SW Finland Research Articles

Temporal and spatial variation in the growth rates of Baltic herring (Clupea harengus membras L.) larvae during summer

It has been suggested that larval survival determines the year-class strength in most marine fish species. During their growth and development, the ability of the larvae to catch prey and avoid predation will increase. However, the factors affecting short-term changes in the growth of Baltic Sea herring have been little studied in the field. We collected Baltic herring (Clupea harengus membras L.) larvae from five different towing areas in the Archipelago Sea (SW Finland) during May and June 1989, right after the main spawning season. Twenty thousand two hundred and ten larvae were analysed and the area-specific growth rate (i.e. increase in standard length) was estimated by tracing the larval cohorts from the length–frequency data. This represents the first Baltic herring study with daily sampling during a long study period. The growth rate was related to environmental factors, such as temperature, number of zooplankters, and wind speed and direction. Large variation in larval growth rate occurred between areas: lowest and highest growth rates were 0.18 and 0.52 mm·day–1. Temperature was an important variable controlling larval-fish growth rate. An increase of one 1°C in average water temperature corresponded to an increase in growth rate of 0.043 mm·day–1. This may have been caused either by a direct temperature effect (changes in metabolic rate) or by the indirect effect of changes in food availability. We also found the densest herring populations in the areas with highest average water temperature. However, temperature and larval growth rate both increased towards the inner archipelago.

Social–ecological feedback links for ecosystem management: a case study of fisheries in the Central Baltic Sea archipelago

In this paper, we address the implications of changing social-ecological feedback links for a sustainable management of coastal regions applying an ecosystem management perspective. This case study focuses on user patterns of fish resources in the Central Baltic Sea archipelago consisting of three sub-regions: Stockholm archipelago, Sweden, the Åland islands and the archipelago of SW Finland. The transition from a region, mainly relying on a mixture of local natural resources towards a region more dominated by the recreational demands of nearby large urban areas, has altered user patterns of fish resources. This transition has partly followed different pathways in the three sub-regions depending on how socio-economic driving forces have been manifested in management actions. Nevertheless, functioning ecosystems are still the basis for the delivery of ecosystem services and a living archipelago system. The significance of capturing and (re)building feedback links into management regarding knowledge on ecosystem services for a sustainable ecosystem management is discussed.

Transitioning from Svecofennian to Transcandinavian Igneous Belt (TIB) magmatism in SE Sweden: Implications from the 1.82 Ga Eksjö tonalite

The Eksjö intrusion forms a major tonalitic body in the Oskarshamn-Jönköping belt (OJB), SE Sweden. This is a NW–SE unit of dominantly intermediate granitoid intrusions, bound by felsic rocks of the Transscandinavian Igneous Belt (TIB). Previous U–Pb data for the Eksjö tonalite (1754±10 Ma) implied that subduction-related magmatism occurred in SE Sweden during a period of time when other data required that such magmatism had already moved further west. New U–Pb zircon dating establishes that the Eksjö tonalite crystallised at 1823±2 Ma and that subduction-related, granitoid magmatism of the OJB occurred in the 1834–1823 Ma interval. Field observations and geochemistry implies fractional crystallisation in either a continental arc or a mature island arc system. Although major portions of the Eksjö intrusion are well preserved, it is cut by NW-trending shear zones attributed to block-related movements that remained active until at least 1.80 Ga. Available constraints for the OJB support models of recurring convergent-margin tectonism along the southwestern margin of Baltica between 1.85–1.82 Ga and, hence, prior to onset of voluminous TIB 1 magmatism (1.81–1.77 Ga). Such a scenario accounts for recurring deformation in SW Finland (1.84–1.80 Ga), broadly coeval deformation in south-central Sweden, and apparent steps in Moho depths between the OJB and the pre-1.85 Ga margin of Baltica.

