West Estonian Archipelago Research Articles

Assessing suitability of multispectral satellites for mapping benthic macroalgal cover in turbid coastal waters by means of model simulations

One of the objectives of monitoring benthic algal cover is to observe short- and long-term changes in species distribution and structure of coastal benthic habitats as indicators of ecological state. Mapping benthic algal cover with conventional methods (diving) provides great accuracy and high resolution, yet is very expensive and is limited by the time and manpower necessary. We measured reflectance spectra of three indicator species for the Baltic Sea: Cladophora glomerata (green macroalgae), Furcellaria lumbricalis (red macroalgae), and Fucus vesiculosus (brown macroalgae) and used a bio-optical model in an attempt to estimate whether these algae are separable from each other and sandy bottom or deep water by means of satellite remote sensing. Our modelling results indicate that to some extent it is possible to map the studied species with multispectral satellite sensors in turbid waters. However, the depths where the macroalgae can be detected are often shallower than the maximum depths where the studied species usually grow. In waters deeper than just a few meters, the differences between the studied bottom types are seen only in band 2 (green) of the multispectral sensors under investigation. It means that multispectral sensors are capable of detecting difference in brightness only in one band which is insufficient for recognition of different bottom types in waters where no or few in situ data are available. Configuration of MERIS spectral bands allows the recognition of red, green and brown macroalgae based on their spectral signatures provided the algal belts are wider than MERIS spatial resolution. Commercial stock of F. lumbricalis in West-Estonian Archipelago covers area where MERIS 300 m spatial resolution is adequate. However, strong attenuation of light in the water column and signal to noise ratio of the sensor do not allow mapping of Furcellaria down to maximum depths where it occurs.

Biogeographical determinants of lichen species diversity on islets in the West-Estonian Archipelago

Questions: Do islet area, number of biotopes and distance from the mainland shape lichen species richness on islets? Are there any species- or substrate group-specific trends associated with these factors? Location: Islets of the west Estonian Archipelago, Estonia. Methods: A species list was compiled for each of the 32 islets and the relative abundance of each species was estimated. The lichens were divided into seven groups according to their substrate preferences. Generalized linear model (GLIM) analysis was applied to test the effect of the islet traits on the number of lichen species on the islets and in the substrate groups. The probability of presence/absence and abundance of the most frequent species according to the islet traits were tested with GLIM and general linear mixed model. Results: The lichen flora of the islets consisted of 326 taxa, the number of lichen species per islet varied from 2 to 197. Total number of species per islet and within the substrate groups was positively correlated with islet area and with number of biotopes, and negatively correlated with distance from the mainland; however, these relationships varied among the substrate groups. Although individual lichen species showed variation in responses, general trends in island biogeography were evident. Conclusions: The distribution pattern of lichens on the studied islets follows the theory of island biogeography: the number of species per islet depends on isolation, area and biotope diversity. Species specific traits, such as dispersal strategy and growth form, as well as availability of a particular substrate are important for formation of the lichen flora on islets.

Growth and Production Rates of Loose-Lying and Attached Forms of the Red Algae Furcellaria lumbricalis and Coccotylus truncatus in Kassari Bay, the West Estonian Archipelago Sea

Two ecologically and morphologically distinct forms of Furcellaria lumbricalis and loose form of Coccotylus truncatus were experimentally tested to obtain information on the growth rates and influence of the habitat depth on their eco-physiological activity. Incubations were carried out in the area inhabited by a loose F. lumbricalis–C. truncatus community in Kassari Bay of the West-Estonian Archipelago Sea, the NE Baltic Sea. During the incubation period (20.04–21.10.2002) loose forms of F. lumbricalis and C. truncatus showed similar dynamics of both growth rate of biomass and primary production while attached form of F.␣lumbricalis had, as a rule, significantly lower growth rate and primary production values. The highest eco-physiological activity was recorded from the shallowest incubation depth (4 m) for all three algal forms. All three tested algal forms had similar pattern of growth during the incubation period – highest growth rates were detected in spring and early summer while during the rest of the incubation period algal biomass was in a steady state when production balanced degradation processes.

