The macroinvertebrate community was studied in 3 reaches along a north-Iberian stream that differ in the amount and nature of food resources. Regardless of shading and water quality, both invertebrate density and biomass were higher at the 2 downstream sites than at the headwater site. The taxonomic composition and functional organization of the faunal assemblages showed clear differences among sites: shredders and gatherers dominated the headwater site, and scrapers or gatherers, depending on the degree of shading and organic pollution, dominated the downtream sites. Macroinvertebrates responded roughly to intersite differences in food resources, but poor relationships between temporal dynamics of shredder or scraper abundance and that of their food were found. Likewise, no clear effect of floods on invertebrate density and biomass was observed.

Tropical island streams worldwide are being threatened by existing or proposed dams and diversions. Numerous streams of the Hawaiian Islands have diversions that remove freshwater for human use; however, little research has addressed diversion effects on aquatic insect communities in tropical streams. We studied the effect of water removal by a stream diversion on density and biomass of two introduced Trichoptera, Cheumatopsyche analis (Banks) (Hydropsychidae) and Hydroptila potosina (Buenoa-Soria) (Hydroptilidae), in Iao Stream, Maui, Hawaii, from April-August 2000. Both species seem to have multivoltine life cycles. Pooled Trichoptera (both species) biomass was significantly greater above the diversion (178.3 mg.m-2 and 112.9 mg.m-2 for upstream and downstream, respectively). For each individual species the mean total instar biomass was significantly reduced below the diversion (38 % and 54 % reduction for C. analis and H. potosina, respectively). Both species had greater densities above the diversion; however, individual larval mass of H. potosina instars, but not C. analis instars, was significantly lower below the diversion. Our results suggest that reduced habitat quality, due to lowered stream flow, limits density of both species below the diversion, whereas lowered food quantity and quality may differentially affect H. potosina biomass through reduced body sizes. These data suggest that water removal not only reduces habitat quality, but significantly lowers the community biomass of these introduced Trichoptera species, affecting the trophic energetics of stream reaches downstream of a diversion in Hawaii. Similar changes to macroinvertebrate communities would be expected below dams and diversions of streams in other tropical regions.

The aim of our paper was to study the space and time variations of phosphorus contents in the sediment, water and tissue of aquatic plants. Tissue Total Phosphorus of six aquatic plants (Callitriche platycarpa, C. hamulata, C. obtusangula, Elodea nuttallii, E. canadensis and Ranunculus peltatus) was analysed alongside the sediment Total Phosphorus (TP) and Soluble Reactive Phosphorus concentrations (SRP) in water, at the same site. Twelve sites were selected, and, samples were collected to test the seasonal and the annual patterns of phosphorus variation in 3 compartments. Streams ranged from oligotrophic to eutrophic waters. The sediments varied from mesotrophic to eutrophic states. A highly significant site effect was shown for water and for sediment. Water SRP varied with time (season, year), whereas no significant time effect was established for the sediment TP. Tissue TP varied according to year and season in Callitriche platycarpa, C. hamulata and E. nuttallii. The tissue phosphorus storage depended on the trophic level of sediment and water and varied according to species. The rank order of tissue TP content was C. obtusangula > R. peltatus ≥ E. nuttallii ≥ E. canadensis > C. platycarpa > C. hamulata. Removal of aquatic plants biomass with its accumulated phosphorus could be an alternative technique to other eutrophication control strategies. Further work is needed to improve our knowledge to estimate the ecological risk of harvesting on biodiversity and on ecosystem function.

This paper describes spatio-temporal variability of the basic ice condition parameters, relationships between selected lakes in terms of those parameters, and frequency of fast (ice cover) and floating ice. Attention is also paid to morphology and topography of ice cover in lakes Jamno, Bukowo, Gardno, and Łebsko during 1960/61-1999/2000. Based on data archived at the Institute of Meteorology and Water Management, the following ice parameters were analysed: date of the first ice appearance; date of the first ice cover formation, date of disintegration of the last ice cover, date of disappearance of the last ice, ice season duration, number of days with ice, number of days with ice cover, ice conditions continuity, and maximum ice thickness in winter. Lakes Jamno and Bukowo, located in the western part of the Polish coast, are characterised by milder ice conditions, compared to the more eastward lakes (the Gardno and the Łebsko). Ice parameters were found to correlate closely, with statistical significance exceeding α = 0.01 and correlation coefficients usually higher than 0.90, between individual lakes, particularly the neighbouring ones. The highest frequencies of fast and floating ice, 70-75 % and about 10 %, respectively (altogether more than 80 %), were recorded in the last pentade of January. Fast ice (ice cover), accounting for 80 % of all the ice types, was found to dominate in the lakes studied; fast ice domination is typical of small and shallow water bodies. Ice cover is formed as a result of uniform increase in ice rind thickness. After the fast ice has decayed, an ice field pushed by the wind may form ice piles rising to a few metres above the water surface. At the beginning of the ice season, the piled ice appears most often on the western and northern shores, while at the end of the season it tends to stay on the eastern shores. The processes, associated with the presence of piled ice on the shore, are destructive not only for the shore, but also for constructions deployed within the ice range. The ice piles also affect transport and accumulation of sediment, mainly in the shore zone.

In karst sink-holes within the environs of Czajków, and in an old fishpond within the Skorocice gypsum valley, 24 taxa of euglenophytes, comprising Euglena (10), Phacus (9), Lepocinclis (2), and Trachelomonas (3) were found. Four of them, Phacus elegans Pochmann, Ph. arnoldii Swirenko var. ovatus Popova, Ph. plicatus Conrad, and Ph. curvicauda Swir. var. robusta Allorge & Lefèvre, are new for the Polish flora, and rarely reported worldwide.

Six species of the sub-family Cyclocypridinae were found in the Upper Miocene of the Turiec Basin, 4 of which are new Cypria isosceles, C. lenticulata, C. polyphema, C. bodergatiae. The differences in arrangement of the zone of the fusion on ventral margin were used to distinguish the species. The genus Cypria is represented in whole area of the Turiec Basin but the species are restricted to the ecologically well determined biotopes. Valve shape is compared with ecological stability of the paleobiotopes.

The larval morphology of 20 water mite species from Alpine springs is described, with that of Protzia distincta, Tartarothyas romanica, Sperchon mutilus, S. resupinus, S. violaceus, Bandakia concreta, Lebertia cuneifera, L. lativentris, L. sefvei, Atractides adnatus, A. panniculatus, A. macrolaminatus and A. walteri being presented for the first time. For the other 7 species (Panisus michaeli, Panisopsis curvifrons, Thyas palustris, Partnunia steinmanni, Sperchon thienemanni, Lebertia zschokkei and Hygrobates norvegicus), old descriptions exist but, in most cases are not accurate enough to be usable in taxonomy. These species have therefore been re-described. Some general observations on larval morphology and taxonomy are discussed. A short survey of the larval descriptions of West-Palaearctic water mites in general and of spring-living taxa in particular is given, together with a perspective for future research into larval morphology in this geographical area.