Diversity patterns of stygobiotic crustaceans across multiple spatial scales in Europe

1. Using species distribution data from 111 aquifers distributed in nine European regions, we examined the pairwise relationships between local species richness (LSR), dissimilarity in species composition among localities, and regional species richness (RSR). In addition, we quantified the relative contribution of three nested spatial units – aquifers, catchments and regions – to the overall richness of groundwater crustaceans.
2. The average number of species in karst and porous aquifers (LSR) varied significantly among regions and was dependent upon the richness of the regional species pool (RSR). LSR–RSR relationships differed between habitats: species richness in karstic local communities increased linearly with richness of the surrounding region, whereas that of porous local communities levelled off beyond a certain value of RSR.
3. Dissimilarity in species composition among aquifers of a region increased significantly with increasing regional richness because of stronger habitat specialisation and a decrease in the geographic range of species among karst aquifers. Species turnover among karst aquifers was positively related to RSR, whereas this relationship was not significant for porous aquifers.
4. The contribution of a given spatial unit to total richness increased as size of the spatial unit increased, although 72% of the overall richness was attributed to among-region diversity. Differences in community composition between similar habitats in different regions were typically more pronounced than between nearby communities from different habitats.
5. We conclude by calling for biodiversity assessment methods and conservation strategies that explicitly integrate the importance of turnover in community composition and habitat dissimilarity at multiple spatial scales.     

Oligochaetes in southern European groundwater: new records and an overview

This work deals with an overview of the faunal composition and presents a general ecological approach to the groundwater oligochaetes in southern Europe. The species richness is high and similar to that of the superficial waters in the same area. Among the 150 species that we found, about 29 are stygobiont, so the total number of stygobiont species in the area studied has been increased to 58. Ten of these species are tubificids with marine phyletic affinities. A list of the most frequently found species and the relative abundance of the different families and genera collected in the main environments investigated are presented. Although enchytraeids often dominated the fauna, lumbriculids and tubificids exhibit a high level of diversity and comprised the majority of stygobiont and stygophilous taxa found. The discovery of members of the family Parvidrilidae in southern European caves is the first outside of North America. This indicates that the family is widely distributed in the Palearctic region and typical of underground waters. Here, we update the previous evaluation of the knowledge about oligochaetes inhabiting groundwater: 96 species of stygobiont freshwater oligochaetes (sensu stricto) are now known in the world and 81 of them have been recorded from the Palearctic region.     

Identifying areas of high importance for orchid conservation in east Macedonia (NE Greece)

The establishment of a network of reserves is of fundamental importance to the loss of biodiversity. Seven different area selection methods for the establishment of a reserve network were applied in the present study: (a) 5% cut-off value of the grid cells with the highest species richness or conservation value, (b) complementarity analysis using as criteria species richness or conservation value or rarest species richness, and (c) mixed complementarity analysis using as criteria species richness or conservation value. These methods were applied in the orchid taxa of east Macedonia. The conservation values of taxa were estimated on the basis of regional rarity, broad-scale rarity, and species specialization. The spatial overlap between the resulting networks and the Natura 2000 network of the study area was assessed. Furthermore, the efficiency of the latter network to protect the orchid taxa of the study area was examined. Our results suggest that: (a) a multiscale estimation of rarity is necessary for the unbiased estimation of species conservation values; (b) species specialization adds valuable ecological information to the assessment of taxa conservation values; (c) complementarity and mixed complementarity analyses on species richness or conservation value safeguard all the taxa of the region; (d) complementarity analysis on the basis of the richness of the rarest species safeguards all the rarest taxa, but not the total number of the remaining taxa; (e) the 5% cut-off value on species richness or conservation value fails to protect all the taxa of the region, including a large number of the rarest taxa; and (f) the Natura 2000 network, despite its large coverage in the study area, fails to safeguard all the taxa, including some of the rarest.     

