B. Papp szerk.: Studia Botanica Hungarica 32. 2001 (Budapest, 2001)

Buczkó, Krisztina; Rajczy, Miklós: Changes of attached diatoms in a dead arm of the Danube between 1992-1999 at Ásványráró (Szigetköz section)

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 I i I _J I I I I I i_ a2n92626 a2n95823 33N95823 a3n97108 a3n98106 a2n97703 a2n97108 a2n98106 a2n97703 a2n99812 a3n99812 a2n99930 a3n99930 Fig. 4. Dendrogram of the sampling points. periphyton changed in 1999 on reed. The most similar samples were collected in 1992, 1995, and 1997. Some differences (more dissimilarities) can be observed in the comparison of years 1997 and 1998, respectively, but the sharp change happened in 1999. This phenomenon corresponds well to the result of PCA (Fig. 3). It means that all coatings have changed in the dead arm as well as the reed periphyton. Fig. 5. Changes of relative abundance of Achnanthes minutissima, the most common taxon on reed between 1992 and 1998. The black blocks indicate the samples collected in 1999.