1.90-1.88 Ga arc and back-arc basin in the Orijärvi area, SW Finland

1.90-1.88 Ga arc and back-arc basin in the Orijärvi area, SW Finland

Effect of industrial pollution on the distribution of 137Cs in soil and the soil-to-plant transfer in a pine forest in SW Finland

The objective of this study was to evaluate the effect of industrial pollution on the distribution of radiocaesium in soil and on its transfer from soil to plants. The study was started in September 2000 in four Scots pine stands located at distances of 0.5, 2, 4 and 8 km along a transect running SE from the Cu–Ni smelter at Harjavalta in SW Finland. Annual emissions from the smelter in 1990 were 80 t of Cu, 31 t of Ni and 9000 t of SO 2, and in 1999 these were 5.9, 0.8 and 3400 t, respectively. At each site, soil profiles were sampled with a corer, and samples were separated into litter (L), organic soil layer (O) and mineral soil layers (B, E). Mushrooms, lichens ( Cladina spp. and Cetraria islandica), lingonberry ( Vaccinium vitis-idaea) and crowberry ( Empetrum nigrum) plants were collected at each site, except at a distance of 0.5 km, where only mushrooms were available. In the organic soil layer, 137Cs activity decreased from 8000 Bq/m 2 at a distance of 8 km from the smelter to 1500 Bq/m 2 at a distance of 0.5 km; in litter, 137Cs concentration increased from 6300 Bq/m 2 at 8 km to 14 000 Bq/m 2 at 0.5 km. 137Cs activity concentration decreased significantly in plants, mushrooms and lichens as the pollution load increased. In lichens, 137Cs activity decreased from 910 Bq/kg at 8 km to 170 Bq/kg at 2 km, while in lingonberry it decreased from 1470 to 20 Bq/kg and in crowberry from 310 to 20 Bq/kg. Aggregated transfer factors for 137Cs decreased in a similar way in lingonberry from 7.6×10 −2 m 2/kg at 8 km to 7.7×10 −4 m 2/kg at 2 km and in crowberry from 1.6×10 −2 to 7.9×10 −4 m 2/kg.

Long-term Changes of a Brackish-water Eelgrass (Zostera marina L.) Community Indicate Effects of Coastal Eutrophication

The distribution and importance of eelgrass (Zostera marina L.) meadows for associated faunal communities in the coastal waters of the Baltic Sea are still poorly known. In these low-saline (5–7), shallow coastal areasZ. marina grows at its limit of distribution, forming mostly patchy meadows. In June 1993, a seagrass locality (Tvärminne, SW Finland) thoroughly studied in 1968–71 was revisited in order to detect possible long-term changes in both vegetation structure (distribution, density, biomass) and benthic fauna (species composition, abundance, biomass, distribution and diversity patterns). The same sampling design as in the 1970s was used in both sparse (<20 shootsm−2) and dense (>150 shootsm−2) Z. marina. In addition, the feeding-efficiency of adult flounder (Platichtys flesus L.) on infauna was measured by counting feeding pits in vegetated and bare sand. The analysis shows that the shoot density had increased in sparse Z. marina, while dense Z. marina patches showed similar biomass values (20gAFDWm−2) as in the 1970s. In contrast to the vegetation, where little apparent change could be recorded, the total abundance and biomass of zoobenthos has increased significantly between 1968–71 and 1993 in the dense Z. marina patches. These changes are mainly attributed to significant increases of the bivalve Macoma balthica L., mudsnails Hydrobia spp. and oligochaetes. In sparseZ. marina diversity in terms of number of taxa exhibited minor changes over time, whereas in dense Z. marina patches the mean number of taxa has increased from 16 to 20. The vegetation cover was sufficient to reduce significantly the predation effects of flounder on seagrass infauna. This study represents a rare example of long-term persistence of seagrass communities in an area where the negative effects of nutrient enrichment are evident. The faunal changes in the Z. marina community indicate increased food availability, which is associated with positive effects of coastal eutrophication.

