Aerobic Bacteria Produce Nitric Oxide via Denitrification and Trigger Algal Population Collapse

Microbial interactions govern marine biogeochemistry. These interactions are generally considered to rely on exchange of organic molecules. Here we report on a novel inorganic route of microbial communication, showing that algal-bacterial interactions are mediated through inorganic nitrogen exchange. Under oxygen-rich conditions, aerobic bacteria reduce algal-secreted nitrite to nitric oxide (NO) through denitrification, a well-studied anaerobic respiration mechanism. Bacteria secrete NO, triggering a cascade in algae akin to programmed cell death. During death, algae further generate NO, thereby propagating the signal in the algal population. Eventually, the algal population collapses, similar to the sudden demise of oceanic algal blooms. Our study suggests that the exchange of denitrification intermediates, particularly in oxygenated environments, is an overlooked yet ecologically significant route of microbial communication within and across kingdoms.

The Use of Algae in the Process of Cadmium and Lead Ions Removal from Wastewater

The study presents the possibility of using chlorophyta in the removal of cadmium and lead ions from industrial wastewater produced after the washing of equipment used in the manufacture of battery and batteries. The process was conducted with the use of two algal cultures: Raphidocelis subcapitata produced in laboratory conditions, and a mixed chlorophyta population collected from a natural, eutrophicated water reservoir with heavy metal ions present in the water and sludge. The study showed that the effectiveness of a pure algal culture is comparable to that of a mixed chlorophyta population, characterized by greater diversity of functional groups at binding sites and higher resistance to stress that may occur in the wastewater environment. The maximum effectiveness of ions sorption was 64% for cadmium (mixed algal population) and 60% for lead (Raphidocelis subcapitata).

Airborne Algal growth on roofs of membrane-structured residences in cold area of Japan

The discoloration of building facades due to airborne algae is observed in our surroundings. The growth conditions of these algae are not yet fully understood, and efficient measures for preventing the growth of the algae are not presently available. The objective of this study was to investigate the effects of the ambient environment and building structure on algal growth. A residential building in a cold region of Japan was surveyed. The roof was a multi-layered structure comprising a semi-transparent film, an air layer, and a layer of insulation from the outside, supported by rafters. The soiled state was visually observed by taking photographs. On the northeast (NE) and northwest (NW) roofs, several black stripes appeared 4 months after cleaning. The soiling increased in the spring and autumn. The soiling first appeared on the film backed by the rafter and then extended to the film backed by the air layer. The condensation time during the day in the rafter part was longer than that in the air-layer part. Condensation occurred during the night, but its frequency exhibited no dependence on the orientation of the roof. Algae tend to die when exposed to an environment with a temperature higher than 45°C. The NE roof had the shortest period with a surface temperature of >45°C. These measurements agreed well with the survey results, which indicated that the soiling mainly occurred on the NE and NW sides of the roofs. The time for algal growth was estimated under the assumption that algae can grow at surface temperatures ranging from 0 to 45°C, in agreement with the observed soiling. The observed soiling changes were well explained by the algal population calculated via a growth predictive model according to the algal temperature and relative humidity.

Production de tilapia marin en circuit ferme en eau verte: le Système Aquacole à Recyclage Integral (SARI).

The Integral Recycling Aquaculture System (SARI) is an artificial ecosystem that combines closed-circuit farming of marine tilapia Sarotherodon melanotheron heudelotii with plankton lagooning in brackish water. Compared to conventional closed circuits in clear water, it provides significant advantages in terms of fresh water and energy savings, as well as in terms of health by limiting the introduction of pathogens. A prototype of the SARI located at the IRD Center in Mbour, Senegal, has made it possible to study the functioning of this breeding system. The tilapia S. m. heudelotii, when raised in intensive or semi-intensive mode, promotes the production of the green algae Chlorella sp. which purifies the environment of nitrogenous waste produced by fish. The algal population is regulated by the production of the rotifer Brachionus plicatilis, which itself serves as a complementary feed for the fry in rearing.

