This paper focuses on the morphology, taxonomy and ecology of the widespread cyanobacteria of the genus Nodularia Mertens ex Bornet & Flahault. In this study the benthic strain of N. sphaerocarpa, isolated from a sand-pit near Olomouc (Czech Republic), is compared with brackish and seawater strains. Changes in morphology and growth parameters (biomass and chlorophyll a) recorded in varying salinity gradients were studied and a 16S rRNA sequencing and AFLP analysis conducted. Morphological and ecophysiological characteristics found were in congruence with molecular data. Three major subgroups of the benthic Nodularia (N. sphaerocarpa, N. moravica and N. harveyana) were found using the polyphasic approach. The results of both the molecular and morphological study clearly separated N. moravica and N. sphaerocarpa, as freshwater species preferring a low salinity and the N. harveyana strains originating from a marine environment preferring a high salinity.
Ichthyophthirius multifiliis Fouquet, 1876, a ciliate parasite, is a cosmopolitan and problematic parasite of cultured freshwater fish. Each geographical isolate of I. multifiliis has variations in life cycle timing under different abiotic water conditions, such as temperature and salinity. We assessed the effects of salinity and temperature on the development and the preferred settlement site of a temperate Australian isolate of I. multifiliis. The time until theront release was significantly different between each temperature; development time was longest at 5 °C with a mean time of 189 h and decreased to a mean time of 11.7 h at 30 °C. At 5 °C our isolate produced a mean of 267 theronts per tomont, which increased to a mean of 493 theronts at 25 °C and reduced to a mean of 288 theronts at 30 °C. Theront length showed an inverse relationship to temperature; mean length was 62 μm at 5 °C and 41 μm at 30 °C. Our isolate reproduced faster at all temperatures and a greater sensitivity to salinity than all reported profiles for temperate isolates. Parasite abundance was highest on the dorsal region of the fish. An accurate understanding of temperature-life cycle information and optimal region to sample for surveillance will aid in the development of specific management plans for the Australian isolate of I. multifiliis, facilitating the strategic timing of treatments., James M. Forwood, James O. Harris, Matt Landos, Marty R. Deveney., and Obsahuje bibliografii
A greenhouse experiment was conducted to study the indirect effects of soil salinity on a caterpillar that induces gall formation on a non-halophilic plant. Larvae of Epiblema scudderiana (Clemens) were allowed to feed on potted goldenrods (Solidago altissima L.) treated with 3 concentrations of NaCl (0, 8,000, 16,000 PPM). Experiments were also carried out with the larvae of two species of leaf beetles, Trirhabda borealis Blake, a leaf-chewer, and Microrhopala vittata F., a leaf-miner, to determine the influence of feeding guild. Adding salt to the soil affected both the plant and insect herbivores. The biomass of roots and shoots as well as root/shoot ratios of salt-stressed plants were lower, relative to controls. The biomass of the fully grown larvae and galls were decreased for the plants treated with the highest salt concentration. The percentage of biomass allocated to the gall was increased by soil salinity. All gall-inducing larvae completed their development (from second to final instar) even though their biomass was significantly reduced in the 16,000 PPM treatment. Soil salinity increased nitrogen concentrations in both gall and stem (normal) tissues but the levels were always higher in the gall. The salt treatments also increased sodium and potassium concentrations in galls and stems. Interestingly, sodium concentrations as well as the ratio of sodium ions to potassium ions increased more rapidly in the stem compared with the gall. Responses of folivorous insects to salt-stressed plants varied. Leaf-chewing larvae ate smaller amounts of plant tissue with high salt content compared with control, which also resulted in shorter feeding periods. The performance of the leaf-mining insect was not affected. However, it was able to complete its larval development within a smaller portion of the leaves. This study showed that soil salinity has a strong negative effect on S. altissima, especially on root development. Conversely, salt stress effects seemed to be progressively decreasing from the stem to the gall to the gall-inducer, which suggests that the gall tissue might act as a buffer against drastic changes in the mineral balance of the host plant. Nevertheless, it seems that unless the host plant dies, larvae of E. scudderiana can always produce a gall in which they can complete their development. On the other hand, leaf-chewing insects appeared to be sensitive to salt-rich tissues since they were deterred by them. Leaf-miners could complete their development with fewer food without any effect on their growth, suggesting that the peculiar tissues on which they feed within leaves became more abundant or nutritious in salt-treated plants.