The role of oligochaetes in the management of waters

To better understand the role of an aquatic oligochaete in the management of water quality, it was determined if oligochaetes were representative of water quality, if indices based on oligochaetes were widely applicable to access water quality, and if oligochaete assemblages were related to environmental factors other than organic pollution. It was found that if only one monitoring sample a year was taken in December, about 73% of the more common species were collected. Seasonality did not seem to affect the taxa collected except for forms in low presence, e.g., Nais. Several indices we used were not applicable to regulated streams. Oligochaete ordination procedures revealed only a partial picture of the environmental conditions of regulated streams.     

Assessing and conserving groundwater biodiversity: synthesis and perspectives

1. This paper is a synthesis of a special issue on groundwater biodiversity with a focus on obligate subterranean species, the stygobionts. The series of papers constitutes a great leap forward in assessing and understanding biodiversity patterns because of the use of large quantitative data sets obtained over a broad geographic scale. They also represent a conceptual shift, away from a purely taxonomic and phylogenetic focus to the analysis of whole groundwater assemblages.
2. The general patterns emerging for groundwater fauna are: very high levels of endemism, low local diversity relative to regional diversity, a limited number of lineages, occurrence of many relicts, and truncated food webs with very few predators.
3. β-Diversity is at least as important as α-diversity in determining total richness at different scales (aquifer, basin and region) and overall taxa richness increases across spatial scales.
4. Advances in understanding groundwater biodiversity patterns further include identification of several important factors related to geology and hydrology that determine the composition of European stygobiotic assemblages.
5. Important challenges for future research include improving sampling strategies, filling gaps in sampling coverage, intensifying research on theoretical and statistical models, and including functional and genetic diversity components in biodiversity assessments.
6. Strategies are proposed for protecting groundwater biodiversity and an argument is made to integrate biodiversity in groundwater management. Applying principles such as complementarity and flexibility for groundwater biodiversity conservation is a major step toward delineating a reserve network that maximise species representation at the European scale.     

Distribution and ecology of Middle Atlantic Bight Oligochaeta

Distribution and ecology of continental shelf oligochaetes are poorly understood. From 1975 through 1977 baseline ecological studies were conducted in the Middle Atlantic Bight prior to oil exploration activities. A total of 38 species in three oligochaete families were collected. Of this total one family and 29 of the species were undescribed at the time of collection. The most abundant and widely distributed species were Limnodriloides monothecus, L. medioporus, Bathydrilus longus, Phallodrilus biprostatus, and Tubificoides diazi. No single species dominated the oligochaete fauna. All the oligochaete species responded to changes in physical parameters over the shelf similarly to the total macrofauna. Seasonal trends within the oligochaetes were not found. Species that preferred coarser sand sediments were all small interstitial forms. The finer sand and eurytopic species were all burrowers. Zoogeographically the Middle Atlantic Bight oligochaetes were predominantly temperate (16 species) with some southern species (8). Seven species were broadly distributed from the Caribbean to Massachusetts or around the world. Seven species were only known from the area studied.Contribution No. 1397 of the Virginia Institute of Marine Science.     

Diversity and distribution of Tubificidae, Naididae, and Lumbriculidae (Annelida: Oligochaeta) in the Netherlands: an evaluation of twenty years of monitoring data

