Karels, A. E. & Oikari, A. O. J. 2000: Effects of pulp and paper mill effluents on the reproductive and physiological status of perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) during the spawning period. — Ann. Zool. Fennici 37: 65–77.
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Mykrä, S., Kurki, S. & Nikula, A. 2000: The spacing of mature forest habitat in relation to species-specific scales in managed boreal forests in NE Finland. — Ann. Zool. Fennici 37: 79–91.
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Laakso, J. & Setälä, H. 2000: Impacts of wood ants (Formica aquilonia Yarr.) on the invertebrate food web of the boreal forest floor. — Ann. Zool. Fennici 37: 93–100.
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Aho, J. & Holopainen, I. J. 2000: Batch spawning of crucian carp (Carassius carassius (L.)) in mono- and multispecies communities. — Ann. Zool. Fennici 37: 101–111.
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Szuma, E. 2000: Variation and correlation patterns in the dentition of the red fox from Poland. — Ann. Zool. Fennici 37: 113–127.
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Merilä, J., Pahkala, M. & Johanson, U. 2000: Increased ultraviolet-B radiation, climate change and latitudinal adaptation — a frog perspective. — Ann. Zool. Fennici 37: 129–134.
Abstract, Full text (print quality pdf)
Karels, A. E. & Oikari, A. O. J. 2000: Effects of pulp and paper mill effluents on the reproductive and physiological status of perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) during the spawning period. — Ann. Zool. Fennici 37: 65–77.
Reproductive and physiological parameters were studied during the spawning period in perch (Perca fluviatilis L.) and roach (Rutilus rutilus L.) downstream of two pulp and paper mills and reference sites in southern Lake Saimaa, Finland. Plasma 17[beta]-estradiol (E2) and testosterone (T) concentrations in female perch and roach decreased during the spawning period. At one of the mill sites, plasma E2 and T concentrations in pre-spawn female and male perch and male roach were significantly higher. As compared with the reference sites, liver ethoxyresorufin O-deethylase (EROD) activity in exposed perch and male roach was 29%–91% higher, and for exposed female roach it was 53%–79% lower. In contrary to perch, EROD activity in male roach was higher than in females. Resin acids concentration in the bile of exposed fish (0.2–2.0 ug ml–1) was higher than at the reference sites, whereas chlorophenolics concentration was similar (0.4–0.7 ug ml–1). Results indicate that exposure to pulp and paper mill compounds still exists, although much lower than before implementation of ECF bleaching and activated sludge wastewater treatment at the mills. Effects of pulp and paper mill effluent on reproduction of spawning fish were inconclusive.
Mykrä, S., Kurki, S. & Nikula, A. 2000: The spacing of mature forest habitat in relation to species-specific scales in managed boreal forests in NE Finland. — Ann. Zool. Fennici 37: 79–91.
Modern forestry alters the structure of boreal forest landscapes, and this affects several forest species with different habitat requirements. Quantitative analyses of the structure of real landscapes are scarce, although this information will be needed in landscape-level planning and management applications. We investigated the occurrence and configuration of mature forest (> 80–100 year) in relation to five different extents (ranging from 20 to 7 854 ha) of circular landscapes around random points in managed forest environment in NE Finland. The habitat type was coarsely chosen according to requirements of certain resident birds and mammals. We present an approach where species-specific home-range scales are related to the observed environmental heterogeneity pattern for assessing the potential of actual landscapes to maintain these species. As a result we found that there is a minority of landscapes where total area of mature forest was comparable to species' home ranges. Irrespective of the scale examined, the average proportion of habitat in a landscape was approximately 15%. Besides that the mature forest was physically fragmented already on a scale relevant to individual animals, the variation in habitat proportion between landscapes decreased rapidly when the landscape extent was increased. This decrease of variation occurs on surprisingly small scales; the forest landscape structure is unintentionally altered due to small-patterned land ownership, even age distribution of managed stands, and small variation in regeneration patch size. In terms of related landscape metrics, we also compare our results with patterns achieved in randomly generated neutral landscape models.
