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41.
We evaluated a simple bioassessment method based on a priori river typology to predict benthic macroinvertebrate fauna in
riffle sites of rivers in the absence of human influence. Our approach predicted taxon lists specific to four river types
differing in catchment area with a method analogous to the site-specific RIVPACS-type models. The reference sites grouped
in accordance with their type in NMS ordination, indicating that the typology efficiently accounted for natural variation
in macroinvertebrate assemblages. Compared with a null model, typology greatly increased the precision of prediction and sensitivity
to detect human impairment and strengthened the correlation of the ratio of observed-to-expected number of predicted taxa
(O/E) with the measured stressor variables. The performance of the typology-based approach was equal to that of a RIVPACS-type
predictive model that we developed. Exclusion of rarest taxa with low occurrence probabilities improved the performance of
both approaches by all criteria. With an increasing inclusion threshold of occurrence probability, especially the predictive
model sensitivity first increased but then decreased. Many common taxa with intermediate type-specific occurrence probabilities
were consistently missing from impacted sites, a result suggesting that these taxa may be especially important in detecting
human disturbances. We conclude that if a typology-based approach such as that suggested by the European Union’s Water Framework
Directive is required, the O/E ratio of type-specific taxa can be a useful metric for assessment of the status of riffle macroinvertebrate
communities. Successful application of the approach, however, requires biologically meaningful river types with a sufficient
pool of reference sites for each type. 相似文献
42.
113 Fishes (pike, vendace and roach) samples were analyzed for chlordane, PCB-and DDT-compounds. The average concentrations in pike () muscle tissue in Finnish lakes were 0.05, 0.01 and 0.01 mg/kg wet weight for PCB compounds, total DDT and chlordanes respectively. The results show that chlordanes are evenly distributed in the Finnish environment which indicate that the main part of chlordanes in Finnish fish is due to long range transportation. 相似文献
43.
Pirjo Peltonen-Sainio Tapio Salo Lauri Jauhiainen Heikki Lehtonen Elina Sievil?inen 《Ambio》2015,44(6):544-556
The Finnish agri-environmental program (AEP) has been in operation for 20 years with >90 % farmer commitment. This study aimed to establish whether reduced nitrogen (N) and phosphorus (P) use has impacted spring cereal yields and quality based on comprehensive follow-up studies and long-term experiments. We found that the gap between genetic yield potential and attained yield has increased after the AEP was imposed. However, many contemporary changes in agricultural practices, driven by changes in prices and farm subsidies, also including the AEP, were likely reasons, together with reduced N, but not phosphorus use. Such overall changes in crop management coincided with stagnation or decline in yields and adverse changes in quality, but yield-removed N increased and residual N decreased. Further studies are needed to assess whether all the changes are environmentally, economically, and socially sustainable, and acceptable, in the long run. The concept of sustainable intensification is worth considering as a means to develop northern European agricultural systems to combine environmental benefits with productivity.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0637-9) contains supplementary material, which is available to authorized users. 相似文献44.
Soil acidity, nutrient availability and livestock density have a major influence on the belowground ecological community. As fast decomposition rates are due mostly to bacterial-based pathways and slower decomposition rates mostly to fungal-based pathways, it is helpful to condense empirical information in the so-called Nematode Channel Ratio (NCR). The NCR is shown to be a good indicator of efficiency in soil decomposition processes. We argue that in intensive agroecosystems, other fungivore members of the decomposer food web may outcompete the hyphal-feeding nematodes. We demonstrate how the NCR can be used to set ecological standards for sustainable use of the soil in agroecosystems. To summarize the interactions between the microbial resources and the decomposer nematofauna according to increasing land management, we propose the use of the fifth percentile as proxy for a sustainable environmental quality of grasslands on sandy soils, and the NCR mean as the upper threshold for low-stocked farms. 相似文献
45.
K. K. Lehtonen 《Marine Biology》1996,126(4):645-654
Seasonal variations in the oxygen uptake rate (
) and ammonia excretion rate (
) of the benthic deposit-feeding amphipod Monoporeia affinis vere studied in an open-sea population of the northern Baltic Sea during three consecutive years (1991 to 1993). In the early summer an increase in the weightspecific
by 22% (standard 1-mg individual) was registered; an even more striking change was noted in the
, which showed an increase in the early summer of ca. six times the extremely low winter/spring valnes. The metabolic changes observed could not be attributed to temperature, which remained at steadystate throughout the year, nor could seasonal variations in the biochemical composition of the amphipods explain the results. Therefor, it is evident that quality-food abundance following the sedimentation of the spring phytoplankton bloom induces the observed early-summer elevations in
and
. In turn, the marked decrease in the
towards autumn reflects the gradual depletion of quality-food in the benthic environment. Atomic O: N ratios indicated that at the sampling location, M. affinis uses lipid almost exclusively for metabolic energy throughout the year, except in early summer when the use of lipid and protein was observed to be almost equal. Results also indicated a time-lag between sedimentation of the phytoplankton bloom and metabolic response in the amphipod population. 相似文献
46.
47.
Topi K. Lehtonen Bob B. M. Wong P. Andreas Svensson Axel Meyer 《Behavioral ecology and sociobiology》2011,65(4):613-619
In many taxa, parental strategies can vary among individuals. This is especially true in species with biparental care, with
males, more often than females, deserting their mates. While there is an abundance of theoretical predictions and empirical
data on factors inducing mate abandonment by males, much less is known about what consequences this may have on female behaviour,
particularly in the field and in non-avian systems. Here, we compared brood defence rate, behavioural defence types, and brood
success of solitary and paired females in two species of Neotropical cichlid fish in their natural habitat. In terms of the
rate of territorial aggression towards potential brood predators, solitary females were able to fully compensate in the absence
of a male but, in so doing, ended up maintaining smaller territories, which appeared to compromise offspring fitness in at
least one of the two species. Hence, our results suggest that even extensive quantitative compensation in parental effort
by solitary females may not be enough to ensure adequate qualitative compensation for the lack of male participation, highlighting
the importance of distinguishing between these two aspects of compensatory parental care. 相似文献
48.
49.
A conflict over male production arises in social insects where workers are able to lay unfertilized male eggs. This happens
because each female (queen or worker) is most closely related to her own sons and is thus predicted to reproduce. The conflict
is modulated by worker policing where workers prevent each other from reproducing by aggression or egg cannibalism. In this
study, we show that in the ant Formica fusca, worker policing occurs by egg cannibalism rather than by overt aggression among workers. Furthermore, we show that, contrary
to bees, wasps and other ant species, egg discrimination in F. fusca is not based only on a universal queen signature chemical and that nest mate recognition of eggs occurs. 相似文献
50.
The profiles of chlorinated terpenes in Finnish environmental samples were compared by GLC-SIM technique with those of toxaphene and Eastern European “dark”. The profiles in the seal blubber in the Northern and in the Eastern Baltic Sea proved to be similar. Chlorinated terpenes were found to be present in Finnish human milk.The spent bleach liquor of pine kraft pulp mill contained components having similar retention times and responses to those from toxaphene components. 相似文献