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211.
A long term observation on biodiversity and biomass of benthic macroalgae in Point 1 of the intertidal zone of the Nanji Islands, Zhejiang were carried out during 1959–2007, including three phases, i.e. 1959–1965, 1980–1985 and 2000–2007. The results show that the species of the benthic macroalgae there disappeared by 41.7%, and decreasing trend of the biodiversity has been getting quick; the community structure clearly shifted, i.e. the proportion of subtropical and warm-temperate species increased, and that of cold-temperate species decreased in the benthic macroalgae assemblage, particularly the calcareous nullipore became an absolutely dominant group. In comparison with the second phase (1980–1985), during the third phase the average annual biomass of the benthic macroalgae decreased by 52.5%; the average spring and winter biomass decreased by 54.1% and 87.2%; while the average summer and autumn biomass increased by 11.1% and 3.2%, respectively. The causes of the decrease in the biodiversity have been discussed, and the authors considered that the climate change and increase in CO2 concentration have been the main reasons to lead berserk growth of the nullipore, resulting in desertification tendency of the intertidal zone of the Nanji Islands. 相似文献
212.
Didier Dogley 《Biotropica》2010,42(5):572-575
The Seychelles has undergone major socio-economic and political changes during the past four decades. Tourism and fisheries, being the mainstay of the country's economy, have positively impacted upon and influenced the form of institution framework and policies in the management of the environment and biodiversity. The Department of Environment, the organization responsible for biodiversity conservation, has changed its core functions over the years to accommodate its obligations under international conventions and again more recently because of a major economic reform program. The creation of several authorities and agencies has resulted in new challenges but at the same time opened up new opportunities. Despite all these changes, the government, with the support of international and local stakeholders, has persevered to safeguard its biodiversity. 相似文献
213.
Shinji Kirihara Toshiki Nakamura Naoto Kon Daisuke Fujita Masahiro Notoya 《Journal of applied phycology》2006,18(3-5):521-527
The Cape Ohma region of Shimokita Peninsula, the northernmost point of Honshu Island, Japan, is subject to both the warm Tsugaru Current and the cold Kurile Current. As a result, the Laminarialean flora includes both cold temperature species (Laminaria japonica Areschoug, Kjellmaniella crassifolia Miyabe and Costaria costata (C. Agardh) Saunders) and warm temperature species (Undaria
peterseniana (Kjellman) Okamura, Ecklonia stolonifera Okamura), as well as Undaria
pinnatifida (Yendo) Okamura, which is distributed in both waters. The frequency of occurrence (as a measure of distribution) and the biomass of these species were recorded in June 1976 (at 50 points in depths between 8–30 m), July 1988 (192 points, 2.5–25 m) and July 2001 (78 points, 2.5–25 m). Comparison of these data revealed a decrease in cold temperature species and an increase in warm temperature species from 1976 or 1988 to 2001. Long-term data of seawater temperature measured at 5 m depth near the study site showed that mean temperatures in the middle of winter (late January to February) in 1989–2000 were 0.9–1.1 ∘C higher than those in 1980–1988. Higher seawater temperatures in the last decade appear to have affected the frequency of occurrence and biomass of the Laminarialean species along the coasts of Cape Ohma. This result supported our previous conclusion that 1 ∘C higher mean seawater temperature in late January caused a decrease in the biomass of L. japonica (by ca. 64%) along the same coast. 相似文献
214.
Verushka Valsecchi Willy Tinner Walter Finsinger Brigitta Ammann 《Vegetation History and Archaeobotany》2006,15(2):99-113
Lake-sediment records were used to reconstruct human impact on the landscape around Lago Lucone (45°33′N, 10°29′E, 249 m a.s.l.),
a former lake in the western amphitheatre system of the Lago di Garda. Presence of prehistoric human populations is attested
by pile-dwelling settlements from the Early-Middle Bronze Age, with one settlement at a distance of only 100 m from the coring
site. Pollen, plant-macrofossil and microscopic charcoal analyses were applied to a 250 cm sediment core with four dates providing
the time control. A mixed oak forest that was important during the Early-Middle Holocene was cleared and replaced by open
vegetation during the Bronze Age (∼2000–1100 b.c.) when open lands were estimated to have covered more than 60% of the total relevant pollen-source area. During a phase of
high human impact, independent climatic proxies suggest warm and dry climatic conditions. Later, ca. 1100 b.c., palaeobotanical evidence indicates a sharp decrease in human pressure in the Lago Lucone area. The comparison with other
sedimentary palaeocultural records shows that the period 1300–1100 b.c. was characterised by general declines of agricultural activities both south and north of the Alps. These declines have been
previously attributed to a change towards wetter and colder climatic conditions in and around the Alps. However, the decline
in human impact around Lago Lucone cannot be exclusively attributed to climatic variation. Therefore other forcing factors
independent of climatic changes, such as cultural crises or changes in spatial organisation of the habitats, cannot be ruled
out under the present state of knowledge. 相似文献
215.
