南海北部HY4－901孔浮游有孔虫特征及意义

南海北部ＨＹ４－９０１孔沉积连续、粒度均匀,浮游有孔虫丰富,共鉴定１０属２６种,其中以暖水种占优势,凉水种也有相当含量。浮游有孔虫组合的研究表明,本区的溶解作用不强,不是影响ＣａＣＯ＿３分布的主要因素。全新世的气温变化,可以分为五期：１）迅速升温期,２）高温期,３）降温期,４）温暖期,５）温凉期。     

ULTRASTRUCTURE OF A NEW INTRACELLULAR SYMBIOTIC ALGA FOUND WITHIN PLANKTONIC FORAMINIFERA1

A small intracellular eukaryotic algal symbiont, 1.5–3.5 μm in diameter, occurs abundantly and persistently in nine planktonic Foraminifera host species. This alga is different from the dinoflagellate, from 8–12 μm in diameter, known to occur in the four spinose species Orbulina universa, Globigerinoides sacculifer, G. ruber, and G. conglobatus. Transmission and epifluorescent microscopy were used to confirm the presence cophyta. The evidence supporting this classification includes the presence of a chloroplastic endoplasmic reticulum surrounding the plastids and tubular cristae, as opposed to flattened cristae, in the mitochondria. Three classes of algae may be represented including the Chrysophyceae, Bacillariophyceae, and Prymnesiophyceae. Ultrastructural analysis indicated that the alga in the spinose Globigerinella aequilateralis resembles a prymnesiophyte because the chloroplasts lack a girdle lamella. The algae in the non-spinose species and the short-spined Globigerina cristata resemble endocytic chrysophytes or diatoms because of the presence of a girdle lamella. Ultrastructural characteristics of the chrysophycophycean alga present in planktonic Foraminifera are discussed and compared to those of non-dinoflagellate symbiotic algae associated with other invertebrate hosts.     

Planktonic foraminifera from the eastern Indian Ocean: distribution and ecology in relation to the Western Pacific Warm Pool (WPWP)

Faunal assemblages, principal component (PCA), canonical correspondence (CCA), and factor analysis are applied to planktonic foraminifera from 57 core-top samples from the eastern Indian Ocean. The foraminiferal lysocline occurs at 2400 m north of 15°S where carbonate dissolution is induced by the Java upwelling system, and occurs deeper south of 15°S where carbonate dissolution is characteristic of the oligotrophic regions in the Indian Ocean. Dissolution effects, the February standing stock at the time of collection of the plankton-tow material, and different production rates explain the different foraminiferal assemblages found between plankton-tow and core-top samples. Core-top samples are differentiated by PCA into four groups — Upwelling, Western Pacific Warm Pool (WPWP), Transitional, and Southern — that are related to environmental variables (temperature, salinity and nutrients); all environmental variables follow a strong latitudinal component as indicated by the CCA analysis. Similarly, three assemblages are recognized by factor analysis: Factor 1 (dominated by Globigerinoides sacculifer, G. ruber, Globigerinita glutinata and Globorotalia cultrata), factor 2 (dominated by Globigerina bulloides and Globorotalia inflata) and factor 3 (dominated by Neogloboquadrina dutertrei) explain more than 92% of the variance, and are related to sea-surface temperature, thermocline depth and nutrient levels. The seasonal influence of the Java upwelling system supplies nutrients, phyto- and zooplankton to the oligotrophic eastern Indian Ocean (factor 1). South of 24°S, a deep chlorophyll maximum, a deep euphotic zone, a deep thermocline, SSTs below 22°C, and brief upwelling pulses seem to explain factors 2 and 3. The ratio of G. sacculifer and N. dutertrei, two mutually excluding species, appears to indicate the southern boundary of the WPWP. This ratio is applied to core Fr10/95-11 to demonstrate past shifts of the southern boundary of the WPWP.     

Planktonic rotifers and temperature

The influence of temperature (t) upon rotifer embryonic development rate (D_e) has been analysed using data from the literature, and the author's own results from experimental and natural populations. For Keratella cochlearis (Gosse), within the temperature range of 1–28°C, this relationship is best expressed by the equation: 1/D_e = 0.002 + 0.00025t + 0.000065t².For Brachionus calyciflorus Pallas, between 8°C and 35°C, the best relationship is given by the equation: 1/D_e = 0.005 + 0.00013t + 0.00013t².Increasing the incubation temperature to 37–40°C resulted in a decrease in development rate and a sharp reduction in life length.Analysis of the relationship between respiration rate and temperature in experimental and natural populations of Brachionus calyciflorus and Hexarthra mira (Hudson) showed that the maximum rate of oxygen consumption occurred at 32–33°C.The effects of temperature upon the ingestion rates of rotifers is greatly influenced by food concentration. Consequently, this factor also influences the secondary production of experimental populations at different temperatures.     

Horizontal and Vertical Distribution of the Zebra Mussel (Dreissena polymorpha,Pallas) Larvae in the Modrac Reservoir,Bosnia and Herzegovina

In the Modrac Reservoir, loaded with coal separation suspended material, rapid development of the zebra mussel (Dreissena polymorpha) took place from at least 1987. It is probably the first distinguished “infection” for this part of Balkan Peninsula, caused by this organism. Horizontal and vertical distribution of this mussel, at 15 different reservoir profiles, had been investigated.     

