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Showing papers by "University of Jyväskylä published in 1990"


Journal ArticleDOI
TL;DR: The observed results demonstrated that in normal locomotion involving the stretch-shortening cycle (SSC) muscle actions, the mechanical response of the triceps surae muscle is very different from the classical curves obtained in isolated muscle preparations.

349 citations


Journal ArticleDOI
TL;DR: The authors examine les effets de manipulations experimentales de chants sur la selection du partenaire par les femelles, and examine the effect of these manipulations on the intensite du chant.

151 citations


Proceedings ArticleDOI
01 Feb 1990
TL;DR: A novel approach to the operational specification of concurrent systems that leads to an object-oriented specification language is presented, where objects are structured as hierarchical state-transition systems, and methods of individual objects are replaced by roles in cooperative multiobject actions.
Abstract: A novel approach to the operational specification of concurrent systems that leads to an object-oriented specification language is presented. In contrast to object-oriented programming languages, objects are structured as hierarchical state-transition systems, methods of individual objects are replaced by roles in cooperative multiobject actions whereby explicit mechanisms for process communication are avoided, and a simple nondeterministic execution model that requires no explicit invocation of actions is introduced. The approach has a formal basis, and it emphasizes structured derivation of specifications. Top-down and bottom-up methodologies are reflected in two variants of inheritance. The former captures the methodology of designing distributed systems by superimposition; the latter is suited to the specification of reusable modules. >

120 citations


Journal ArticleDOI
TL;DR: Despite the complex multijoint character of TRT, its fractions could be analysed during the early phases on the blocks and large individual variations until the end of the first contact after the blocks resulted in non-observable MT in some individual cases.
Abstract: Eight male sprinters were filmed running three maximal starts over 3 m on a long force platform. The subjects were divided into two groups (n = 4) according to the leg on which the electromyograph (EMG) electrodes were fixed. When in the set position one group had electrodes on the front leg (FLG) and the other group on the rear leg (RLG). The EMG activities of the gastrocnemius caput laterale muscle (GA), vastus lateralis muscle (VL), biceps femoris caput longum muscle (BF), rectus femoris muscle (RF) and gluteus maximus muscle (GM) were recorded telemetrically using surface electrodes. Total reaction time (TRT) was defined as the time from the gun signal until a horizontal force was produced with a value 10% above the base line. Pre-motor time was defined as the time from the gun signal until the onset of EMG activity and motor time (MT) as the time between the onset of EMG activity and that of force production. Reproducibility of the reaction time variables was satisfactory (r = 0.79-0.89; coefficient of variation = 8.8%-11.6%). The TRT was 0.121 s, SD 0.014 in FLG and 0.119 s, SD 0.011 in RLG. The MT ranged from 0.008 s, SD 0.009 (GM) to 0.057 s, SD 0.050 (GA) in FLG and from 0.018 s, SD 0.029 (GA) to 0.045 s, SD 0.009 (GM) in RLG. In some individual cases there were no MT values before horizontal force production.(ABSTRACT TRUNCATED AT 250 WORDS)

116 citations


Journal ArticleDOI
TL;DR: The biomass of both worms decreased during the experiment, the N released from decomposing tissues did not explain the increase in N leached in the presence of earthworms, and the worms influenced the level of PO43−−P only slightly.
Abstract: The earthworms Lumbricus rubellus (Hoffmeister) and Dendrobaena octaedra (Savigny) were studied in the laboratory to determine their effects on decomposition and nutrient cycling in coniferous forest soil. CO2 evolution was monitored, and pH, PO 4 3− −P, NH 4 + −N, NO 3 − −N, total N, and total C in the leaching waters were measured. After three destructive samplings, numbers of animals, mass loss, pH, and KCl-extractable nutrients were analysed. The earthworms clearly enhanced the mass loss of the substrate, especially that of litter. L. rubellus stimulated microbial respiration by 15–18%, whereas D. octaedra stimulated it only slightly. The worms significantly raised the pH of the leaching waters and the humus; L. rubellus raised the value by 0.2–0.6 pH units and D. octaedra by 0.1–0.4 units. Both worms increased N mineralization. Although the biomass of both worms decreased during the experiment, the N released from decomposing tissues did not explain the increase in N leached in the presence of earthworms. The worms influenced the level of PO 4 3− −P only slightly.

