Swedish East Coast Research Articles

An evaluation of the Late Weichselian Swedish varve chronology based on cross-correlation analysis

The Swedish varve chronology is based on the correlation of overlapping varve-thickness diagrams. The traditional visual match between single diagrams has been based on, e.g., significant yearly thickness variations or specific marker varves, but attempts to verify these correlations by statistical methods are rare. To test if these visual correlations can be regarded as correct, i.e. statistically significant, we applied cross-correlation measures to overlapping varve diagrams from two local varve chronologies established in southeastern Sweden. Out of a total of 363 analysed connections, only 78 were found to fulfill the statistical requirements for a perfect match. In 96 cases the statistical measures suggested alternative placements to the published links. However, we found that for 179 correlations the published varve-diagram connections are statistically not valid and that in 11 cases the overlap between diagrams is too short to allow for valid cross-correlation analysis. This large number of uncertain varve-diagram correlations in both local chronologies shows that the detailed timing of the ice recession along the south Swedish east coast can only be reconstructed through complementary varve chronological investigations. Our investigations emphasize the need to corroborate visual varve-diagram correlations through statistical analyses, before the Swedish varve chronology can be regarded as a valid, high-precision time scale.

The impact of age, lactation and dietary habits on PCB in plasma in Swedish women

The mean concentration of the chlorinated biphenyl 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB-153) in plasma from 192 fishermen's wives from the Swedish east coast was on a fresh weight basis 960 (range 80–4300) pg/g and lipid adjusted 160 (range 20–780) ng/g lipid. The concentration of CB-153 in plasma was significantly influenced by age, total lactation time and place of living during childhood and adolescence (fishing village vs. other place). The residential variable probably reflects early life consumption of fish from the Baltic Sea (at the Swedish east coast) contaminated with persistent organochlorine compounds.

Benefits from fish stocking—experiences from stocking young-of-the-year pikeperch, Stizostedion lucioperca L. to a bay in the Baltic Sea

To evaluate the economic viability of fish stocking, it must be possible to identify the stocked fish in the wild. To find a suitable marking method, young-of-the-year (YOY, length 8–10 cm) pikeperch ( Stizostedion lucioperca) were tagged in different ways and stocked in ponds. Over a 185-day winter period, there was no significant size-dependent mortality, but clear differences in mortality among fish marked in different ways. Fingerling and streamer-tagged fish had significantly lower survivorship than fin-clipped (left pelvic fin) and colour-marked (Alcian Blue) fish, which were not different from controls. Seventeen thousand, seven hundred sixty-six YOY pikeperch were fin-clipped and released in a large bay of the Baltic Sea on the Swedish east coast in October 1991. The following year, 23% of all 1-yr-old fish caught came from this stocking. The proportion of marked fish was considerably higher close to the release site, showing that they were relatively stationary during their first year of life. A simple economic analysis demonstrates that pikeperch stocking can be very profitable. Based on the capital invested in the stocked YOY, the economic yield corresponds to an annual interest rate of 43%.

Population size, migration routes and breeding origin of Purple Sandpipers Calidris maritima wintering in Sweden

We analysed the occurrence and breeding origin of Purple Sandpipers Calidris maritima wintering in Sweden, using data from long-term surveys along the Swedish west coast, sightings in other parts of the country, and ringing data from Sweden, Svalbard and the Baltic Sea coasts. About 2,000 Purple Sandpipers were estimated to winter in Sweden. Most of them (75%) occurred in the outer archipelago off the west coast, where birds arrived in October and November. This arrival coincided with the migration of birds along the east coast and across Sweden. Sightings and ringing recoveries confirmed that some wintering birds followed a migration route along the Swedish east coast and across northern Finland, but the data also showed that some wintering birds originated from Svalbard and migrated along the Norwegian coast. Accordingly, bill-length distribution of birds captured at the Swedish west coast indicated that at least two populations regularly occur here. Most birds had bill-lengths similar to Svalbard breeders, but several had bills longer than the maximum measurement recorded at Svalbard. Bill-lengths of migrating Purple Sandpipers captured at the Baltic Sea coasts, as well as sightings and recoveries of birds ringed in Sweden, suggested that the long-billed Purple Sandpipers use the migration route along the Swedish east coast. Probably, these birds originate from breeding grounds on the Taymyr Peninsula.

