Evidence of the existence of a toxic form of Cylindrospermopsis raciborskii (Nostocales,Cyanobacteria) in Japan

Cylindrospermopsis raciborskii is a common, bloom‐forming, planktonic, freshwater cyanobacterium. Toxic populations producing cylindrospermopsin can cause water‐safety problems. Although C. raciborskii is distributed worldwide, the presence of cylindrospermopsin‐producing strains of C. raciborskii was initially reported only in Australia and recently in Thailand. Here, we report the isolation of a toxic strain of C. raciborskii (ISG9) from a freshwater sample collected in Okinawa in 2008. This is the first report describing toxin expression in this species in Japan, detected from a subtropical area. The C. raciborskii species is known to produce cylindrospermopsin as a dominant toxin; however, in this new isolate, the dominant toxin expressed was deoxy‐cylindrospermopsin. The discovery of a toxic strain of C. raciborskii in southern Japan emphasizes the need for basic monitoring schemes for this species in water supplies located in the temperate regions of Japan because of its possible expansion and distribution to other geographic areas.     

New insights into the distribution of alien cyanobacterium Chrysosporum bergii (Nostocales,Cyanobacteria)

Invasive and alien cyanobacteria are considered as a serious threat to aquatic ecosystems due to their ability to produce cyanotoxins and outcompeting native species. Among cyanobacteria, Nostocales is a group with strong competitive advantages including the production of resting cells, ability to fix nitrogen or high affinity to phosphorus. A species Chrysosporum bergii has broadened its original distribution from brackish and seawater habitats of Caspian and Aral Seas to northern regions of Europe. The aim of our study was to expand the knowledge on the distribution of C. bergii, its preferred habitats in the invaded areas and examine whether the biomass of C. bergii is related with biomass of other alien or native cyanobacteria. We examined the phytoplankton community composition and the abiotic factors in randomly selected lakes of western Poland. For the first time, we showed that it occurs widely in lakes of this region. However, it occurred in one third of the investigated lakes and its contribution to total phytoplankton biomass was low. It occurred more frequently in shallow lakes with low conductivity and dissolved phosphorus, yet with higher total phosphorus concentration. The most remarkable finding was a negative relationship of C. bergii biomass with the biomass of native A. gracile, but a positive relationship with an invasive cyanobacterium C. raciborskii. This result suggests that these alien species occur under similar environmental conditions in Polish lakes. Moreover, the morphological features of C. bergii in Poland were similar to those of Anabaena bergii var. limnetica Couté et Preisig from Lithuania and Anabaena bergii from Czech Republic.     

Modelling species distributions to predict areas at risk of invasion by the exotic aquatic New Zealand mudsnail Potamopyrgus antipodarum (Gray 1843)

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Colonization,stability, and adaptation in a transplant experiment of the polymorphic land snail Cepaea nemoralis (Gastropoda: Pulmonata) at the edge of its geographical range

At the eastern margins of the geographical distribution in Europe, populations of Cepaea nemoralis are sparse and limited to urban environments to which they are possibly confined by relatively warmer climates. In 1999 we introduced 1101 C. nemoralis individuals originating from nine urban populations to a rural location in the area. The snails established a viable population, which suggests that confinement to urban settings is dispersal‐ rather than climate‐limited. The snails filled available habitats at a rate of approximately 400–600 m² year^?1. On the whole, morph frequencies remained remarkably stable; changes that occurred are attributable to segregation of alleles or chromosomes. However, snails responded to habitat heterogeneity: consistent and predictable divergence occurred between habitat types, such that light‐shelled snails were repeatedly more frequent in the open than in adjoining shaded habitats. This suggests the operation of climatic and/or visual selection. As the whole area encompassing seven distinct habitat patches was only 0.3 ha, and the maximum duration of population divergence was only 11 years (fewer than four snail generations), these results indicate extremely small temporal and spatial scales of adaptation during initial phases of population establishment and spread. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 462–470.