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Ekologija / Ecology

ISSN 0235-7224
ISSN 2029-0586 (online)

2008 m. Nr. 2

Distribution of juvenile river lamprey (Lampetra fluviatilis L.) in different habitats
Rita JANKAUSKIENĖ, Alma JURGAITYTĖ

The impact of anthropogenic pressure on the distribution of juvenile river lamprey (Lampetra fluviatilis L.) in different habitats was investigated. All samples were collected in the midstream of the Minija from June to September 2006. The research covered about 100 meters of the river where, according to the local microenvironment, 20 investigation points were chosen. All the points differed from each other by water depth, the type of substratum, spread of vegetation coverage, and anthropogenic pressure. The highest density of individuals was typical of points with no anthropogenic pressure, in which the substratum contained coarse sand. In such points the density of individuals reached 2 ind m–2. The ANOVA table showed a statistically significant correlation between the density of individuals and anthropogenic pressure (F = 4.37, p < 0.05). In most points, the biomass was about 200 mg m–2. The study results have shown that lamprey juveniles prefer coarse sand. In such type of substratum, the mean density was about 2 ind m–2. In the substratum that mostly contained pebble, no individuals were found. Statistical analysis showed that the correlation between the length of individuals and water depth was statistically significant (r = 0.13, p < 0.05). The research showed that lamprey juveniles avoid shallow water. Vegetation coverage in lamprey habitations was a positive factor (F = 7.65, p < 0.05).

Keywords: anthropogenic pressure, river lamprey, Lampetra fluviatilis L., water depth, substratum type, spread of vegetation

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