The role of aquaculture in the eutrophication process of the Archipelago Sea, SW Finland

The role of aquaculture in the eutrophication process of the Archipelago Sea, SW Finland

The merging of human activity and natural change: temporal and spatial scales of ecological change in the Kokemäenjoki river delta, SW Finland

Human cultures have had important influences and major impacts on nature and its natural state along rivers. Riversides have been settled for thousands of years and human interpenetration of nature along rivers is multilevel both in time and space. In this descriptive article, we discuss how human activities have changed in the Kokemäenjoki river delta in the northern Baltic, SW Finland and how these altered activities have influenced the formation structure and ecological dynamics of the delta. Vegetational changes during the last 100 years are used as a proxy of environmental change. We study the complicated human culture–nature interpenetration at different temporal and spatial scales. The Kokemäenjoki river delta was formed during deglaciation after the last Ice Age. Because of rapid land uplift (about 0.7 cm per year) and the fluvial load transported by the river, the delta is moving towards the sea at a quick pace. Livestock farming has kept meadows open and shaped their vegetation for thousands of years, and field clearing has had significant impacts on the delta since the 16th century. Further, disturbances such as damming or the establishment of factories along rivers have also shaped the Kokemäenjoki river delta for centuries, changing the river’s role in transporting organisms and debris. Remarkably, structural changes associated with agricultural land use in the late 19th and in the middle of 20th century and damming for hydropower purposes in the 1920s and 1940s, seem to have had only a minor influence regarding the vegetation dynamics in this wetland habitat. It seems that the delta can retain its conservation value in the future. Land uplift ensures that new wetland habitats are constantly created. Since the delta has experienced human impact from the very beginning of its formation, it appears that the occurring vegetation has adapted to those influences and the interrelation of human presence.

Variable responses of waterfowl breeding populations to long‐term removal of introduced American mink

It is suspected that feral American mink, an introduced predator in Europe, have seriously affected local densities of birds breeding in archipelagos and coastal areas. We studied the effects of mink removal on breeding densities of waterfowl in two manipulation and two control areas in the outer archipelago of SW Finland, Baltic Sea. The study was conducted in two phases: during 1992–2001 a total of 98 mink was removed from 60 islands and islets (total area 72 km2) whereas on 37 islands and islets (35 km2) mink was not removed. Additional mink removal and control areas were established during 1998–2001 to replicate the experiment. The breeding densities of the shelduck, tufted duck and the velvet scoter increased as a response to mink removal, while in the control areas their populations remained unchanged. The breeding densities of mallards increased during the first 7 yr of mink removal, but a steep decrease in the last study year resulted in a statistically non‐significant overall increase. The species with low breeding densities (the gadwall, northern shoveler, pintail and the red‐breasted merganser) increased as well. In contrast, the populations of large waterfowl species, the mute swan, greylag goose, common eider and the goosander, did not show obvious increases in breeding densities after mink removal. We conclude that feral mink may locally limit the breeding densities of some smaller waterfowl species and thus reduce the diversity of the waterfowl community in the outer archipelago.

Early Holocene regressive spit-platform and nearshore sedimentation on a glaciofluvial complex during the Yoldia Sea and the Ancylus Lake phases of the Baltic Basin, SW Finland

The depositional history of the Virttaankangas plain, a fan-like enlargement of the large Säkylänharju glaciofluvial ridge in SW Finland, is examined. The Säkylänharju ridge has been interpreted as having formed as an interlobate esker, and the morphology of the Virttaankangas plain as representing predominantly subaqueous glaciofluvial to glaciolacustrine deposition. This investigation uses new sedimentologic outcrop data, with extensive subsurface drilling, GPR surveys, seismic soundings, and gravimetric measurement data provided by groundwater investigations, to describe the stratigraphy, morphology and depositional history of the plain. In contrast to earlier interpretations, the results emphasise the role of littoral processes in the origin of the Virttaankangas plain. The plain is interpreted as having originated during the development of a progradational sequence of spit-platform and superimposed nearshore sediments deposited during the glacio-isostatic forced regression of the Yoldia Sea and Ancylus Lake phases of the Baltic Basin (9900–9000 14C BP). Documented depositional history supports an interval of retarded regression at the beginning of the Ancylus Lake phase I (9500–9200 14C BP) in the Säkylänharju area.

