Nature in the MSU WSBS vicinity
Е.Ю. Замесова, Е. Д. Краснова, Ф.А. Романенко, А. В. Чесунов
The Nikolai Pertsov White Sea Biological Station is situated in the northern part of the Republic of Karelia near the Arctic circle (66º33'N and 33º06'E) (Fig. 1). The biological station settlement is situated on the northern shore of the Kindo Peninsula, which is a small area of about nine square kilometers of the projecting coastline of the Karelian White Sea coast. To the north, it faces the ostrov Velikiy island, which is a part of the Kandalaksha State Nature Reserve, from which it is separated by the Velikaya Salma strait, from 0.7 km to 2.4 km wide.
The territory of the MSU WSBS neighborhoods, covered by biodiversity studies and by the lists of this Catalogue, includes the eastern part of the peninsula, bounded on the west by two marine bays, jutting into the mainland towards each other (the Kislaya inlet from the south and the Ermolinskaya bay from the north), and by the line of bogs, marshes, the Verkhnee Ershovskoe Lake, and the Nizhnee Ershovskoe Lake.
The sea water area, covered by the biodiversity study, is adjacent to the coast of the Kindo peninsula; its width does not exceed 2.5 km. It covers part of the Rugozerskaya inlet, with the western boundary running along the alignment of the Ermolinskaya Bay (the southern point) - the Gorodetskiy Porog rapids (the northern point); the Velikaya Salma strait across its whole width, with the eastern boundary of a conventional line that crosses it from north to south and passes through the Krestovye islands. On the south side of the Kindo peninsula, the water area includes the coastal zone 2.5 km wide, tapering to the tip of the Zelenyy Mys cape, and the entire Kislaya bay. At a greater distance from the biological station, there are a few more study areas of the field practices and WSBS research - the Chernaya Reka River estuary to the west and the Nilma river estuary to the south, small islands of Kastyan, Velichaikha, and Kokoikha, to the east.
The north coast of Karelia is characterized by moderately cold climate with extended spring and autumn. The average annual temperature is about 0,5 ° C; the coldest month of the year is February, with average monthly temperatures ranging from -10° to -12°C; and the warmest month of the year is July, with average monthly temperature of +13,2°C. The length of frost-free period is 120 days, at not very high temperatures. The vegetation period (i.e., the number of days per year, with temperatures equal to or above +5°C) is 127 days, the daytime temperature sum is 1290°C. The active vegetation period (i.e. the number of days per year with a temperature equal to or above +10°C) is 70 days, the daytime temperature sum is 896°C. The number of days with snow covers is more than 190, the average snow depth is 40-60 cm. The annual rainfall is 390-420 mm, including 290-300 mm in the the warm period. Evaporation is insignificant, its average value is 150 mm/year (Romanov, 1961).
Geomorphology of the region
Most part of the Kindo peninsula is formed by the gneiss-amphibolite dome of the Rugozerskaya hill, with maximum height of 103 m above sea level, which has been experiencing postglacial uplift at a rate of 3-4 mm per year. The most common rocks in this area are Archean gneiss dated 2.7-2.8 billion years old. The upper part of the Rugozerskaya hill appears as ridges with rounded tops ("whale backs")up to 100 m wide, separated by marshy hollows about 15-25 m deep. On the surface of most ridges, there are no loose sediments; and at the bottoms and side of the hollows, the sediment depth reaches up to several meters. The hill slopes are covered by thin, up to 1-2 m, layer of ice and water-ice deposits. The relief of the slopes traces tectonic faults in the form of steep rocky ledges about 15-40 m high (in the Biofiltry Bay), terrace-like steps and cracks up to 2-3 m deep. Several small basins, up to 0.5 km in diameter, situated in the central and eastern parts of the massif of the Rugozerskaya hill, are taken by peat lakes, one of which is used as a source of potable water and undergoes large seasonal level changes, due to increased water consumption in summer. The Rugozerskaya hill is fringed by marine terraces, reaching maximum width in the west, near the Ershovsky lakes. Open-casts of the terraces reveals graded sand series, underlain by boulder and pebble beds, and sandy clays. In one of these cuts, located at a height of 20 m relative to the modern sea level, at a depth of 2.6 m from the surface, in clays, there were found numerous shells of bivalves Tridonta borealis, Elliptica elliptica, Hiatella arctica, brachiopods Hemithyris psittacea and others. Their age, determined by radiocarbon dating, is 7160 ± 90 years (Shevchenko, 1999), which allows to date formation of this surface to the maximum of the Tapes transgression in the middle Holocene. The modern marine terrace up to 2 m high and up to 100 m wide, mildly sloping down to the intertidal zone, is composed of mainly sands and gravels, often silty, with lots of boulders. As a result of tectonic uplift of the coast, this surface has recently gone out of the level of flood tide, and continues to experience impacts from wave and ice during storms and surges.