A Case Study of the Near-Neutral Coastal Internal Boundary-Layer Growth: Aircraft Measurements Compared with Different Model Estimates

A simplified version of a model of the internalboundary layer evolution is compared with aircraftmeasurements across the southern part of the east coast ofSweden (Blekinge). The two flight occasions used hererepresent relatively high wind velocities and negligiblesurface heat flux. Both the vertical potential temperaturegradient and the surface temperaturedifference between land and sea are small. Modelpredictions of the internal boundary-layer (IBL)height agree well with data, for both short and largerdistances from the coastline. The contributions to theIBL growth from the mechanical turbulence and theZilitinkevich correction are discussed, as are thesensitivities of the growth to a number of physicalparameters. In near neutralconditions, the vertical potential temperaturegradient is found to be an important parameter for thegrowth of the IBL.

Historical deposition rates of Cd, Cu, Pb, and Zn in Norway and Sweden estimated by210Pb dating and measurement of trace elements in cores of peat bogs

From six ombrotrophic mires located far from distinct local sources in Sweden and Norway, a core was sampled in bog hummocks in 1988 and dated by 210Pb. Ten slices from each core were analyzed for Cd, Cu, Pb, and Zn. Based on the datings, the accumulation rates of Cd, Cu, Pb, and Zn have been estimated for the last 150 years. A reasonable agreement exists in the comparison between the recent deposition in the peat bog and nearby bulk deposition measurements. Highest deposition has been measured in southern Norway and the western part of Sweden. Generally, deposition has increased during the last 150 years, except at a station on the east coast of Sweden. In a study in Sweden where heavy metals have been measured in mosses every five years time since 1970, significant decreases in the concentrations of heavy metals have been found. Similar decreases have not been measured in the present study, although both methods are expected to reflect atmospheric deposition. Several studies have indicated that peat bogs are not suitable for measuring the historical evolution of trace metals. However, despite the disagreement, the recent literature suggests that it can be done with reasonable accuracy when performed with samples from hummocks in the peat bog.

Dietary intake of fish contaminated with persistent organochlorine compounds in relation to low birthweight.

The purpose of this study was to assess the hypothesized association between persistent organochlorine compounds through the consumption of fatty fish from the Baltic Sea (at the Swedish east coast) and low birthweight. During the period 1973-1991, 72 cases of low birthweight (1500-2750 g) were selected from among infants born to fishermen's wives within a cohort from the Swedish east coast. For each case two referents were selected. The mothers were interviewed about their dietary and smoking habits and place of living during childhood and adolescence. A high total current intake of fish from the Baltic Sea (> or = 4 meals per month) tended to increase the risk of having an infant with low birthweight [adjusted odds ratio (OR) 1.9, 95% confidence interval (95% CI) 0.9-3.9]. The effect was more conspicuous for the boys (OR 3.4, 95% CI 1.1-11). No such effects were observed when the estimated intake of fish was considered for the period in which the infant was born. However, mothers who had grown up in a fishing village had an increased risk of having an infant with low birthweight (OR 2.1, 95% CI 1.0-4.3). The variable "grown up in a fishing village" can be interpreted as an indirect measure of a mother's accumulated consumption of fish from the Baltic Sea. This idea supports an association between a high consumption of contaminated fish from the Baltic Sea and an increased risk for low birthweight. The effect estimates based on the mothers' reported fish consumptions were dependent on the period under consideration and therefore were somewhat ambiguous.

