خيارات البحث
النتائج 1 - 3 من 3
Size-dependent depletion and community disturbance of phytoplankton under intensive oyster mariculture based on HPLC pigment analysis in Daya Bay, South China Sea النص الكامل
2016
Jiang, Tao | Chen, Feiyu | Yu, Zonghe | Lü, Lin | Wang, Zhaohui
In this study, we conducted a 14-month investigation in Daya Bay, southern China to understand the effects of oyster farming on phytoplankton community and biomass by using size-fractionated phytopigments. Results proved the filtering effects of oysters on phytoplankton biomass. During the oyster culture period, the average concentration of total chlorophyll a (sum of size-fractionated Chl a) within the farming area was approximately 60% lower than that at the reference site. Phytoplankton depletion in the aquaculture zone mainly occurred in micro-sized fractions (>20 μm) of Chl a, fucoxanthin, and peridinin. The influence of oyster filtration on nano-sized (2.7–20 μm) pigments seemed less than that on micro-sized ones. The depletion of peridinin and 19′-hex-fucoxanthin in aquaculture zone was higher than those of the other pigments, which indicated that flagellated cells might be selectively filtered by oysters and could be more easily influenced by oyster aquaculture. The pico-sized Chl a (<2.7 μm) comprised 24% of total Chl a on the average in the aquaculture zone during the cultural period compared to 6% in the reference site. Picoeukaryote abundance, which was determined via flow cytometry, was significantly higher in the aquaculture zone than in the non-aquaculture areas. The abundance of picoeukaryote is significantly and positively correlated with the concentrations of pico-sized prasinoxanthin, violaxanthin, and neoxanthin, indicating that picoeukaryote is dominated by those in prasinophyte. The results suggest that oyster aquaculture might stimulate the growth of prasinophyte, although the seasonal variations are mainly controlled by the water temperature in the study area. This research highlights the successful use of size-fractionated phytopigments to estimate size-specific phytoplankton biomass and community, which can be applied as a routine method to monitor the environmental effect and food resources of bivalve aquaculture.
اظهر المزيد [+] اقل [-]Effects of nitrogen deposition and soil fertility on cover and physiology of Cladonia foliacea (Huds.) Willd., a lichen of biological soil crusts from Mediterranean Spain النص الكامل
2011
Ochoa-Hueso, Raúl | Manrique, Esteban
Effects of nitrogen deposition and soil fertility on cover and physiology of Cladonia foliacea (Huds.) Willd., a lichen of biological soil crusts from Mediterranean Spain النص الكامل
2011
Ochoa-Hueso, Raúl | Manrique, Esteban
We are fertilizing a thicket with 0, 10, 20 and 50kg nitrogen (N) ha⁻¹ yr⁻¹ in central Spain. Here we report changes in cover, pigments, pigment ratios and FvFm of the N-tolerant, terricolous, lichen Cladonia foliacea after 1–2 y adding N in order to study its potential as biomarker of atmospheric pollution. Cover tended to increase. Pigments increased with fertilization independently of the dose supplied but only significantly with soil nitrate as covariate. β-carotene/chlorophylls increased with 20–50kgNha⁻¹yr⁻¹ (over the background) and neoxanthin/chlorophylls also increased with N. (Neoxanthin+lutein)/carotene decreased with N when nitrate and pH seasonalities were used as covariates. FvFm showed a critical load above 40kgNha⁻¹yr⁻¹. Water-stress, iron and copper also explained variables of lichen physiology. We conclude that this tolerant lichen could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes.
اظهر المزيد [+] اقل [-]Effects of nitrogen deposition and soil fertility on cover and physiology of Cladonia foliacea (Huds.) Willd., a lichen of biological soil crusts from Mediterranean Spain النص الكامل
2011
Ochoa Hueso, Raúl | Manrique, Esteban | Biología
Estamos fertilizando un matorral con 0, 10, 20 y 50 kg de nitrógeno (N) ha−1 año−1 en el centro de España. Aquí informamos cambios en la cobertura, los pigmentos, las proporciones de pigmentos y FvFm del liquen terrícola Cladonia foliacea, tolerante al N, después de 1 a 2 años de agregar N para estudiar su potencial como biomarcador de la contaminación atmosférica. La cobertura tendió a aumentar. Los pigmentos aumentaron con la fertilización independientemente de la dosis suministrada, pero sólo significativamente con el nitrato del suelo como covariable. Las β-caroteno/clorofilas aumentaron con 20–50 kg N ha-1 año-1 (en comparación con el fondo) y las neoxantina/clorofilas también aumentaron con N. (Neoxantina+luteína)/caroteno disminuyó con N cuando se utilizaron los valores estacionales de nitrato y pH como covariables. FvFm mostró una carga crítica superior a 40 kg N ha-1 año-1. El estrés hídrico, el hierro y el cobre también explicaron variables de la fisiología del liquen. Concluimos que este liquen tolerante podría usarse como biomarcador y que las respuestas al N son complejas en paisajes heterogéneos de tipo mediterráneo.
اظهر المزيد [+] اقل [-]Physiological and biochemical investigations into the yellowing of spruce and higher altitudes. Pt.3: Light and yellowing
1990
Siefermann-Harms, D. (Kernforschungszentrum Karlsruhe (Germany, F.R.). Inst. fuer Genetik undToxikologie)
