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Water is life, and millions of people, mainly chil-dren, die each year because they use fresh water ofbad quality (www.who.com). Water qualitydepends on, and can be determined by, extantdiversity of organisms within the water body. Thefall and decline of biodiversity levels in freshwatersis therefore an issue of more than academic inter-est, as has been pointed out correctly byDe Meester & Declerck (2005). Their opinion pa-per analyses the ways in which scientists can re-spond to the needs of society, by formulatingpriorities in research on aquatic (freshwater) bio-diversity. It is pleasing to see that their views takeseveral time scales into account, i.e. they makesuggestions for a short-term science policy, butalso take into account the needs of future gener-ations, a view all too often neglected.Hypotheses and databasesThe Meester & Declerck (loc.cit.) confirm the needof both fundamental and applied research, andpoint out that both approaches need to havequality as their first criterion. However, they con-tinue by saying that good quality fundamentalresearch must an sich mostly (read always) behypothesis driven; supporting purely descriptiveresearchmustbeavoidedasmuchaspossible.Suchviews are pervasive in limnological and ecological(ecosystem) research, but they fall short of beingadequate for this and several other research disci-plines as well. Moreover, there is a small problemwith hypothesis-testing research: where do thesehypotheses come from? Mostly this issue is dis-missed off-handedly: it doesn’t matter very muchwhere they come from, as long as we formulatethem so that they can be tested. We argue thatinductive research, gathering descriptive informa-tion arranged in large databases, will showgeneralised patterns that allow the formulation oftestable hypotheses. As such, inductive (descrip-tive) science is an essential part of hypothesis dri-ven research. Descriptive research provides the fuelon which the hypothesis-testing engine must run.Unfortunately, it is increasingly difficult toobtain funding for inductive research, unless weare talking about huge and flashy projects thatappeal to the imagination, such as the Hubbletelescope in space and the human genome project.Also, it is becoming increasingly difficult to pub-lish the results of descriptive research projects, asinternational journals, including Hydrobiologia,increasingly shy away from it because it is thoughtthat such papers are bad for impact factors. Sev-eral initiatives resulting from the Convention onBiological Diversity, such as the Global Biodiver-sity Initiative (GBIF) set up international net-works that will have as main goal to manage,integrate and analyse large databases. This type ofwork must continue to receive support, eventhough it will for many years fall short of therequirement to do ‘hypothesis-based’ research. Bydatamining existing literature, such projects willvalidate past research investment and will makeexisting data available for future meta-analyses.All of that is important and essential for researchon biodiversity (Schram, 2004).However, very few initiatives allow for the col-lection of new data of this type, and mostdescriptivesurveysmustbedone‘ontheside’,orbesneaked into more applied projects. It is vital thatsuch research receives support in its own standing.Taxonomy and phylogenyA case-in-point, where reduced recognition ofinductive sciences becomes a real problem, is insystematic research, which includes both