Data from 24 water management districts and the rivers Rhine and Meuse in the Netherlands were used to study geographical distribution, relative occurrence, and environmental requirements of 76 aquatic oligochaetes (families Tubificidae, Naididae, and Lumbriculidae) (Annelida, Clitellata). Approximately 50% of the 76 species that occur in the Netherlands are uncommon, rare, or very rare. The other half of the species are common, very common or abundant. The abundant species are: Stylaria lacustris, Ophidonais serpentina, Limnodrilus claparedeianus, Limnodrilus hoffmeisteri, and Lumbriculus variegatus. With the exception of several brackish water species (those restricted in distribution to water management districts close to the sea that are influenced by salt water influx) and specific running water species (restricted mainly to the eastern part of the Netherlands), most of the species occurred throughout the whole Netherlands. The species distribution was related to environmental variables using ordination. In general, species distribution was correlated with either large waters with high chloride and phosphorus concentrations and a high hydrogen ion concentration (as pH), or with small forested (running) waters in more natural (undeveloped) areas that occasionally become intermittent. Vegetation cover was positively correlated with several swimming species in the family Naididae. While the distribution of aquatic oligochaetes in some families occurring in the Netherlands is known to some extent, the occurrence and distribution of rare and small taxa, particularly those that are difficult to identify taxonomically, is virtually unknown. Some of the rare oligochaete taxa, especially those associated with unique habitats, have received only cursory attention. Also in the data studied, the observations of the more rare species were too few to draw conclusions. To improve our knowledge of oligochaete distribution in the Netherlands, additional research should focus on rare species associated with special habitats and water types (natural areas) and those taxa in poorly known families. The standardisation of sampling and processing methodologies, particularly the use of nets and sieves with fine-meshed screening, will ensure the collection of the smaller species of oligochaetes. Subsequently, oligochaetes should be identified to species level by experienced taxonomists trained in oligochaete identification. Finally, many aquatic oligochaete species are identifiable only when sexually mature and therefore the time of year in which samples are collected is critical to the accurate representation of true oligochaete diversity at any given site. For analysing the relation between species and environmental variables the best option is to use composite data from spring and autumn.     

Beyond Masses and Blooms: The Indicative Value of Oligochaetes

The European Water Framework Directive (WFD) defines a framework for assessing water bodies in Europe in the future. The conditions in the Directive impose a strong demand for “new” assessment systems. The AQEM project developed an assessment system for European streams using macroinvertebrates. Almost 900 samples were taken in about 400 streams covering 29 stream types distributed over eight countries. The role of the Oligochaeta within this European database was analysed. Almost half a million specimens of oligochaetes were collected in 772 samples. Eight families, 41 genera and 69 species were recorded, although identification emphasised the families Tubificidae and Naididae. Three countries identified oligochaetes to species level, most others restricted their identifications to easy identifiable taxa. Numbers of specimens, species, genera and families differed strongly between the countries due to method, although standardised, and taxonomic knowledge. About 50% of all collected oligochaete taxa had assigned biological and ecological indicator values for metric calculation in the AQEM assessment system. A further refinement of this indication list as well as increased coverage of oligochaete taxa was advised. Weighted averaging was used to evaluate the relation between oligochaete distribution and ecological quality class. It was concluded that when higher taxonomic levels are used in assessment, the quality evaluation results become biased. Furthermore, oligochaetes can tell us much more about the ecological status of streams than is commonly assumed. Differences in ecological optima among Limnodrilus udekemianus, Ilyodrilus templetoni, Aulodrilus pluriseta, Nais communis, and Spirosperma ferox are shown.     

Conservation challenges in a threatened hotspot: agriculture and plant biodiversity losses in Baja California,Mexico

Modern agricultural practices pose serious threats to biodiversity worldwide. Species losses from habitat conversion are well documented, but indirect impacts such as reduced water availability to adjacent ecosystems are less known. San Quintín is an important agricultural valley in the mediterranean climate region of Baja California, Mexico. The region is also a hotspot of plant species richness and endemism. Plant species in the region are here analyzed by comparison of the contemporary flora to historical botanical collections to identify extirpations. Historical collections indicate that habitat loss to agriculture has been a direct cause of species losses. As importantly, the unsustainable extraction of groundwater has apparently led to salt water intrusion, resulting in the loss of 22 native plant taxa, including 13 rare plants. Seventy-eight percent of all the vernal pool taxa have been lost from the flora (including 85 % of the rare taxa) and 11 % of plants of riparian and pond habitat (including 25 % of the rare taxa) are no longer found in the region. Unsustainable agricultural practices continue to threaten fragile coastal ecosystems and are a serious challenge to current and future conservation efforts. Ironically, these same practices frequently result in abandonment of cultivated areas. Owing to indirect impacts, conservation of biodiversity and large-scale agricultural operations are even less compatible on a regional scale than indicated by direct impacts. It is vital that sustainable agricultural practices be adopted locally and globally to avoid further losses of biodiversity.     

