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1.
The ability of Arizona Common and Coastal Bermuda grass [Cynodon dactylon (L.) Pers.] to synthesize amino acids and proteins during water stress was investigated. Amino acids were continually synthesized during the water stress treatments, but protein synthesis was inhibited and protein levels decreased. 相似文献
2.
根据2008年10月4日至8日北部湾海域生态环境综合调查资料,对北部湾海域小型底栖动物的类群组成、丰度和生物量分布进行了分析研究,结果表明,研究海域的小型底栖动物平均丰度约为399.09±452.20 had·10cm-2,平均生物量约为359.56±324.45μg·10cm-2;按丰度来讲,分选出的14个类群中,自由生活海洋线虫的丰度为最优势,约占总丰度的92.69%,其次为底栖桡足类和多毛类,分别约占总丰度的3.28%和2.47%;线虫、多毛类和桡足类分别约占总生物量的41.16%、38.34%和6.76%。研究海域的钦州、防城港市沿岸海区小型底栖动物平均丰度相对较高,其平均丰度约为614.98±799.63 ind·10cm-2;涠洲岛周边海区和北海南部近岸海区平均丰度分别约为481.68±240.03 ind·10cm-2和278.14±126.38 ind·10cm-2;对照海区的小型底栖动物平均丰度约仅有197.37±116.72 ind·10cm-2。根据各站位小型底栖生物的种类组成及其丰度进行了多样性分析,各站位丰富度指数介于0.466~1.516之间,均匀度指数介于0.203~1.13之间,Shannon-Weiner指数(H')介于0.141~0.783之间。根据类群组成及其丰度进行组平均法聚类分析,把研究海区各站位分成了3个不同的底栖生物群落。研究海区线虫和桡足类丰度的比率变化范围在5.02~223.83之间。 相似文献
3.
The role of meiobenthos in lake ecosystems 总被引:1,自引:0,他引:1
Evgeny A. Kurashov 《Aquatic Ecology》2002,36(3):447-463
It is shown that meiobenthos plays an important role in the secondary production by zoobenthos in lakes, as well as in the degradation of organic matter. In large lakes (Lake Ladoga, Lake Onega, Lake Päijänne, Lake Constance), the ratio of meiobenthic production to the production of macrobenthos is on average 50–61%. In the small Latgalian lakes (Latvia), this proportion is different: in the profundal of these lakes it varies from 92.5% in a naturally clean mesotrophic lake to 0.0004% in the most eutrophic lake, and in the littoral of lakes – from 578–1476% in mesotrophic lakes to 148–306% in eutrophic ones. The level of production of littoral meiobenthos does not depend on the trophic status of the lake, and can be equally high both in undisturbed mesotrophic lakes and in strongly eutrophicated lakes. The intensity of production of the littoral meiobenthos in oligotrophic and mesotrophic lakes, on the one hand, and in eutrophic lakes on the other, are not reliably distinguished. There is a clear tendency for a decrease of the role of profundal meiobenthos with regard to the transformation of energy flows in lake ecosystems, both with an increase in eutrophication and with an increase in the amount of organic matter in the benthal available from phytoplankton. 相似文献
4.
Several new techniques have been developed to allow the geochemical characterization of shallow pore waters in reefs. First,
a new method was developed for using non-metallic well-points to sample pore waters from shallow depths (<1 m) in coral reefs
with unconsolidated substrates. These PVC well-points can be made faster and at less expense than well-points made of stainless
steel. They also eliminate metal contamination and are free from the problems of corrosion in sea water. Additional improvements
in sampling techniques maximize the spatial resolution of geochemical gradients and address the problems of atmospheric contamination
associated with the sampling of dissolved gases. Data taken from Checker Reef, Oahu, Hawaii, illustrate the application of
these methods.
Accepted: 1 December 1999 相似文献
5.
