Naslov
Effects of artificial flow retardation on distribution of taxa with different flow preferences in the tufa barrier habitats (Plitvice Lakes, Croatia)

Autori
Miliša, Marko ; Matoničkin Kepčija, Renata ; Ostojić, Ana ; Sertić, Mirela ; Primc-Habdija, Biserka ; Habdija, Ivan

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Ecological Complexity and Sustainability, Abstracts of EcoSummit 2007 / Bai-Lian Li et al. - Peking : Organization Comittee of Ecosummit 2007, 2007

Skup
EcoSummit 2007

Mjesto i datum
Peking, Kina, 22.05.2007. - 27.05.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
macrophyte removal; tufa barriers; flow velocity; Croatia

Sažetak
The aim of this study was to determine whether and to what extent flow disturbance caused by macrophyte (willows) removal influences the macroinvertebrate taxa. This problem was raised when the macrophyte removal was proposed as an instrument of impeding the eutrophication process and barrier deterioration (by willow roots) in the Plitvice Lakes. Macrophyte removal results in reduced introduction and retention of organic matter, however the influence on the macroinvertebrate assemblages was to be addressed. The research was done on the tufa barriers. Sampling was done monthly on 6 dates before and 7 dates after the removal of macrophytes on the impact site and simultaneously on the control site (upstream barrier free of manipulation). Core samples of barrier bed (separated into three vertical layers) were taken from two rheotopes (fast: >100 cm/s and slow: <100 cm/s). Most abundant taxa, of which two rheophilic (Amphinemura sp. and Hydropsyche sp.) and three indifferent (Oligochaeta, Riolus sp. and Chironomidae) according to Schmedtje (1995), were chosen for the analyses. Macrophytes removal caused a significant decrease in flow velocity (Table 1). The rheophilic taxa were found mostly in the top layer and the indifferent taxa were found throughout the vertical profile. The flow retardation generally caused a statistically significant or borderline significant (U-test p<0.05 or <0.09 respectively ; borderline significant changes were considered to avoid Type II errors (Zar, 1996)) decrease in taxa density for both groups at both hydraulic habitats (Figure 1). The retardation of flow caused both groups (rheophilic and indifferent) to find suitable habitats elsewhere. This effect diminished with depth of the substrate. The hypothesis of migration caused by flow velocity change was corroborated by the significant decrease in taxa densities in the deeper layers at fast flow habitats and at slow flow habitats and simultaneous negligible changes in the density of respective taxa in the top layer of the fast flow habitat (where comparably faster flows remained). In comparison with some previous flow disturbance studies (Dole-Olivier et al., 1997 ; Matthaei et al., 1997 ; Kaenel & Uehlinger, 1999 ; Lancaster, 1999) two main differences occurred in our study on tufa barriers: 1) the decrease in taxa densities was caused by flow retardation rather than acceleration and 2) hyporheic zone did not act as a refugium. While significant changes caused by macrophyte removal were observed, in our opinion macrophyte removal should not be dismissed as an instrument of preservation of the integrity of tufa barriers.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA