Dan L. Danielopol

Present state and future prospects for groundwater ecosystems.

SUMMARY Ecological and socioeconomic aspects of subterranean hydrosystems have changed during the past 40‐50 years. The major environmental pressures (mainly anthropogenic ones) impact the quantity and quality of groundwater resources and the state of subsurface ecosystems, and it is expected that the environmental pressures on groundwater will continue, at least until 2025, unless new environmental policies change this state of affairs. The world demographic increase and the general rise of water demand constitute one of the major environmental pressures on groundwater

Paleoecology of limnic ostracodes: A review of some major topics

Abstract The paleoecology of limnic ostracodes is reviewd in the context of the evolution of their environment. In order to understand why there is a rich ostracode fossil record we examine data such as the quantitative and qualitative distribution of living ostracode species and ostracode assemblages (ways of describing and limitations). Importance of biological and physico-chemical factors for the local accumulation of high numbers of ostracodes and diversified assemblages is emphasized. We discuss the limits of extrapolations of information from ecology to paleocology. We stress how paleontological knowledge can be applied to neontological studies. The possibility of using Holocene ostracodes as indicators of morphometric changes of lakes, temperature, salinity, eutrophication and as a criterion of meromictic conditions is demonstrated. Relationships between ostracodes and the chemical environment and particularly the morphological response of the carapace are considered: e.g., diversity and qualitative composition of assemblages and chemical stability, types of carapace mineralization and ornamentation and chemistry of bottom waters. These ideas, developed from studies on Recent material, are tested for limnic Cenozoic faunas. In the Mesozoic, the main questions arising from the study of nonmarine ostracodes deal with the possible evaluation of paleosalinities in marginal lagoonal environments (Purbeck-Wealden) and with evaluation of depth and hydrochemical and paleoclimatological regime in truly lacustrine intracratonic basins. Some peculiarities of Paleozoic nonmarine ostracode assemblages are described. The paleoecological cause of changes in diversity of several ostracode groups in the Carboniferous and Permian is emphasized.

Incorporating ecological perspectives in European groundwater management policy

Implementation of the European Union (EU) Water Framework Directive (WFD 2000) and its planned supplement ‘Directive on the Protection of Groundwater against Pollution’ (EU GWD [European Union Groundwater Directive] 2003) demands an initial characterization of all groundwater bodies by national and regional authorities. The main criteria considered in the Directives to define the groundwater (GW) status are quality (chemical) and quantity, but there is the obvious omission of ecological perspective in these. A directive for a comprehensive policy dealing with GW protection at the level of the EU is a prerequisite for human welfare. Additionally, recognition of GW-dependent ecosystems (GDEs) in the EU is equally important for their sustainable management. GW management and policy should recognize the ecological functions of GW and their interactions with GDEs. As they can stretch across national and regional boundaries, political recognition of their importance and the necessity for ecological consistency of management plans have to be emphasized. During the last three decades, a number of researchers have focused their attention on the dynamics and functioning of GW ecosystems and this work could serve as a basis for identifying impacts of changes in key attributes of GDEs. Detailed aspects of GW ecosystems have been comprehensively dealt with (Gibert et al . 1994; Wilkens et al . 2000; Griebler et al . 2001; Danielopol et al . 2003). Changes in key attributes of GW ecosystems have had consequences for the environment in the EU and USA (Klijn & Witte 1999; Winter 1999; Sophocleous 2002; Winter et al . 2003).

Environmental changes and diversification ofCyprideis in the Late Miocene of the Styrian Basin (Lake Pannon, Austria)

The turnover from the Sarmatian Paratethys Sea into Lake Pannon around 11.6 Ma seriously impacted aquatic biota like ostracods and triggered their adaptation to the changed environments. One survivor of this ecological switch is certainly the genusCyprideis, which is well known for its radiation in Lake Pannon. A high-resolution micropalaeontological investigation of a transgressive-regressive sedimentary cycle just above the Middle/Late Miocene boundary focused on the taxonomy of the foundCyprideis species. Species-diagnostic characters were evaluated applying qualitative as well as lineal and geometric morphometric analyses. These examinations led to the introduction of two new ostracod species (Cyprideis kapfensteinensisGross n. sp. andCyprideis mataschensisGross n. sp.), which diverge only indistinctly in outline, but are undoubtedly separated by their size and hinge structure along with considerable differences in number of posteroventral spines. We conclude that these co-occurring species were two sympatric species, which were probably adapted to different microhabitats.C. kapfensteinensis is only recognised in the interval at the peak of the transgression, which corresponds to the maximum deepening of the lake in this area and with meso-/polyhaline conditions. In contrast,C. mataschensis seems to be a more euryplastic species because it appears well before this event and is also recorded in the regressive prodelta sediments up section.

Psychrodromus gen.n. (Crustacea, Ostracoda), with Redescription of the Cypridid Genera Prionocypris and llyodromus

The diagnoses of the genera Prionocypris and llyodromus are revised and two representative species, P. serrata and I. varrovillius, redescribed. Psychrodromus gen.n. is created for some species hitherto assigned either to Prionocypris or llyodromus. Detailed redescriptions of Ps. olivaceus (type species), Ps. robertsoni as well as information on Ps. fontinalis, Ps. turcicus and “Ilyodromus” estonicus are presented in order to establish the morphologic particularities of the new genus, which is Palearctic in its present distribution. Numerous morphologic structures, mostly hitherto ignored, proved to be useful in our systematic studies. The existence of several independent phylogenetic lines, in taxa once grouped loosely together, is established.

