Diana M. P. Galassi

Groundwater copepods: diversity patterns over ecological and evolutionary scales

Copepods are common components of the groundwater fauna, and greatly increase the diversity of groundwater communities. With more than 900 species/subspecies known from continental groundwaters, stygobiont copepods inhabit all kinds of aquifers (karstic, fissured, porous), as well as surface/subsurface ecotones (land/water and water/water). The polyhedral and varied structure of the stygohabitats is reflected in the surprising mixture of functional morphologies and habitat exploitations experienced by groundwater copepods. Morphological adaptations and specializations are discussed, as well as the chronology of their appearance in the evolutionary history of several taxa. Diversity patterns of copepod assemblages in groundwater are examined under both structural and functional profiles, as well as across a range of scales. Structure and function operate in an interactive, sometimes hierarchical ways, as well as scales. On the ecological scale, local heterogeneity and patchiness in geomorphic and hydrologic characteristics, as well as biotic interactions, are to be considered causal factors affecting the diversity patterns over a range of spatial and temporal scales. On the evolutionary scale, it is widely accepted that stygobiont copepods evolved from ancestors living in marine, freshwater and semiterrestrial environments. They gained access to the groundwater through major highways represented by the interstitial and the crevicular/karstic corridors. ‘Phylogenetic diversity’ in groundwater copepod taxocoenoses is viewed as a heterogeneous assemblage of species belonging to different phylogenetic lineages, which entered groundwater at different times and by different ways.

Stygobiotic crustacean species richness: a question of numbers, a matter of scale

Species richness in ground water is still largely underestimated, and this situation stems from two different impediments: the Linnaean (i.e. the taxonomic) and the Wallacean (i.e. the biogeographical) shortfalls. Within this fragmented frame of knowledge of subterranean biodiversity, this review was aimed at (i) assessing species richness in ground water at different spatial scales, and its contribution to overall freshwater species richness at the continental scale; (ii) analysing the contribution of historical and ecological determinants in shaping spatial patterns of stygobiotic species richness across multiple spatial scales; (iii) analysing the role of β-diversity in shaping patterns of species richness at each scale analysed. From data of the present study, a nested hierarchy of environmental factors appeared to determine stygobiotic species richness. At the broad European scale, historical factors were the major determinants in explaining species richness patterns in ground water. In particular, Quaternary glaciations have strongly affected stygobiotic species richness, leading to a marked latitudinal gradient across Europe, whereas little effects were observed in surface fresh water. Most surface-dwelling fauna is of recent origin, and colonized this realm by means of post-glacial dispersal. Historical factors seemed to have also operated at the smaller stygoregional and regional scales, where different karstic and porous aquifers showed different values of species richness. Species richness at the small, local scale was more difficult to be explained, because the analyses revealed that point-diversity in ground water was rather low, and at increasing values of regional species richness, reached a plateau. This observation supports the coarse-grained role of truncated food webs and oligotrophy, potentially reflected in competition for food resources among co-occurring species, in shaping groundwater species diversity at the local scale. Alpha-diversity resulted decoupled from γ-diversity, suggesting that β-diversity accounted for the highest values of total species richness at the spatial scales analysed.

Nitrate source and fate at the catchment scale of the Vibrata River and aquifer (central Italy): an analysis by integrating component approaches and nitrogen isotopes

The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits.

Human alteration of groundwater–surface water interactions (Sagittario River, Central Italy): implication for flow regime, contaminant fate and invertebrate response

Many rivers worldwide are undergoing severe man-induced alterations which are reflected also in changes of the degree of connectivity between surface waters and groundwater. Pollution, irrigation withdrawal, alteration of freshwater flows, road construction, surface water diversion, soil erosion in agriculture, deforestation and dam building have led to some irreversible species losses and severe changes in community composition of freshwater ecosystems. Taking into account the impact of damming and flow diversion on natural river discharge, the present study is aimed at (i) evaluating the effects of anthropogenic changes on groundwater/surface water interactions; (ii) analyzing the fate of nitrogenous pollutants at the floodplain scale; and (iii) describing the overall response of invertebrate assemblages to such changes. Hydrogeological, geochemical and isotopic data revealed short- and long-term changes in hydrology, allowing the assessment of the hydrogeological setting and the evaluation of potential contamination by nitrogen compounds. Water isotopes allowed distinguishing a shallow aquifer locally fed by zenithal recharge and river losses, and a deeper aquifer/aquitard system fed by surrounding carbonate aquifers. This system was found to retain ammonium and, through the shallow aquifer, release it in surface running waters via the hyporheic zone of the riverbed. All these factors influence river ecosystem health. As many environmental drivers entered in action offering a multiple-component artificial environment, a clear relationship between river flow alteration and benthic and hyporheic invertebrate diversity was not found, being species response driven by the combination of three main stressors: ammonium pollution, man-induced changes in river morphology and altered discharge regime.