Horizontal distribution of vendace larvae in Lake Pyhäjärvi (SW Finland): effect of wind-induced currents

(2002). Horizontal distribution of vendace larvae in Lake Pyhajarvi (SW Finland): effect of wind-induced currents. SIL Proceedings, 1922-2010: Vol. 28, No. 2, pp. 726-730.

Contents of Cu, Ni and Zn in smelter-polluted soil–plant systems

Intact soil profiles including litter layer and ground vegetation were taken at five distances (0.5, 2, 4, 8 and 60 km) from a Cu–Ni smelter in Harjavalta, SW Finland. The soil cores were placed in 10 l pots and a 4 year-old, bare-rooted pine seedling ( Pinus sylvestris L.) was planted in each. The containers were incubated for17 months in controlled greenhouse conditions. At the end of the experiment the seedlings were harvested and soil samples were taken from each pot and analysed for Cu, Ni and Zn. The absence of atmospheric metal deposition had no reducing effect on the exchangeable heavy-metal contents of the soil pots. Metal uptake by the plant seedlings during the experiment had a negligible effect on the exchangeable heavy-metal content of the soil cores from the most polluted sites. The increase in both the exchangeable and the total humus Cu, Ni and Zn concentrations in the 0.5 km soil cores during the experiment suggested that there were pools of accumulated metals in the thick litter layer on top of the humus.

Systematic Assessment of Maps as Source Information in Landscape-change Research

A methodology is proposed for systematic map assessment to contribute to landscape-change research. Two major topic areas are dealt with, namely: content, quality and usefulness of landscape information on different maps; and methods used in the spatial conversion of maps into digital systems (e.g. geographical information systems). The major focus is on information about physical landscape characteristics (e.g. land cover) and land uses. The approach was tested using a sequence of nine large- and medium-scale basic maps of the island of Ruissalo in SW Finland from between 1690 and 1998. Fundamental differences were found in the thematic consistency of landscape information, mainly related to the scale, purpose and generalization of landscape information on different maps. Spatial matching was tested for a set of three old maps using four image rectification functions. The results showed that spatial matching of old maps is difficult, and success in rectification is influenced by many factors. Evaluation and selective transformation of landscape information from maps and the use of supportive information from other sources can assist in landscape-change analysis based on map sequences.

Low-Temperature Mobility of Rare Earth Elements (REE), U, and Th at the Olkiluoto Site, SW Finland

ABSTRACTThis work is a first effort to link hydrogeological measurements to structural modeling by using the mobility of rare earth element (REE), U, and Th at the Olkiluoto site. REE, U and Th concentrations were measured in 5 groundwater samples located at depths varying between 132 and 446 m in three drill holes at the Olkiluoto site. The pH of groundwater samples are all about 8 and Eh(Pt) varies from –50 to –200 mV. Also the REE, U and Th concentrations of rock samples collected from core sections in the vicinity of water conducting fractures were measured to examine rock-water interactions in the system. The rock samples were cut into slices parallel to the fracture surface. An aliquot of each slice was leached with 0.5 N acid nitric to examine the readily leachable REE, U and Th fraction of each slice. The groundwater samples were normalized to each of the analyzed rock samples. Although the REE concentrations of the water samples are overall depleted in all the REEs compared to the rocks and leachates, and whole REE spectra could not be obtained for any of the groundwater samples, enrichment in the intermediate REE (IREE) with respect to the light REE (LREE) is observed.An increasing loss of REE and U from rock matrix towards fracture surface is observed in samples at depths of 141, 159, and 466 m. Loss of U is also observed in a sample at about 246 m depth. Loss of Th is only observed at the depths of 159 and 246 m. The loss of U (readily leachable fraction) in the rock samples was found to be linked to the hydraulic conductivity in the related water-conducting fractures.

