75 research outputs found
Effect of large- and small- bodied zooplankton on phytoplankton in a eutrophic oxbow
Macrozooplankton and microzooplankton effects on the phytoplankton were measured in situ in a eutrophic lake. Indigenous phytoplankton were incubated for 5 days in 301 mesocosms with either the macro- and microzooplankton (complete), microzooplankton only (micro) or no zooplankton
(none). Changes in phytoplankton biovolume were investigated. Rotifer densities became significantly
higher in the 'micro' treatment than in the 'complete' and 'none' treatments. Total algal biovolume changed little in the 'complete' and 'none' treatments, but increased significantly in the 'micro' treatment. The results suggest that macrozooplankton (Daphnia magna) suppressed it and
microzooplankton (Keratella cochlearis) enhanced it. They had opposite net effects on the phytoplankton.
Suppression of microzooplankton by Daphnia probably had an indirect negative effect on the phytoplankton
Remarkable impact of PAHs and TPHs on the richness and diversity of bacterial species in surface soils exposed to long-term hydrocarbon pollution
Nowadays, because of substantial use of
petroleum-derived fuels the number and extension of
hydrocarbon polluted terrestrial ecosystems is in growth
worldwide. In remediation of aforementioned sites bioremediation
still tends to be an innovative, environmentally
attractive technology. Although huge amount of information
is available concerning the hydrocarbon degradation
potential of cultivable hydrocarbonoclastic bacteria little is
known about the in situ long-term effects of petroleum
derived compounds on the structure of soil microbiota.
Therefore, in this study our aim was to determine the longterm
impact of total petroleum hydrocarbons (TPHs),
volatile petroleum hydrocarbons (VPHs), total alkyl benzenes
(TABs) as well as of polycyclic aromatic hydrocarbons
(PAHs) on the structure of bacterial communities of
four different contaminated soil samples. Our results
indicated that a very high amount of TPH affected positively
the diversity of hydrocarbonoclastic bacteria. This
finding was supported by the occurrence of representatives
of the a-, b-, c-Proteobacteria, Actinobacteria, Flavobacteriia
and Bacilli classes. High concentration of
VPHs and TABs contributed to the predominance of actinobacterial
isolates. In PAH impacted samples the concentration
of PAHs negatively correlated with the diversity
of bacterial species. Heavily PAH polluted soil samples
were mainly inhabited by the representatives of the b-, c-
Proteobacteria (overwhelming dominance of Pseudomonas
sp.) and Actinobacteria
In Vitro and In Vivo Effect of Poplar Bud Extracts on Phytophthora infestans: A New Effective Biological Method in Potato Late Blight Control
The effect of populin extract from black poplar (Populus nigra) on seven different late blight strains was tested under laboratory and field conditions. The growth rate of hyphae was found to be significantly lower in vitro after 3 and 4 v/v% populin applications. Stain M16 was resistant to populin treatment under lab conditions, however. Both 5% and 10% concentration populin reduced the M16 strain’s severity on potato leaves under field conditions and proved to be even more effective than conventionally used fungicides Infinito 687 Sc and Valis M. Higher infection intensity at the 1% level was observed after 24 h using Valis M, and the same trend toward 10% infection remained after 48 and 72 h as well. Low, almost-no-infection intensity was detected after populin 5% and 10% treatment under an open field condition. Altogether, it can be concluded that populin extract can be a low-cost option for growers and an environmentally friendly approach in late blight control
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