The importance of the riparian ecotone and river hydraulics for sustainable basin-scale restoration scenarios

1. The effect of riparian ecotone functional complexity and stream hydraulics on an upland river ecosystem has been analysed. 2. The amount of nutrients retained by bottom sediment was lowest on a sandy substrate (range: 26–104 mg m⁻² P-PO₄) and highest in wetland bays (range: 558–5368 mg m⁻² P-PO₄). A stream bed covered by Berula erecta had about three times higher retentive nutrient capacity ( x̄ = 584 mg m⁻² day⁻¹) than did a sandy substrate( x̄ = 205 mg m⁻² day⁻¹). 3. The amount of allochthonous organic matter (CPOM) deposited on the stream bed decreased with current velocity. The trophic potential of CPOM, measured as total protein, was significantly correlated with the amount of deposited CPOM (r = 0.863; p<0.00001) and depended on stream order. 4. Both invertebrate and fish biomass in the upland river were significantly correlated with calcium/bicarbonate (benthos: r = 0.858; p<0.006; fish: r = 0.918; p<0.001). 5. Fish biomass, diversity and species richness were highest in pools, lower in riffles and lowest in the run/transition zone. 6. Macroinvertebrate biomass was highest at an intermediate riparian ecotone complexity with an adequate supply of organic matter and incident light. Fish biomass followed the same trend, being lowest in heavily shaded areas and in open channels without riparian vegetation (range: 1–4.5 g m⁻²), but highest in ecotones of intermediate complexity (range: 1.6–92.8 g m⁻²). The ‘cascading effect’ of invertebrate density depletion, which was inversely related to fish biomass, was observed seasonally. 7. The above results indicate that riparian ecotone structure and the heterogeneity of the stream channel may regulate biodiversity, productivity and nutrient retention in the fluvial corridor. These quantitative data help to create alternative scenarios for sustainable river basin management. © 1998 John Wiley & Sons, Ltd.     

Glochidial infestation of fish by the endangered thick‐shelled river mussel Unio crassus

相似文献   

Early development and allometric growth in hatchery‐reared Eurasian perch,Perca fluviatilis L.

The morphological development and allometric growth patterns of Eurasian perch, Perca fluviatilis L., a highly valued commercial species, were studied under intensive rearing conditions from hatching up to 50 DPH (Days Post Hatch). Based on the external morphology, four different phases during early development of Eurasian perch were identified: pre‐flexion larva 0–20 DPH (5.70–10.16 mm TL); flexion larva 22–30 DPH (11.09–15.14 mm TL) and post‐flexion larva/juvenile 32–50 DPH (18.00–24.75 mm TL). The results indicate that growth period when final replacement of all temporary (larval) structures and most important changes in the shape of P. fluviatilis occurred (between 13.95 and 24.06 mm TL, during flexion and post‐flexion phase) can be considered as a transitional period between the larva and juvenile. All body segments, except trunk length and tail length showed fast growth (positive allometry) throughout the entire studied period or up to the respective inflexion point with a common tendency to isometry. In addition, the specific behaviours (e.g. pelagic way of life) of Eurasian perch larvae resulted in some characteristic allometric growth patterns in the posterior region, different from the majority of other teleosts. The results are discussed with respect to the ontogeny of the functional morphology under both ecological and aquaculture considerations.     

Bound amino acids in humic acids from arable cropping systems

We investigated the varying concentrations of bound amino acids in humic acids (HA) extracted from soils under both crop rotation and continuous cropping of rye. The experiment was created in 1957. Since then, winter rye had been grown continuously and also the sequence of the 7 yr rotation had been started: potato, spring barley, alfalfa, alfalfa, oil seed rape, winter rye, and winter rye. Soils were fertilized with NPK and manure. Continuous cropping of rye increased total acidity of soils and the contents of carboxylic and phenolic groups in HA. The total amounts of the bound amino acids in HA from soils under crop rotation were higher than from continuous cropping of rye. Fertilization with NPK increased the contents of bound amino acids more than manure. Neutral amino acids dominated in all samples of HA, and basic amino acids had the lowest concentrations. In both types of cultivation, glutamic acids, glycine, alanine, valine, and lysine dominated. The proline contents in HA from continuous rye cropping were higher than in HA from soils under crop rotation. The concentrations of β‐alanine and lysine were higher in HA from crop rotation indicating a higher microbial biomass since these compounds are typical constituents of bacteria cell walls.     

