Lake Kinneret long-term data of the epilimnetic concentrations (ppm) and loads (tones) of the total Nitrogen (TN), total Phosphorus (TP), total inorganic Nitrogen (TIN), total Dissolved Phosphorus (TDP), Phytoplankton...Lake Kinneret long-term data of the epilimnetic concentrations (ppm) and loads (tones) of the total Nitrogen (TN), total Phosphorus (TP), total inorganic Nitrogen (TIN), total Dissolved Phosphorus (TDP), Phytoplankton groups’ biomass, water level (WL) and Jordan River Discharge were analyzed. Previously collected data compiled aimed at an insight into the causative background for the modification of Phytoplankton community change. The study was carried out by searching for relations between algal groups’ densities and nutrient conditions in the Epilimnion by the use of statistical methods (Simple and Fractional Polynomial Regressions). The study is aimed at analyzing the relations between algal biomass and nutrient contents. It was found that Nitrogen decline and slight increase of phosphorus were followed by Peridinium (Photo 1)?decline and biomass increase of non-peridinium algae. It is suggested that nitrogen supply for algal growth is mostly from external sources, and the reduction of nitrogen in the epilimnion was caused by external removal. Contrary to nitrogen, phosphorus sourcing is only partly external (dust deposition, drainage basin) and mostly internal through double channels: Microbial mineralization of bottom sediments and Peridinium cysts mediation. The resulted complexity of the Kinneret ecosystem structure is nitrogen limitation, and enhancement of Non-peridinium algal growth, mostly Cyanobacteria.展开更多
Surface ornamentations of the cell walls of 24 desmid species varieties and forms belonging to 7 genera were studied under a scanning electron microscope (SEM). Among these desmids, 1 species and 1 variety are new to ...Surface ornamentations of the cell walls of 24 desmid species varieties and forms belonging to 7 genera were studied under a scanning electron microscope (SEM). Among these desmids, 1 species and 1 variety are new to science, 13 species, varieties and forms are recorded in China for the first time. These desmids are subdivided into homogeneous and heterogeneous types based on the characteristic ornamentations on their cell walls. A unique ornamentation pattern, the centre of each scrobiculation with a small punctum regularly arranged on the cell wall, and very fine puncta scattered on the cell wall can only be revealed under high SEM magnification.展开更多
This is the first comprehensive ultrastructural study on dwarf males with external gametangia in the ge in the genus Oedogonium,from androspore germination to the liberation of mature male gametes.The ultrastructure o...This is the first comprehensive ultrastructural study on dwarf males with external gametangia in the ge in the genus Oedogonium,from androspore germination to the liberation of mature male gametes.The ultrastructure of the process in O.macrandrium Wittrok is similar to that of Bulbochaete hiloensis(Nordstedt)Tiffany,butwith two remarkable differences.In O.macrandrium:(1)instead of a true transverse wall,only condensed mucilage appears between the gametes of each antheridial cell,and (2)the cell wall between the basal cell and the basal most antheridial cell has simple plasmodesmata similar to those present in the transverse walls of vegetative cells,which are absent in B.hiloensis.展开更多
文摘Lake Kinneret long-term data of the epilimnetic concentrations (ppm) and loads (tones) of the total Nitrogen (TN), total Phosphorus (TP), total inorganic Nitrogen (TIN), total Dissolved Phosphorus (TDP), Phytoplankton groups’ biomass, water level (WL) and Jordan River Discharge were analyzed. Previously collected data compiled aimed at an insight into the causative background for the modification of Phytoplankton community change. The study was carried out by searching for relations between algal groups’ densities and nutrient conditions in the Epilimnion by the use of statistical methods (Simple and Fractional Polynomial Regressions). The study is aimed at analyzing the relations between algal biomass and nutrient contents. It was found that Nitrogen decline and slight increase of phosphorus were followed by Peridinium (Photo 1)?decline and biomass increase of non-peridinium algae. It is suggested that nitrogen supply for algal growth is mostly from external sources, and the reduction of nitrogen in the epilimnion was caused by external removal. Contrary to nitrogen, phosphorus sourcing is only partly external (dust deposition, drainage basin) and mostly internal through double channels: Microbial mineralization of bottom sediments and Peridinium cysts mediation. The resulted complexity of the Kinneret ecosystem structure is nitrogen limitation, and enhancement of Non-peridinium algal growth, mostly Cyanobacteria.
文摘Surface ornamentations of the cell walls of 24 desmid species varieties and forms belonging to 7 genera were studied under a scanning electron microscope (SEM). Among these desmids, 1 species and 1 variety are new to science, 13 species, varieties and forms are recorded in China for the first time. These desmids are subdivided into homogeneous and heterogeneous types based on the characteristic ornamentations on their cell walls. A unique ornamentation pattern, the centre of each scrobiculation with a small punctum regularly arranged on the cell wall, and very fine puncta scattered on the cell wall can only be revealed under high SEM magnification.
基金Funds were provided by the Universidad Nacional del Sur(UNS,SGCyT),Grant PGI 24/B151 to EJC.
文摘This is the first comprehensive ultrastructural study on dwarf males with external gametangia in the ge in the genus Oedogonium,from androspore germination to the liberation of mature male gametes.The ultrastructure of the process in O.macrandrium Wittrok is similar to that of Bulbochaete hiloensis(Nordstedt)Tiffany,butwith two remarkable differences.In O.macrandrium:(1)instead of a true transverse wall,only condensed mucilage appears between the gametes of each antheridial cell,and (2)the cell wall between the basal cell and the basal most antheridial cell has simple plasmodesmata similar to those present in the transverse walls of vegetative cells,which are absent in B.hiloensis.