The soil cover of the Kindo peninsula is very colorful and complex, due to the relief mosaic, as well as to lithological and hydrological conditions. The area is dominated by podzolic soils. The most developed and mature podzols are formed under coniferous shrub-green forests on well drained deep sands of marine terrace II. Marsh soils are also ubiquitous, from the hollows in top ridges, to the coasts, and estuaries of streams. In the coastal zone, under coastal meadows, marsh soils with signs of soil salinity are formed. On the rocks, in places where loose products of weathering of the bedrock accumulate, under the cover of mosses and lichens primitive shallow soils are formed. All types of soil have a shortened genetic profile and peaty upper humus horizon (Evdokimova, 1972).
Terrestrial plant communities
Geobotanical zoning classifies the area covered by the Catalogue, as part of the Kola-Karelian subprovince of the Nordic taiga province, which is divided into several districts. Together with all the Louhi Administrative Region of the Republic of Karelia, it is a part of the Pjaozerskiy-Topozerskiy district, which is a lakeside plateau, slightly elevated in the west and sloping gently down to the east, devoided of high hills, with thinned and clarified boreal forest. Pine is the main tree species in the area. Pine forests occupy 80% of the area (Ramenskaya, 1983).
Pine forests form natural ecological patterns according to the moisture levels in soils: in the most humid places - on the peat marsh ridges, there are individual dwarf pines of curved shapes; less flooded, but still swampy flat areas or gentle slopes are occupied by pine forest with wild rosemary and ground covered by sphagnum moss; on better-drained gently sloping areas, there are pine forests with blueberry, and green mosses in the bottom level; on the upper parts of slopes with rocky or sandy soils, with the lack of moisture, there are pine forests with cranberry. Tops of the "whale backs" are usually occupied with sparse pine forests with ground covered with lichens. Spruce forests are rare in the Biological Station vicinity; forests with spruce can be found on the banks of lakes, near streams, around marshes, and along the sea coast (Vital, 1999).
The age of most forests is less than 70 years, due to frequent forest fires, hurricanes, and most important, mass forest cutting carried out in 20-30s. On paces of cuttings and old fires, there have appeared birch forests with an addition of aspen, pine, fir, with ground covers composed by different herbs, shrubs and green moss, or by sedge and horsetail. Along the sea coast, there are primary birch forests with crooked trees and crowberry cover. (Vital, 1999).
Bogs taking 6% of the Kindo Peninsula, are situated in gullies, lacustrine depressions, flat terraces and in lower slopes of ridges. The most common wetland type is aapa bog, i.e. vast treeless ridge pattern marshes, typical for the northern taiga with similar plant communities. Peat ridges are covered with sphagnum moss, and high places with plants typical for raised bogs.
The grassland area of the peninsula is very low. Along the sea coast, there is a narrow strip of coastal meadows or wetlands of varying salinity: large-grained grasses, small-grained grasses, and sedge-rush. On the northern coasts facing the open sea, instead of coastal meadows there develops a particular type of tundra-like vegetation - thick hedges of crowberry shrubs (Empetrum hermaphroditum), mixed with other low-growing shrubs: Alpine Bearberry (Arctostaphylos alpina), cranbery, and bearberry (Breslina, 1980). Under the coastal crowberry shrubs, a specific type of soil is formed: a so-called "dry peat". Dry meadows are found in small fragments on the shores of the Ershovskiy lakes, where the dominating grass types are hair grass and motley grass. On under ridge plains, there are areas of lowland reed or mixed reed and hair grass meadows, invaded by moss. (Vekhov, Bogdanova, 1971).