Carrot root size distribution in response to biostimulant application

In 2009–2011, in Poland (53°13′N, 17°51′E), field experiments were conducted concerning the influence of biostimulants Kelpak SL and Asahi SL on the size grades of yield of carrot cv. ‘Karotan’. Kelpak SL is produced from seaweed Ecklonia maxima; Asahi SL is composed of nitrophenols. Biostimulants were sprayed from fourth-leaf stage of carrot, once, twice or three times in growing period. Seaweed extract was used at total doses of: 0, 2, 3, 4, 5, 6 and 7?l?ha^?1, while Asahi SL at 1?l?ha^?1. It was found that biostimulants had a favourable effect on total and commercial root yield, but this effect was dependent on the type of preparation, the dose, the time and the number of treatments. The best results in increasing the commercial yield were achieved after a single application of Kelpak SL at doses 2 or 3?l?ha^?1 at the fourth-leaf stage (13.1% and 12.4% respectively, compared to the control). Both biostimulants Kelpak SL and Asahi SL positively affected the root size distribution by increasing the yield of medium roots (1.9–3.8?cm in diameter) as well as large roots (3.8–5.0?cm), by 30.5% and 15.8%, respectively.     

The Impact of Fertilization Methods on the Nutrient Balance and Changes of Soil Chemical Features in Crop Rotation

The effect of various fertilization methods on the simplified nutrients balance and changes of soil chemical features in crop rotation was estimated on the basis of 7-year (1994-2000) studies carried out on loess-based, sedimentary-gley, light-clay soil. Different fertilization methods were used: A - mineral fertilization; B - mineral and manure fertilization; C - straw, green manure and mineral fertilization; D - ecological compost and biodynamic preparation fertilization. Particular fertilization methods caused a significant differentiation of the nutrients balance. A positive phosphorus balance was found out in all the fertilization systems. It has been observed that the nitrogen and potassium carry-in with fertilizers was higher than the carry-out with crops in system B and C. A favorable calcium balance was achieved in systems C and D while a favorable magnesium balance - only in the ecologically fertilized systems (D). The changes of soil chemical features were only insignificantly dependent on the nutrient balance. After seven years of research, the contents of humus, phosphorus, potassium, magnesium and calcium increased while the soil reaction decreased in the soil of all the fertilized systems except the ecologically fertilized system.     

Apoptotic cell death in the porcine endometrium during the oestrous cycle

It has been reported that apoptosis plays an essential role in controlling the physiological cell kinetics in the human and rodent endometrium but this type of death has never been studied in the porcine endometrium. The aim of this study was to investigate the apoptotic cell death in the porcine endometrium during the middle (Days 9-11) and late (Day 13) luteal phase, during the luteolysis (Day 15) and early follicular phase (Days 17-19) of the oestrous cycle. Apoptotic cells were identified by in situ DNA 3'-end labelling method. It was revealed that the greatest number of apoptotic cells in the luminal and glandular epithelium was found on Days 17-19 and on Day 15 of the oestrous cycle, respectively. In the stroma, the greatest number of these cells was found on Days 9-11. Our data have shown that in the porcine endometrium, both epithelial and stromal cells undergo apoptosis and that the number of apoptotic cells varies depending on the phase of the oestrous cycle.     

Erythrocyte osmotic fragility test as the measure of defence against free radicals in rabbits of different age

Peroxidation of the unsaturated bonds of membrane lipids increases fragility and cellular lysis of red blood cells. Erythrocyte susceptibility to the free radicals (peroxyl radicals) generated in vitro by 2,2'-azo-bis(2-amidinopropane) hydrochloride (AAPH) was evaluated and expressed as 50% maximal haemolysis time (HT50) in 3 groups of rabbits of different age. Erythrocytes of 1.5-month-old rabbits were more sensitive to free radicals than those of 3.5- and 6-month-old ones. In the three groups, significant negative correlation (r = -0.8 to -0.98) between the lipid peroxidation rate (thiobarbituric acid reactive substances; TBARS concentration) in blood plasma and the erythrocyte resistance to free radicals was found. This result suggests that the plasma antioxidant defence system is interrelated with that of the red blood cells and that the erythrocytes can be a good model for studies of oxidative stress. The simple haemolysis test reflecting the free radical defence can be useful for evaluating the antioxidant properties of various compounds.     

Cono- and seminiphagous insects of Abies alba Mill. in the Gorce National Park in Poland during 1996?–?1998

A study was conducted on the insects infesting seeds and cones of Abies alba Mill. in the Gorce National Park, in southern Poland during 1996–1998. A total of 856 cones were collected from 66 trees growing at 11 sites located in partially or strictly protected forest reserves. Of this sample, 217 cones with 54,958 seeds were dissected. This study yielded 5,816 specimens of insects, namely: seminiphagous Resseliella piceae Seitn., Megastigmus suspectus Borr. as well as conophagous Earomyia impossibile Morge, Barbara herrichiana Obr. and Dioryctria abietella (Den. et Schiff.). The most abundant species was R. piceae with 4,186 individuals. The index of cone infestation was calculated. It showed great variability between forest reserves and study-years. The numbers of insect individuals, numbers of viable and infertile seeds, and seeds damaged by M. suspectus and R. piceae, in both strict and partial reserves in the consecutive years were compared statistically. The test of significant differences between two frequencies at 0.05 level was used in statistical analysis. In both strict and partial reserves, statistically significant differences were found between studied variables.