The study of biodiversity in freshwater habitats: societal relevance and suggestions for priorities in science policy.- Biodiversity: a resource with a monetary value?.- Linking science and policy for biodiversity.- Relevance and policy dimensions of research on biodiversity in freshwater ecosystems: a developing country perspective.- Conservation of freshwater biodiversity: does the real world meet scientific dreams?.- Taxonomy and systematics in biodiversity research.- Future priorities in science policy for biodiversity studies: a comment on the target review by Luc De Meester and Steven Declerck.- Towards a coherent and high-quality science policy on biodiversity.- An assessment of animal species diversity in continental waters.- Does inland aquatic biodiversity have a future in Asian developing countries?.- Recovery in diversity of fish and invertebrate communities following remediation of a polluted stream: investigating causal relationships.- Ecological remarks on Mastigodiaptomus nesus Bowman, 1986 (Copepoda: Calanoida) in a Mexican karstic sinkhole.- Consumptive and non-consumptive effects of turbellarian (Mesostoma sp.) predation on anostracans.- Changes in functional biodiversity in an invaded freshwater ecosystem: the Moselle River.- The impact of stocking on the genetic structure of European grayling (Thymallus thymallus, Salmonidae) in two alpine rivers.- Connectivity and nestedness of the meta-community structure of moss dwelling bdelloid rotifers along a stream.- Implications of taxonomic modifications and alien species on biological water quality assessment as exemplified by the Belgian Biotic Index method.- A large-scale stream benthic diatom database.- A review on the present status and management of mangrove wetland habitat resources in Bangladesh with emphasis on mangrove fisheries and aquaculture.- Coexistence of two similar copepod species, Eudiaptomus gracilis and E. graciloides: the role of differential predator avoidance.- Native and exotic Amphipoda and other Peracarida in the River Meuse: new assemblages emerge from a fast changing fauna.- Phylogeography and speciation in the Pseudocrenilabrus philander species complex in Zambian Rivers.- Short term spatial and temporal variation of phytoplankton in a shallow tropical oligotrophic reservoir, southeast Brazil.- The female reproductive organ in podocopid ostracods is homologous to five appendages: histological evidence from Liocypris grandis (Crustacea, Ostracoda).- Daphnia species diversity in Kenya, and a key to the identification of their ephippia.- Some aspects of water filtering activity of filter-feeders.- Recent ostracods (Crustacea, Ostracoda) found in lowland springs of the provinces of Piacenza and Parma (Northern Italy).- Representation of aquatic invertebrate communities in subfossil death assemblages sampled along a salinity gradient of western Uganda crater lakes.- Life history strategies of cladocerans: comparisons of tropical and temperate taxa.- Phylogeographic history of the genus Tropheus, a lineage of rock-dwelling cichlid fishes endemic to Lake Tanganyika.- Plankton richness in a eutrophic reservoir (Barra Bonita Reservoir, SP, Brazil).- The effect of turbidity state and microhabitat on macroinvertebrate assemblages: a pilot study of six shallow lakes.

During our study of biodiversity of Rotifera in PR China, as model taxon of freshwater Micrometazoa, we came across several records that warrant revision regarding species of genus Mytilina Bory de St. Vincent, 1826 (Rotifera, Monogonta, Mytilinidae). In addition to this review we describe a new species encountered during examination of freshwater habitats of Inner Mongolia, P.R.China. This new species, Mytilina wangi n. sp., appears to belong to the Mytilina mucronata - ventralis complex but differs from the known taxa in the group by its domed lorica and relatively short toes. We provide an annotated checklist of the Chinese representatives of the genus and discuss the species of the M. mucronata-ventralis group. We suggest treating M. brevispina (Ehrenberg, 1830) and M. ventralis (Ehrenberg, 1830)(synonym: M. macracantha (Gosse, 1886)) as separate species-level taxa rather than as two infrasubspecific variants of the same species, and argue that Mytilina trigona var. bispinosa Wang, 1961 is a misidentified M. acanthophora Hauer, 1938 rather than an infrasubspecific variant of M. trigona (Gosse, 1851).

We studied the distribution of Lepadellidae (Rotifera) in freshwater habitats in the floodplain of the River Rusizi in northwest Burundi. Twenty-three species belonging to Colurella Bory de St. Vincent, 1824 (3 species), Lepadella Bory de St. Vincent, 1826 (18 species) and Squatinella Bory de St. Vincent, 1826 (2 species) are recorded, 22 of them are new to Burundi. One of the taxa encountered probably represents an unnamed species. Lepadella arabica Segers & Dumont, 1993 is recognised as junior subjective synonym of Lepadella eurysterna Myers, 1942 (syn. nov.). Most of the taxa recorded are cosmopolitan or tropicopolitan, two are restricted to the tropical regions of the Old World and Australia, and one, Squatinella lunata Segers, 1993 is an Ethiopian endemic.

Results are presented of a historical analysis of taxonomic research on Rotifera, as reflected by the case of α-taxonomy of Lecanidae and Dicranophoridae. The number of available names established, as well as the fraction presently considered valid are counted per decade. Two peak periods in taxonomic research are revealed, viz. a minor one in the last decades of the 19th century, and a major one in the 1920s–1930s. Especially work published during the second period contains a high proportion of names that are currently considered valid. The second half of the 20th century witnessed a decrease in quantity, but also in quality of taxonomic research. The basic cause for this is probably the typological approach to a group exhibiting high intraspecific morphological variability, but also poor taxonomic education, as reflected by a high incidence of insufficient descriptions, and poor knowledge of the rules governing zoological nomenclature, are of incisive importance.