Rubus vestervicensis (Rosaceae) — its hybrid origin revealed by DNA fingerprinting

Kraft, T., Nybom, H. & Werlemark, G. 199.5. Rubus vestervicensis (Rosaceae) — its hybrid origin revealed by DNA fingerprinting. — Nord. 3. Bot. 1.5: 237–242. Copenhagen. ISSN 0107‐055X.The large number of species in Rubus subgenus Rubus are thought to have arisen, at least in part, through hybridiation between facultatively apomictic species. R. vestervicensis is known only from a small island off the Swedish east coast. It has been suggested that it is a hybrid between R. grabowskii and R. pedemontanus. We have compared these species with DNA fingerprinting and our results support the hybridization hypothesis. All bands found in the fingerprint of R. grabowskii and about half of the bands found in R. pedemontanus were present in R. vestervicensis, suggesting that the latter species was derived from fertilization of an unreduced R. grabowskii egg cell with R. pedemontanus pollen.

Fish consumption and exposure to persistent organochlorine compounds, mercury, selenium and methylamines among Swedish fishermen

This study assessed dietary habits and exposure to selenium, persistent organochlorine compounds, methylmercury, and methylamines among Swedish fishermen. Two hundred and fifty randomly selected subjects from a cohort of 2896 fishermen from the Swedish east coast (Baltic Sea) and 8477 fishermen from the west coast (Skagerrak and Kattegatt) were interviewed along with 250 referents. Subgroups of fishermen and referents from different coastal areas were also selected for blood and urine sampling. The interview data showed that fishermen ate almost twice as much fish as the 250 referents from the general population. The blood levels of mercury were twice as high, and the plasma selenium levels were 10-15% higher in the fishermen than in the referents. There was, however, no difference between the fishermen's cohorts with respect to these variables. Fishermen from the east coast ate more fatty fish than fishermen from the west coast, and they also had higher blood levels of persistent organochlorine compounds such as polychlorinated biphenyls and polychlorinated dibenzo p-dioxins and furans (present in fatty fish species in the Baltic Sea) than both the westcoast fishermen and the referents. A cohort of Swedish eastcoast fishermen might be a suitable study base for epidemiologic studies on the mortality and cancer morbidity associated with dietary exposure to persistent organochlorine compounds.

Mortality and cancer incidence among Swedish fishermen with a high dietary intake of persistent organochlorine compounds.

The objective of this study was to determine mortality and cancer incidence in two cohorts of Swedish fishermen with different dietary intakes of persistent organochlorine compounds. The following two cohorts of Swedish fishermen were established: a cohort of 2896 subjects from the Swedish east coast (on the Baltic Sea), and a cohort of 8477 subjects from the Swedish west coast. Mortality and cancer incidence were studied in these cohorts and comparisons were made both with the regional populations and between the cohorts. The incidences of stomach and squamous cell skin cancers among the eastcoast fishermen were elevated as compared with those of the regional population [standardized incidence ratio (SIR 1.6, 95% confidence interval (95% CI) 1.0-2.4 and SIR 2.3, 95% CI 1.5-3.5 respectively] and with the westcoast cohort (IRR 2.2, 95% CI 1.3-3.5 and IRR 1.9, 95% CI 1.2-3.1, respectively), while that of colon cancer was decreased. Moreover, mortality from multiple myelomas was increased among the eastcoast fishermen as compared with that of the general population [standardized mortality ratio (SMR) 3.1, 95% CI 1.2-6.4) and the westcoast fishermen (IRR 3.2, 95% CI 1.2-8.7). A 12% decreased mortality in ischemic heart disease was found for the eastcoast cohort. A slight, but significant increase in such deaths was noted among the westcoast fishermen. High consumers of fatty fish, contaminated with organochlorine compounds, had an increased risk for stomach and skin cancer. They also had a suggestive decrease in mortality from ischemic heart diseases.

