Biological Soil Crusts from Coastal Dunes at the Baltic Sea: Cyanobacterial and Algal Biodiversity and Related Soil Properties

Microb Ecol DOI 10.1007/s00248-015-0691-7 SOIL MICROBIOLOGY Biological Soil Crusts from Coastal Dunes at the Baltic Sea: Cyanobacterial and Algal Biodiversity and Related Soil Properties Karoline Schulz 1 & Tatiana Mikhailyuk 2 & Mirko Dreßler3 & Peter Leinweber4 & Ulf Karsten1 Received: 16 March 2015 /Accepted: 12 October 2015 # Springer Science+Business Media New York 2015 Abstract Biological soil crusts (BSCs) are known as indicate that BSCs in coastal dunes of the southern Baltic Sea Becosystem-engineers^ that have important, multifunctional represent an ecologically important vegetation form with a ecological roles in primary production, in nutrient and hydro- surprisingly high site-specific diversity of 19 cyanobacteria, logical cycles, and in stabilization of soils. These communi- 51 non-diatom algae, and 55 diatoms. All dominant species of ties, however, are almost unstudied in coastal dunes of the the genera Coleofasciculus, Lyngbya, Microcoleus, Nostoc, temperate zone. Hence, for the first time, the biodiversity of Hydrocoryne, Leptolyngbya, Klebsormidium,and cyanobacterial and algal dominated BSCs collected in five Lobochlamys are typical aero-terrestrial cyanobacteria and al- dunes from the southern Baltic Sea coast on the islands Rügen gae, respectively. This first study of coastal sand dunes in the and Usedom (Germany) was investigated in connection with Baltic region provides compelling evidence that here the physicochemical soil parameters. The species composition of BSCs were dominated by cyanobacteria, algae, or a mixture cyanobacteria and algae was identified with direct determina- of both. Among the physicochemical soil properties, the total tion of crust subsamples, cultural methods, and diatom slides. phosphorus content of the BSC-free sand was the only factor To investigate the influence of soil properties on species com- that significantly influenced the cyanobacterial and algal composition, the texture, pH, electrical conductivity, carbonate munity structure of BSCs in coastal dunes. content, total contents of carbon, nitrogen, phosphorus, and 3− the bioavailable phosphorus-fraction (PO4 ) were analyzed Keywords Cryptogamic crusts . Biocrusts . Sand dunes . Soil in adjacent BSC-free surface soils at each study site. The data algae . Cyanobacteria . Diatoms . Phosphorus Electronic supplementary material The online version of this article (doi:10.1007/s00248-015-0691-7) contains supplementary material, Introduction which is available to authorized users. Coastal dunes are unique ecosystems in the transition zone * Karoline Schulz [email protected] between terrestrial and marine environments, where interactions between geology, climate, and vegetation create highly dynamic environments [1, 2]. These eolian and sand-driven 1 Institute of Biological Sciences, Applied Ecology and Phycology, landforms are formed by the interaction of wind and waves, University of Rostock, Albert-Einstein-Str. 3, 18059 Rostock, Germany and exhibit, related to their temporal and spatial dynamics, intrinsic values as important and unique habitats. Additionally, 2 M.H. Kholodny Institute of Botany, National Academy of Science of Ukraine, Tereschenkivska St. 2, Kyiv UA-01001, Ukraine coastal dunes provide an essential source of natural sand re- plenishment and serve as protective barriers against coastal 3 Institute of Biological Sciences, Department of Botany and Botanical Garden, University of Rostock, Wismarsche Str. 8, flooding and erosion [1, 3]. Coastal dune systems are harsh 18051 Rostock, Germany environments with a wide variety of environmental stresses 4 Faculty of Agricultural and Environmental Science, Soil Science, such as strong wind and substrate mobility, scarcity of nutri- University of Rostock, Justus-von-Liebig-Weg 6, ents and soil water, occasionally extremely high temperatures 18051 Rostock, Germany near surface, intense radiation, flooding, and salt spray [1, 4]. K. Schulz et al. Under these conditions, the growth and the development of a Consequently, the aim of the present study was, for the first closed vascular plant cover are limited, and only specialized time, to comprehensively investigate BSCs in coastal dunes of organism communities can be established, which include bio- the temperate zone on the German Baltic Sea islands Rügen logical soil crusts (BSCs). and Usedom, with a special focus on the diversity of BSCs are soil particle-associated communities of cyanobacteria and algae as well as on the influence of abiotic cyanobacteria, algae, microfungi, lichens, liverworts, mosses, parameters. and bacteria in different proportions, living within or immedi- The main questions of this study were the following: ately on top of the uppermost