To evaluate the effects of a deposit-feeding bivalve on meiobenthic assemblage structure in muddy habitats, a laboratory experiment was performed at the Askö Laboratory in the northwestern Baltic proper. Microcosms, surface area 104 cm2, containing a c. 7-cm thick layer of sieved (0.5 mm) sublittoral mud were established in June 1990. Two months later the tellinid bivalve Macoma balthica was added in quantities varying from 0 to 40 individuals per microcosm. After 5 months the effects of the bivalves on the meiofauna were surprisingly small. The density of harpacticoid copepods was lowest (P <0.05) in microcosms containing a high density of M. balthica. It is suggested that competition for food resources was responsible for this pattern. For all other meiofaunal groups, including nematodes which were the most abundant taxon (99%), no significant differences (P>0.05) were observed among treatments. The assemblage structure of the nematodes was similar between treatments. The vertical distribution of both major taxa and nematode species appeared to be unaffected by the presence of the bivalve. 相似文献
6.
Water quality is vital to human life and economy. However, one sixth of the world’s population suffers from lack of safe drinking
and domestic water. Aiming to improve the capability of predicting and responding to river pollution disasters, this project
collaborated with local offices of Chinese National Bureau of Water Resource to explore new solutions to coping with the ever-growing
threat of river water pollution. We presented a distributed data analysis algorithm, Infinitesimal Dividing and Analysis,
to efficiently locate pollution sources with data gathered from a ubiquitous wired/wireless sensor network. We elaborate on
a π-calculus based paradigm to enhance collaboration and interaction among individual monitoring stations. Based on these two
enabling technologies, we applied our framework to water quality monitoring at two carefully chosen sites in China. 相似文献
7.
Recent data and opinions on meiofaunal ecology are briefly reviewed; and from scattered data, the place of turbellarians in the meiobenthic community is discussed. Turbellarian diversity, density, and biomass are higher in sandy habitats than in muddy bottoms. In sand, turbellarian diversity is of the same magnitude as that of other important meiofaunal taxa, while densities range between 7–25% of the total meiofauna. Mean individual turbellarian dry weight seems to be four times that of nematodes and in sandy habitats turbellarian biomass may be equal to or excede that of nematodes. Most turbellarian species may be considered as predators and in this respect may take the place occupied by macrofaunal species in muddy sediments. mens.
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8.
Effects of manipulation of food supply on estuarine meiobenthos 总被引:1,自引:0,他引:1
A comparative mesocosm experiment was carried out to determine the effects of natural foods of different quality and quantity on the structure of natural meiobenthic communities collected in undisturbed sediment from the polluted Westerschelde and the comparatively undisturbed Gironde estuaries. Nematode communities are more diverse and species rich in the latter estuary. The organic matter or foods used were phytoplankton, green alga, salt marsh plant detritus and leaf litter detritus which were added at three dose rates including a high dose. There was no change in community structure in response to the treatments in either of the estuarine meiobenthic communities. Analysis of all the results from this experiment indicate that the food quantity manipulations had almost no effect on the deposit feeding meiofauna. It may be that the reserves of organic matter within the sediment were sufficient to satisfy their dietary requirements for the duration of the experiment. The abundance of diatom/epigrowth feeding nematodes which were initially dominant in the Gironde, declined substantially suggesting that they may have been food limited since diatoms were not among the sources of organic matter added to the mesocosm. There was no specific response to the five different types of organic matter added to the mesocosm 相似文献
9.
Small-scale spatial distribution of marine meiobenthos: the effects of decaying macrofauna 总被引:2,自引:0,他引:2
Emil Ólafsson 《Oecologia》1992,90(1):37-42
Summary To evaluate the effects of decaying animals on small-scale horizontal distribution of meiobenthos in muddy habitats, a laboratory experiment was performed at the Askö Laboratory in the northwestern Baltic Sea. A microcosm (35×55×28 cm) containing a ca. 7-cm thick layer of sieved (0.5 mm) sublittoral mud was established in June 1990. Three months later specimens of the bivalve Macoma balthica were collected and killed in boiling water. The sediment inside the microcosm was implanted with empty shell, empty shell and dead animal or left alone. At the end of the experiment (17 days) visual examination of the microcosm revealed black spots at the sediment surface where dead animals had been implanted. The densities of nematodes, the most abundant group (98%), were not significantly different between areas. However total non-nematode fauna was found in much lower numbers (P<0.01) in the black spot areas. A multivariate analysis (detrended correspondence ordination) of nematode species abundance data separated samples from the black spot areas from the others. Of the 25 nematode species recorded in the microcosm, there was a significant difference between areas for four species. The decaying animals clearly attracted Monhystera disjuncta which was almost 6 times as abundant in the black spot areas compared to control and shell areas. Both the overall dominant species, Leptolaimus elegans and Calomicrolaimus honestus were found in lower numbers in the areas of dead Macoma than in control and shell areas. Sabatieria pulchra was found in lower numbers in the control areas compared to shell and dead animal areas. The overall structure of the nematode assemblage indicated a shift to lower dominance in the dead animal areas and it is speculated that decomposing animal tissue may be of primary importance regarding spatial distribution of meiobenthos. 相似文献
10.