The effect of apical dominance on the branching architecture of Arctostaphylos uva-ursi in four contrasting environments

We studied horizontal spreading and axillary bud activation of colonizing branches of a clonal dwarf shrub, Arctostaphylos uva-ursi, in SW Finland in four habitats with varying pollution, nutrient, light and competition levels. A. uva-ursi showed high plasticity in the proportion of released buds, which changed according to the stress and resource level of the habitats. Apical dominance of lateral branching was the strongest in the resource-poor habitats (low soil nutrient or low light levels). However, when the apex of the parent shoot was terminated (due to mortality of an apical bud or the formation of an inflorescence) the disruption of apical dominance caused intensive branching in the poor habitats. Apical dominance of the dominant shoots was much weaker in the resource-rich habitats. When nutrient availability and light level were relatively high, branching frequency was high in both intact (expanded) and terminated parent shoots. Shoot mortality and the proportion of terminated shoot apices was the highest in the polluted habitat, as a result of soil toxicity. This caused intensive branching in all shoot hierarchies, which may enhance the plant’s survival in heavy metal polluted soil. We conclude that plastic branching enables this species to recover after damage, or to respond to changed resource levels according to the ‘reserve meristem hypothesis’. The branching response to different environmental conditions was simulated by means of an L-system architectural model based on the demographic and morphological parameters measured in each habitat.

Ultrastructural element localization by EDXS in Empetrum nigrum

Empetrum nigrum L. is one of the few species growing on highly polluted areas in the northern boreal forests and it accumulates considerable amounts of heavy metals especially in its older stems. Previous-year stems of Empetrum nigrum were collected from two different sites located at distances of 0.5 km (highly contaminated) and 8 km (low contaminated) from a Cu–Ni smelter at Harjavalta, SW Finland. The element (Al, As, Cu, Fe, Mn, Zn, Ca, K, P, S, Mg, Na) localization was performed by energy-dispersive X-ray spectroscopy (EDXS) after cryofixation, freeze-drying and pressure infiltration of the material. The results showed higher levels of Cu, As and Fe in cell compartments of E. nigrum close to the smelter than at further distance. The Al and Zn levels, in contrast, showed no clear differences between the sites. Cu was distributed homogeneously in the tissue and occurred in vacuoles, cytoplasm, cell walls as well as in lumens of the vascular tissue. The higher amounts of As were localized in the outer regions of the stem cross-section and the amounts were higher in the primary cell walls of living (ray cells, phloem) than dead cells (xylem, sclereids). Ray cells, phloem and sclereids had elevated Fe amounts compared to the other tissues in the contaminated stem samples but owing to the high variation between the replicates, no significant differences were found. Based on the rather homogeneous localization of Cu, As and Fe in the living tissue and increased levels of Cu, As and Fe in vacuoles, cell walls and cytoplasm near the smelter, it seems that more than one specific mechanism contribute to the heavy metal tolerance of E. nigrum. Macronutrients did not show clear differences between the two distances or connection to heavy metal localization. Neither the role of complexing agents in heavy metal tolerance in the cytoplasm or vacuoles could be shown by this study. Because of the more frequent localization of electron dense phenolic material in the polluted samples, it might also have a function in the heavy metal tolerance of E. nigrum.

Effects of compensatory fertilization on pollution-induced stress in scots pine

We tested the hypothesis that compensatory fertilization of Scots pine (Pinus sylvestris L.) stands polluted by theHarjavalta copper-nickel smelter in SW Finland alleviates thestress imposed by metal-contaminated soils. The treatments inthe experiment consisted of control, liming, slow-release mineral mixture and stand-specific fertilization, which comprised at least methylene urea and ammonium nitrate. Stresswas assessed by needle fluctuating asymmetry (FA) which increases with an increase in developmental instability. Sevenyears after the treatments, we found pronounced variation inboth FA and needle length among study sites (0.5, 2, 4 and 8 km from the smelter) and among treatments. FA increased and needlelength decreased with proximity to the pollution source. Variation in FA was independent of tree size (used as index ofgrowth rate in even-age stand); the effects of the treatmentson needle length, on the other hand, were expressed only inmedium-sized and large trees. Liming best alleviated pollutionstress, while the application of a slow-release mineral mixtureincreased FA by 30%. In pollution-stressed stands FA correlatedpositively with constitutive resin flow but was independent of volume growth. Our findings suggest that physiological stress (indicated by increase in developmental instability) and tree growth or stand productivity are not directly linked to one another, and that some increase in productivity can be achievedwithout the alleviation of pollution-induced stress.