Hydrology and Diatom Phytoplankton of High Arctic Lakes and Ponds on Store Koldewey,Northeast Greenland

We document hydrological and phytoplankton characteristics of nine lakes and two ponds on Store Koldewey, a culturally undisturbed island off Northeast Greenland. The limnological survey included the recording of temperature, conductivity, oxygen concentration and saturation, pH, ionic composition, transparency, and the diatom phytoplankton community. In summer 2003, the lakes were cold, monomictic, thermally unstratified, alkaline and likely oligotrophic water bodies. Diatom phytoplankton was present in six lakes and consisted of four dominant species (Aulacoseira tethera, Cyclotella pseudostelligera, C. rossii, and Fragilaria tenera). The concentration of planktonic diatoms varied distinctly between the lakes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Seasonal Dynamics of Planktonic Community Metabolism in Newly Constructed Tropical Ponds in a Swampy Area

Studies on community metabolism in newly constructed ponds on a swampy area were made over a period of twenty-four months from November, 1981 to October, 1983. The fluctuations in the gross and net primary productions, photosynthetic efficiency and assimilation efficiency are discussed. The productivity of ponds was apparently influenced by the physico-chemical and biological environment of the water. pH, secchi disc transparency, phosphate and nitrate-N were negatively correlated with gross primary productivity, while temperature, conductivity, total alkalinity and ammonium-N showed positive correlation. The phytoplankton also exhibited positive correlation with primary production. The P/R ratio ranged between 1.79 and 2.91, indicating a high degree of self maintenance of the system. The solar energy conversion efficiency through photosynthesis ranged between 0.17 % and 1.08 % in the first year and 0.09 % and 0.05 % in the second year. Annual average assimilation efficiency ranged between 37.32 % and 56.58 %.     

Comparative susceptibility of planktonic and 3‐day‐old Salmonella Typhimurium biofilms to disinfectants

Aims: To compare the susceptibility of a 3‐day‐old biofilm and planktonic Salmonella to disinfectants at different exposure times. We hypothesize that Salmonella biofilms are more resilient to disinfectants compared to planktonic Salmonella. Methods and Results: The susceptibility of planktonic cells to disinfectants was tested by a modified version of the Council of Europe suspension test EN 1276. Salmonella biofilms were formed using the Calgary Biofilm Device. Results show that 3‐day‐old Salmonella biofilms are less susceptible to the disinfectants benzalkonium chloride, chlorhexidine gluconate, citric acid, quaternary ammonium compounds, sodium hypochlorite (SH) and ethanol, compared to planktonic Salmonella. Surprisingly, the results also demonstrate that low concentrations of SH were more effective against a 3‐day‐old biofilm compared to high concentrations of SH. Conclusions: While all the disinfectants evaluated were able to reduce biofilm‐associated cells at concentrations and contact times sufficient to eliminate planktonic cells, there were still sufficient viable cells remaining in the biofilm to cause further contamination and potential infection. Significance and Impact of the Study: Protocols for the use of chemical disinfectants need to include biofilm susceptibility testing. There is a requirement for an effective and standardized tool for determining the susceptibility of biofilms to disinfectants.     

Visible laser and UV-A radiation impact on a PNP degrading Moraxella strain and its rpoS mutant

The role of stationary phase sigma factor gene (rpoS) in the stress response of Moraxella strain when exposed to radiation was determined by comparing the stress responses of the wild-type (WT) and its rpoS knockout (KO) mutant. The rpoS was turned on by starving the WT cultures for 24 h in minimal salt medium. Under non-starved condition, both WT and KO planktonic Moraxella cells showed an increase in mortality with the increase in duration of irradiation. In the planktonic non-starved Moraxella, for the power intensity tested, UV radiation caused a substantially higher mortality rate than did by the visible laser light (the mortality rate observed for 15-min laser radiation was 53.4 +/- 10.5 and 48.7 +/- 8.9 for WT and KO, respectively, and 97.6 +/- 0 and 98.5 +/- 0 for 25 s of UV irradiation in WT and KO, respectively). However, the mortality rate decreased significantly in the starved WT when exposed to these two radiations. In comparison, rpoS protected the WT against the visible laser light more effectively than it did for the UV radiation. The WT and KO strains of Moraxella formed distinctly different types of biofilms on stainless steel coupons. The KO strain formed a denser biofilm than did the WT. Visible laser light removed biofilms from the surfaces more effectively than did the UV. This was true when comparing the mortality of bacteria in the biofilms as well. The inability of UV radiation to penetrate biofilms due to greater rates of surface absorption is considered to be the major reason for the weaker removal of biofilms in comparison to that of the visible laser light. This result suggests that high power visible laser light might be an effective tool for the removal of biofilms.     

Islands increase genetic subdivision and disrupt patterns of connectivity of intertidal snails in a complex archipelago

The view that marine species with planktonic dispersal have highly connected, demographically open populations is giving way to recognition that populations may often be largely self-recruiting, or demographically closed. This raises the question of what local conditions might favor isolation of populations. To test the importance of islands for local isolation in species with planktonic larvae, we examined allozyme variation among 35 populations of the intertidal snail Austrocochlea constricta in the Houtman Abrolhos Islands, Western Australia, spanning 60 km. Heterogeneity of allozyme frequencies among populations was high, with average F(ST) of 0.237, indicating highly localized populations. Increased subdivision was associated with islands at different scales: between island groups, separated by deep water gaps, and between disconnected sets of islands within groups. At short distances, up to two km, subdivision increased fivefold between islands compared with that between populations on the same island. Along 11 km of continuous, sheltered shore, there was isolation by distance but among a linear series of islands over similar distance, there was greater subdivision at short distances but no association with distance. These patterns had been seen previously in the direct-developing snail Bembicium vittatum, but its finding in A. constricta confirms for a planktonic disperser the importance of this complex archipelago for both retention of locally produced larvae and disruption of patterns of connectivity. Taken together, these results indicate that islands can increase both the "open" and the "closed" components of recruitment and that applicable models of genetic connectivity depend substantially on local conditions.