Croatian freshwater bryoflora-diversity and distribution

Area of Science:

• Freshwater bryology
• Plant taxonomy and distribution
• Ecological survey

Background:

• The Water Framework Directive mandates ecological assessments of European waters.
• Freshwater bryophytes are crucial bioindicators of water quality and habitat health.
• Croatia's diverse aquatic ecosystems present a unique opportunity to study bryoflora.

Purpose of the Study:

• To conduct an extensive field survey of freshwater bryophytes across Croatia (2016-2021).
• To create the first comprehensive floristic catalogue of Croatian freshwater bryoflora.
• To analyze the distribution, diversity, and ecological patterns of these species nationally.

Main Methods:

• Field surveys conducted at 786 sampling sites across running and standing waters in Croatia.
• Identification and cataloging of 83 bryophyte species (68 mosses, 15 liverworts).
• Analysis of species richness, frequency, distribution patterns, life forms, and life strategies.

Main Results:

• Recorded 83 bryophyte species, with an average richness of 4.17 species per site.
• Identified *Fontinalis antipyretica*, *Rhynchostegium riparioides*, *Leptodictyum riparium*, and *Cratoneuron filicinum* as most frequent.
• Found higher bryophyte diversity in the Dinaric Ecoregion (karstic rivers) than the Pannonian Ecoregion (lowland watercourses).
• Over 70% of species were rarely found; most were facultative aquatics, not truly aquatic.
• Dominance of circumpolar and European (temperate) chorotypes observed.
• Aquatic trailings and turfs were the most frequent life forms; perennials and colonists were dominant life strategies.

Conclusions:

• The Dinaric Ecoregion offers more suitable habitats for truly aquatic bryophytes compared to the Pannonian Ecoregion.
• In the Pannonian Ecoregion, bryophytes primarily inhabit periodically submerged riparian zones.
• This study provides a foundational understanding of Croatian freshwater bryoflora, essential for water management and conservation.