Opposing fitness consequences of colour pattern in male and female snakes

AbstractLocal populations of the adder, Vipera berus, are polymorphic for dorsal colour pattern, containing both melanistic (black) and zig‐zag patterned individuals. Colour patterns in snakes influence crypsis and thermoregulatory capacity and therefore may be subjected to natural selection. To find an explanation for the maintenance of this polymorphism I examined temporal and spatial variation in morph frequency, and tested for differential selection among morphs using data from a six year capture‐mark‐recapture study. The data derive from six groups of islands in the Baltic Sea off the Swedish east coast, two mainland localities near the coast, and one inland locality.Morph frequency did not change over time within a population but varied among populations: melanistic individuals were not found at the inland locality, but comprised from 17 to 62% of the coastal and island populations. Adders frequently moved between islands within a group, but the tendency to disperse was independent of morph. These results suggest that the polymorphism is stable and maintained by a deterministic process. Scar frequency was twice as high among melanistic as among zig‐zag snakes, and melanistic individuals were easier to capture, indicating that predation may be higher on the melanistic morph. Colour morphs did not differ in body size, but analysis of recapture data shows evidence for differential survival among morphs. Zig‐zag males survived better than melanistic males, but the relative survival rates of morphs were reversed in females. This difference was consistent through time and may be due to sexual differences in behaviour, with melanism increasing predation intensity when associated with male but not with female behaviour. Opposing fitness consequences of colour pattern in the two sexes may help maintain colour polymorphism within populations of Vipera berus.

The Swedish Time Scale: A Potential Calibration Tool for the Radiocarbon Time Scale During the Late Weichselian

The Swedish Time Scale (STS) is aca.13,300-yr-long varve chronology that has been established for the Swedish east coast from >1000 overlapping clay-varve diagrams. We describe the present state of the STS and illustrate the application of this worldwide unique varve chronology for AMS radiocarbon measurements. The results are compared to other14C-dated calendar-year chronologies: dendrochronology, laminated lake sediments and U/Th. Our data set agrees with the oldest part of the dendrochronological calibration curve, and with AMS14C-dated lake lamination data and U/Th on corals down toca.12 ka calendar years bp. Further back in time, the AMS-dated part of the STS partly compares well with lake lamination chronologies and shows that the difference between14C and calendar years decreases rapidly between 12,600 and 12,800 calendar years bp. Such a development seems to contrast with U/Th measurements on corals. We suggest that the cause for the divergence among three supposed calendar-year chronologies lies in the fact that the data points on the marine14C-U/Th curve are more widely spaced in time than the tightly grouped set of terrestrial AMS14C dates, and thus are not able to reflect short-term changes in atmospheric14C. Therefore, we argue that the use of the pre-Holocene part of the calibration program is premature and inadvisable.

1,2,3,5,6,7-Hexachloronaphthalene and 1,2,3,4,6,7-hexachloronaphthalene - selective retention in rat liver and appearance in wildlife

The two isomers 1,2,3,5,6,7- and 1,2,3,4,6,7-hexachloronaphthalene are shown to be selectively retained in the liver of rats orally dosed with the commercial PCN product Halowax 1014. The retention was further studied by dosing rats orally with a mixture of the two compounds. The rats were sacrificed after 1, 10, 35 and 120 days, respectively. The two hexachloronaphthalenes were found to be strongly retained in the liver and the concentration ratios liver/adipose tissue were remarkably high. 1,2,3,5,6,7- And 1,2,3,4,6,7-hexachloronaphthalene were also found to be present in two environmental samples from the Swedish east coast, cod liver and guillemot egg.

