engleski

Spatial and temporal variability of macroalgal assemblages along the gradient of urbanisation on the western Istrian coast (northern Adriatic, Croatia)

Few studies in the past have found a decline and changes of flora association for the northern Adriatic due to anthropogenic disturbances. In addition, the quantitative data on the abundances of the most common algal species at different spatial and temporal scales for this region are scant. In this research differences in composition and abundances of macroalgal assemblages along a gradient of urbanisation were tested. Destructive sampling was repeated during a period of one year to investigate the distribution of macroalgal assemblages within 3 different areas: (i) within a radius of 50 m ; (ii) 1 to 3 km and (iii) more than 10 km with respect to the direct sewage outfall in the town of Rovinj. Differences among canopy forming species at the scale of sites and areas were identified. In spring there was no evidence of biomass differences of Cystoseira compressa among the 3 investigated areas, despite the prediction that its abundance would be greater in pristine areas. The abundances of Cystoseira barbata and Cystoseira crinita were significantly greater in putatively pristine areas and their abundances did not differ during the investigated period. Biomass of leathery macroalgae groups was greater at pristine sites in the winter-spring period while that of the sheet groups was greater in polluted areas in the same period. These results form the background for future research related to understanding ecological processes responsible for distribution and dynamics of macroalgal assemblages in natural and urbanised environments.

northern Adriatic; anthropogenic disturbances; leathery macroalgae group; Cystoseira compressa; C. barbata; C. crinita

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