Phylogeny and biogeography of the genus Pseudectinosoma, and description of P. janineae sp. n. (Crustacea, Copepoda, Ectinosomatidae)

Recent stygobiological investigations carried out in the circum‐Mediterranean area resulted in the discovery of a new species of the genus Pseudectinosoma Kunz, described herein as P. janineae sp. n. The taxonomic status of the genus is reviewed in a phylogenetic perspective. The origin of the present‐day distribution of the genus Pseudectinosoma is reconstructed both from patterns of relationships among the species and from palaeogeographical data.

Little Known Harpacticoid Copepods From Italy, and Description of Parastenocaris Crenobia N. Sp. (Copepoda, Harpacticoida)

Little known harpacticoid copepods are recorded from subterranean habitats of Italy and Parastenocaris crenobia n. sp. is described from a rheocrene spring of Abruzzo (central Italy). Elaphoidella rossellae Pesce, Galassi & Apostolov, 1987 is herein synonymized with Elaphoidella plutonis plutonis Chappuis, 1938. Supplementary descriptions and illustrations are given for E. plutonis plutonis, with taxonomic, zoogeographical and ecological remarks.

Nitocrellopsis rouchi sp. n., a new ameirid harpacticoid from phreatic waters in France (Copepoda: Harpacticoida: Ameiridae)

Ongoing investigation of the interstitial communities of the River Rhône revealed the presence of a new species of Ameiridae Monard, 1927. Both sexes of Nitocrellopsis rouchi sp. n. are described herein. Re-examination of type-material (when available) of Nitocrellopsis ioneli (Dumont & Decraemer, 1974), N. petkovskii (Rouch, 1987), N. hippocratis (Cottarelli & Forniz, 1993) and N. hellenica (Cottarelli & Forniz, 1993) and other Nitocrella-related genera sensu Petkovski (1976), revealed differences in cephalic appendage morphology between species which are discussed together with the identification of some minute morphological characters observed for N. rouchi with the aid of scanning electron microscopy. A generic diagnosis is given, together with type-species designation to make available the generic name. A key to species of Nitocrellopsis gen. mov. is provided.

Parastenocaris lorenzae n.sp., and first record of Parastenocaris glacialis Noodt (Copepoda, Harpacticoida) from Italy

Parastenocaris lorenzae n.sp. is described from rhithrostygal of the Sangro river (Abruzzo, Central Italy). Parastenocaris glacialis Noodt, 1952 is for the first time recorded from Italy. The presence of borealpine elements in ground waters of Central Apennines is briefly discussed.

Two new species of Nitocrella from groundwaters of Italy (Crustacea, Copepoda, Harpacticoida)

Abstract Two new species of Nitocrella Chappuis, 1923, N. pescei sp. n. and N. kunzi sp. n., from the Presciano spring system (Tirino River, Abruzzo, central Italy) are described. Both species fit into the hirta‐group of Nitocrella, as defined by Petkovski (1976). From an ecological point of view, they are true stygobiont species, linked to different biotopes of the crenal habitat.

Developmental endpoints of chronic exposure to suspected endocrine-disrupting chemicals on benthic and hyporheic freshwater copepods

The aims of this study were: (i) to assess if carbamate pesticides and ammonium, widely detected in European freshwater bodies, can be considered ecologically relevant endocrine-disrupting chemicals (EDCs) for benthic and interstitial freshwater copepods; and (ii) to evaluate the potential of copepods as sentinels for monitoring ecosystem health. In order to achieve these objectives, four species belonging to the harpacticoid copepod genus Bryocamptus, namely B. (E.) echinatus, B. (R.) zschokkei, B. (R.) pygmaeus and B. (B.) minutus, were subjected to chronic exposures to Aldicarb and ammonium. A significant deviation from the developmental time of unexposed control cultures was observed for all the species in test cultures. Aldicarb caused an increase in generation time over 80% in both B. minutus and B. zschokkei, but less than 35% in B. pygmaeus and B. echinatus. Ammonium increased generation time over 33% in B. minutus, and 14, 12 and 3.5% for B. pygmaeus, B. zschokkei and B. echinatus, respectively. On the basis of these results it can be concluded that chronic exposure to carbamate pesticides and ammonium alters the post-naupliar development of the test-species and propose their potential role as EDCs, leaving open the basis to search what are the mechanism underlying. A prolonged developmental time would probably produce a detrimental effect on population attributes, such as age structure and population size. These deviations from a pristine population condition may be considered suitable biological indicators of ecosystem stress, particularly useful to compare polluted to unpolluted reference sites. Due to their dominance in both benthic and interstitial habitats, and their sensitivity as test organisms, freshwater benthic and hyporheic copepods can fully be used as sentinel species for assessing health condition of aquatic ecosystems as required by world-wide water legislation.