Algal diversity and community composition of peat bogs in Poland (Central Europe)

Aims: Peat bogs are ecosystems with a high degree of spatial heterogeneity and varied characteristic structure. Nutrient poor peat bogs are one of the most important providers for maintaining the biodiversity of algae sensitive to eutrophication. However, they are also one of the most threatened oligotrophic biotopes in Europe. Algae, especially desmids and diatoms, are the dominant aquatic organisms in European peat bogs. Despite their importance, long-term algal species monitoring is limited, although it is a crucial aspect of algal biodiversity conservation. Study area: The acidic oligo-ombrotrophic Biale Lugi peat bogs located in the southern part of Poland. Methods: We sampled five peat bogs zones (riparian, alder carr, marshy coniferous forest, transitional mire and raised bog) in two summer vegetation seasons (2010 and 2011), and compared our findings with the algological material collected in 1996-1998, and also in 1999-2000, to assess local diversity of freshwater algae over the long-term. We examined diatom and desmid species diversity in acidic oligo-ombrotrophic peat bogs and determined the main environmental factors influencing their development. In each zone, physical (stream, river width, depth, temperature) and chemical (dissolved oxygen, conductivity and pH) data were collected. The color, water turbidity and concentration of orthophosphates, nitrates, ammonium nitrogen and sulfates were investigated. Results and conclusions: Altogether, we found 65 desmid and 115 diatom taxa. Carbon, hydrogen, nitrogen, phosphorus and iron concentrations were found to have a positive effect on the development and biodiversity of the studied algal assemblages. Significant differences occurred among the spatial distribution of desmids and diatoms in relation to the zone type. The highest Shannon H' diversity index was recorded for alder carr, whereas the lowest for the raised bog. Our results confirm that desmids and diatoms are dominant aquatic groups in Polish and European peat bogs and are strongly influenced by environmental factors.