A Study Of Hydrodynamic And CoastalGeomorphic Processes In Küdema Bay,The Baltic Sea

The aim of the paper is to analyze relationships between hydrodynamic and geomorphic processes in a small bay in the West-Estonian Archipelago. The area consists of a Silurian limestone cliff exposed to storm activity, and a dependent accumulative distal spit consisting of gravel and pebble. Changes in shoreline position have been investigated on the basis of large-scale maps, aerial photographs, topographic surveys and field measurements using GPS. Waves and currents were investigated using a Recording Doppler Current Profiler RDCP-600 deployed into Kudema Bay in June 2004 and the rough hydrodynamic situation was simulated using hydrodynamic and wave models. The main hydrodynamic patterns were revealed and their dependences on different meteorological scenarios were analyzed. It was found that due to exposure to prevailing winds (and waves induced by the longest possible fetch for the location), the spit elongates with an average rate of 14 m/year. Major changes take place during storms. Vitalization of shore processes is anticipated due to ongoing changes in the regional wind climate above the Baltic Sea.

Classification and description of phytobenthic communities in the waters of the West-Estonian Archipelago Sea

Three separate coastal sea areas were investigated in terms of phytobenthic community structure in the waters of the West-Estonian Archipelago in the Baltic Sea. The phytobenthos species composition was similar in the three regions while the structure of the communities referred to different environmental conditions. The classification of the phytobenthic communities in the area was made using cluster analyses. The defined and described 19 classification units were compared with classification systems that have been published before. Most of the classification units defined in the present study were similar to the units defined by other authors. Depth and substrate had considerable influence on the phytobenthic communities in three areas: in the westernmost, exposed sea area phytobenthic communities changed continuously along the depth gradient without forming distinct belts while in the more sheltered central areas wide, depth-related phytobenthos belts were described.

Vegetation development and introduction of agriculture to Saaremaa Island, Estonia: the human response to shore displacement

Three pollen profiles from Saaremaa Island (West Estonian Archipelago) record vegetation history from the early Holocene up to the present, and land-use history since the late Mesolithic. A new numerical zonation approach for distinguishing between human and climatic impacts in the pollen record in boreal forest is suggested. Zonation and correlation of the studied profiles suggests four pollen-assemblage zones, regarded as regionally significant. Land uplift, in interaction with a milder climate and easily cultivated soils, facilitated by changing economy, has been the most important factor during the colonization and management of coastal areas. Human impact on Saaremaa Island may be divided into four main phases: (a) Mesolithic and Early Neolithic forest disturbance by hunter-gathering people; (b) forest clearances, pastoral farming and first attempts of cereal cultivation by Neolithic people; (c) more regular cultivation with introduction of slash-and-burn agriculture since the Late Neolithic; (d) permanent field cultivation since the Migration Period/Viking Age.

WATERLAIN GLACIAL DIAMICTON ALONG THE PALIVERE ICE-MARGINAL ZONE ON THE WEST ESTONIAN ARCHIPELAGO, EASTERN BALTIC SEA

On both the distal and proximal sides of the Palivere end-moraine zone on the West Estonian Archipelago, a sporadic distribution of up to 25 m thick subaqueous waterlain glacial diamicton (WGD) was observed. The WGD lies at an altitude between - 15 and + 10 m relative to contemporary sea level. During the Palivere stadial the distribution area of the WGD was at least 50-60 m below the water table of the Baltic Ice Lake. The WGD was deposited at the grounding zone of the glacier by continuous subaqueous basal meltout from floating ice with minor involvement of sediment flows, dumping, and grounding. In texture, the WGD resembles glaciolacustrine clay with increased amounts of gravel and clay fractions. Compared to the basal tills of the area, the WGD contains less gravel (21.5% and 6.8%, respectively) but is rich in silt and clay fractions. Petrographic, mineralogical, and chemical analyses show a similar source for the Palivere basal till and the WGD.

COMPARARISON OF GEOLOGICAL SETTINGS AT POSSIBLE DEEP HARBOUR SITES, NORTH-WESTERN SAAREMAA ISLAND

The investigations carried out on Tagamoisa Peninsula (north-western Saaremaa Island, West Estonian Archipelago) were aimed at finding the deep harbour site with most favourable hydrogeological and geological conditions. Three possible sites were studied: Undva on the eastern coast of Uudepanga Bay, and Suuriku-Kuriku and Vaigu on the western coast of the Tagalaht Bay. The investigations show that in spite of active shore processes between Suuriku and Kuriku cliffs, geological and hydrogeological conditions for establishing the deep harbour are somewhat more favourable in this area than at Undva (dredging volumes as well as the amount of filling material needed for jetties and quays were not considered). At Undva dredging would be more work- consuming and to obtain fresh high quality drinking water is more complicated. Vaigu is less favourable because in the harbour basin area a thick layer of sand occurs on the seafloor.