Laakso, J. & Setälä, H. 2000: Impacts of wood ants (Formica aquilonia Yarr.) on the invertebrate food web of the boreal forest floor. — Ann. Zool. Fennici 37: 93–100.
We studied the impact of wood ants on the structure and functioning of the invertebrate food web of boreal forest during a three-year period. Special emphasis was put on the detritus-based food web. The density of wood ants was reduced > 90% by eliminating whole wood ant colonies from five areas in Central Finland, and leaving five areas as controls. We monitored the growth of spruce, pine and birch seedlings planted on homogenised plots, and development of the invertebrate community in soil and vegetation. The ant removal had little effects on the structure of the invertebrate food web. However, biomasses of predators caught in pitfall traps were 60% smaller under high ant density than under low ant density. Also, at the end of the experiment the biomass of the lumbricid earthworm Dendrobaena octaedra was reduced by 54% in the homogenised plots without ant nests. Removal of wood ants had no influence on soil microbial biomass, concentration of soil mineral nitrogen, plant N uptake, or plant growth.
Aho, J. & Holopainen, I. J. 2000: Batch spawning of crucian carp (Carassius carassius (L.)) in mono- and multispecies communities. — Ann. Zool. Fennici 37: 101–111.
Open-water field studies were conducted to clarify the reproductive biology of crucian carp in mono- and multispecies fish communities in eastern Finland. Between late May and mid-July, ready-to-spawn (ripe) crucian carp entered traps mainly during periods of rising water temperature. The males tended to be smaller but remained ripe longer than the females. In all populations the gonadosomatic index of females was variable throughout the summer, but in May it was higher in fish from the multispecies community than in those from the monospecific communities. Crucian carp is a batch spawner in all the water bodies studied. After a minimum temperature of ca. 18 °C, the timing of spawning is set by any clear increase in water temperature. Normally there were two spawnings during the 65-days reproductive period. The higher the mean temperature in May, the earlier the first spawning was.
Szuma, E. 2000: Variation and correlation patterns in the dentition of the red fox from Poland. — Ann. Zool. Fennici 37: 113–127.
Analysis of variation in tooth size in a population of red fox, Vulpes vulpes (Linnaeus, 1758) from Poland based on three indices (coefficient of variation CV, variation index VSD, residual standard deviation RSD) and its correlation with average tooth size revealed two contradictory patterns. The CV and VSD were significantly correlated with average tooth sizes, while RSD values was independent. It was, therefore, concluded that RSD is the most reliable index for assessing population variation. The least variable position in the red fox dentition are M1 and M1, whereas the most variable is M3. The strongest sexual dimorphism in tooth size in Polish red foxes is observed in the canines. The strongest between-tooth correlations were in the premolar region. Moreover, a strong correlation in both tooth length and tooth width was found between opposite canines. Both functional and developmental factors determine patterns of morphological variation in the dentition.
Merilä, J., Pahkala, M. & Johanson, U. 2000: Increased ultraviolet-B radiation, climate change and latitudinal adaptation — a frog perspective. — Ann. Zool. Fennici 37: 129–134.
According to a traditional view, organisms and populations inhabiting high latitudes are likely to be exposed to lower effective doses of potentially harmful solar ultraviolet-B radiation (UV-B) than those inhabiting lower latitudes. We challenge this traditional view by demonstrating that due to differences in phenology, populations occurring at high latitudes may actually be exposed to much higher effective doses of UV-B radiation than those occurring at lower latitudes. Related to this, we point out a possibly wide-spread interaction between climate change and ozone depletion which can effectively mask (or delay the appearance of) the negative effects of increased solar UV-B radiation on organismal fitness. These points are illustrated with examples from amphibians, which have been recently suggested to be particularly vulnerable for UV-B mediated fitness loss.