Larger areas support more species. To test the application of this biogeographic principle to ponds, we consider the relationship between size and diversity for 80 ponds in Switzerland, using richness (number of species) and conservation value (score for all species present, according to their degree of rarity) of aquatic plants, molluscs (Gastropoda, Sphaeriidae), Coleoptera, Odonata (adults) and Amphibia. Pond size was found to be important only for Odonata and explained 31% of the variability of their species richness. Pond size showed only a feeble relationship with the species richness of all other groups, particularly the Coleoptera and Amphibia. The weakness of this relationship was also indicated by the low z-values obtained (< 0.13). The SLOSS analyses showed that a set of ponds of small size has more species and has a higher conservation value than a single large pond of the same total area. But we also show that large ponds harbour species missing in the smaller ponds. Finally, we conclude that in a global con- servation policy (protection, restoration, management), all size ranges of ponds should be promoted

1. Generalized additive models (GAMs) were used to predict macroinvertebrate taxonomic richness and individual taxon diversity at the reach level across seven European glacier-fed river sites from a set of 11 environmental variables. Maximum water temperature and channel stability were found to explain the most deviance in these models. 2. Using this information, and data from other recent studies of glacier-fed rivers, a modi®ed conceptual model based on Milner & Petts (1994) is presented which predicts the occurrence of macroinvertebrate families and subfamilies as determined by maximum water temperature (Tmax) and channel stability. This deterministic model only applies to the summer meltwater period when abiotic variables drive community structure. 3. Where maximum water temperature is below 2 °C, Diamesinae chironomids are typically the sole inhabitants, but where Tmax >2 °C but <4 °C Orthocladiinae are found and, where channels are more stable, Tipulidae and Oligochaeta also occur. Above 4 °C Perlodidae, Taeniopterygidae, Baetidae, Simuliidae and Empididae can be expected to be part of the glacier-fed river community, particularly in Europe. 4. At other times of the year when environmental conditions ameloriate, glacial rivers support higher macroinvertebrate abundance and diversity, with a number of taxa present that are not found during the summer melt period. 5. Dispersal constraints in¯uence macroinvertebrate assemblages of many glacier-fed rivers located on islands and in some alpine areas

1. A study on glacial stream ecosystems was carried out in six regions across Europe, from Svalbard to the French Pyrenees. The main aim was to test the validity of the conceptual model of Milner & Petts (1994) with regard to the zonation of chironomids of glacier-fed rivers along altitudinal and latitudinal gradient. 2. Channel stability varied considerably, both on the latitudinal and altitudinal scale, being lowest in the northern regions (Svalbard, Iceland and Norway) and the Swiss Alps. Water temperature at the upstream sites was always <2 °C. 3. There was a prominent difference in taxonomic richness between the Alpine and the northern European regions, with a higher number of taxa in the south. In all regions, the chironomid community was characterized by the genus Diamesa and the subfamily Orthocladiinae. Of a total of 63 taxa recorded, two (Diamesa bertrami and Orthocladius frigidus) were common in all the regions except Svalbard. 4. On the basis of cluster analysis, seven distinct groups of sites were evident amongst glacial-fed systems of the ®ve regions (Pyrenees excluded). This classi®cation separated the glacier-fed streams on geographical, latitudinal and downstream gradients. 5. Canonical Correspondence Analysis (CCA) of environmental variables was carried out using 41 taxa at 105 sites. Slope, water depth, distance from source, water temperature and the Pfankuch channel stability index were found to be the major explanatory environmental variables. The analysis separated Diamesinae and typical upstream orthoclads from the other chironomids by low temperature and high channel instability. 6. In all six regions, Diamesa was present closest to the glacier. Within 200 m of the glacier snout, other genera of Diamesinae were found together with Orthocladiinae. Pioneer taxa like Diamesa species coexisted with later colonizers like Eukiefferiella minor/®ttkaui in relatively unstable channels. 7. The longitudinal succession of chironomid assemblages across altitudinal and latitudinal gradients in glacial streams followed the same pattern, with similar genera and groups of species. The general aspects of the conceptual model of Milner & Petts (1994) were supported. However, Diamesa species have wider temperature limits than predicted and other Diamesinae as well as Orthocladiinae colonize metakryal habitats. Correspondence: Brigitt