The Karelian coast is composed mainly by crystalline rocks of the Baltic shield. Because of the extremely indented coastline, it belongs to the fiord/skerry coastal landscape. Numerous bays with low shores resemble fjords, highly common along the coasts of Sweden and Finland. Along the entire coastline, there are numerous large and small islands, small rocky islets called "ludy", and the White Sea analogs of skers called "korgi" - rocky banks, bare at low tide. (Kaplin et al ., 1991). Finer scalloped irregularity of the littoral is imposed upon the fiord/skerry coastal landscape: concaves of the coastline stretching from a few dozen to several hundred meters, bounded by rocky headlands or outputs of coarsely fragmented rocks, embed lower order scallops, formed by different-scale circulations of tidal wetlands and wave flows.
The Kandalaksha Bay shores, including the Kindo Peninsula, experience rapid tectonic uplift, which began after the last glaciation and has been continuing nowadays. The average rate of uplift of the described area is 3-4 mm per year, which makes it possible to observe coast increasing and changes in its outline during a researcher life: islands attach to the mainland, lagoons close and dry, uplifting of underwater thresholds leads to emergence of land bridges and turning of sea water bays into desalinated lakes.
In the vicinity of the MSU White Sea Biological Station, as elsewhere in the Kandalaksha Bay, tides are regular, semidiurnal, with amplitudes up to 2.5-3.5 m. Because of the high irregularity of the coastal line, tidal current velocities range from 0.2 - 0.5 m/s, reaching 3 m/s in narrow straits and sea rapids. Asymmetry is one of the features of the tidal wave in the Kandalaksha Bay: the flood tide lasts 1,5-2,2 hours less, compared to the ebb tide.
Hydrological features of the waters
Most of the waters surrounding the Kindo peninsula are relatively shallow, with the exception of the Velikaya Salma, which has along its bottom a trench with the depth of 25 meters in front of the biological station settlement, increasing to 50 m to the east. Strong tidal currents in the Velikaya Salma ensure uniformity of the water parameters along its entire thickness, whereas in the eastern deep part, there forms a three layer stratification, typical for the White Sea.
Water salinity levels of the waters around the Kindo peninsula are low: -16 to 28 ‰.; the minimum salinity level is during the spring melting of ice; the maximum salinity level is in winter. In the estuary of the Chernorechenskaya bay, taking stock of the Chernaya river, the surface salinity decreases to 2-4 ‰. Sea surface temperature undergoes significant seasonal variations, while at greater depths it is low and more constant: down to -1,5°C in local depressions (pits) on the seaward outlet of Salma. Near the surface, in summer the water warms up to +15-16ºC, and at the tops of shallow bays, even up to +20ºC and above. The warmest month is July, but already by August the temperature drops to +10ºC and continues to decrease. In November, the water temperature throughout its depth drops to -1,4ºC, and only in April, rises to zero. Freezing-over begins in October, when the air temperature drops below zero, permanent ice cover is formed in December and lasts until March. Strong currents in the Velikaya Salma strait, in the Eremeevskiy rapid, in the Krivoi rapid and several other rapids, prevent them from freezing; there always remain clearings, increasing in size during thaws and contracting during severe frosts.In April, the ice cover begins to crack, separate ice floes break away from the fast shore ice, tidal currents carry them in the clearings, where they gradually crumble and melt. In the bays, deeply protruding into the mainland, the Kislaya inlet and the Ermolinskaya bay, the ice cover lasts longer and melts on the spot. Complete cleaning of waters from ice occurs in the first half of May.