We investigated phylogenetic relationships of phylum Rotifera using cladistic analysis to uncover all most-parsimonious trees from a data set comprising 60 morphological characters of nine taxa: one Acanthocephala, six Rotifera, and two outgroups (Turbellaria, Gnathostomulida). Analysis of our matrix yielded a single most-parsimonious tree. From our analysis we conclude the following: (1) Class Digononta is paraphyletic; (2) it is still premature to reject rotiferan monophyly; (3) the classification hierarchy that best conforms to this morphologically based, cladistic analysis is similar to several traditional schemes. In spite of these results, it is significant that this analysis yielded a tree that is incongruent with those trees developed from molecular data or by using the principles of evolutionary taxonomy.

Recent studies on morphology, karyotype, genetics including allozyme constitution and reproductive behaviour of ‘S-’ and ‘L-type’ B. plicatilis showed that these types are best treated as different species. A reexamination of existing available names revealed B. plicatilis O. F. Muller, 1786 and B. rotundiformis Tschugunoff, 1921 as the correct names for the ‘L-’ and ‘S-type’, respectively.

Ninety-three freshwater habitats in the north-eastern part of Thailand were surveyed for rotifers during March-October 1993. Two hundred species were identified, 120 of which are new to Thailand. Brachionus africanus Segers, B. lyratus Shephard and Trichocerca hollaerti De Smet are new to Asia. Brachionus niwati n.sp. is described and figured. Brachionus donneri Brehm, Keratella edmondsoni (Ahlstrom) and Lecane blachei Berziņs, endemic to south and southeast Asia, were found also.

We review the rare Chinese rotifer Notholca dongtingensis Zhuge, Kutikova & Sudzuki, 1998, including abundant mate-rial collected during the winter months of 2009–2011 in and around the man-made Dishui Lake Southeast of Shanghai,PR China. Both an SEM study of its trophi and an account of its intraspecific variability are provided. The latter consistsin particular of a unique and previously unknown type of spine formation involving the anterolateral spines, a characterpreviously considered morphologically constant and even diagnostic in Notholca and related genera. The observations in-dicate that phenotypic plasticity invoked by a plesiomorphic triggering mechanism is not per se connected to the type orposition of structures developed, but may activate responses resulting in the formation of quite different, autapomorphic structures throughout monogonont Rotifera.

In response to a clear gap in knowledge on the biodiversity of sessile Gnesiotrocha rotifers at both global as well as regional Southeast Asian scales, we performed a study of free-living colonial and epiphytic rotifers attached to fifteen aquatic plant species in Thale Noi Lake, the first Ramsar site in Thailand. We identified 44 different taxa of sessile rotifers, including thirty-nine fixosessile species and three planktonic colonial species. This corresponds with about 40 % of the global sessile rotifer diversity, and is the highest alpha-diversity of the group ever recorded from a single lake. The record further includes a new genus, Lacinularoides n. gen., containing a single species L. coloniensis (Colledge, 1918) n. comb., which is redescribed, and several possibly new species, one of which, Ptygura thalenoiensis n. spec. is formally described here. Ptygura noodti (Koste, 1972) n. comb. is relocated from Floscularia, based on observations of living specimens of this species, formerly known only from preserved, contracted specimens from the Amazon region. In addition, ten of the species recorded are added to the fauna of the Oriental region, twenty-seven are new to Thailand.

Rotifers are obligate aquatic animals that are reputed to have particularly efficient mechanisms to survive extreme, or prolonged periods of drought, in the form of inconspicuously small resting stages, hidden between plant litter and sediment. In order to study this phenomenon, we conducted a hatching experiment on dry sediment from two billabongs in Victoria, Australia, which had been stored under dehydrated conditions for about one year. Here, we report on the diversity of rotifers that hatched during the experiment. A total of 48 species, a majority of which belong to groups of sessile rotifers, were recorded, including several new or interesting taxa. Two new taxa are described: Floscularia wallacei n. spec., and Pentatrocha gigantea n. gen., n. spec., the largest rotifer ever recorded. Ptygura ctenoida Koste & Tobias, 1990 is raised to species rank.