Cypripedium calceolus L.

A perennial herb with horizontal rhizome (diameter about 6mm) up to 10cm underground. Roots long and fleshy, diameter up to 2mm. Stem 20-60(70) cm, glandular-pubescent with brown basal sheaths; leaves 3-5, elliptical to ovate-oblong, acute to acuminate, sparsely pubescent (oval lanceolate, somewhat pleated, large), (7)11-17(22) cm long, (3)5.58(10) cm wide, veins obvious, bracts leaf-like, exceeding flowers; flowers 1-2(3) large; perianth segments purple-brown; dorsal outer tepal ('sepal') lanceolate, suberect, 3.5-6cm long and 1.5-2.5 cm wide; lateral 'sepals' joined, hanging below labellum 3.5-5.5 cm, free tips up to 5mm; inner tepals ('petals') 4-7 cm long and 0.5-1 cm wide, horizontal, twisted; labellum yellow, shoe-shaped (length 34cm, width 2-3 cm, depth 1.5-2 cm), reflexed, covered with viscous hairs inside, not spurred; staminode petaloid shield-shaped, white with red spots, 1-1.2 cm long, 0.7-0.9 cm wide; ovary elongate, somewhat curved, pubescent (glandular hairs), not twisted, pedicellate. Two fertile anthers, one on each side of style; stigma and staminode forming a flat appendage on the front of the column. Capsule up to 3 cm long and about 0.9 cm in diameter, containing 6000-17 000 seeds; seeds oblong about 1 mm long with a mass of a few micrograms (seed volume 0.02 mm3). From continental Europe, the all-yellow flowered var. fiavum Rion has been recorded (Davies et al. 1984). This exceedingly rare orchid was formerly more widespread in northern England in limestone woodland; it is more plentiful in wooded sites in northern Europe, but everywhere has suffered from collecting.

Bioaccumulation of Toxic Organic Compounds and Their Isomers into the Organism of Seals in West-Estonian Archipelago Biosphere Reserve

The Estonian coastal waters serve as the south-eastern boundary of the regular distribution of the grey (Halichoerus grypus and ringed Phoca hispida) seal in the Baltic Sea. During the annual molt period in May–June (in the Estonian coastal waters), the stock size is estimated to be 1200–1500 grey seal individuals – that is, roughly 25% of the whole Baltic population. If we compare the chlororganic contents of seals in different areas the Baltic Sea, we can see that the northern part of the Gulf of Riga and Vainameri Sea is the reference area of the Baltic Sea.

SEA-LEVEL RISE IMPACT ON COASTAL AREAS OF ESTONIA

Due to long coastline (3,794 km in total) and extensive low-lying coastal areas, global climate change through sea-level rise will strongly affect the territory of Estonia. A number of valuable natural ecosystems (both, marine and terrestrial) containing rare plant communities often rich in species, but also suitable breeding places for birds will be in danger. Most sandy beaches high in recreative value will disappear. However, isostatic land uplift and location of coastal settlements at a distance from the present coastline reduce the rate of risk. Four case study areas characterizing all the shore types of Estonia have been selected for sea-level rise vulnerability and adaptation assessment. Preliminary results and estimates of vulnerability to 1.0 m sea-level rise by 2075 for two case study areas – Hiiumaa, West-Estonian Archipelago and Parnu-Ikla, south-western coast of the mainland – are presented in this paper.

Human impact on the landscape of small islands in the West-Estonian archipelago

Research on the development of the interrelationships between society and environment is crucial for the understanding of contemporary landscapes. The West-Estonian archipelago provides an opportunity for such investigations because of its small size, landscape diversity, and well-defined economic activities.

Human impact on the landscape of small islands in the West-Estonian archipelago

Human impact on the landscape of small islands in the West-Estonian archipelago