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The results of a faunistic survey of water mites from five spring areas in Macedonia are presented. Only in three investigated areas were water mites found. 13 species were identi fied, 2 of which ( Lebertia longiseta and Hygrobates setosus ) are reported as new for the Balkan Peninsula, and 1 ( Lebertia porosa ) as a new for Macedonia. The ecological significance of the researches is briefly discussed
A total of 5,613 macroinvertebrate specimens, belonging to 43 taxa of varying systematic positions, were collected at four study sites in the Minina River. Dominant in the material collected were Gammarus sp. (33.9%), Chironomidae larvae (30.4%) and Ephemera sp. larvae (7.0%). More individuals (3,551) and taxa (39) were caught in the lentic zone than in the lotic zone (2,062 specimens and 30 taxa). The biological diversity index ranged from 1.57 to 3.14 within the sites and from 1.04 to 3.77 within habitats (zones of the river). The taxonomic composition and the abundance of the fauna were mainly in fluenced by biotic factors (e.g. amount of aquatic vegetation) and abiotic factors (e.g. water current and type of bottom sediment), while human impact (presence of hydraulic structures, straightening of the river bed) did not significantly affect the fauna.
Background. Increasing global usage of inorganic fertilizers, including phosphate-based fertilizers has its negative consequences on the aquatic environment. Effects of single superphosphate fertilizer (SPF) remain unknown, particularly its influence on the respiratory dynamics of fish under continuous exposure. We investigated the effects of single SPF on the survival and respiratory dynamics of Nile tilapia, Oreochromis niloticus, under laboratory conditions. Materials and Methods. Nile tilapia fingerlings (of mixed sex) (5.40 . 0.03 g) were exposed to various concentrations of the fertilizer in five treatment regimes (in triplicate): 0.88, 1.75, 3.50, 7.00, 14.00 g . L–1 (and 0.00 g . L–1 for control). Each replicate was carried out in a 30-L circular plastic tank based on 20 fingerlings. The study involved: the mortality estimation, the oxygen consumption, the histopathological effects on fish gills, and the activities of lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH) in liver of fish exposed to sublethal concentrations (0.44, 0.22, 0.11, 0.06, and 0.03 g . L–1) of single SPF for eight weeks under laboratory conditions. Results. Acute concentrations of SPF had serious adverse effects on mortality, oxygen consumption and opercular ventilation rates of exposed fish. All variables showed a dose-dependency. A mean value of 96-h LC50 of the SPF to the test fish was calculated to be 3.76 g . L–1. At various acute concentrations, oedema and hyperplasia of gill lamellae were observed in exposed fish. Exposure of the fish to sublethal concentrations of the SPF resulted in reduction in the levels of lactate dehydrogenase and alcohol dehydrogenase activities in liver. Conclusion. Concentrations of SPF in natural water bodies are deleterious to aquatic fauna. With rapid global economic development and need for more food production, pollution from agricultural fertilizers remains a major threat to the aquatic ecosystem. Therefore it is ultimately important that a balance is struck between achieving economic excellence and environmental protection through good pollution management strategies.
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