1. The influence of 11 environmental variables on benthic macroinvertebrate communities was examined in seven glacier‐fed European streams ranging from Svalbard in the north to the Pyrenees in the south. Between 4 and 11 near‐pristine reaches were studied on each stream in 1996–97. 2. Taxonomic richness, measured at the family or subfamily (for Chironomidae) levels for insects and higher levels for non‐insects, increased with latitude from Svalbard (3 taxa) to the Pyrenees (29 taxa). 3. A Generalized Additive Model (GAM) incorporating channel stability [Pfankuch Index (PFAN)], tractive force, Froude number (FROU), water conductivity (COND), suspended solids (SUSP) concentration, and maximum temperature explained 79% of the total deviance of the taxonomic richness per reach. Water temperature and the PFAN of stability made the highest contribution to this deviance. In the model, richness response to temperature was positive linear, whereas the response to the PFAN was bell‐shaped with an optimum at an intermediate level of stability. 4. Generalized Additive Models calculated for the 16 most frequent taxa explained between 25 (Tipulidae) and 79% (Heptageniidae) of the deviance. In 10 models, more than 50% of the deviance was explained and 11 models had cross‐validation correlation ratios above 0.5. Maximum temperature, the PFAN, SUSP and tractive force (TRAC) were the most frequently incorporated explanatory variables. Season and substrate characteristics were very rarely incorporated. 5. Our results highlight the strong deterministic nature of zoobenthic communities in glacier‐fed streams and the prominent role of water temperature and substrate stability in determining longitudinal patterns of macroinvertebrate community structure. The GAMs are proposed as a tool for predicting changes of zoobenthic communities in glacier‐fed streams under climate or hydrological change scenarios.

Recent molecular studies of symbiotic dinoXagellates (genus Symbiodinium) from a wide array of invertebrate hosts have revealed exceptional Wne-scale symbiont diversity whose distribution among hosts, regions and environments exhibits signiWcant biogeographic, ecological and evolutionary patterns. Here, similar molecular approaches using the internal transcribed spacer-2 (ITS-2) region were applied to investigate cryptic diversity in Symbiodinium inhabiting soritid foraminifera. Approximately 1,000 soritid specimens were collected and examined during a 12-month period over a 40 m depth gradient from a single reef in Guam, Micronesia. Out of 61 ITS-2 types distinguished, 46 were novel. Most types found are speciWc for soritid hosts, except for three types (C1, C15 and C19) that are common in metazoan hosts. The distribution of these symbionts was compared with the phylotype of their foraminiferal hosts, based on soritid small subunit ribosomal DNA sequences, and three new phylotypes of soritid hosts were identiWed based on these sequences. Phylogenetic analyses of 645 host-symbiont pairings revealed that most Symbiodinium types associated speciWcally with a particular foraminiferal host genus or species, and that the genetic diversity of these symbiont types was positively correlated with the genetic diversity found within each of the three host genera. Compared to previous molecular studies of Symbiodinium from other locations worldwide, the diversity reported here is exceptional and suggests that Micronesian coral reefs are home to a remarkably large Symbiodinium assemblage.

