engleski

Effects of the substratum on morphology and abundance of Fucus virsoides (Fucales, Heterokontophyta) in the northern Adriatic Sea

The brown algae Fucus virsoides J. Agardh is an endemic and euryhaline species which occurs in the Adriatic Sea. It grows exclusively on rocky bottoms and occupies the narrow mid intertidal zone. Destructive sampling of Fucus settlements was performed during the spring period in two regions in the northern Adriatic - north of Istria along the Slovenian coast and the south Istrian coast (Croatia). In each region, on different types of substrata (limestone and sandstone on the Slovenian coast ; limestone and concrete on the south Istrian coast), two locations were randomly chosen. In this study differences in Fucus morphology (thallus length and branching) and abundance between the two regions and among different types of substrata were tested. On comparing the limestone substrata of the two regions Fucus abundance was greater in south Istria. In this region the abundance of Fucus was significantly greater on limestone than on concrete substrata, while in Slovenia no differences in abundance between sandstone and limestone substrata were found. The thallus length of Fucus was significantly higher on concrete substrata in the south Istrian region and there were no differences in its length when comparing between the limestone substrata of the two regions. A similar trend among substrata and regions was found for thallus branching. Further investigation on the distribution and ecology on F. virsoides is needed to understand better its biogeographical patterns in the Adriatic Sea.

Fucus virsoides; limestone; sandstone; concrete; Slovenian coast; Istrian coast; abundance; morphology

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