Outdoor pond cultivation of the subtropical marine red algaGracilaria tenuistipitata in brackish water in Sweden. Growth, nutrient uptake, co-cultivation with rainbow trout and epiphyte control

Pond cultivation of the subtropical, euryhaline macroscopic red algaGracilaria tenuisipitata var.liui Zhanget Xia was carried out in brackish seawater (6–7‰) in the Gryt archipelago on the east coast of Sweden, using four outdoor tanks of 30–40 m3. Growth rate and nutrient uptake in batch culture were measured with the aim of estimating the water purification capacity ofG. tenuisipitata in outdoor conditions. Its ability to withstand epiphytic infections was also studied. An average growth rate of 4‰ biomass increase per day was recorded during two seasons with a maximum growth rate of 9‰ d−1. The initial biomass was usually 1 kgFW m−3 (FW, fresh weight). The nutrient uptake capacity was on average ca. 1 g Ni kgFW−1 d−1 and 0.08 g Pi kgFW−1 d−1 and the uptake rates for NH4+-N were higher than those for NO3−-N. Both the growth rate and the nutrient uptake rate were highest at the highest water temperature. Co-cultivation with rainbow trout (Oncorhynchus mykiss) was tested: with trout fodder as the only nutrient inputG. tenuistipitata could grow and maintain low levels of Ni and Pi with optimum efficiency at a trout: alga ratio of 1:1 (w:w). Epiphytic growth of filamentous green and brown algae was limited, probably as a result of the high pH values caused by inorganic carbon uptake byG. tenuistipitata. The growth ofEnteromorpha intestinalis, the only significant epiphyte, was completely inhibited and the majority of plants died by a few days treatment with 100 µg 1−1 Cu2+, a concentration that did not severely affectG. tenuistipitata. We conclude thatG. tenuistipitata can be cultivated in outdoor ponds in southern Sweden during 5–6 months of the year using aerated or unaerated batch cultures and that wastewater from trout cultivation may be used as a nutrient source, resulting in purification with respect to N and P.

Alternative nitrogen reduction policies in the Mälar region, Sweden

The load of nitrogen to the Stockholm archipelago from the Mälar region, a drainage basin located on the east coast of Sweden, must be reduced in order to decrease eutrophication. Costs for two alternative nitrogen policies are estimated: (i) current policy defined as total costs for reducing the nitrogen emission at each source by 50%, and (ii) an alternative policy defined as the minimum cost for reducing the load of nitrogen to the Stockholm archipelago by 50%. Results demonstrate that the cost of the first alternative greatly exceeds the cost for the second alternative. One important reason is that in the second alternative the functioning of the Mälar lake ecosystem as a nitrogen sink is accounted for, which implies cost savings since less man-made reduction is required at the emission sources. Another factor is the identification of a new ecological technology—restoration of wetlands—a low cost measure for reducing the load of nitrogen.

Landsat TM based quantification of chlorophyll-a during algae blooms in coastal waters

Abstract Simultaneous acquisition of Landsat TM imagery and sea truth data from sample sites in Himmerfjarden bay on the Swedish east coast was conducted on 10 May 1988, and 7 May 1990. The data were used to develop and verify regression models for the estimation of surface chlorophyll-a concentrations. The case 2 waters studied partly hold suspended sediment concentrations known to complicate the mapping of chlorophyll-a. The disturbing spectral influence from suspended sediment was reduced by using a process based on an existing Landsat TM sediment retrieval algorithm and a priori knowledge about water depths, bottom sediments and river outlets. The results suggest that a ratio of TM bands TMl/(log TM3+1) should be used in waters influenced by terrigenous influx and the earlier suggested ratio of TM bands 1/2 only in ocean waters. The discrimination power indicated a capability to quantify chlorophyll in connection with algae blooms.