millimeter of soil thereby forming coherent layers at the soil surface [5]. BSCs are dis- 1. Which species occur in these specific coastal dune BSCs tributed worldwide in all climatic zones [e.g., 6–8], and as and which are dominant? multifunctional communities, they have important ecological 2. Do certain soil properties influence the species composi- roles. They stabilize the soil surface [9], increase the content tion of the BSCs in coastal dunes? of soil organic matter and the nitrogen concentration through photosynthesis and nitrogen fixation [10, 11], influence nutrient cycling [12], modulate hydrological processes [13], and consequently, influence the establishment and performance of Material and Methods vascular plants [14]. BSCs are highly diverse communities. There are hundreds Study Area of different species of cyanobacteria and algae which can be found in association with BSCs [15]. Especially, large fila- BSCs were investigated in coastal dunes on the two larg- mentous cyanobacteria as well as filamentous algae are im- est islands of Germany, Rügen, and Usedom (926 and portant for the development of BSCs, because their filaments 445 km2, respectively). Rügen and Usedom are located and sticky mucilaginous sheaths glue soil particles together. In at the southwestern shore of the Baltic Sea belonging to contrast, due to their limited biomass, unicellular the German federal state of Mecklenburg-Western Pomer- cyanobacterial and algal species are usually of secondary im- ania (Fig. 1). Both islands are influenced by an oceanic portance in the formation of BSCs. Most of these unicellular continental transitional climate. The mean annual tempera- species are green algae which can reach high species numbers ture is 8–8.5 °C with the lowest mean temperature of −3– in soil crusts [5]. Furthermore, Bacillariophyceae are also typ- 1 °C in January and highest mean temperature of 19– ical components to be found in BSCs [16, 17]. 20 °C in August. The mean annual precipitation varies The distribution of all BSC-associated organisms and their between 500 and 600 mm, with February being the month further development result from complex interactions with the with lowest mean precipitation and July that with the prevailing environmental factors. Microclimatic conditions highest mean precipitation, 30–40 and 50–70 mm, respec- (e.g., temperature and moisture), soil texture, pH, and carbon- tively (measurement period of all climatic factors: 1961– ate content are only some of the abiotic factors that alter BSCs 1990; [26]). [18, 19]. However, these pedo-climatic and biogeochemical BSCs were investigated along a transect at the three factors vary from site to site, sometimes over orders of mag- study sites Glowe, Prora, and Baabe on Rügen and the nitude, and thus, disclosing their effect on the BSC commu- two study sites Karlshagen and Zempin on Usedom, nity structure still requires site-specific studies over a wide stretching from the northeast coast of Rügen in a south- range of terrestrial habitats. eastern direction to the northwest coast of Usedom Most of the knowledge that exists about the distribution, (Fig. 1). The investigated coastal dune systems differed adaptations, and functions of crust organisms is derived in their morphological characteristics, vegetation cover, from studies on BSCs in semiarid and arid environments, and degree of degradation. The dunes in Glowe and where they can be a main component of the vegetation [20, Prora had a width between 4 and 8 m, while in Baabe, 21]. Taking into account the crucial ecological functions of Karlshagen, and Zempin, the dunes reached widths be- BSCs in terrestrial ecosystems, it is surprising that BSCs in tween 15 and 20 m. Moreover, the two latter systems habitats of temperate regions with more humid conditions were with 4 m twice as high as the three other dunes. are only fragmentarily investigated [see also 22]. One of All dune systems were partly fenced except the one in these habitats is the coastal dune system. The limited liter- Prora. Hence, this latter dune was highly degraded due to ature about BSCs in coastal dunes worldwide indicates that human trampling and showed only little vegetation with they contribute to the stabilization, enrichment of nutrients, a dominance of Festuca sp. The other dune systems had and the establishment of higher plants in these ecosystems undestroyed and dense vegetation mainly consisted of [9, 23–25]. However, BSCs in coastal dunes of the temper- Ammophila arenaria (L.) Link. In addition, Hippophae ate region are still almost unstudied. rhamnoides L., Artemisia campestris L., Artemisia Biological Soil Crusts from Coastal Dunes at the Baltic Sea Fig. 1 The islands Rügen and Usedom, and the investigated dune study sites (c) belonging to the federal state of

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