112 citations


Journal ArticleDOI
TL;DR: The present results in female subjects indicate the important role of training-induced adaptations in the nervous system for muscular power development during prolonged training and an important indicator of the trainability of an individual.
Abstract: Training-induced adaptations in the neuromuscular and endocrine systems were investigated in seven females during prolonged power type strength training. Great (p less than 0.05) changes occurred primarily during the earlier weeks of the 16-week training especially in the time of force production (from 161 +/- 107 to 93 +/- 65 ms to produce a 500 N force) and, correspondingly, in the average forces in the earlier positions of the (absolute) force-time curve of the leg extensor muscles. These changes were accompanied by significant (p less than 0.05) increases in the neural activation of the trained muscles in the earliest positions of the IEMG-time curve. Hypertrophic changes, as judged from muscle fibre area data of both FT and ST types, were only slight (ns.) during the entire training period. No statistically significant changes occurred during the training in mean concentrations of serum testosterone, free testosterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), cortisol, progesterone, estradiol (E2) or sex hormone-binding globulin (SHBG). However, the individual mean serum levels of both total and free testosterone correlated significantly (r = .81-.95, p less than 0.05-0.01) with the individual changes during the training in the time of force production and in the forces in the force-time curve of the trained muscles. The present results in female subjects indicate the important role of training-induced adaptations in the nervous system for muscular power development. In females testosterone may be of great importance for muscular power and/or strength development during prolonged training and an important indicator of the trainability of an individual.

103 citations


Journal ArticleDOI
TL;DR: The pT-spectra of negative particles from 200 GeV/nucleon O + Au and S + S collisions, measured at CERN by the NA35 collaboration, are fitted by a thermal distribution of massive pions which are strongly out of chemcial equilibrium.

96 citations


Journal ArticleDOI
TL;DR: The results suggest that (1) the relationships between training and performance can be described by the systems model, (2) the estimated index of fitness has a physiological meaning and the fatigue index remains to be clarified.
Abstract: A systems model, providing an estimation of fatigue and fitness levels was applied to a 1-year training period of six elite weight-lifters. The model parameters were individually determined by fitting the predicted performance (calculated as the difference between fitness and fatigue) to the actual one. The purpose of this study was to validate the systems model by comparing the estimated levels of fatigue and fitness with biological parameters external to the model calculation. The predicted and the actual performances were significantly correlated in each subject. The calculated fitness and fatigue levels were related to serum testosterone concentration, testosterone: cortisol and testosterone: sex hormone binding globulin ratios. The best results were obtained by the comparison between fitness and testosterone levels, which varied in parallel in each subject. In two subjects this correlation was significant (r = 0.91, P less than 0.05, and r = 0.92, P less than 0.01). The fitness changes calculated in each subject between the 15th and the 51st weeks of training were significantly correlated with the changes in serum testosterone concentration measured in the same period (r = 0.99, P less than 0.001). For the whole group testosterone and fitness variations were also significantly intercorrelated (r = 0.73, P less than 0.001). Correlations, less homogeneous and less significant, were calculated also for other hormones and ratios. These results suggest that (1) the relationships between training and performance can be described by the systems model, (2) the estimated index of fitness has a physiological meaning. The fatigue index remains to be clarified.

