically more heterogeneous and surrounded by practically non-aquiferous igneous rocks that may limit dispersal. Conversely, the Western
Lessinian basin hosted a high density of stygobitic cyclopoid species. This spatial pattern suggests different colonization pathways for the two taxa, with a strong effect of igneous rocks in hampering dispersal of most harpacticoids. Lithological
barriers seemingly did not affect non-stygobitic copepods, which were found across the whole area. Altogether, these results emphasize the key role played by the interaction of hydrological features, climate, and lithology in determining different
copepod biodiversity patterns in the unsaturated karst. |
| Text | 478754 2023 10.3389/fevo.2023.1143874 ISI Web of Science WOS 000956583900001 Scopus 2 s2.0 85150967523 Unsaturated karst Caves Groundwater Copepoda Alpha diversity Aernel density estimation Environmental factors shaping copepod distributions in cave waters of the Lessinian unsaturated karst NE Italy Vaccarelli I.; Cerasoli F ; Mammola S.; Fiasca B.; Di Cicco M.; Di Lorenzo T.; Stoch F.; Galassi D.M.P. 1 Department of Life, Health and Environmental Sciences, University of L Aquila, L Aquila, Italy; University Institute of Higher Studies in Pavia, Pavia, Italy; Molecular Ecology Group MEG , National Research Council of Italy CNR , Water Research Institute IRSA , Verbania, Italy; Laboratory for Integrative Biodiversity Research LIBRe , Finnish Museum of Natural History LUOMUS , University of Helsinki, Helsinki, Finland; National Biodiversity Future Center, Palermo, Italy, IRET CNR, Istituto di Ricerca sugli Ecosistemi Terrestri del CNR, Florence, Italy; Evolutionary Biology and Ecology, Universite Libre de Bruxelles, Bruxelles, Belgium The unsaturated karst represents a transitional zone connecting the land surface to the water table of the underlying saturated zone through percolating water and small perched aquifers. It constitutes a significant groundwater reservoir and hosts a high biodiversity of specialized and endemic species. Whereas investigating this ecotone can shed light on the invertebrate diversity of the whole karst system, ecological studies in the unsaturated karst have been hampered by access, mapping, and sampling challenges. We studied the unsaturated zone of 52 caves in the Lessinian Massif NE Italy , which is dominated by carbonate rocks interspersed with spot areas composed mainly of igneous rocks. Our aim was to understand which ecological and historical factors may have shaped the distribution of the groundwater crustacean copepods at a regional spatial scale in the Lessinian unsaturated karst. We collected 33 species belonging to the orders Harpacticoida and Cyclopoida. Species richness estimators and related species accumulation curves suggest an exhaustive sampling effort. A hydrologic analysis performed in a Geographic Information System environment divided the study area in three distinct drainage basins Eastern Lessini, Lessinian Core, and Western Lessini. Regression analyses indicated that richness of non stygobitic copepods i.e., surface water species which exploit groundwater for different purposes was mainly driven by inter basin differences. Richness of stygobitic copepods i.e., obligate groundwater dwellers was instead strongly related to lithological features and responded negatively to surface thermal variability. Next, we used a kernel density estimation to spatially explore diversity patterns in the area. The highest density of stygobitic harpacticoids was identified in the Eastern Lessinian basin, which is lithologically more heterogeneous and surrounded by practically non aquiferous igneous rocks that may limit dispersal. Conversely, the Western Lessinian basin hosted a high density of stygobitic cyclopoid species. This spatial pattern suggests different colonization pathways for the two taxa, with a strong effect of igneous rocks in hampering dispersal of most harpacticoids. Lithological barriers seemingly did not affect non stygobitic copepods, which were found across the whole area. Altogether, these results emphasize the key role played by the interaction of hydrological features, climate, and lithology in determining different copepod biodiversity patterns in the unsaturated karst. Published version Environmental factors shaping copepod distributions in cave waters of the Lessinian unsaturated karst NE Italy Vaccarelli_et_al_2023_FEVO.pdf Articolo in rivista Frontiers Media 2296 701X Frontiers in Ecology and Evolution Frontiers in Ecology and Evolution Frontiers in Ecology and Evolution Front. ecol. evol. tiziana.dilorenzo DI LORENZO TIZIANA stefano.mammola MAMMOLA STEFANO |