Width and type of the soils, making up the littoral - the part of the coastal zone, which is submerged at high tide and dries of at low tide - depends on the nature of underlying bedrocks, wind impacts, strength and direction of coastal currents, and on the runoff presence. In the MSU WSBS area, the width of the intertidal littoral zone varies from several meters to two or three hundred of meters. At sites exposed to strong surf, littoral is usually narrow, only a few meters in width. It can be rocky, in the form of rounded contours of "mutton foreheads", cobble, gravel, or sand and gravel. Most of the coastline in the biological station vicinity is not as exposed to wave impact, hence the littoral there is wider, up to several tens of meters. On such areas between the high tide quadrature and the low tide quadrature levels, there is usually a zone of soft soils, usually siltstone (aleurite) and sand, with admixtures of coarsely fragmented stuff; at the lower boundary of the drying there usually spreads a boulder zone, formed by the interaction of landfast ice and tidal fluctuations; and seaward of it there is tidal beach or hillside, which goes under the syzygial low tide level. In recess parts of the bays, coastal line complexes are different: a significant part of the coastal zone is occupied by marshes, gradually turning into a dried flat-aleurite clay zone, from a few tens to few hundreds of meters wide.
In the uppermost part of the littoral with soft soils, one can find communities of vascular plants, or halophytes: sea aster (Aster tripolium), sea plantain (Plantago maritima), sea arrowgrass (Triglochin maritima), and sea milkwort (Glaux maritima). At the very top of the belt of halophytes and on the supralittoral area, there often stretches a belt of rushes (Juncus atrofuscus). Most part of the intertidal zone sand is usually free of vegetation; on silt areas there are thickets of the sea grass Zostera (Zostera marina), which in former times exceeded by its biomass all other coastal macrophytes. Mass mortality of the plant, which occurred in the White Sea in the mid 60-ies of XX century, led to almost complete disappearance of this plant thickets. The registered a revival of Zostera is very slow. Although the plants can already be found along the whole coast, they are mostly small and young. Former thick "forests" of plants of two meters high, which existed in particular in the Ermolinskaya and in Chernorechenskaya bays, have not yet recovered. The lower part of the intertidal zone in the MSU WSBS vicinity, is almost everywhere covered with dense thickets of fucus, attached to boulders. Below the maximum low tide level, in the upper sublittoral zone, there extend underwater "forest" of kelp. At depths ranging from 10 to 15 m, red algae reign.
The marine biota of the MSU WSBS vicinity is quite rich and in general might not be very different from the biota of the White Sea as a whole. The littoral fauna is not as diverse as the sublittoral one, but it is quantitatively abundant, and its inhabitants are perfectly adapted to the experience of low tides. They are moving crustaceans (gammarids), gastropods (littorina, or winklets), burrowing polychaetes, bivalves (mya and macoma), attached barnacles (balanus), mussels, anemones and many others. Most species living in the littoral zone refers to the so-called boreal community; the main part of their habitat is located to the south, and the White Sea is an extreme north-eastern limit of their habitat. Below the zero depth (the lowest low tide level) there is a sublittoral zone. Communities of plants and animals are distributed in belt zones, which are determined by light and temperature conditions, and within the belts, by soil type and trophic conditions. Here co-exist animals from the boreal and borealarctic communities, whereas in the deepest places, where near-zero or even negative water temperatures are maintained throughout the year, there is a community of a small amount of typical Arctic species.
In zooplankton of the area covered by the Catalogue, two faunal communities interchange during the year. In the spring, summer and autumn, there dominates the shallow planktonic complex of planktonic larvae of benthic invertebrates; adult forms are mostly boreal, relatively heat-loving animals, whose numbers increase during the warmer months, and in cold times, many species disappear. Several species of planktonic crustaceans, such as Centropages hamatus, Temora longicornis and Acartia bifilosa, hibernate only as resting eggs, which had settled to the bottom. In winter to replace the boreal community, few species of the Arctic community come from deep central parts of the White Sea, in particular, copepods Metridia longa and Calanus glacialis. Diverse of bottom soils: from rocky, boulder, and pebble to sand, silt and coquina beds, rich growths of benthic macrophytes, mosaic of small and deep areas, good aeration of the bottom at all depths - all this taken together creates favourable conditions for habitats of many species with different environmental requirements, which enables the high biodiversity in the MSU WSBS vicinity.