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121.
Fish recruitment, dispersal, and trophic interactions in a heterogeneous lotic environment 总被引:1,自引:0,他引:1
Isaac J. Schlosser 《Oecologia》1998,113(2):260-268
I examine how dispersal of juvenile creek chubs (Semotilusatromaculatus) from beaver ponds into adjacent stream environments interacts with temporal abiotic variability to influence fish foraging,
growth, and long-term persistence in the lotic ecosystem. Minnow trapping in upstream and downstream beaver ponds, along with
weir traps used to monitor directional movement, indicated that most chubs colonized the stream from the downstream beaver
pond. Large annual fluctuations in density of age 0 creek chubs occurred in the stream over a 10-year sampling period. Multiple
regression analysis indicated that stream temperature, precipitation, and the density of reproductive creek chubs were not
correlated with summer density of age 0 chubs in the stream. The factor most strongly associated with increased density of
age 0 creek chubs was creation of the downstream beaver pond during the 6th–7th years of the study, suggesting dispersal from
the pond was the primary factor determining age 0 fish density in the stream. Most individuals in the strong year classes
neither persisted in the stream through their first winter nor resulted in an increased abundance of older age classes in
later years. Comparison of age 0 fish density in summer to the proportion of fish surviving to age 1 in spring suggested that
overwinter mortality was density dependent. Furthermore, a comparison of the size structure for age 0 individuals in summer
to age 1 individuals the following spring indicated that winter mortality was size dependent. Experiments in an artificial
stream adjacent to the natural channel revealed that fish growth was strongly density dependent, decreasing as fish density
increased across both spring and summer, and elevated and low discharge. The decline in invertebrate prey captured by the
fish and the subsequent decline in fish growth appeared to be particularly pronounced under low discharge in summer. Changes
in juvenile creek chub density had no significant effect on benthic insect or crustacean abundance, suggesting that exploitative
competition for limited invertebrate drift resources was a more important cause of density- dependent growth than depressed
local benthic invertebrate abundance. These results suggest that lotic regions adjacent to beaver ponds act as potential reproductive
“sinks” for dispersing juveniles confronting seasonal and flow-mediated restrictions on resource acquisition and growth, and
the occurrence of seasonal bottlenecks to their survival, especially harsh winter conditions.
Received: 9 September 1996 / Accepted: 8 August 1997 相似文献
122.
Maya Nustorova Diana Braikova Adriana Gousterova Evgenia Vasileva-Tonkova Peter Nedkov 《World journal of microbiology & biotechnology》2006,22(4):383-390
Summary The effect of adding alkaline hydrolysate of sheep’s wool waste on the chemical and microbiological properties of a park soil
(Sofia, Bulgaria) has been assessed in a 9 month laboratory experiment. The waste product contained 75–80% water-soluble materials:
peptides, amino acids, salts, dyes, lipids, some carbohydrates, potassium ions, and it seemed likely that the hydrolysate
obtained could be used as a harmless and valuable fertilizer in agriculture. It was demonstrated that the organic material
positively influenced microbial soil populations and ryegrass growth. As the remaining partially degraded keratin is highly
dispersed it should act as a slow release fertilizer thus feeding plants additionally. The results suggest that the wool hydrolysate
is beneficial for improving soil characteristics and could successfully be used as alternative biofertilizer. The authors
hope that by utilization of the keratin wastes, the environment around leather and fur plants could be influenced positively
and that the expense of removing the wastes to controlled landfill sites and part of the expenses for sustaining the latter
will be saved. 相似文献
123.
光合细菌产氢条件的研究 总被引:15,自引:0,他引:15
从被有机物污染的土壤及水域中分离得到13株属于红螺菌科的光合细菌,对其在苹果酸、乳酸、葡萄糖、乙酸、丙酸及丁酸中的光致产氢现象进行了研究。最高产氢量为39.8ml·20ml菌液~(-1)·48h~(-1),产氢活性为7.8ml·g生物量~(-1)·h~(-1)”。底物对不同菌株的产氢量与产氢活性均具有影响,pH对产氢过程也有明显的作用,大于6000lx的光强度对提高产氢活性已无明显作用。固定化细胞在静态培养条件下也能提高产氢能力,但延长产氢时间的作用不明显。 相似文献
124.
Rex Sallabanks 《Oecologia》1992,91(2):296-304
Summary The fate of fruits from a population of European hawthorn (Crataegus monogyna) in western Oregon, USA, was examined over a two-year period. Only one frugivore, the American robin (Turdus migratorius) foraged on the C. monogyna fruits, making this an unusually straightforward fruit-frugivore system. Dispersal efficiency was low, with an average 21% of seeds being dispersed (carried away from parent plants) each year; the most common fate of fruits was to simply fall. Robins dropped 20% of the fruits that they picked, and defecated/regurgitated 40% of the fruits (seeds) that they swallowed, beneath parent plants. One trait, gruit abundance, strongly affected the probability of bush visitation by robins, bushes with larger fruit displays being preferred. Both absolute dispersal success (number of seeds) and dispersal efficiency (proportion of seeds; success per propagule) were also found to be correlated most strongly with initial fruit abundance. Individual plant fecundity and fruit quality were found to vary little between years; as a result, dispersal efficiencies for individual plants were also annully consistent. Larger (older) plants produced more fruits and therefore had higher fitness. These results suggest that the optimal fruiting strategy for C. monogyna is therefore to get as big as possible as quickly as possible by delaying fruiting until later in life. 相似文献
125.
