hrvatski

Rasprostranjenost i morfološka varijabilnost invazivnih vrsta Elodea nuttallii (Planch.) H.St.John i Elodea canadensis Michx u Hrvatskoj

An invasive species Elodea nuttallii is recorded for the first time in Croatian flora. It has been recorded in all countries of the Danube River Basin and represents the most rapid current invader in water bodies. In Croatia E. nuttallii was recorded in 2006 in melioration channels of Kopački rit (Baranja). After its establishment, E. nuttallii begins to spread on eastern and northern part of drainage channel network in the few last years. Our results show the linear spreading direction of E. nuttallii that was also described in some neighbouring countries (Hungary, Slovenia, Serbia). High water levels are the key processes that link the main river with drainage network system, the stagnant water in channels and are probably responsible for spreading and directing pathway of E. nuttallii in the investigated flooded area. E. nuttallii and E. canadensis show wide range of morphological variation. It is a key characteristic of aquatic plant invasiveness but it has also caused many identification problems. Due to some disagreements among authors about the distinguishing characteristics of Elodea species, we measured the most important characteristics indicated in literature: leaf width at the mid point, leaf length, width/length ratio, leaf width 0.5 mm below the tip, angle at the apex and internode length. 24 fresh collected samples of E. canadensis and E. nuttallii from the 7 sites in Croatia and from different years (period 2006-2009) were analysed morphometrically in the laboratory. In spite of some overlap in leaf length and width of two Elodea species, differences of all measured morphological traits except internode length are statistically significant. In Elodea nuttallii leaf width, length and internode length show a higher morphological variability as a result of higher adaptive strategy to environmental parameters. Leaf width 0.5 mm below the tip and the angle at the apex has been found as the most reliable to distinguish E. nuttallii and E. canadensis and they can be used for quick determination in field surveys.

Elodea nuttallii; Elodea canadensis; invazivne vrste; rasprostranjenost; morfološka varijabilnost

nije evidentirano

engleski

Distribution and morphological variations of invasive macrophytes Elodea nuttallii (Planch.) H.St.John and Elodea canadensis Michx in Croatia

An invasive species Elodea nuttallii is recorded for the first time in Croatian flora. It has been recorded in all countries of the Danube River Basin and represents the most rapid current invader in water bodies. In Croatia E. nuttallii was recorded in 2006 in melioration channels of Kopački rit (Baranja). After its establishment, E. nuttallii begins to spread on eastern and northern part of drainage channel network in the few last years. Our results show the linear spreading direction of E. nuttallii that was also described in some neighbouring countries (Hungary, Slovenia, Serbia). High water levels are the key processes that link the main river with drainage network system, the stagnant water in channels and are probably responsible for spreading and directing pathway of E. nuttallii in the investigated flooded area. E. nuttallii and E. canadensis show wide range of morphological variation. It is a key characteristic of aquatic plant invasiveness but it has also caused many identification problems. Due to some disagreements among authors about the distinguishing characteristics of Elodea species, we measured the most important characteristics indicated in literature: leaf width at the mid point, leaf length, width/length ratio, leaf width 0.5 mm below the tip, angle at the apex and internode length. 24 fresh collected samples of E. canadensis and E. nuttallii from the 7 sites in Croatia and from different years (period 2006-2009) were analysed morphometrically in the laboratory. In spite of some overlap in leaf length and width of two Elodea species, differences of all measured morphological traits except internode length are statistically significant. In Elodea nuttallii leaf width, length and internode length show a higher morphological variability as a result of higher adaptive strategy to environmental parameters. Leaf width 0.5 mm below the tip and the angle at the apex has been found as the most reliable to distinguish E. nuttallii and E. canadensis and they can be used for quick determination in field surveys.

E. nuttallii; E. canadensis; invasive species; distribution; morphological variation

nije evidentirano