Summary 1.Floodplains are species-rich environments often strongly impacted by human activities. In particular, the negative effects of progressive and rapid disconnection of secondary channels have led to restoration programmes and a growing interest in restoration ecology. 2. Current restoration strategies in large river floodplains focus on the macroinvertebrate response related to the increases in lateral connectivity of the secondary channels. We constructed a framework to assess a gradient of hydrological connectivity among 13 secondary channels and the main channel of a large river, and we modelled the response of a set of macroinvertebrate metrics to this gradient. Comparisons between predicted and observed metrics in restored channels allowed us to measure the effect of an increase in the hydrological connectivity on the biological characteristics of macroinvertebrate assemblages. 3. The pre-restoration framework enabled a clear ordering of channels into three types according to levels of hydrological connectivity. Rarefied richness and species traits, responding to the connectivity gradient, showed a net difference between disconnected channels and the main river channel. We were able to highlight a predation-colonization trade-off along the gradient of hydrological connectivity with a maximum colonization potential in the most connected channels. 4. Post-restoration sampling showed deviations of the restored channels from their expected ecological state. A large proportion of colonizers were favoured by the restoration operations and non-native species occurred in the restored channels. 5. Synthesis and applications. Macroinvertebrate biodiversity in large river floodplains is shaped by lateral hydrological connectivity. Increasing hydrological connectivity led to an increase in colonization rate. One year after restoration, the increase in lateral connectivity had shifted the restored sites away from the predicted state. This unpredictability is, in part, a consequence of the rapid colonization by non-native species of new habitats created by the restoration measures. We recommend that floodplain-scale restoration should focus on diversification of the hydrological connectivity of channels, thereby conserving a maximum of functional characteristics in macroinvertebrate communities.

1. Glacier-fed streams are characterised by low spatial but high temporal heterogeneity, manifested in seasonal and diurnal discharge and suspended sediment peaks induced by glacial runoff. These streams shelter macroinvertebrate communities adapted to such harsh environmental conditions. Studies relating macroinvertebrate traits to environmental conditions in glacial streams could provide important insights into the structure and function of glacial stream communities. 2. From data collected in three glacial streams from the central Swiss and southern French Alps, we analysed the relationships among six biological traits to define five groups of macroinvertebrate taxa with similar suites of traits. 3. The longitudinal distribution of the five groups and of individual traits was analysed, as well as their variation according to a glaciality index combining water temperature, conductivity, suspended solids and substrate stability. 4. The trait diversity along the three streams showed a strong upstream-downstream gradient. The upper reaches were dominated by a single group of taxa characterised by small, crawling, deposit feeders. The other trait-based groups appeared progressively downstream. 5. Changes in the relative frequency of trait-based groups along the glaciality gradient highlighted the dominance of all-rounder resistant/resilient traits in the three streams and confirmed that environmental conditions in the glacial streams are too harsh or uniform to allow macroinvertebrate communities to develop alternative suites of traits. The findings are discussed in relation to the question of trait coding in the available literature

ABSTRACT1. As ponds are now recognized as freshwater habitats clearly distinct from lakes and running waters, there is a need for standardized tools for assessing their ecological integrity and status, and particularly their biodiversity.2. A standardized method was developed for sampling and assessing the species richness of ponds. Experiences accumulated in previous studies, together with data gathered from 80 Swiss ponds, provided the basis of the proposed method.3. Five taxonomic groups were chosen as complementary representatives of pond inhabitants: aquatic plants, aquatic Gastropoda, aquatic Coleoptera, adult Odonata and Amphibia.4. To sample aquatic flora, quadrats are located along transects perpendicular to the longest axis of the pond. The number of quadrats is calculated from a relationship with pond area. A nonparametric estimator (Jackknife-1) is used to estimate the true species richness from the observed richness.5. Aquatic invertebrates (Gastropoda, Coleoptera) are collected with a hand net. Sampling is stratified within the dominant habitats. The number of samples is calculated from a relationship with pond area. As with the vegetation, the Jackknife-1 estimator is used to estimate the true species richness.6. The species richness of adult Odonata is assessed using a standardized field survey method combining observations from early and late summer. The species richness is corrected with an abundance-based estimator (Chao1). The species richness of Amphibia is obtained from an exhaustive inventory.7. For the assessment of biodiversity, species richness values derived from measurements are compared to values predicted for conditions that enable a high species richness. Generalized Additive Models are used to predict species richness from environmental predictors characterizing the pond. The ratio of measured richness to predicted richness allows the allocation of a quality status to each pond. Results are divided into five biological quality classes, as recommended in the EC Water Framework Directive (WFD).