No abstract

A B S T R A C TPrevious studies reported that landscape-level factors are vital to support diversity of spiders in strongly modified arable lands and disturbed habitats such as managed semi-natural grasslands. Cropland management (ploughing, fertilization, and pest management) Q3 and agricultural practices (mowing and grazing) destroy and/or modify regularly the spider assemblages; thus, continuous recolonization from the surrounding landscape is vital to sustain the species pool. On the contrary, we hypothesized that in unmanaged grasslands, the spider assemblages are stable and the importance of recolonization is limited, the local factors become much more important drivers in shaping spider assemblages than landscape-level factors. We tested the importance of local and landscape-level factors on the abundance and species richness of spiders in unmanaged grasslands. At the landscape-level, we found that only the isolation had significant effect on the total abundance, on the abundance of hunting and habitat specialist species, and on the abundance of a frequent species (Gnaphosa mongolica). At the local scale, however, four out of five studied factors influenced significantly the species richness and abundance of spider assemblages and the abundance of two frequent species (Alopecosa psammophila, Berlandia cinerea). Species richness and abundance increased by plant cover, litter cover, and patch size, while decreased by bare ground cover. We found that in unmanaged grasslands, the local factors had vital role in maintaining the spider species richness; this is just the opposite conclusion that was earlier reported for agricultural ecosystems, where landscape-level effects had crucial role providing the species for continuous recolonization.2015 Published by Elsevier B.V. the local scale and the landscape-level scale) in these habitats 33 (Tscharntke et al., , 2012Batáry et al., 2008

The diet of some populations of Lissotriton montandoni from north-western Romania is composed of prey belonging to 20 categories. The food components of the Carpathian newts are similar to those of other species of newts. Most of the prey are aquatic animals, but terrestrial prey also has a high percentage abundance. The consumed prey categories are common in the newts' habitats as well, but in natural ponds the prey item with the highest abundance in the diet is not the most frequent one in the habitat. Thus, although the Carpathian newts are basically opportunistic predators, they still display a certain trophic selectivity

Feeding dried and vitamin C enriched decapsulated Artemia cysts to African catfish larvae increased their growth rate significantly after 6 days over those fed only freshly decapulated cysts. Groups fed with Artemia nauplii had a significantly higher growth during the experiment, although this difference was not considerably important in practice. Tank colour had no influence on growth. Because of their lower price, the decapsulation of lower quality cysts can be an appropriate feed source in intensive cultures of African catfish larvae. 1999 The Fisheries Society of the British Isles

Experiments were carried out to test the fertilizing capacity and viability of cryopreserved African catfish (Clarias gariepinus) sperm following post-thaw storage at 4°C and following activation with water. In the first experiment, cryopreserved sperm was thawed and stored in a refrigerator for time periods ranging from 0 to 96 h before being used for fertilization. In all cases sperm stored for 24 h resulted in the highest fertilization percentages (37 ± 9%) which was significantly higher than that observed with sperm used for fertilization immediately after thawing (21 ± 4%, P < 0.05).These observations were later confirmed by flow cytometric assessment of membrane integrity of spermatozoa which showed an increase of the percentage of membrane-intact cells from 2 h post-thaw (66 ± 3%) to 26 h (77 ± 3%). In the second experiment, thawed and fresh sperm of African catfish was activated with water and used for fertilization at different time periods post-activation ranging from 0 to 120 s. The highest fertilization rate with cryopreserved sperm (72 ± 12%) was observed when eggs were fertilized with sperm activated for 20 s, however, sperm cells activated for 120 s were still able to fertilize eggs, albeit at a low rate (2 ± 3%). It was also noted that in the second trial of experiment 2 cryopreserved sperm resulted in significantly higher fertilization percentages than freshly extracted semen (P < 0.05).