Hidden biodiversity in the groundwater of the Danube Flood Plain National Park (Austria)

A high number of stygobites (35 taxa) was recorded within a protected area, the Lobau in Vienna. It is shown that within National Parks, the identification of biodiversity hotspots of stygobites represents an attractive scientific activity, which increases the cultural value of protected landscapes.

World subterranean ostracod biogeography: dispersal or vicariance

Origins of the present day distribution of several freshwater and marine phyletic groups of ostracods are described using both Recent and fossil data. Six examples of subterranean ostracods distributed world-wide are discussed. The first two examples (i.e. the Candoninae Namibcypridini and the Sphaeromicolinae) seemed, in a first approach, to fit well with the ‘vicariance model’ but a detailed study demonstrate that their present day distribution can not be seen as a consequence of any geological events. The four other examples (the Xestoleberis arcturi species group, the Tuberoloxoconcha, the Cavernocypris and Fabaeformiscandona wegelini) fit well with the ‘dispersionist model’. We propose a biogeographical model similar to the dispersal one which foccus on the ecological processes occurring at local and/or regional scales. Some present day species or their epigean ancestors may originally have been more widely dispersed. These species were predisposed to colonize subsurface habitats; a process that could occur polytopically and at various times. It is the degree of ecological flexibility, the width of ecological tolerance, the type of preadaptations, and the capacity to perceive and successfully invade new environments that allow subsurface ostracods to migrate actively or be dispersed passively through both subterranean and epigean aquatic systems and to settle in new places. But no centers of origin and direction of dispersal can be identified in our data. There is little known about the autecology of subterranean ostracod taxa with broad geographical ranges. Samples should be collected at fine (habitat) and broad scales (regional surveys) so that we can better understand the modes of ostracod dispersal across a range of spatial scales.

Developmental trajectories in geographically separated populations of non-marine ostracods: morphometric applications for palaeoecological studies

Developmental trajectories refer here to patterns of size and shape changes in ostracod valves during the sequence of post-embryonic growth stages. The information obtained from the study of such patterns has significant applications for evolutionary biology and/or (palaeo) ecology. Using geometric morphometrics methods, we describe the developmental trajectories of three ostracod species with valves retrieved from the sediments of lakes Mondsee (Austria), Hańcza (Poland) and Iseo (Italy). Size and shape data result in distinct developmental trajectories. Ontogenetic changes agree with predictions of Prizbram’s and Brooks’ laws. Patterns of valve shape change provide information which might be of use to the taxonomic definition of evolutionary lineages and to the development of studies of allometry and heterochrony in non-marine ostracods.

Evolutionary and taxonomic aspects within the species group Pseudocandona eremita (Vejdovsky ´ ) (Ostracoda, Candonidae)

The contribution deals with evolutionary and taxonomic aspects of the stygobitic ostracod lineage Pseudocandona eremita (Ostracoda, Candonidae). It is based on a comparative study of the morphology of both the carapace and limbs of individuals belonging to eight populations from Romania (three reproducing bisexually, the others by parthenogenesis). Left valves display various outline shapes, classified in two morphotypes, the “dorsally rounded shape” and the “triangular shape”. The intra- and interpopulation shape variability of these valves is described using geometric morphometrics and multivariate statistics. It is shown that the more flat carapace occurs frequently in populations living in gravel-sand habitats. Moreover, variability of 12 morphological limb characters taken on females is quantitatively evaluated by discriminant analysis. The character state of the m process of the male copulatory organ gives the most reliable information for the separation of the three bisexual populations in different species: P. serbani Danielopol, P. danubialis sp. nov. and P. transylvanica sp. nov. Short descriptions of the latter two species are presented. For the five parthenogenetic populations where no particular discriminant trait could be found, a solution of compromise is adopted, i.e. they are temporary assigned to Pseudocandona eremita (Vejdovský, 1882, Thierische Organismen der Brunnenwasser von Prag. Prag) sensu lato.

Oxygen dependent habitat selection in surface and hyporheic environments by Gammarus roeseli Gervais (Crustacea, Amphipoda): experimental evidence

Field distributions of benthic and hyporheic invertebrates are dynamic and are influenced by many physical and chemical factors. A laboratory flume containing natural gravel substrates was used to test the hypothesis that the amphipod Gammarus roeseli Gervais actively selects habitat based on two important environmental variables, dissolved oxygen concentration and direction of water flow. Under homogeneous oxygen concentrations throughout the flume, amphipods accumulated downstream. During trials with uniformly hypoxic conditions throughout the flume, G. roeseli moved to stones and screens at the water surface and above, into the zone normally saturated with humidity. This behavior, termed aquatic surface respiration, may enhance survival during periods of oxygen deficiency. Oxygen gradients were created in the flume by injecting water of differing oxygen concentrations into the head and the center of the channel. A statistically significant response to these gradients by G. roeseli demonstrates active selection of regions with more favorable oxygen concentrations.