A population of the tropical redclaw crayfish Cherax quadricarinatus was reported for the first time in Europe. The redclaw population was first found in 2009 in the natural river oxbow lake Topla with thermal hot water springs in eastern Slovenia. The species is known to be invasive in tropical and subtropical regions, but this is the first record from the temperate climate zone. The population was sex- and age-structured. The low density indicated that the population was still in the growth phase of colonization, or that habitat conditions for the species in the oxbow lake were suboptimal. The redclaw individuals were found at temperatures of up to 40°C, but the bulk of the population with sexually mature individuals was restricted to regions between 21 and 31°C. According to the modelled limits of annual water temperature fluctuation, further expansion of the redclaw is expected in the thermal oxbow lake, but invasion to adjacent rivers is less probable. As a rapidly growing large crayfish, the redclaw could pose a threat to local ecosystems in specific thermal water bodies with unique fauna and flora.
COBISS.SI-ID: 2398799
Alien or non-native species are considered as one of the most important factors influencing global biodiversity lost. Consequences of alien species introductions were frequently extinctions of native species and impacts of alien species are expressed at genetic, individual and population level leading into changes of natural communities and ecosystems. Although first introductions had taken place already 10,000 years ago with the start of human population expansion on the planet, the introduction rate of alien species in natural ecosystems has exponentially increased in the last 100 years. In the article, the fundamental ecological principles of invasion process are given, which consists of several invasion stages: introduction, establishment, spread and impact on native species and ecosystems. The most searched and published examples of alien species in Slovenia are used as examples, which indicate the magnitude of the problem also in Slovenia.
COBISS.SI-ID: 1743996