90 citations


Journal ArticleDOI
TL;DR: It is shown that the highly skewed mating distributions observed in a black grouse lek in three years were indeed different from random expectations, and it is suggested that females copying the mate choice of others enhance this skew.
Abstract: It has been suggested that the non-random mating often observed in lekking species is a consequence of either male-male competition or active female mate choice. Here we show that the highly skewed mating distributions observed in a black grouse lek in three years were indeed different from random expectations. We suggest that females copying the mate choice of others enhance this skew. Observations in favour of copying are: females pay multiple visits to the lek during several days; females arrive and move in bands which makes it possible to observe the visits to male territories and matings of other females; in the main lek in the study area, males often mated in sequence indicating that by being visited by many females and by mating the attractiveness of males increased. However, this last effect was only evident in one of the years of the study, and only on the largest lek which had exceptionally many female visits this year. In leks with a smaller number of visiting females, copying, even if present, is difficult to detect without experiments since almost all females tend to copulate with the top-male.

67 citations


Journal ArticleDOI
TL;DR: The populations of Friends reached densities twice as high as those of Strangers with a significantly higher rate of recruitment and survival of the young, which may have been due to mutual familiarity decreasing antagonism towards the juveniles.
Abstract: We examined demographic effects of familiarity and relatedness in the bank vole Clethrionomys glareolus (Schreber) in four 0.5-ha enclosures in Central Finland. In two enclosures were mature voles which had overwintered together and some of their mature off-spring (hereafter referred to as “Friends”), and in the other two individuals of the same species captured from different localities near the study area (“Strangers”). The experiment lasted from June to September. The populations of Friends reached densities twice as high as those of Strangers with a significantly higher rate of recruitment and survival of the young. This may have been due to mutual familiarity decreasing antagonism towards the juveniles. The conflicting results obtained from studies of Clethrionomys and Microtus are discussed. We believe that these genera represent behavioural adaptations to different habitats and ways of life. Most behavioural population regulation hypotheses are based on studies of Microtus. We conclude that these results should be applied with great caution to other rodent genera.

64 citations


Journal ArticleDOI
TL;DR: The results suggest the importance of cellular redox state and the role of a lower degree of enzymatic antioxidants in training-induced protection against ischemic injuries in Langendorff-perfused rat hearts.
Abstract: Endurance training by swimming (219-229 h) resulted in a significant protection against hypoxia/reoxygenation-induced injuries in Langendorff-perfused rat hearts. The protection was manifested as improved flow characteristics and a smaller release of creatine kinase into the perfusate. The concentration of thiobarbituric acid reactive substances (TBARS) was lower in the trained than in the respective control hearts. The trained hearts also showed a lower reoxygenation-induced increase in TBARS. The myocardium of the right ventricle and that of the left subepimyocardium were the most affected by reoxygenation. The swimming program induced a decrease in the activities of catalase and glutathione reductase in all parts of the myocardium measured. A decrease in vitamin E concentration in the subendomyocardium of the left ventricle and an increase in the activity of thioredoxin reductase also occurred. An increase in the concentration of reduced glutathione due to training was also observed, especially in the left subepimyocardium, whereas the glutathione disulfide concentration and the activity of superoxide dismutase were unaffected. The activity of glucose 6-phosphate dehydrogenase increased in the right ventricle. The results suggest both the importance of cellular redox state and the role of a lower degree of enzymatic antioxidants in training-induced protection against ischemic injuries.

Book ChapterDOI
TL;DR: It is explained that offspring raised by polygynously mated males receive less food as a result of the reduced male feeding assistance at such nests, and that secondary females raise fewer offspring that most likely are of poorer quality than offspring of monogamous and primary females.
Abstract: Publisher Summary The chapter discusses on the evolution of polyterritoriality in Ficedulu hypofeuca species. It estimates the costs and benefits to males and females, and uses the results to evaluate current alternative polygyny models. This chapter also explains that secondary females raise fewer offspring that most likely are of poorer quality than offspring of monogamous and primary females. This is probably not because the secondary females are of lower quality than other females settling at the same time, but because one could not find any differences in age or morphology of simultaneously mated monogamous and secondary females. The main reason is that offspring raised by polygynously mated males receive less food as a result of the reduced male feeding assistance at such nests. Pied flycatcher females primarily utilize territorial cues rather than male characteristics when choosing a mate. This applies both to monogamous, primary, and secondary females.

