Temperature effect on the sensitivity of the copepod Eucyclops serrulatus (Crustacea, Copepoda, Cyclopoida) to agricultural pollutants in the hyporheic zone

Abstract The sensitivity of freshwater invertebrates to agricultural pollutants is supposed to increase with rising temperature due to global warming. The aim of this study was to measure the effect of temperature on the lethal toxicity of ammonia-N, the herbicide Imazamox and the mixture of the two chemicals, in the adults and the juveniles of a population of the copepod Eucyclops serrulatus. This is a widely distributed species found in surface waters, in transitional habitats between surface water and groundwater, and in genuine groundwater environments. We tested the sensitivity by short-term bioassays (96 h) at 15°C and 18°C, respectively. Our results highlighted the following: (1) increasing temperature affected the sensitivity of the adults to ammonia-N and of the juveniles to the mixture, all of which were more sensitive to its detrimental effects at 18°C; (2) the juvenile stages were more sensitive than the adults to all toxicants, and (3) for all combinations of chemicals and temperatures, the effects were synergistic and approximately one order of magnitude greater than those expected according to a concentration addition model when comparing the LC50 for each chemical in the mixture with the LC50s of chemicals individually assayed. Overall, in a context of global change, ammonia-N and mixtures of agricultural pollutants may affect the survival rate of species that spend a part or the whole life-cycle in the hyporheic habitat, with detrimental effects to biodiversity and ecosystem services provided by the hyporheic biota

Towards evidence-based conservation of subterranean ecosystems

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.Peer reviewe

The impact of nitrate on the groundwater assemblages of European unconsolidated aquifers is likely less severe than expected

In this study, we analyzed the structure of the stygobiotic copepod assemblages of an unconsolidated European aquifer (VO), in southern Italy, that has been subject to persistent nitrate contamination for over 15 years. To this end, we monitored 25 bores where groundwater was contaminated only by nitrate, and no other chemical pollutants were reported as being above detection limits from 2009 to 2014. We monitored these bores three times, namely in autumn 2014 and in spring and autumn 2015. We expected that the chronic exposure to high nitrate concentrations had a significant and evident impact on the stygobiotic copepod assemblages. Unexpectedly, the assemblages were highly diversified. The stygobiotic species richness (SSR) accounted 17 species, a value that exceeded the European mean value (SSR = 12 species). However, the species density was only 0.6 species/km2, lower than the European mean value (= 1.6 species/km2). Moreover, the juvenile copepods were numerically less abundant than the adults and the biomass-abundance model showed signs of alteration of the structure of the copepod assemblages. This study highlighted that (i) nitrates, even at high concentrations, probably have a less severe impact on groundwater assemblages of unconsolidated aquifers than expected and (ii) the analysis of population traits and biomasses can detect signs of alteration of these assemblages that would, otherwise, not be visible from the analysis of the sole species richness and abundances

Environmental Quality of Deep Groundwater in the Lessinian Massif (Italy): Signposts for Sustainability

Groundwater conservation and management planning in the Lessinian Massif (Veneto, Italy)is herein discussed following an ecological approach dealing with stygobiont species. Theaim was to provide baseline signposts for the sustainable management of groundwater sites in order to guarantee the preservation of the stygobiota. The approach is organised in the following steps: 1) groundwater biodiversity assessment; 2) selection of priority sites for conservation; 3) selection of respect zones for the priority sites; 4) evaluation of the main anthropogenic risk drivers; 5) assessment of aquifer intrinsic vulnerability; 6) evaluation of risk; 7) proposal of sustainability signposts

A new protocol for assessing the conservation priority of groundwater-dependent ecosystems

Species of conservation concern are usually considered important elements in site prioritization for biodiversity conservation. To overcome the lack of information on species conservation status, multidimensional measures of species rarity can be used as proxies of species vulnerability. Under this assumption, a two-step protocol for site prioritization of aquatic groundwater-dependent ecosystems is proposed using invertebrate vulnerability estimated from species' traits. In the first step, each species occurring in the sites of interest are scored according to their vulnerability. In the second step, sites are prioritized using species' scores. Species vulnerability scores are based on five dimensions, for which various traits are scored: (i) geography, (ii) ecology, (iii) biology, (iv) population, and (v) evolutionary history. For each species, the scores of the various traits belonging to the same dimension are multiplied to obtain a synthetic score. These scores are then ranked into four classes and, for each dimension, each species receives a new score that reflects its rank. The sum of these scores represents the species' overall score. Site conservation priorities are assessed by combining species scores into three indices: Sum of Species Scores, Biodiversity Conservation Concern (which relates the sum of species scores with the local species richness) and Groundwater Biodiversity Concern (which is the average of the former two). The protocol is illustrated using case studies in Italy and it is fully implemented in the software AQUALIFE which is freely available at: http://app.aqualifeproject.eu by registered users. Sensitivity analyses showed that the protocol is robust against the lack of information on species biology or sampling limitations. However, trait scoring rests with the user, who must be familiar with the study group. This approach can be applied at any spatial scale and to different types of aquatic groundwater-dependent ecosystems