Pollen allergen reports help to understand preseason symptoms

Early symptoms of pollen allergies arefrequently reported before pollination periodof allergenic plant starts. At northernlatitudes the main concern is Betulaceae-trees(alders, hazel, birches). Pollen allergeninformation, based on the analysis of actualairborne allergen concentrations, beside thetraditional pollen reports, based on pollencounts, has been given in SW Finland since1998. 1–2 weeks before the onset of floweringpollen allergens are detected airborne inquantities high enough to provoke symptoms.Information is given on radio and in localnewspapers. During the first season of the newservice (1998) we carried out a questionnairestudy. The results showed that new informationservice, though not as frequently used as wehad hoped for, was useful to allergic personsfor starting their medication in time. Theyalso received explanation for their earlierinexplicable symptoms. We recommend bothinformation services to be run concurrently togive the best information to the public.

VSP in crystalline rocks—from downhole velocity profiling to 3-D fracture mapping

Abstract VSP surveys have been carried out at several potential nuclear waste disposal sites in Finland since the mid 1980s. To date, more than 200 three-component profiles have been measured. The main purpose of the surveys was to detect fracture zones in the crystalline bedrock and to determine their positions. Most seismic events could be linked to zones of increased fracturing observed in the borehole logs. The more pronounced seismic reflectors could be correlated with hydro-geologically significant zones, which have been the main targets in the investigations. Processing and interpretation methods have been developed specifically for VSP surveys in crystalline rocks: • Weak reflections from thin fracture zones are enhanced by multi-channel filtering techniques based on the Radon transform. • The position and orientation of the fracture zones are determined by polarisation analysis and by combining data from several shot points. • The compilation of the results from several boreholes gives a comprehensive image of the fracture zones at the scale of the whole site. The discussion of the methodology is based on examples from the Olkiluoto site, in SW Finland.

High summer concentrations of mercury in big perch (Perca fluviatilis L) from the Tvärminne archipelago (SW Finland) and Nåtö (Aland Islands) Baltic sea.

During high summer seasons in 1994-1999 84 big (20-42 cm total length) female perch (Perca fluviatilis L) were sampled from the waters around Tvärminne Zoological Station on the Hanko-Hangö peninsula on the SW coast of Finland for mercury analysis. Additional sampling of 13 big female perch during the same season were carried out from the waters of Nåtö Biological Station on the Aland Islands in 1997-1998. High summer is the most important season for perch fishing and consumption not only for private families during leisure time but also for professional fishery including trade and export, processing and preparations for restaurants. Fillets of big specimen of perch, s.c. "fillet perch" or "sea perch" from outer coastal waters were chosen for the study to find out the levels of mercury concentration in these desirable fish. The mean concentration of mercury in the dorsal muscle tissue (fillet) of big female "sea perch" from the coastal waters of Tvärminne Zoological Station was calculated to 0.22 (SD 0.08), range 0.08-0.43 mg/kg, f wt and for big female perch from the waters of Nåtö Biological Station to 0.18 (SD 0.07), range 0.07-0.30 mg/kg, f wt respectively. The results show a considerably lower mercury level in big "fillet perch" caught from the outer coastal waters in both Finland (and Estonia) compared with the levels recorded of big "fillet perch" from fresh water lakes and reservoirs. Thus, the common expression "sea perch" may also be used in the form "Baltic sea perch" meaning big healthy perch with low concentrations of mercury and caught from the outer coastal waters in S and SW Finland (and W Estonia) when marketing perch for human consumption.