Journal Article
TL;DR: The present fatiguing loading resulted in all athlete groups in significant (p less than 0.05-0.001) worsening in maximal force, in the times of force production and in the maximal rates of forceProduction and relaxation.
Abstract: Acute effects of fatigue produced by a maintained 60% isometric loading on force production and relaxation characteristics of the leg extensor muscles were studied in male endurance (n = 9), power (n = 6) and strength athletes (n = 9). The initial non-fatigued isometric force-time curves differed considerably (p less than 0.05-0.001) between the groups so that the times of force production were the shortest and correspondingly the maximal rate of force production the greatest in the power athletes but the longest and the smallest in the endurance athletes. The endurance time of 70.7 +/- 32.9 s at the 60% fatiguing loading was in the endurance athletes longer (p less than 0.01) than in the power (30.6 +/- 7.1 s) and strength groups (31.7 +/- 5.5 s). The present fatiguing loading resulted in all athlete groups in significant (p less than 0.05-0.001) worsening in maximal force, in the times of force production and in the maximal rates of force production and relaxation. However, this worsening in the endurance athletes in maximal force (to 92.9 +/- 7.1%) as well as in the maximal rates of force production (to 79.2 +/- 20.8%) and relaxation (to 73.1 +/- 29.2%) were significantly (p less than 0.05-0.01) smaller than the corresponding decreases in the power athletes (to 64.3 +/- 8.0%, 74.8 +/- 7.4% and to 40.9 +/- 12%, respectively) and in the strength athletes (to 65.7 +/- 7.0%, 56.7 +/- 16.0% and to 34.8 +/- 6.7%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Journal ArticleDOI
TL;DR: In this article, the authors have analyzed polychlorinated dibenzo-p-dioxins, dibenzofurans, coplanar PCBs and other dioxin-type of toxins in Baltic salmon, cod, ringed seal and grey seal.

Journal ArticleDOI
TL;DR: In this paper, topsoil and earthworm samples collected from three Finnish sawmill environments were analyzed for polychlorinated phenols, 2,3,4,6-tetrachloro- and pentachlorophenol, and their metabolites.

Journal ArticleDOI
TL;DR: In this article, a long-term experiment was carried out in macrocosm systems simulating the complexity of coniferous forest soil, where removed microcosms containing birch litter, spruce litter, or humus were inserted into the substrate humus in the macrocosms.
Abstract: Long-term experiments (97–98 weeks) were carried out in macrocosm systems simulating the complexity of coniferous forest soil. The macrocosms were partially sterilized by freezing, thawing and drying, then re-inoculated with microbes alone or microbes + soil fauna. Removable microcosms containing birch litter, spruce litter, or humus were inserted into the substrate humus in the macrocosms. Two experiments used organic matter only, and in the third there was mineral soil below the humus. The macrocosms were incubated in climate chambers that simulated both summer and winter conditions. At 4- to 6-week intervals the substrates were irrigated for analyses of pH, total N, NH 4 + −N, NO 3 − −N, and PO 4 3− −P in the leachates. At the end of each growing season a destructive sampling was performed, including analyses of KCl-extractable N and P. Leaching of NH 4 + and PO 4 3− from both the litter and the total systems was significantly enhanced by the soil fauna. There were also differences in mineralization of N and P between the refaunated systems, apparently due to divergent development of the faunal communities. In general, fauna affected KCl-extractable nutrients from the litter positively, although this effect was less evident than in the leaching water. In the humus and mineral soil the fauna significantly increased the release of N and P, especially in the later stages of the experiments. Soil pH was higher in the presence of fauna, but there was no difference in the pH of the leachates. Not only invertebrate-microbial interactions, but also mutual relationships among fauna were important in the nutrient dynamics.