The African rhombic egg eater (Dasypeltis scabra) is a colubrid snake feeding exclusively on bird eggs. Frequency of feeding is governed by the seasonal availability of bird eggs; i.e., long fasting intervals change with relatively short periods when plenty of food is available. Intermittent feeding snakes show a remarkable postprandial increase of metabolic rate and digestive organ size. The postprandial increase in metabolic rate (specific dynamic action, SDA) in snakes is affected by meal size, temperature, and meal composition. A major portion of SDA in snakes is allocated to gastric function and the breakdown of the meal. We hypothesize that SDA in egg eaters is lower than in other snake species, because egg eaters feed on “liquid” food that does not require enzymatic breakdown in the stomach. We also hypothesized that other components of the postprandial response of egg eaters (e.g., size changes of the intestine and the liver) do not differ from other snakes. The standard metabolic rate and metabolic response to feeding were measured using closed-chamber respirometry. Size changes of small intestine and liver were measured using high-resolution transcutaneous ultrasonography. Standard metabolic rates of fasting egg eaters were in the same range of mass specific values as known from other snakes. Within 24 h after feeding, oxygen consumption doubled and peaked at 2 days after feeding. At the same time, the size of the small intestine and the cross-sectional diameter of the liver increased. Within 2 days after feeding, the size of the mucosal epithelium doubled its thickness. Liver size increased significantly within 24 h reaching maximum size 2–4 days after feeding. The size of both organs returned to fasting values within 7–10 days after feeding. The postprandial response of African rhombic egg eaters shows the same pattern and dynamics as known from other snake species. However, the factorial increase of metabolic rate during SDA is the lowest reported for any snake. A comparison with literature data supports the idea that SDA is mainly determined by gastric function and that it is low in egg eaters because they do not have to break down solid meals in the stomach as other snake species do. 相似文献
216.
Forti G Agostiano A Barbato R Bassi R Brugnoli E Finazzi G Garlaschi FM Jennings RC Melandri BA Trotta M Venturoli G Zanetti G Zannoni D Zucchelli G 《Photosynthesis research》2006,88(3):211-240
This historical review was compiled and edited by Giorgio Forti, whereas the other authors of the different sections are listed alphabetically after his name, below the title of the paper; they are also listed in the individual sections. This review deals with the research on photosynthesis performed in several Italian laboratories during the last 50 years; it includes research done, in collaboration, at several international laboratories, particularly USA, UK, Switzerland, Hungary, Germany, France, Finland, Denmark, and Austria. Wherever pertinent, references are provided, especially to other historical papers in Govindjee et al. [Govindjee, Beatty JT, Gest H, Allen JF (eds) (2005) Discoveries in Photosynthesis. Springer, Dordrecht]. This paper covers the physical and chemical events starting with the absorption of a quantum of light by a pigment molecule to the conversion of the radiation energy into the stable chemical forms of the reducing power and of ATP. It describes the work done on the structure, function and regulation of the photosynthetic apparatus in higher plants, unicellular algae and␣in photosynthetic bacteria. Phenomena such as photoinhibition and the protection from it are also included. Research in biophysics of photosynthesis in Padova (Italy) is discussed by G.M. Giacometti and G.␣Giacometti (2006). 相似文献
217.
Succession of bacterial community composition over two consecutive years in two aquatic systems: a natural lake and a lake-reservoir 总被引:1,自引:0,他引:1
The succession in bacterial community composition was studied over two years in the epilimnion and hypolimnion of two freshwater systems: a natural lake (Pavin Lake) and a lake-reservoir (Sep Reservoir). The bacterial community composition was determined by cloning-sequencing of 16S rRNA and by terminal restriction fragment length polymorphism. Despite large hydrogeological differences, in the Sep Reservoir and Pavin Lake the dominant bacteria were from the same taxonomic divisions, particularly Actinobacteria and Betaproteobacteria. In both ecosystems, these major bacterial divisions showed temporal fluctuations that were much less marked than those occurring at a finer phylogenetic scale. Nutrient availability and mortality factors, the nature of which differed from one lake to another, covaried with the temporal variations in the bacterial community composition at all sampling depths, whereas factors related to seasonal forces (temperature and outflow for Sep Reservoir) seemed to account only for the variation of the hypolimnion bacterial community composition. No seasonal reproducibility in temporal evolution of bacterial community from one year to the next was observed. 相似文献
218.
