The predatory behavior of adult females of Thermocyclops decipiens in relation to two cladoceran prey, Ceriodaphnia cornutaand Diaphanosoma spinulosum, was analyzed by laboratory observations. The number of attacks, captures, and ingestionswere quantified. Probabilities of capture after attack (C/A) and ingestion after capture (I/C) were calculated as indicators of preypost-encounter vulnerability. T. decipiens attacked, captured and ingested both cladoceran species, but vulnerabilities of preywere relatively low. C/A was higher in C. cornuta than in D. spinulosum. Larger individuals of D. spinulosum showed higherC/A and I/C than smaller individuals but no effects of size were observed in C. cornuta. The ability of escape as well as thestrength and shape of carapace, seem to partially explain differences in vulnerability among these species. Our results suggestthat intensity of mechanical perturbations and other size-dependent factors, but not body size alone, could be important in determiningpost-encounter prey vulnerability among individuals of a same species.

Wetlands are one of the most altered natural systems due to the creation and development of agricultural landscapes. Some ofagriculture’s impacts are in relation to water quality decreases, due to the use of potentially toxic herbicides or pesticides, andthey are responsible of ecological alterations. This study shows the negative effect that two pesticides generate in a populationof the copepod Arctodiaptomus salinus in an aquatic ecosystem that is surrounded by intensive olive tree cultivation. Adultfemales and egg sacs of that calanoid copepod were exposed to different concentrations of copper sulphate and the pesticidedimethoate, to examine their tolerance response. The adult lethal concentration obtained was lower than the regular dose of pesticideused in olive agriculture. These results also reflect the negative effect over A. salinus secondary production as a consequenceof the increase in females and nauplii mortality and by the hatching rate reduction.

Microcystis aeruginosa mainly occurs as single cells in laboratory cultures, but in the colonial morph under natural conditions.This phenomenon suggests that some factors may be responsible for the typical occurrence of colonies in lakes. Todemonstrate this possible effect, lake water with abundant or few zooplankton was filtered through a 0.15 µm membrane filter,and used as test water. Microcystis aeruginosa was cultured in BG-11 medium, with or without test water. The results showedthat filtered lake water with abundant zooplankton could induce colony formation in M. aeruginosa, whereas M. aeruginosapopulations in the control and the treatment of filtered lake water with few zooplankton were still strongly dominated by unicellsand paired cells, and no colony was formed. In the treatment of filtered lake water with abundant zooplankton, some coloniesof several, dozens, and sometimes even hundreds of M. aeruginosa cells were formed. The unicells reduced to 53.4±6.5%and the proportion of cells in colonies increased from 0 to 24.5±4.6% of the populations. The mean number of cells per unit ofM. aeruginosa in the treatment of filtered lake water with abundant zooplankton was promoted significantly compared withthose of the control and the treatment of filtrated lake water with few zooplankton. In addition, no significant difference in growthrate was detected between the control and the treatments, regardless to the filtered lake water (i.e. with abundant zooplanktonor with few zooplankton). Thus, we concluded that colony formation in our experiment was probably not associated withthe nutrition difference but with some dissolved substances probably released from abundant zooplankton in the natural lakewater, which may be one of the environmental factors responsible for the colonial form in M. aeruginosa.

The aim of this work was to evaluate the potential of aquatic macrophytes as biological indicators of the environmental conditionsof rivers in north-eastern Spain. To this end, twenty five river basins were studied to assess the species composition andabundance of macrophytes, and to examine their relation with different geographic, morphometric, mineralization, and trophicstatus parameters. Of the twenty six macrophyte species found, five appeared to be useful as biological indicators of the environmentalconditions of the rivers. L. minor was a good indicator of high mineralization (i.e., conductivity and Cl-) and high trophicstate (especially, N-NO2 -). C. stagnalis was a good indicator of high P-PO4 3- concentrations. P. crispus, P. polygonifolius,and R. penicillatus seemed to be useful indicators of high N-NO3 - concentration. We conclude that, in our study area, aquaticmacrophytes can indeed be used as biological indicators of the environmental conditions of rivers.

The species diversity of Clitellata (a group of annelid worms) is described for three river systems in different parts of southernSweden. The water of one river (Säveån) discharges into the harbour of Göteborg on the Swedish west coast, that of theother two rivers (Svartån and Kilaån) into the Baltic Sea. A total of 143 species, representing the taxa Enchytraeidae (61),Propappidae (1), Lumbricidae (15), Lumbriculidae (6), Tubificidae (4 Rhyacodrilinae, 33 Naidinae, 13 Tubificinae), andHirudinida (10), are reported. Of these, 24 enchytraeids and six lumbricids were found only in the riparian zone, i.e., in the semiaquatichabitats of the river banks. Six species of Enchytraeidae could not be assigned to any known species and are likely tobe new to science. In addition, the following species are recorded from Sweden for the first time : Achaeta brevivasa, Fridericiabenti, F. healyae, F. lenta, F. sylvatica, Oconnorella tubifera (all Enchytraeidae), Aporrectodea limicola (Lumbricidae),Stylodrilus brachystylus (Lumbriculidae), Dero dorsalis, Nais behningi, Haber speciosus, and Peipsidrilus ?saamicus (allTubificidae). Overall, the species composition is typical of today’s fauna of the once glaciated Northern Europe, but for the familyEnchytraeidae, the biogeographical affinity of Sweden is stronger with Denmark and Germany than with, e.g., the British Islesand the eastern parts of Central Europe.

Macunahyphes, gen. nov. is proposed to include Tricorythodes australis (Banks). In the present paper, the new taxon is describedan illustrated from imagos and nymphs. The unique characters present in Macunahyphes gen. nov. are: in the male imago,(1) forceps tri-segmented with first segment distomedially projected, (2) penis with very wide base, becoming thinner toward asubapical constriction, and then slightly widening again, penis lobes of each side almost completely fused except apical insicion,(3) penes with a ventral projection covered with spines, and in the nymph, (4) glossae and paraglossae almost completelyfused, with a circular outline, and (5) femora with numerous robust serrate setae.

Three males of Cryptocandona vavrai were discovered in geographically distant sites (UK, France, Romania), representingdifferent environments (surface and underground waters). The species may be considered a parthenogen with rare occurrence ofsingle males, the morphology of which was hitherto poorly known. The first complete description of males is given, which, togetherwith comparative descriptions of females from surface waters at the UK site and underground waters at an additional sitein eastern France, as well as consideration of the shape and size of the last juvenile stages, permits the presentation of a morecomplete description and an amended diagnosis of the species. Cryptocandona vavrai takes an intermediate position in thegenus, lodged between stygobitic species and the cluster of more primitive C. reducta and C. brehmi. Due to a number of traits(broad calcified inner lamella of the valves, 3rd ramus podomere of the antennule lacking the posterior seta, hook-like shortestterminal seta of the cleaning leg, specific morphology of the male prehensile palps and hemipenis lobes) C. vavrai is fairly easilyrecognised, although there seems to be considerable intraspecific variation. The comparison between females from surfaceand underground waters revealed substantial elongation of the apical antennal claws, aesthetascs and the distal claw of the walkingleg in the latter population. The major difference recorded among the compared males is the underdevelopment of the externalclaw z2 on the 3rd endopodial podomere of the antenna in the male from the underground waters in Romania. The revealedvariation could indicate that some populations may deserve a separate (sub-specific) taxonomic status. Finally, available data onthe distribution and ecology of this species are summarised.