Relative change in stream discharge from a tropical watershed improves predictions of fecal bacteria in near-shore environments

Statistical models poorly predict bacteria in near-shore environments of tropical islands due to inaccuracies in runoff and discharge characterization of storm events. Intense, short duration storms on small, steeply sloped watersheds produce high rates of runoff, resulting in rapid pulses of discharge that influence the physical and physiological conditions of the fate and transport of pathogens. As such, increasing rates of discharge are expected to have a different influence on sediment transport and pathogen load compared to decreasing rates of discharge. Regression modeling was used to examine the affect of antecedent streamflow on the interaction between environmental parameters and two fecal indicator bacteria, enterococci and Clostridium perfringens. Including the relative change in discharge incorporates a proximate representation of the energy available to transport particulates, improving predictions of near-shore water quality. Understanding factors that influence pathogen loads improves management of watersheds and protects public health.     

黄河三角洲外来入侵物种米草对底泥微生物群落的影响

对黄河三角洲2个米草分布区及2个非米草分布区底泥中微生物生物量进行了测定,结果显示:大米草(S. anglica)分布区底泥中细菌、放线菌、真菌、反硝化细菌、硫酸盐还原细菌总数显著多于非米草分布区,米草的分布促进了底泥中微生物量的增加;互花米草(S. alterniflora)分布区的细菌、真菌总数多于大米草分布区,而其它微生物量则少于大米草分布区.     

H2 PRODUCTION BY ANABAENA VARIABILIS MUTANT IN COMPUTER CONTROLLED TWO-STAGE AIR-LIFT TUBULAR PHOTOBIOREACTOR

ＩＮＴＲＯＤＵＣＴＩＯＮＨ2,ａｓａｎｏｎｐｏｌｌｕｔｉｎｇｆｕｅｌ,ｓｅｅｍｓｔｏｂｅａｐｒｅｆｅｒａｂｌｅａｌｔｅｒｎａｔｉｖｅｅｎｅｒｇｙｓｏｕｒｃｅｏｆｔｈｅｆｕｔｕｒｅ.Ｓｔｕｄｙｏｎｂｉｏｈｙｄｒｏｇｅｎ,ｃｏｖｅｒｉｎｇｇｅｎｅｔｉｃ,ｐｈｙｓｉｏｌｏｇｉｃａｌａｎｄｂｉｏｃｈｅｍｉｃａｌａｓｐｅｃｔｓ,ｈａｓｂｅｅｎａｃｔｉｖｅｌｙｐｕｒｓｕｅｄｉｎｔｈｅｌａｓｔ100ｙｅａｒｓ,ｉｎｔｈｅａｔｔｅｍｐｔｔｏｐｒｏｄｕｃｅｒｅｎｅｗａｂｌｅＨ2,ｐａｒｔｉｃｕｌａｒｌｙｒｅｎｅｗａｂｌｅ“ｓ…     

分离自桉树枯叶拮抗菌株的鉴定及拮抗性试验

从桉树枯叶中分离到的4株微生物菌株,对好食脉孢霉(Neurospora sitophila)具有拮抗作用。其中ED013、ED018和ED015抑菌圈之间差异不显著,与对照无菌水和多菌灵有极显著性的差异。ED014抑菌圈比前3个菌株效果差,但也与照无菌水和多菌灵有极显著性的差异。根据形态特点及生理生化测定结果鉴定4株菌株属于芽孢杆菌(Bacillusspp.)。     

Freshwater seepages and ephemeral macroalgae proliferation in an intertidal bay: II. Effect on benthic biomass and metabolism

Intertidal soft-sediments biomass and metabolism are naturally heterogeneous in time and space at different scales. Particular perturbations such as freshwater seepages and seasonal proliferation of ephemeral macroalgae can intermittently and/or locally create additional variability in these systems. Since the impacts of such environmental stresses on natural processes are not well understood, the hypothesis that they would affect the functioning of the benthic system was tested. An intertidal bay whose structure and functioning has been previously described and where a carbon budget has been calculated, was chosen. The results showed that the metabolism of the intertidal sediments was greatly impacted by the above perturbations. Freshwater seepage increased meiofauna and microalgae biomasses and enhanced the total benthic metabolism (increasing community respiration and gross primary production until 4 and 2 fold respectively) without altering its seasonal trend. Ephemeral macroalgae proliferation had a more important effect on the total benthic metabolism, increasing community respiration and gross primary production 8 and 12 fold respectively and leading to a change in the seasonal trend.     

Effects of ambient DIN:DIP ratio on the nitrogen uptake of harmful dinoflagellate Prorocentrum minimum and Prorocentrum donghaiense in turbidistat

The effects of varying nitrogen (N): phosphorus (P) ratios on the growth and N-uptake and assimilation of the harmful dinoflagellates Prorocentrum minimum and Prorocentrum donghaiense were examined in turbidistat culture experiments. Algal cultures were supplied with media containing PO34? in various concentrations to obtain a wide range of N:P ratios. Experiments to determine rates of N uptake and assimilation of different N sources (NO3?, NH4+, urea and glycine by P. minimum and NO3?, NH4+ by P. donghaiense) were conducted using 15N tracer techniques at each N:P ratio. The growth rates suggested nutrient limitation at both high and low N:P ratios relative to the Redfield ratio. On a diel basis, the growth of both species was regulated by the light-dark cycle, which may be a result of regulation of both light- dependent growth and light-independent nutrient uptake. Maximum growth rates of both species always occurred at the beginning of light phase. In P-rich medium (low N:P ratio), both species had higher N assimilation rates, suggesting N limitation. Low assimilation coefficients at high N:P ratios suggested P limitation of N uptake and assimilation. NO3? and NH4+ contributed more than 90% of the total N uptake of P. minimum. Reduced N sources were more quickly assimilated than NO3?. Highest average daily growth rates were recorded near an N:P ratio of 12 for both species. The N uptake rates of cultures at N:P ratios near Redfield ratio were more balanced with growth rates. The linkage between growth rates and N uptake/assimilation rates were conceptually described by the variation of cell N quota. The N:P ratios affect the N uptake and growth of Prorocentrum spp., and may regulate their bloom progression in eutrophic ecosystems.     

Seasonal variations of biomarker responses in the marine blue mussel (Mytilus spp.)

Biomarkers, which can detect changes at the biochemical level, have been used for many years as early warning tools in environmental monitoring. In order to distinguish between natural variability and the potential effects of anthropogenic pollution, it is essential to identify background levels and establish the potential influence of abiotic (season, temperature and salinity) and biotic (gametogenesis) factors. In this study, we examined various biomarkers of stress (glutathione S-transferase (GST)), reproduction (vitellin-like proteins) and damage (lipid peroxidation (LPO) and DNA damage (DNA)) in marine mussels (Mytilus spp.) from a known pristine hybrid zone. Levels of all biomarker expression varied between seasons and appeared to be linked to the reproductive cycle. Oxidative stress in winter, with low GST expression and a higher expression of LPO and DNA damage displayed could be explained by low food availability. These data provide vital baseline information for future ecotoxicological and environmental monitoring studies.