Koyu A Gokcimen A Ozguner F Bayram DS Kocak A 《Molecular and cellular biochemistry》2006,284(1-2):81-85
Abstact Cadmium is one of the most toxic pollutants in environment. Cadmium accumulation in blood affects the renal cortex and causes
renal failure. In this study, we aimed to evaluate the effects of cadmium on rat liver tissue. Eighteen male albino rats aged
ten weeks old were used in the study. 15 ppm of cadmium was administered to rats via consumption water daily. At the end of
the 30th study day, the animals were killed under ether anesthesia. After the liver tissue samples were taken, histopathological
and biochemical examinations were performed. Histopathologic changes have included vacuolar and granular degenerations in
hepatocytes, heterochromatic nucleuses and sinusoidal and portal widenings. Central vein diameters were normal in cadmium
exposed group. Whereas, there was statistically significant difference between two groups by means of sinusoidal (p< 0.001) and portal triad diameters (p< 0.01). Malondialdehyde (MDA) is an indicator of lipid peroxidation. In this study, MDA was used as a marker of oxidative
stress-induced liver impairment in cadmium exposed rats. Superoxide dismutase (SOD) and catalase (CAT) activities were also
measured to evaluate the changes in antioxidative system in liver tissues. Current findings showed that MDA levels were increased
and SOD and CAT activities were decreased in cadmium exposed group compared to control group. The difference between two groups
was statistically significant (pvalues: MDA,p< 0.01; CAT,p< 0.01 and SOD,p< 0.05). In conclusion, these findings suggest the role of oxidative mechanisms in cadmium-induced liver tissue damage 相似文献
219.
Conformational changes of beta-lactoglobulin (beta-LG) induced by anionic phospholipid (dimyristoylphosphatidylglycerol, DMPG) at physiological conditions (pH 7.0) have been investigated by UV-VIS, circular dichroism (CD) and fluorescence spectra. The experimental results suggest that beta-LG-DMPG interactions cause beta-LG a structural reorganization of the secondary structure elements accompanied by an increase in alpha-helical content, and a loosening of the protein tertiary structure. The interaction forces between beta-LG and DMPG are further evaluated by fluorescence spectra. The fluorescence spectral data show that conformational changes in the protein are driven by electrostatic interaction at first, then by hydrophobic interaction between a protein with a negative net charge and a negatively charged phospholipid. 相似文献
220.
Annually laminated lake sediments and environmental changes in Bashang Plateau, North China 总被引:2,自引:0,他引:2
Qiumin Zhai Zhiyong Guo Rongquan Li 《Palaeogeography, Palaeoclimatology, Palaeoecology》2006,241(1):95-102
Angulinuo Lake is the biggest lake on the Bashang Plateau, North China, and is 47.6 km2 in area and 2-6 m in depth. A core from the inner part of Angulinuo Lake was sliced and the sediment was observed by Scanning Electronic Microscope (SEM). Annual laminations characterized by variable color and grain size were found and interpreted as recording the cyclic deposition of lacustrine clay and aeolian dust. The results of chemical analysis of coarse grains conducted by SEM-EDAX, and grain size analysis of modern aeolian dust in the ice on Angulinuo Lake, support an aeolian origin for the light coarse layers. Image analysis technique was used to calculate the size and number of coarse grains in each layer. The coarse grains were fractionated into four classes: > 42 μm, 14-42 μm, 14-4.2 μm and 1.4-4.2 μm. In general, the abundance of the four classes shows similar temporal variation patterns. Around Angulinuo Lake, the winter monsoon is strong and transports aeolian dust into the lake. When the winter monsoon is strong, the size and amount of coarse grains are expected to increase. We infer that the winter monsoon was weaker during 8430-5440 year BP, and was unstable in the later part of this period. From 5440 year BP, the winter monsoon became stronger, and then weaker from 3250 to 2490 year BP. During 2490-1170 year BP, the winter monsoon was slightly stronger, but since 1170 year BP, it has become weaker again. The changes of the winter monsoon intensity recorded in the annual laminations in Angulinuo Lake sediments correspond well to environmental changes in North China and to changes in sea level during the same period. Periods of weaker winter monsoon correspond to times of higher sea levels while the periods of stronger winter monsoon correspond to the Neoglaciation stage in China and the periods of lower sea levels. 相似文献