Pichler M Knicker H Kögel-Knabner I 《Journal of industrial microbiology & biotechnology》2001,26(1-2):83-89
In Central Europe, composting and anaerobic digestion of municipal solid waste (MSW) is used as pretreatment before landfilling
to reduce landfill emissions. MSW samples were analyzed before, during, and after pretreatment to assess the stability of
the organic matter. Chemolytic, nuclear magnetic resonance (NMR) spectroscopic, and respiration parameters were correlated
to evaluate a substitution of the time-consuming respiration analysis by chemical parameters. 13C cross polarization magic angle spinning (CPMAS) NMR spectroscopy showed a preferential biodegradation of O-alkyl carbon
(carbohydrates) and a selective accumulation of plastics during all pretreatments, confirming findings from chemolytic analyses.
Principal component analysis exhibited a strong association between the respiration rate, the carbohydrate content, and the
O-alkyl C content, corroborating that carbohydrates are the most important compounds of MSW with regard to the emission potential.
Rank correlation (Spearman) also showed strong relationships between the respiration rate and the content of carbohydrates
(r=0.75) and of O-alkyl C (r=0.72). Journal of Industrial Microbiology & Biotechnology (2001) 26, 83–89.
Received 20 April 2000/ Accepted in revised form 21 July 2000 相似文献
126.
Rhizopus arrhizus, strain DAR 36017, produced L(+)-lactic acid in a simultaneous saccharification and fermentation process using starch waste effluents. Lactic acid at 19.5-44.3 g l(-1) with a yield of 0.85-0.96 g g(-1) was produced in 40 h using 20-60 g starch l(-1). Supplementation of nitrogen source may be unnecessary if potato or corn starch waste effluent was used as a production medium. 相似文献
127.
Daphnia pulex clones originating from twelve small pond habitats were exposed to chemical cues from a size-selective predator, larvae of the phantom midge Chaoborus. Exposure delayed the onset of reproduction and increased the size at first reproduction. On the other hand, the neonates produced by these larger mothers were slightly smaller than the neonates produced by the smaller control mothers. In cladocerans, neonate size is usually positively correlated to the size of the mother. Thus exposure to Chaoborus kairomone apparently had direct effects on neonate size counterbalancing the maternal effects. Daphnia clones collected from Chaoborus-free and Chaoborus-rich environments exhibited different responses. In first adult instar, the clones from Chaoborus inhabited environments increased their offspring size under Chaoborus exposure whereas clones from Chaoborus-free environments did not. This may reflect clonal adaptation to the predation prehistory of their original habitat since larger neonates more quickly reach a size protected from the predator. 相似文献
128.
The biogeochemical processes that drive nutrient transformations and recycling in organic marine sediment-water environments were studied for 17 months in a zero-effluent intensive recirculating culture system. The system consisted of a 10 m3 gilthead seabream (Sparus aurata) tank coupled to aerobic and anaerobic water treatment elements. Nutrients and alkalinity were measured in the system to quantify the main biogeochemical processes. Fractions of the carbon fed in feed were found in fish (18.3%) and in sludge (11%); the missing carbon was respired by fish (45%) and by aerobic (8.4%) and anaerobic (7.7%) microorganisms. Fractions of the nitrogen fed in feed were found in fish (15.4%) and in sludge (14.3%); the missing nitrogen was eliminated by nitrification-denitrification. Most of the phosphorus and ash fed in feed and not found in fish accumulated within the sludge in the system. The rates of nitrification, denitrification and sulphate reduction increased with time, reaching 0.3 g N m− 2 d− 1, 53 g N m− 2 d− 1 and 145 g S m− 2 d− 1, respectively. Nitrification developed more rapidly than denitrification, leading at first to nitrate accumulation (to 20 mmol NO3 l− 1 by day 200) and a decrease in alkalinity. Once denitrification surpassed nitrification, nitrate concentrations decreased, eventually being reduced to < 0.3 mmol NO3 l− 1 by day 510, and alkalinity stabilized. Toxic hydrogen sulphide, generated within the anaerobic sludge, was oxidized by oxygen and nitrate as it diffused through the anaerobic-aerobic sediment-water interface. When nitrate levels in the water above the sludge dropped below 2 mmol l− 1, sulphide was also oxidized in the fluidized bed reactor. Denitrification reduced nitrate in the water, respired (jointly with sulphate reduction) carbon in the sludge, oxidized the hydrogen sulphide, and contributed to stabilization of alkalinity and accumulation of polyphosphate in bacteria as a major sink of labile P. 相似文献
129.
130.
Ying Xiong Chaitanya Raj Adhikari Hidetaka Kawakita Keisuke Ohto Katsutoshi Inoue Hiroyuki Harada 《Bioresource technology》2009,100(18):4083-4089
Persimmon waste was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named DMA persimmon waste gel (DMA-PW). It was found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) in hydrochloric acid medium. In contrast, base metals such as Cu(II), Zn(II), Fe(III), and Ni(II) were not practically adsorbed. The formation of ion pairs of the metal chloro complex anions with the protonated adsorption gels was proposed as the main adsorption process. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 5.63 mol/kg dry gel and comparable capacities, i.e., 0.42 and 0.28 mol/kg for Pd(II) and Pt(IV), respectively. According to the kinetic and electrochemical studies, the adsorption rate of Au(III) was greatly enhanced by the chemical modification. Also, its excellent adsorption characteristics for the precious metals were confirmed by adsorption and elution tests using a column packed with the DMA-PW gel. 相似文献