Vertical and horizontal distribution of meiofauna was studied off Goa coast. Bottom deposit included mainly fine sand and silt. Total number of animals ranged from 250 to 2925/10 cm2. Highest faunal density was in the top 6 cm layer. The fauna consisted of two main groups, nematodes and foraminiferans which together formed 60 to 80% of the total meiofauna. Fine sand supported a rich fauna. Interstitial water and organic content of the sediment was found to be the limiting factor in the distribution of meiobenthos. 相似文献
11.
Structural characterization of the 60-kDa bermuda grass pollen isoallergens, a covalent flavoprotein
Liaw S Lee DY Chow LP Lau GX Su SN Chow L 《Biochemical and biophysical research communications》2001,280(3):738-743
Our studies suggest a tripartite structure for the 60-kDa allergen of Bermuda grass pollen (BG60) including a short N-terminal segment, a FAD-binding domain, and a C-terminal domain. The lower molecular weight isoallergens lack the N-terminal segment. The higher protease susceptibility and the lower melting temperature of approximately 20 degrees C of the lower molecular weight isoforms suggest that the N-terminal segment is essential for a compact structure. Database screening reveals that the protease-digested peptide sequences (approximately 180 residues in total) share 40% identity with the plant berberine bridge enzymes. In particular, a 24-residue peptide sequence displays high similarity to a conserved FAD-binding motif. The spectroscopic and SDS-PAGE analyses suggest that the cofactor FAD is covalently linked to the central domain. Therefore, we conclude that BG60 is identified as the first flavinylated allergen. 相似文献
12.
The numbers and biomass of meiobenthic invertebrates of nine representative mountain lakes were assessed relative to the macrobenthic invertebrates retained on 0.425 mm mesh. The meiobenthos accounted for an average of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaSGaaeaaca% aIXaaabaGaaG4maaaaaaa!3777!\[{\raise0.7ex\hbox{$1$} \!\mathord{\left/{\vphantom {1 3}}\right.\kern-\nulldelimiterspace}\!\lower0.7ex\hbox{$3$}}\]of the total biomass and 97% of total numbers retained on 0.045 mm mesh. In general surveys in these lakes, the use of 0.250 mm mesh instead of 0.425 mm mesh would be unlikely to improve estimates of total numbers and biomass enough to justify the additional effort needed. Accepting the meiobenthic turnover rate to be three to five times that of the macrobenthos, meiobenthic production is probably close to or much higher than the macrobenthic production in these lakes. 相似文献
13.
Kryvokhyzhyna Mariia Majdi Nabil Oprei Anna Mutz Michael Risse-Buhl Ute 《Hydrobiologia》2022,849(8):1905-1921
Hydrobiologia - Stream sediments move at low flow forming migrating ripples. These ripples can cover substantial areas where benthic communities experience erosion-resting cycles of sand grains.... 相似文献
14.
15.
Understanding the interspecific variation in body size across macroclimatic gradients has been of paramount importance to naturalists and biogeographers. Bergmann’s rule, which describes a trend of increasing body size polewards, is arguably the best-known ecogeographical rule in terrestrial environments but remains largely unexplored in the marine realm. In this study we tested Bergmann's rule in marine ray-finned fishes (Pisces, Actinopterygii), analyzing the relationship between body size and latitude in 5662 species. To examine possible underlying mechanisms, we adopted a cross-species approach to evaluate the association of body size with four predictors: Sea Surface Temperature, Net Primary Productivity, Salinity, and Human impact. We analyzed the relationships between body size and environmental and anthropogenic variables building mixed linear models, which considered the taxonomic structure in the data. We conducted complementary analyses dividing the data into five latitudinal bands. Actinopterygii showed a clear Bergmannian pattern, with the largest species observed in temperate regions, being the first global analysis on ray-finned fishes showing a pattern consistent with Bergmann’s rule. Sea Surface Temperature and Net Primary Productivity were the best predictors, in accordance with the time to sexual maturity and resource availability hypotheses. Our analyses based on latitudinal bands showed a differential response of body size to the environment, with temperature, salinity and human impact more strongly associated with size variation at cold environments. These results agree with previous studies on Bergmann’s rule for terrestrial ectothermic, freshwater and marine fishes. Our findings suggest that temperature rise in the ocean and growing human impact may have effects on the distribution of body size, thus altering ecosystem functioning. Fundamental differences often assumed to exist between marine and terrestrial systems are not so evidently reflected in the emergence of large-scale body size gradients. 相似文献
16.