Radioactivity in Fucus vesiculosus L. from the Baltic Sea following the Chernobyl accident

The brown alga Fucus vesiculosus L. has been used as a bioindicator for the investigation of the impact of the Chernobyl accident on the spatial and temporal distribution of radionuclides in the Baltic Sea. The investigations were performed in July 1986, about 2 months after the accident, and in August–September 1987. In July 1986 the gamma-emitting radionuclides 134Cs, 137Cs, 103Ru, 106Ru and 110 m Ag were detected in F. vesiculosus along the Swedish east, south and southwest coasts. The activity concentrations of 137Cs varied from 600 Bq/kg (dry wt) at the northernmost locality (Simpnäs) to 20 to 25 Bq/kg (dry wt) at the southeast coast. In August–September 1987 the activity concentrations of radiocaesium had increased by a factor of 2 to 3 at most localities off the Swedish east coast, compared with the results from 1986. We did not observe any increase of transuranic radionuclides or 99Tc in the algae. The subsequent extent of the radionuclide contamination in the Baltic Sea, primarily caesium, from Chernobyl was studied at one locality on the Swedish south coast from April 1987 to November 1988. A pronounced increase in the activity concentrations was observed during 1988, indicating an outflow of water, containing relatively higher levels of Chernobyl derived radionuclides, from the Baltic Sea.

Effects of temperature on spring bloom dynamics of epilithic diatom communities in the Gulf of Bothnia

Abstract. In order to forecast consequences of climatic changes for littoral algae in coastal ecosystems, the effects of temperature increase on spring bloom dynamics of epilithic diatom communities were studied in two ways: (1) Communities were compared from sites receiving different amounts of cooling water discharge from a nuclear power plant. (2) Communities from the exceptionally warm spring of 1989 were compared with those from the same sites in the preceding normal years. The studies were carried out in and around the Forsmark Biotest Basin, an artificial waterbody that receives brackish cooling water from the Forsmark nuclear power plant on the Swedish east coast. Species composition and biomass data from 200 epilithic diatom samples taken in the period January‐May from 1983 to 1989 were analysed.Multiple regression analysis was used to show the responses of diatom cover, community diversity and abundances of individual taxa to water temperature and other environmental factors. Constrained ordination (CCA) was used to display the relationship of overall community composition to environment. Increased water temperature resulted in higher biomass through a chain of ecological effects. Strong reduction of ice cover was crucial in this chain, resulting in reduced loss of diatom cells by reduced abrading and higher primary production by higher availability of light, nutrients and substrate.The conclusion is that large blooms of fast‐growing epilithic diatoms in large colonies can occupy the niche that emerges when the ice‐free season is prolonged in the northern Baltic Sea and areas similar in salinity and climatic conditions. Dramatic species shifts may only be expected if the winter ice cover is totally absent.

Effects of pulp mill effluents on vertebrae of fourhorn sculpin,Myoxocephalus quadricornis, bleak,Alburnus alburnus, and perch,Perca fluviatilis

Laboratory investigations with juvenile fourhorn sculpin,Myoxocephalus quadricornis, exposed for 4 1/2 months to four pulp mill effluents resulted in elevated frequencies of vertebral deformation. Vertebrae composition and mechanical strength were altered as a result of the treatment. The same parameters were also altered for bleak,Alburnus alburnus, exposed for 3 1/2 months to the same effluents. The response pattern was, however, different and no vertebral deformation could be confirmed by X-ray technique. A field survey on feral perch,Perca fluviatilis, sampled in the vicinity of two kraft pulp mills with and without bleaching, respectively, on the Swedish east coast (Gulf of Bothnia) gave results similar to those obtained for bleak.

Regional economic structures: An analysis of the Viking Age silver hoards from Öland, Sweden

Abstract Regional Viking Age economy (AD 800–1100) is investigated through an analysis of the silver hoards on the island of Öland, off the Swedish east coast. The complex character of the hoards, i.e. their mixture of foreign coins, bars and ingots, hacksilver and complete objects, is regarded as being particularly meaningful, reflecting a non‐uniform economy. This is related to social structure in which control of exchange is an essential factor, the different kinds of ‘money’ circulating in different economic spheres within society. Continuous and more explicit economic activities are restricted and mainly connected to super‐regional and long‐distance exchange.