Journal ArticleDOI
TL;DR: Chlorohydrocarbons and free and chemically bound chlorophenols, catechols and guaiacols were measured from lake sediments in Central Finland as mentioned in this paper, where they occurred at low backround levels except chlorocymenes from pulp mills and PCBs near the city of Aanekoski.

Journal ArticleDOI
TL;DR: In Ehrlich ascites cells, vinblastine does not prevent the entry of hydrolases into autophagic vacuoles, which calls into question the importance of microtubules in the transport of lysosomal enzymes into Autophagic Vacuoles.

Journal ArticleDOI
TL;DR: In this article, a coniferous forest floor was simulated using microcosms containing birch litter, spruce litter, or humus, and two experiments used organic matter only, and another included a layer of mineral soil below the humus.
Abstract: Long-term experiments (ca. 2 years) were carried out in laboratory systems that simulated the complexity of a coniferous forest floor. The test materials were partially sterilized by freezing and thawing, and reinoculated with (1) microbes alone or (2) microbes with fauna. Removable microcosms containing birch litter, spruce litter, or humus were inserted into a humus substrate. Two experiments used organic matter only, and another included a layer of mineral soil below the humus. Both were incubated in climate chambers that simulated both summer and winter conditions. The evolution of CO2 was measured at regular intervals. In order to determine the C content of the leachates, the macrocosms and the microcosms were watered periodically.

Journal ArticleDOI
TL;DR: In this paper, the half life of the double beta decay of 76Ge into the ground state of 76Se was calculated in a relativistic quark confinement model using the neutron-proton quasi-particle random phase approximation.

Journal ArticleDOI
TL;DR: In this paper, the collective structure of 108,110,110 Ru and 112 Ru has been studied at the IGISOL facility through the beta decay of 110 Tc and 112 Tc.

Journal ArticleDOI
TL;DR: Alarm responses of wild-captured individual willow tits to model sparrowhawks, Accipiter nisus, flying over a test chamber were studied, and there was individual variation in the responses, with older males giving the call more frequently than females or young males.

Book ChapterDOI
01 May 1990
TL;DR: The study shows that a little experience had been gained in adapting data dictionaries to methodologies but no such attempts had been made with CASE tools, and in general no systematic approach had been followed in the adaptation.
Abstract: In spring 1989 we surveyed the experiences of some Finnish companies in methodology modelling (metamodelling) and adaptation of tools and methodologies to each other (methodology adaptation). The companies represented software production, banking, wood and metal industry, and wholesale trade. The study was carried out as a field study where we interviewed method developers, systems analysts and their supervisors. The goal of the survey was to find out whether there was need for metamodelling or methodology adaptation in general and how this need had been satisfied. The study shows that a little experience had been gained in adapting data dictionaries to methodologies but no such attempts had been made with CASE tools. One reason for this was that few methodological guidelines were extensively employed and supported in organisations. In general no systematic approach had been followed in the adaptation. We also explored possible causes for encountered difficulties and conditions for successful metamodelling and methodology adaptation. A crucial success factor was the adaptability and ease of use of the tool. In general the causes for the success are similar to those of information systems development in general. These include sufficient resources and management support, concrete benefits for those who do the actual work and friendly user interfaces.

Journal ArticleDOI
TL;DR: This paper shows how a visual, interactive, dynamic multiple objective linear programming decision support system can effectively be used for analyzing input-output models and studying the quantitative effects of economic or political crises to the Finnish economy.
Abstract: This paper shows how a visual, interactive, dynamic multiple objective linear programming decision support system can effectively be used for analyzing input-output models. We have applied our approach to studying the quantitative effects of economic or political crises to the Finnish economy. Examples of such crises are nuclear power plant accidents, trade embargoes, and international conflicts. An input-output model of the Finnish economy with 17 industries sectors is employed. Our system has been implemented on a microcomputer and is being used by the National Board of Economic Defense. Several typical case situations are discussed.