Oligochaete drift in a large river (French Upper Rhône): the effect of life cycle and discharge

In the framework of a macroinvertebrate drift study, the oligochaete community was analysed over one year (1989) at six sites located in a partly impounded reach of the Upper Rhône River (France). Drift composition between sites was somewhat affected by the environmental conditions. These differences were caused by significant deviations in drift rates (P < 0.05) of endobenthic oligochaetes and non-swimming Naididae. There was no significant difference (P > 0.05) among the swimming Naididae. As the latter strongly dominated, global spatial differences in the drift were weak. Temporal changes constituted the main source of variability in drifting oligochaetes. Life cycles and reproductive ecology of four major swimming Naidid species, Nais elinguis, Stylaria lacustris, Nais christinae, and Nais barbata, explained most of the drift structure over the year. Hydrological fluctuations also affected drift structure, both for swimming and non-swimming species. Taxon richness and relative abundance in the drift were very similar to those obtained in the river benthos from a reference reach previously studied. There was a lack of stygobiont and stygophilous species that are frequent in area of groundwater seepage. Biological and environmental implications of oligochaete drift are stressed. The drift phenomenon is appropriated to provide ecological informations on oligochaete communities in fast flowing and deep, large rivers.     

The insular herpetofauna of Mexico: Composition,conservation, and biogeographic patterns

We compile a Mexican insular herpetofaunal checklist to estimate endemism, conservation status, island threats, net taxonomic turnover among six biogeographic provinces belonging to the Nearctic and Neotropical regions, and the relationships between island area and mainland distance versus species richness. We compile a checklist of insular herpetofaunal through performing a literature and collection review. We define the conservation status according to conservation Mexican law, the Red List of International Union for Conservation of Nature, and Environmental Vulnerability Scores. We determine threat percentages on islands according to the 11 major classes of threats to biodiversity. We estimate the net taxonomic turnover with beta diversity analysis between the Nearctic and Neotropical provinces. The Mexican insular herpetofauna is composed of 18 amphibian species, 204 species with 101 subspecies of reptiles, and 263 taxa in total. Endemism levels are 11.76% in amphibians, 53.57% in reptiles, and 27.91% being insular endemic taxa. Two conservation status systems classify the species at high extinction risk, while the remaining system suggests less concern. However, all systems indicate species lacking assessment. Human activities and exotic alien species are present on 60% of 131 islands. The taxonomic turnover value is high (0.89), with a clear herpetofaunal differentiation between the two biogeographic regions. The species–area and species–mainland distance relationships are positive. Insular herpetofauna faces a high percentage of threats, with the Neotropical provinces more heavily impacted. It is urgent to explore the remaining islands (3,079 islands) and better incorporate insular populations and species in ecological, evolutionary, and systematic studies. In the face of the biodiversity crisis, islands will play a leading role as a model to apply restoration and conservation strategies.     

Do biodiversity hotspots match with rodent conservation hotspots?

Biodiversity hotspots are used widely to designate priority regions for conservation efforts. It is unknown, however, whether the current network of hotspots adequately represents globally threatened taxonomic diversity for whole plant and animal groups. We used a mammalian group traditionally neglected in terms of conservation efforts, the rodents, in order to test whether biodiversity hotspots match the current distribution of threatened taxa (genera and species). Significantly higher numbers of threatened rodent genera and species fell within biodiversity hotspots; nonetheless over 25% of the total threatened genera and species did not occur in any biodiversity hotspot. This was particularly true for the Australian region, where 100% of the threatened genera and species fell outside biodiversity hotspots, with many threatened taxa found in Papua-New Guinea. We suggest to officially including Papua New Guinea among biodiversity hotspots for rodents, and also the steppic/semidesert areas of central Asia.     