MONITORING OF DRINKING WATER RESERVOIRS OF KOPARGAON CITY WITH SPECIAL REFERENCE TO ALGAL FLORA AT YESGAON, DIST. AHMEDHNAGAR MAHARASHTRA (M.S.), INDIA

Algal collection from 5 drinking water storage reservoirs of Kopargaon city was carried out for one year. A total 39 genera and 62 species belonging to four classes were encountered during investigation period. Present studies revealed that, algal population was not found homogenous throughout the year, but it showed seasonal variation. During monsoon the algal population recorded was less, which increases in winter and found more in summer season. Chlorophyceae was found to be the dominant group throughout the investigation period in all storage tanks consisting of large number of genera and species. Many planktonic, some benthic and epiphytic algae were encountered during investigation period at all five water storage reservoirs. The commonly occurred genera were Ankistrodesmus, Closterium, Cosmarium, Spirogyra, Ulothrix from class Chlorophyceae, while from Cyanophyceae, Merismopedia, Microcystis, Oscillatoria, and Lyngbya are dominating forms. Desmids wear found in dominant condition in all storage tanks indicating unpolluted condition of water. Maximum population of Cosmarium was recorded during summer season, while Closterium species were recorded throughout the year. Other genera recorded were Staurastrum, Xanthidium, Euastrum, Micrasterias, Arthrodesmus, Desmidium, etc. Diatoms were recorded more in number during winter, while Euglenophycean members were sparsely reported only in summer. During present studies tremendous variations in Desmid diversity was noticed during summer and winter as compared to monsoon season.

PHYTOPLANKTON DEVELOPMENT DEPENDING ON THE SEASON IN THE PONDS OF THE CLEANING FACILITIES

The article presents an ecofloristic analysis of the natural algal population of reservoirs used as biological storage ponds, sedimentation tanks. Studies have shown that phytoplankton communities in reservoirs are not constant, and the composition and quantitative indicators of algaein them vary depending on meteorological conditions. In this Chapter, we consider seasonal changes in the abundance and biomass of phytoplankton, as well as their ratios in different ponds

Studies on the periodicity of chlorophyceae of Jait Sagar lake, Bundi (Rajasthan)

The Chlorophyceae periodicity of Jait Sagar lake had been studied during Jan 2013 to Dec 2013. A total number of 44 species belonging to 15 genera of Chlorophyceae class were identified. Some of common genera belonging to Chlorophyceae of Jait Sagar lake were Pediastrum, Scenedesmus, Cosmari-um, Spirogyra, Closterium etc. The occurrence of algae varied in different study areas in various months. Scenedesmus showed a maximum popula-tion. Some species were common to all the seasons while others were repre-sented only at a particular season. The algal population was found to be maximum in summer season and the lowest in winter. Water becomes greenish due to population of Microalgae such as Pediastrum, Scenedesmus, Cosmarium and Closterium during May-October. Seasonal successions of phytoplankton are affected by strong seasonal ecological influences. In the present investigation it was observed that high temperature and pH were favourable for rapid development of Chlorophyceae.

ALGAL DYNAMICS OF RIVER PANDU IN RELATION TO AMBIENT ENVIRONMENT

An investigation on river Pandu in the year 2009-2010 was carried out to explore its current status in terms of physico-chemical and phycological profile. The study revealed that algal spectrum of the river was connected with the intensity of pollution in the river. River, at present is a perturbed ecosystem due to heavy anthropogenic stress on it. Despite abundant nutrients and other factors responsible for propping algal growth, river had a meak algal population and low diversity as compared to other perennial rivers indicating the grossly polluted unhealthy condition of the river. Algae are natural inhabitants of aquatic environment; and act as natural purifiers due to their nutrient gleaning and oxygenating capabilities; they are more sensitive than animals to industrial and municipal wastes. Maximum number of species existed at station-1 followed by stations-4 and 6 and then at station-5. Lowest species representation has been noticed at stations-2 and 3. Species number and algal population too declined sharply at stations-2 and 3 as compared to station-I. Sharp decline in algal population at stations-2 and 3 may be attributed to certain obvious reasons such as low transparency and reduced illumination as a consequence of residual fly ash discharged by PTPP drain at station-2. Except station-1, all downstream stations show grossly polluted condition of the river.DOI: http://dx.doi.org/10.3126/eco.v20i0.11325Ecoprint: An International Journal of EcologyVol. 20, 2013Page : 9-17