Journal Article
TL;DR: Endurance capacity (aerobic) and strength capacity were greater in the athletic group than in the control group and it was suggested that training background and more advanced biological maturation of the athletes affected especially their strength capacity.
Abstract: Endurance, strength and speed capacity were investigated among prepubescent male weight lifters (EL), endurance runners (ER) and sprint runners (SR). The subjects were selected by their coaches and all of them were classified as promising and successful junior athletes in the age groups of 10-13 years. Twelve boys belonged to athletic group (AG) and their performance capacity was compared to normally active control (C) boys (n = 9). Biological age was significantly (p less than 0.05) greater in AG (11.3 +/- 0.9 years) than in C (10.2 +/- 1.4 years) but in chronological age there was no difference between the groups. Maximal oxygen uptake was significantly (p less than 0.05) higher in AG (62.3 +/- 3.1 ml.kg-1.min-1) than in C (55.4 +/- 7.7 ml.kg-1.min-1). The endurance runners had the highest value (66.5 +/- 2.9 ml.kg-1.min-1). In anaerobic characteristics there were no significant differences. The rise of centre of gravity (0.26 +/- 0.03 m) of AG in a test for the best drop jump was clearly (p less than 0.05) higher than that (0.22 +/- 0.03 m) of C. The weight lifters and sprint runners were the best in the test for force production. AG had significantly (p less than 0.01) shorter choice reaction time (261 +/- 39 ms) than C (344 +/- 81 ms). Testosterone correlated with jump performances (p less than 0.05), biological age (p less than 0.01) and chronological age (p less than 0.001). Growth hormone correlated significantly only with biological age (p less than 0.05) and testosterone (p less than 0.001). In conclusion, endurance capacity (aerobic) and strength capacity were greater in the athletic group than in the control group and it was suggested that training background and more advanced biological maturation of the athletes affected especially their strength capacity. The parameters used in this investigation can be utilized for talent selection in sport.

Journal ArticleDOI
01 Sep 1990-Ophelia
TL;DR: Some zooplankton species were clearly following the decrease in salinity: neritic copepod and cladoceran species diminishing in abundance and brackish- water and limnetic species increasing.
Abstract: The abundance of crustacean mesozooplankton was monitored by monthly sampling in the Archipelago Sea (Northern Baltic) during the years 1976-1984. Changes in the abundance of crustacean mesozooplankton species are compared with changes in water temperature, nutrient levels, chlorophyll-a, salinity and population densities of the Baltic herring (Clupea harengus membras L.). There was a rise of water temperature during the study period (about laC on average). The chlorophyll values were increasing, as were the nutrient levels in winter. Salinity was decreasing (on average 0.5‰ S). The biomass and abundance ofplanktivorous Baltic herring were increasing by about 30 and 50 per cent, respectively. Some zooplankton species were clearly following the decrease in salinity: neritic copepod and cladoceran species diminishing in abundance and brackish- water and limnetic species increasing. The dominant copepod species showed mixed responses. These could not be attributed to any single environmental factor....

Journal ArticleDOI
TL;DR: In this article, the initial stages of plant succession (from 0 to 8 or 9 yr) were studied on abandoned peat harvest sites of two adjacent areas in Finland at the Mustasuo area only 13 field layer species, all perennials, and 3 ground layer species became established during that period and species composition stayed relatively constant All species occurred sparsely with low biomass.
Abstract: Initial stages of plant succession (from 0 to 8 or 9 yr) were studied on abandoned peat harvest sites of two adjacent areas in Finland At the Mustasuo area only 13 field layer species, all perennials, and 3 ground layer species became established during that period and species composition stayed relatively constant All species occurred sparsely with low biomass The Riitasuo area was colonized by 43 field layer and 19 ground layer species during the first 8 yr of succession In that area the originally plantless sites were totally covered by plants within a few years Many of the first species to arrive were annuals, most of which were soon replaced by perennial species The great differences between the two areas in the rate and pattern of early succession are suggested to arise from differences in the seed sources and in the physical and chemical characteristics of the soil The areas were found to differ especially by the thickness of the remaining peat layer, by the particle size distribution of the peat soil and by the contents of nitrate and ammonium nitrogen of the soil

