Dynamics of cyanobacteria and cyanobacterial toxins and their correlation with environmental parameters in Tri An Reservoir, Vietnam

This study evaluates the water quality from Tri An Reservoir, a drinking water supply for several million people in southern Vietnam, in terms of cyanobacterial biomass and their potent toxins, microcystins (MCs). Cyanobacteria, their toxins and environmental parameters were monitored monthly for 1 year (April 2008–March 2009) at six stations covering a transect through the reservoir. Dynamics of cyanobacterial abundance in relation to cyanobacterial biomass, toxins and environmental factors were investigated. Environmental variables from Tri An Reservoir favored algal and cyanobacterial development. However, cyanobacterial biomass and proportion varied widely, influenced by physical conditions, available nutrients and nutrient competition among the phytoplankton groups. Cyanobacterial biomass correlated slightly positively to temperature, pH and biochemical oxygen demand (BOD5), but negatively to total inorganic nitrogen concentrations. During most of the sampling times, MC concentrations in the reservoir were quite low (≤0.07 μg L−1 MC-LR equivalent), and presented a slight positive correlation to BOD5, total nitrogen:total phosphorus ratio and cyanobacterial biomass. However, in cyanobacterial scum samples, which now and then occurred in the reservoir, MC concentrations reached up to 640 μg g−1 DW−1. The occurrence of MC in the reservoir poses a risk to local residents who use the water daily for domestic purposes.

Timiş River (Banat, Romania) Benthic Macroinvertebrate Communities Structure Spatial Dinamic

ABSTRACT This study presents the description of the structure of benthic macroinvertebrate communities of the Timiș River (Danube Watershed) in correlation with environmental parameters. The results are based on quantitative benthic macroinvertebrates (105 samples) taken in 2011 (June-September) from 21 stations of the the Timiş River, situate between its sources and the Romanian-Serbian border (241 km). The assessed biotope variables were: altitude, slope, riverbed width, depth, substratum types, channel modification and water physico-chemical caracteristics. The results of the study reveal that the spatial structure of benthic macroinvertebrates is induced by the substrate type, by the minor riverbed modifications in comparison with the natural conditions and the quantities of oxidable matters in the water.

Suppression of indigo bush with pod pests

The recorded seed predators of Amorpha fruticosa L., indigo bush weevils and pteromalid wasps, were the subject of laboratory and field research studies in the period from 2006 to 2011. Sample analyses were carried out on more than 30 localities in Serbia with the aim of measuring the summarized pre-dispersal and post dispersal predation preferences. The percentages of the total pre-dispersal (max?33%) and post-dispersal re-infested material (over 95%), make these insects serious candidates for host-plant suppression. Their bionomics were monitored through continuous collection, dessection and observation of infested seeds, in correlation with environmental parameters, especially water-level fluctuations in endangered forests.