The predictability of temporal changes was analysed in the population density of three meiobenthic copepod species, and for three parameters characterizing this community. For Paronychocamptus nanus and Tachidius discipes a large part of the variation in time scales longer than 1 year is explainable as cyclic factors. In P. nanus clear cyles with periods of 2 years and 1.5 years were found. These cyclic factors can be extrapolated for prediction. In Canuella perplexa almost all the variation was due to unpredictable long-term drift. Community parameters are generally better predicted than population densities. In our data set total density of the copepods was the best parameter to monitor. Monitoring does not necessitate a strict sampling scheme; irregular quarterly sampling from the P. nanus series showed that the essential features of the series were still discernible. 相似文献
17.
18.
南黄海冬季小型底栖生物丰度和生物量 总被引:5,自引:1,他引:5
分别于2003年1月和2004年1月在南黄海广大陆架浅海水域进行小型底栖生物调查.结果表明,两个航次的小型底栖生物平均丰度分别为 (954.20±269.47) ind·10 cm-2和(1 186.12±486.07) ind·10 cm-2;平均生物量分别为(954.38±403.93)μg·10 cm-2和(1 120.72±487.21) μg·10 cm-2.两个航次小型底栖生物丰度值、生物量和生产力均无显著变化(P>0.05).共鉴定出20个小型底栖生物类群,按丰度,自由生活海洋线虫为最优势类群,两个航次的优势度分别为87%和90%,其他优势类群依次为桡足类、多毛类和动吻类;按生物量依次为线虫34%~38%,多毛类25%~33%,介形类9%~22%,桡足类8%.96.64%的小型生物分布在0~5 cm的表层沉积物内,线虫和桡足类分布在0~2 cm的比例分别为72.48%和89.46%.小型底栖生物的生物量与沉积物砂含量(%)、粉砂含量(%)和叶绿素a含量呈显著相关.代表性站位的种类组成和多样性分析显示了沿岸、黄海冷水团和东、黄海交汇区3个不同的底栖生物群落. 相似文献
19.
The influence of mangrove-derived tannins on intertidal meiobenthos in tropical estuaries 总被引:13,自引:0,他引:13
D. M. Alongi 《Oecologia》1987,71(4):537-540
Summary Mangrove-derived tannins negatively effected laboratory-reared nematode populations and natural communities of meiobenthos in tropical mangrove forests along the northeastern coast of Australia. In the low and mid intertidal zones of five mangrove estuaries, nearly all of the dominant meiofaunal taxa correlated negatively with concentrations of sediment tannins. Only nematodes correlated with low tannin concentrations in the high intertidal zones. The negative exponential equation y=be
-mx
represented the best-fit for most of the meiofauna-tannin relationships. The mangrove-dwelling nematode, Terschellingia longicaudata did not grow (r=0.001) in the laboratory on fresh, tannin-rich leaves of the red mangrove, Rhizophora stylosa. Population growth of the nematode was significantly greater on fresh, tannin-poor leaves of the grey mangrove, Avicennia marina (r=0.081) with best growth (r=0.112) attained on a diet of tannin-free, mixed cereal. These preliminary field and laboratory results suggest that hydrolyzable tannins leached from mangrove roots and leaf litter are an important factor regulating intertidal meiobenthic communities in tropical mangrove forests along the northeastern Australian coast. 相似文献
20.
Seasonal dynamics of population densities and the qualitative composition of meiobenthos were studied in a strait between
Popova and Reineke islands in Amurskii Bay (Sea of Japan). Two peaks of population density were revealed: a spring-summer
peak and an autumn peak. No correlation was found between the depth, qualitative characteristics of the ground, and population
density of meiobenthos. 相似文献