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Water contraction drives stronger the formation of diatom assemblages in stream than human induced microhabitat-variability
211-228Views:205Today, climate change, together with other anthropogenic influences is considered as a major threat affecting aquatic ecosystems in several ways. Here, altering water contraction (standing and flowing phases) and human-induced habitat variability (natural and artificial stream sections) were studied as modifying factors driving community changes in benthic diatom assemblages of a Hungarian small lowland stream (Létai-ér). We assumed notable compositional differences between phases and habitats, but we expected these differences to decrease with drying. Moreover, lower diversity was hypothesized in assemblages of both artificial section and flowing phase. While taxonomic composition did not reveal significant differences between the sections, well pronounced compositional changes were found between phases. Surprisingly, no significant diversity changes were observed during water contraction. Compared to the natural microhabitat, however, artificial stream section was found to maintain more diverse diatom community. These results emphasize that modification effects of climate change induced hydrological extremes can lead to remarkable compositional changes in benthic algal assemblages even on a short time scale, that must be taken into account in both water management and nature conservation strategies.
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Occurrence and habitat conditions of Gagea minima along the Sorok stream (W Hungary)
189–194Views:136Gagea minima (L.) Ker Gawl. is a Eurasian bulbous species. It occurs sporadically in Hungary, but so far only one current occurrence is known from the Western Transdanubia. In recent years, a large metapopulation has been found in a 15 km long section of the Sorok stream. Its habitat is the high sandy bank above the stream, where it lives mostly in nitrophilous vegetation under non-native tree species. Its long-term persistence in this secondary habitat may have been facilitated by its bulbs, which may have been regularly dispersed by periodic disturbance. Myrmecochory may also have played a role in the local establishment of subpopulations. A number of recently found populations indicate that data on the distribution of the species is still incomplete. The lack of data is probably due to its short flowering period and relative inconspicuousness. Gagea minima is considered a valuable relict species in the altered environment of the Sorok stream and its surroundings.
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A new alien species in Hungary: Limnobium laevigatum (Hydrocharitaceae)
9-15Views:245The South American Spongeplant (Limnobium laevigatum (Humb. & Bonpl. ex. Willd.) Heine) is a floating aquatic plant native to freshwater habitats of tropical and subtropical Central and South America. It is frequently used for ornamental purposes in ponds and aquariums, and became invasive in the recent decades around the world. It has a high reproductive potential and a high dispersal capacity as well. It can form massive floating mats causing light limitation and creating anoxic conditions in the underlying water column, which strongly reduces native animal and plant biomass and diversity. It can also hamper navigation and water flow in rivers and canals. It has been introduced to the United States, Australia, Indonesia, Japan, Zambia and Zimbabwe. There is only one previous record in Europe (Belgium). This article is about the first record of Limnobium laevigatum in Hungary. I found two localities situated near Tata-Naszály and Dunaalmás (North-western part of Hungary). Both localities are fed by hot-water springs. It forms a small but dense population in Dunaalmás located near to the hot spring. The population in Tata-Naszály can be found in a 1.3 km long section of a stream, where it formed a sparse population in 2018.
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Short communications
103-105Views:891. Thelypteris palustris Schott in Börzsöny Mts (N Hungary)
2. Potential neophytes in the face of habitat colonization along the Tócó stream in Debrecen