In recent years, policy-makers have sought the development of appropriate tools to prevent and manage introductions of invasive species. However, these tools are not well suited for introductions of non-target species that are unknowingly released alongside intentionally-introduced species. The most compelling example of such invasion is arguably the topmouth gudgeon Pseudorasbora parva, a small cyprinid species originating from East Asia. A combination of sociological, economical and biological factors has fuelled their rapid invasion since the 1960s; 32 countries (from Central Asia to North Africa) have been invaded in less than 50 years. Based on a combination of monitoring surveys (2535 populations sampled) and literature reviews, this paper aims to quantify and characterise important invasion parameters, such as pathways of introduction, time between introduction and detection, lag phase and plasticity of life history traits. Every decade, five new countries have reported

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Abstract:Results of the investigation of the aquatic macroinvertebrate fauna along a 504 km stretch of the Danube River in Serbia are presented. A total of 74 macroinvertebrate taxa were observed during a 2001 survey. Oligochaeta and Mollusca were the principal components of the community with regard to species richness and abundance. Based on data on the qualitative composition of the macroinvertebrate fauna, a correspondence analysis divided the investigated stretch in three sectors -upper (Pannonian), Iron Gate sector and entrance sector to the Iron Gate stretch. The distribution patterns of certain species supported the division of sectors defined by correspondence analysis.

As a result of freshwater fish parasitofauna investigations, throughout the past 75 years, the number of parasitic species is presented. This paper reviews the history, current state, and tendencies of the fish parasitofauna studies in Serbian open waters. Up to now, in total 170 parasitic species have been reported. Systematic parasitofauna investigations have been carried out on 54 freshwater fish species in waters of the Danube River Basin in Serbia, also in hill-mountanious watercourses, lakes and salmonid fishpond of Sjenicko-Pesterska plateau (south-west region of Serbia), Homolje area (east Serbia), and in Vlasina lake (south-east Serbia). This data review pointed that it is necessary to continue the investigation on fish parasites in Serbia. The data on freshwater fish parasites are important for evaluation of general influence on the community structure.

The activities of total superoxide dismutase (Tot-SOD), manganese-containing superoxide dismutase (Mn-SOD), copper zinc containing superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) protein concentration, as well as protein and SOD electrophoretic profiles in the liver and muscle of barbel (Barbus barbus) and its intestinal parasite Pomphoryinchus laevis from the river Danube, within the suburban area of Belgrade, Serbia (the stretch between Višnjica and Grocka) in spring and summer were investigated. Specific activities of Tot-SOD, Mn-SOD, Cu/Zn-SOD were higher in spring, while specific CAT activity was higher in summer in all investigated samples. Temperature influence on the antioxidant defense enzymes in barbel tissue and in its intestinal parasite Pomphoryinchus laevis, as well as seasonal patterns, are evident. Our work represents the first study of SOD and CAT activities in the barbel and its intestinal parasites and shows that barbel and acanthocephalans are very useful for biomonitoring studies in aquatic ecosystems