Habitat variability of the Littorelletea uniflorae plant communities in Polish Lobelia lakes

Research was carried out to determine aquatic oligochaete habitat preferences in the Rokytná River (Thaya River basin), a sixth order highland stream in the Czech Republic during the period of April 1999–April 2001. Quantitative samples were collected and current velocity and basic physico-chemical variables were measured monthly in four typical habitats in the Rokytná River. During this study, 28, 842 individuals representing 44 oligochaete species or higher taxa were collected. Temporal variability of proportional occurrence of trophic groups found on selected habitats (gathering collectors and grazers) was analysed. Habitat preferences of oligochaete species were evaluated by Canonical Correspondence Analysis (CANOCO). Biochemical oxygen demand (BOD) and nitrate (NO₃⁻) ion concentration were the most important variables explaining the distribution of Oligochaeta along the first axis. Current velocity (at 40% of the depth) and presence of oligochaetes associated with the habitat where gravel bars never formed were the most important variables along the second axis. Both axes were correlated with the temperature, reflecting the sampling in summer along the first axis and sampling in late spring along the second axis. The amount of organic matter (BOD) and concentrations of NO₃⁻ ions represented both oligochaete food source and decomposition products contributing to the growth of algae. Current velocity and preferred habitat explained the spatial pattern of oligochaete distributions.     

The distribution of aquatic oligochaetes in the fenland area of N.W. Overijssel (The Netherlands)

A synoptic study of the aquatic ecosystems in the Dutch province of Overijssel revealed the presence of 33 oligochaete taxa in the fendland area of N.W. Overijssel. The material was collected at 101 sampling sites in 1981. Oligochaetes were grouped by means of a normal and inverse cluster analysis. Although most oligochaetes are quite biquitous, differences in occurrence and abundance were observed and related to minor differences in environmental parameters.     

Lacustrine,profundal meiobenthic oligochaetes as indicators of trophy and organic loading

Meiobenthic and macrobenthic oligochaetes were collected from two depths in Lake Päjänne and examined together with environmental data in which two environmental gradients can be seen. Numbers of Piguetiella blanci, Aeolosoma quaternarium and Aeolosoma hemprichi were positively correlated with oxygen saturation and negatively correlated with total phosphorus and COD suggesting that these species are indicators of oligotrophic conditions. Numbers of Amphichaeta leydigii, Specaria josinae and Vejdovskyella comata were positively correlated with total phosphorus which implies that these species prefer eutrophic conditions. The last three species and Dero digitata showed positive correlations with COD and organic sedimentation, which suggests that they also indicate organic loading. A decrease in aeolosomatid biomass was seen with increasing phosphorus and organic loading. The average body size of detritus-feeding naidids in the upper part of the profundal zone was reduced by organic loading, and more clearly eutrophication, which emphasizes the importance of including meiobenthic oligochaetes in pollution investigations. Of the naidid and aeolosomatid species, Chaetogaster langi preferred the greatest depths of the profundal zone while most of the other species were more abundant at 20 m rather than at the maximum depth. Clustering of the oligochaete taxa supported these observations and clustering of sampling stations based on oligochaete variables generally corresponded to clustering based on environmental data.     

Evaluating reserves for species richness and representation in northern California

The Klamath‐Siskiyou forests of northern California and southern Oregon are recognized as an area of globally outstanding biological distinctiveness. When evaluated at a national or global level, this region is often, necessarily, considered to be uniformly diverse. Due to large variation in biotic and abiotic variables throughout this region, however, it is unlikely that biological diversity is uniformly distributed. Furthermore, land management decisions nearly always occur at spatial scales smaller than this entire region. Therefore, we used field data from a random sampling design to map the distribution of local and regional richness of terrestrial molluscs and salamanders within northern California's portion of the Klamath‐Siskiyou region. We also evaluated the protection afforded by reserves established for varying reasons (e.g. for inspiration and recreation for people vs. species conservation) to hotspots of species richness and species representation of these taxa. No existing reserves were created with these taxa in mind, yet it was assumed that reserves established largely around considerations for the northern spotted owl (Strix occidentalis caurina) would afford adequate protection for many lesser‐known species. Species of terrestrial molluscs and salamanders share two general features: (1) they have extremely low vagility, and (2) they are often associated with moist, cool microclimates. Existing reserves disproportionately included areas of hotspots of species richness for both taxa, when hotspots included the richest c. 25% of the area, whereas non‐reserved lands contained greater than expected areas with lower species richness. However, when a more strict definition of hotspot was used (i.e. the richest c.10% of areas), local hotspots for both taxa were not disproportionately found in reserves. Reserves set aside largely for human aesthetics and recreation and those set aside for biodiversity both contributed to the protection of areas with high (greatest 25%) species richness. Existing biodiversity reserves represented 68% of mollusc species and 73% of salamander species, corresponding to the 99th and 93rd percentiles, respectively, of species representation achieved by simulating a random distribution of the same total area of reservation. Cumulatively, however, reserves set aside for inspiration and biodiversity represented 83% of mollusc species and 91% of salamander species. The existing reserves provide conservation value for terrestrial molluscs and salamanders. This reserve network, however, should not be considered optimal for either taxa.     