Journal ArticleDOI
TL;DR: It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.
Abstract: Serum hormones and physical performance capacity in boy athletes (AG;n = 19) were investigated during a 1-year training period (between the ages of 11.6 and 12.6 years). Six young untrained boys served as the control group (CG). The mean serum testosterone concentration increased significantly in AG (P<0.05) following the training period from 2.92 nmol·l−1, SD 1.04 to 5.81 nmol·l−1, SD 1.33. Significant differences were not observed in the cortisol, sex hormone binding globulin and growth hormone levels during the follow-up period. The AG clearly increased speed (P<0.001), speed-strength (P<0.01-P<0.001) and anaerobic capacity (P<0.001) whereas CG had only slight increases (NS) in physical performance capacity during a 1-year period. During the last 6-month training period significant positive correlations (r=0.490–0.58;P<0.05 -P<0.01) were observed in AG between the relative changes in testosterone, testosterone: cortisol ratio and growth hormone and the relative performance change in speed, maximal isometric force and endurance, respectively. At the end of the period significant positive correlations were observed in all subjects between the level of testosterone and speed-strength (r=0.52–0.64;P<0.01 -P<0.001) and anaerobic capacity (r=0.49;P<0.05). It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.

Journal ArticleDOI
TL;DR: A sample of 7266 fish from 31 species was obtained from the north-eastern Bothnian Bay, Baltic Sea, from 1975 to 1982, and acanthocephalans were considered to be dominant in seven species of fish, cestodes in 12, digeneans in three and nematodes in one host species.
Abstract: A sample of 7266 fish from 31 species was obtained from the north-eastern Bothnian Bay, Baltic Sea, from 1975 to 1982. Twenty-six fish species were found to be infected with seven acanthocephalan species identified as Echinorhynchus salmonis, E. bothniensis, E. borealis, E. gadi, Acanthocephalus anguillae, A. lucii and Neoechinorhynchus rutili. Acanthocephalus lucii was the only acanthocephalan not to attain sexual maturity M at least one species of fish. Fourteen new host records were found for E. bothniensis. A total of 1576 acanthocephalan infections was found; in most cases these were single species infections, but in 108 cases infections of two, and in two cases of three species were observed. The most prominent host-parasite relationship involved E. salmonis and Coregonus widegreni, where the total of 11 505 worms taken from 1164 fish was roughly ten times the number of any of the other acanthocephalan parasites taken from all its hosts. Echinorhynchus gadi was encountered only in Gadus morhua. The fish of the Bothnian Bay were not considered to offer an important environment for E. gadi, E. borealis or A. lucii. Acanthocephalus anguillae was common only in Leuciscus idus while the range of hosts for N. rutili was found to be broad with 15 of 18 infected fish species being genuine definitive hosts. Larger host fish tended to be more frequently and heavily infected than smaller ones with all acanthocephalan species except for N. rutili. Female fish were usually more heavily infected than males and the frequency distributions of numbers of acanthocephalans per fish were often observed to be overdispersed. The occurrence of non-acanthocephalan species of helminth in the alimentary tracts of 23 species of fish was recorded during the survey. On the basis of estimates of Berger-Parker indices, acanthocephalans were considered to be dominant in seven species of fish, cestodes in 12, digeneans in three and nematodes in one host species. Observations were also made on acanthocephalans in lampreys. The relevance of some of the findings for acanthocephalan transmission and adaptation to new environments is discussed briefly.Page620. 620. . 620. . 620 .. 621 .. 622 .. 623 Introduction . . . Materials and methods . Collection of fish . . . . . . Post-mortem examination of fish Parasite examination . . Hosts . . . Acanthocephalan identity * Address for correspondence619 0952-8369/90/004619 + 21 $03.00 © 1990 The Zoological Society of London