Search

Copepods (Crustacea: Copepoda) are widespread in aquatic ecosystems worldwide and represent an important component of the meiobenthic metazoan assemblages of lake littorals. Yet, little is currently known about the diversity of benthic copepods in lentic habitats. We gathered information on the benthic copepod assemblages of the littoral zone of Lake Maggiore as part of the Interreg Italy-Switzerland 2014-2020 Parchi Verbano Ticino project (ID: 481668), funded by the European Regional Development Fund (ERDF). Lake Maggiore is a large and deep temperate lake in north-western Italy human-managed from mid-March to mid-September. This contributes to substantial changes in water levels in relation to human activities such as hydropower, industrial and agricultural uses. We compiled a dataset listing 234 occurrences of benthic copepod species recorded from three littoral sampling sites situated in three protected areas, two of which are part of the Natura 2000 network in Italy and one is part of the Emerald Network in Switzerland. We collected the specimens during the summer-autumn period in 2019-2021. We identified the copepods at the species level and created a dataset with individual georeferenced occurrence records for each species, organized in a standardized Darwin Core Archive format. We made available, through the Global Biodiversity Information Facility (GBIF), a total of 13 distinct taxonomic entities and 234 unique georeferenced occurrence records related to the benthic copepod assemblages of the littoral zone of Lake Maggiore (Tabilio Di Camillo et al., 2023). The dataset has the potential to support the authorities in charge of managing Lake Maggiore’s water levels in addressing the ecological risk relevant to the littoral zone and in developing shared implementation strategies for sustainable water management.

In groundwater-fed springs, habitat characteristics are primarily determined by a complex combination of geomorphic features and physico-chemical parameters, while species assemblages are even more intricate. Springs host species either inhabiting the spring mouth, or colonizing spring habitats from the surface or from the aquifers which feed the springs. Groundwater species living in springs have been claimed as good candidates for identifying dual aquifer flowpaths or changes in groundwater pathways before reaching the spring outlets. However, the reliability of spring species as hydrological biotracers has not been widely investigated so far. Our study was aimed at analysing a large karstic spring system at three nested spatial scales in order: i) to assess, at whole spring system scale, the presence of a groundwater divide separating two aquifers feeding two spring units within a single spring system, by combining isotope analyses, physico-chemistry, and copepod distribution patterns; ii) to test, at vertical spring system scale, the effectiveness of copepods in discriminating surface and subsurface habitat patches within the complex mosaic spring environment; iii) to explore, at local spring unit level, the relative role of hydrochemistry and sediment texture as describers of copepod distribution among microhabitats. The results obtained demonstrated the presence of a hierarchical spatial structure, interestingly reflected in significant differences in assemblage compositions. Copepod assemblages differed between the two contiguous spring units, which were clearly characterized by their hydrochemistry and by significant differences in the groundwater flowpaths and recharge areas, as derived by the isotope analyses. The biological results suggested that stygobiotic species seem to be related to the origin of groundwater, suggesting their potential role as hydrological biotracers. At vertical scale, assemblage composition in surface and subsurface habitats was significantly different, both between spring units and among microhabitats, supporting strong habitat preferences of copepod species. At the smaller local scale, the response to habitat patchiness of subsurface copepod assemblages resulted in distribution patterns primarily defined by sediment texture, while the sensitivity to differences in hydrochemistry was negligible.

Springs are amongst the most relevant Groundwater Dependent Ecosystems (GDEs) and are key research environments in freshwater ecology and biology. The strict dependency on ground water of surface spring biodiversity is well known, whereas the biodiversity occurring below the spring is very poorly known. This study analyzes copepod assemblages in the subsurface habitat of a karstic rheo-limnocrenic spring in relation to seventeen environmental parameters. Subsurface copepod assemblages were sensitive to microspatial variation in habitat structure, and species distributions were mostly driven by groundwater flowpath and substratum type, resulting in biologically distinct limnocrenic and rheocrenic sectors at the spring system scale. Habitat patchiness was reflected in differences in the microdistribution of subsurface copepods, stygobiotic assemblages being more sensitive to the measured environmental gradients than non-stygobiotic ones. In spite of the apparent stability of spring environments, copepods, as a target group, performed well as descriptors of sediment texture and hydrodynamics, and may offer relevant information for a better understanding of the potential changes generated by anthropogenic disturbance on these ecosystems..