Biodiversity surrogate effectiveness in two habitat types of contrasting gradient complexity

Enormous and increasing loss of biodiversity requires evaluation of surrogate taxa as a tool for conservation biology and new reserve selection, in spite of the fact that this approach has become questionable. The aim of this study was to assess the effect of gradient complexity on species richness and community composition among three taxonomic groups. We compared efficiency of vascular plants to indicate diversity of cryptogams (bryophytes, lichens) and snails in two contrasting habitat types (treeless fens and forests) within the same geographic region. We examined correlation of their species richness (Spearman rank correlation), community composition (Bray–Curtis similarity, Mantel test) and their responses to environmental variables (detrended and canonical correspondence analysis). We also focused on Red List species. We found that spatial congruence among studied taxa was affected by habitat type, however vascular plants were good indicator of snail biodiversity in both habitats. Nevertheless, all significant positive correlations of species richness were associated with the congruence in main environmental gradients. Although there was a consistency in significantly positive cross-taxon correlation in community similarity, the congruence was insufficient for conservation purposes. Furthermore we confirmed the necessity of integration of at-risk species in conservation planning as Red List species were poor indicators for total species richness and vice versa. We suggest the complementation of existing reserve network with small-scale protected areas focused on conservation of at-risk ecosystems, communities or species. In this study vascular plants were not found as a sufficient indicator for fine-filter conservation of other taxa.     

Environmental factors affecting the distribution and abundance of cyst-forming Myxobolus spp. and their cyprinid hosts in 3 lakes in Algonquin Park,Ontario

In 1999, 4 species of cyprinid were surveyed for myxozoan parasites in a watershed in Algonquin Park, Canada, Kathlyn Lake. Broadwing Lake, and Lake Sasajewun were included. Eight species of Myxobolus were found that differed in their prevalence and distribution among the 3 lakes. The oligochaetes and environmental parameters, including sediment types and aquatic plants, of these 3 lakes were surveyed the following year. Oligochaetes belonging to 17 species were collected from the 3 lakes. The distribution patterns of the oligochaete fauna, with respect to the environmental variables, were examined using canonical correspondence analysis. Naidids were predominant in all 3 lakes, particularly in the pebbly and sandy sediment of Lake Sasajewun. The highest percentage of tubificids occurred in the detritus and muddy substrate of Broadwing Lake. These findings indicate that the prevalence of certain oligochaetes is congruent with the absence or presence of particular myxozoan species and that substrates and aquatic plants influence the distribution of certain oligochaete species.     

Conserving taxonomic complexity

Traditional species-based conservation programmes are appropriate in situations where species are readily identifiable. However, in certain taxonomically complex groups of organisms, generally characterized by the presence of uniparental lineages and reticulate evolution, it is not possible to classify biodiversity into discrete and unambiguous species. Attempts to impose species-based conservation on such taxonomically complex groups are proving untenable, and threaten to divert scarce resources and taxonomic expertise from the conservation of other priority groups. We argue here that a new approach should be adopted for taxonomically complex groups. We advocate the conservation of evolutionary processes that generate taxonomic biodiversity, rather than the preservation of a limited number of poorly defined taxa arising from this evolution.