Environmental Quality of Deep Groundwater in the Lessinian Massif (Italy): Signposts for Sustainability

Groundwater conservation and management planning in the Lessinian Massif (Veneto, Italy)is herein discussed following an ecological approach dealing with stygobiont species. Theaim was to provide baseline signposts for the sustainable management of groundwater sites in order to guarantee the preservation of the stygobiota. The approach is organised in the following steps: 1) groundwater biodiversity assessment; 2) selection of priority sites for conservation; 3) selection of respect zones for the priority sites; 4) evaluation of the main anthropogenic risk drivers; 5) assessment of aquifer intrinsic vulnerability; 6) evaluation of risk; 7) proposal of sustainability signposts

Potential factors driving the distribution of subterranean invertebrates in karst groundwaters of the Rotolo Cave (southern Italy).

The study of subterranean environments is hindered by the lack of information that does not allow to fully explain the subsurface abiotic and biotic dynamics, especially when considering the 3D interactions in the deep karst. The fragmented knowledge of mechanisms and factors regulating the subsurface environment and its biological features makes it difficult to assess the connections between the various components, and the changes related to anthropogenic impacts. Challenges for data collection in karst are mainly referred to explorations and surveying in caves, because they are difficult to access. Despite the limitation in accessing the subsurface, karst groundwaters offer privileged sites to study ecosystems of high intrinsic value due to their specialized fauna (stygofauna), often comprising rare and endemic species. The aquatic cave-dwelling organisms live in fissures of the rock mass and in larger conduits and channels, resulting in consequential relations with the aquifer hydrogeological dynamics. The extreme vulnerability of karst and the occurrence of low resilient communities therein, requires urgent monitoring and conservation tools to protect the underground ecosystems in their entirety. This work offers the basis for setting practical conservation actions by means of a systematic and long-term scientific program in the Apulian karst. The carbonates of Apulia host significant groundwater resources and over 2000 caves in need of protection. Many efforts have to be made to assess the abiotic dynamics, together with the status of the stygodiversity. A first attempt was carried out at Grave Rotolo, the deepest cave in Apulia, where cavers have reached the groundwater bodies. A preliminary screening of both saturated and unsaturated karst (May-October 2021) allowed us to assess the minimum theoretical number of species living in the system through asymptotic species richness estimators (Chao1, Chao2, Abundance Coverage Estimator, Incidence Coverage Estimator). This karst system harbors a diverse and composite array of species across groundwater habitat types. Indeed, the faunal sampling underestimated the theoretical true baseline richness level of the cave (range 16.77-76.05%). In addition, the sites where the groundwater fauna live in the cave could be related to complex subsurface flow pathways or different recharge areas, as suggested by the differences observed in species compositions and species abundances among different cave water bodies. Therefore, the combined biological and hydrogeological approach could shed light on their mutual information, where the biological component may work as hydrogeological tracer of the karst system. These tools are necessary to select proper monitoring sites, and define the most appropriate sampling and analytic techniques for achieving a better understanding of the groundwater dynamics and species partitioning in deep karst environments

Dataset of benthic copepods in the littoral zones of Lake Maggiore

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 to the species level level and created a dataset with individual georefer-enced 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. 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 imple-mentation strategies for sustainable water management

Jumping into the grids: mapping biodiversity hotspots in groundwater habitat types across Europe

Biodiversity hotspots are routinely identified by grid-based analyses, despite grids encompassing different habitats, thus hindering the potential to assess which habitat type accounts for the conservation priority assigned to a grid. In this study, we aimed at identifying the main hotspots for the conservation of the European stygobitic Crustacea Copepoda Harpacticoida at the groundwater habitat scale. A multi-metric approach was used, based on six biodiversity indicators: species richness, endemicity, evolutionary origin, phylogenetic rarity, taxonomic distinctness, habitat specificity. The Hot Spot Analysis, based on the statistics Getis-Ord Gi*, was used to compare the local to the global average values of each indicator to identify hotspots of conservation. The operational units used to perform the analyses were the groundwater habitat types, in order to gather all the possible patterns of spatial occupancy in terms of habitat variability. Eight biodiversity hotspots of stygobitic Crustacea Harpacticoida were highlighted: 1) the Pyrenees (Spain and France), 2) the Jura Massif (France), 3) the Alpine arc (France, Switzerland and Italy) embracing southward the River Po alluvial plain and the Slovenian External Dinarides, 4) the Central Apennines (Italy), 5) the Carpathian and Balkan mountains in Romania and at the boundary between western Bulgaria and north-west Macedonia, 6) the Dinaric Alps (from Croatia to Albania), 7) the Sardinia Island, 8) an area in central-northern Europe embracing Denmark, the Netherlands and Germany. The hotspots showed a clear spatial distribution in southern Europe where they were distributed predominantly south to the 45th parallel, in line to what reiteratively observed in previous studies. Many hotspots embraced more than one habitat type. The adoption of discrete groundwater habitat types as working spatial units rather than grids provided a higher resolution of where the stygobitic harpacticoid species effectively live, with the possibility of intervening more precisely to preserve them and their habitats