Search results for "Alga"

Biologically Active Organic Compounds, Especially Plant Promoters, in Algae Extracts and Their Potential Application in Plant Cultivation

2015

Seasonal succession and growth in the plankton communities of the Gulf of Riga in relation to long-term nutrient dynamics

1999

To study temporal changes in phyto- and zooplankton in the Gulf of Riga monitoring data covering the period of 1972–1995 were analyzed. Changes in external nutrient supply have turned P limitation, during the 1980s, into the present deficiency of Si for the spring bloom. Contrary to depletion of the N and Si pools, the internal sources and sinks were responsible for input of P into the pelagic ecosystem in the 1990s. Restructuring of the nutrient pool reshaped the pelagic planktonic communities. Changes of the species composition and food-web relationships occurred. Till the 1990s, an increase of diatoms in the summer phytoplankton and an increase of herbivores in zooplankton took place. La…

Melosira distans var. tenella and Eunotia zasuminensis, two poorly known planktonic diatoms in Finnish lakes

1986

The occurrence and ecology of two poorly known planktonic diatoms, Melosira distans var. tenella (Nyg.) M.-B. Florin and Eunotia zasuminensis (Cabejsz.) Korner in central Finland is discussed. Both species have their maximum in late summer when water temperature is > 15°C and they prefer slightly acid water (pH < 7), low conductivity (less than 4 mS/m) and a moderate degree of dystrophy with C.O.D. 10–20 mg O2/l and water colour 60–120 mg Pt/1. Melosira distans var. tenella was found in ca. 80% of the central Finnish lakes studied, but it is not reported in previously published papers. Eunotia zasuminensis is rarer, but is, however, recorded in at least 22 lakes in central Finland.

Triggering collective action for bio-energy supply chain through contract schemes

2016

This paper discusses contractual features to manage and coordinate a hypothetical bio-energy supply chain. The present study focuses on farmers operating in two Regions of Italy, namely Sicily and Campania, somewhat representative of areas with high potential of investments in new bioenergy supply value chain. Farmers were asked to choose whether to participate or not in a collective investment regulated by contract schemes. Monetary trade-offs were then computed among contract attributes. A specific questionnaire was submitted to a sample of farmers selected on the basis of their potential capability of investments. A stated preference modelling approach was implemented so that farmers cou…

A new method to isolate lichen algae by using percoll® gradient centrifugation

2001

AbstractA rapid method to isolate intact functional algae from the lichens Evemia prunastri and Ramalina farinacea has been developed. This method is based on the use of Percoll® gradients after mechanical disruption of lichen thalli. Results obtained show that the algal preparations were virtually free of contamination by fungal hyphae. The purified algal cells were photosynthetically active and without symptoms of photoinhibition, which indicates their functional integrity. This method may be used for the isolation of intact algae from a broad range of lichen species.

Phytoplankton structure in different lake types in central Finland

1986

Phyloplankton structure and its relation to physical and chemical properties of the water was studied in 58 central Finnish lakes. The biomass ranged from 0.2 to 14.2 g m−3 and the number of taxa per sample ranged from 33 to 152. The lakes were grouped into 5 types according to their trophic state: eutrophic, dyseutrophic, mesotrophic, oligotrophic, and acid oligotrophic lakes. The average biomass in eutrophic lakes was 5.57 g m−3, in dyseutrophic 3.54 g m−3, 1.23 g m−3 in mesotrophic, 0.52 g m−3 in oligotrophic and 0.39 g −3 in acid oligotrophic lakes. The average number of taxa per sample in the corresponding lake types were 109. 1, 79.3, 97.9, 90.9 and 43.8, respectively. The phytoplankt…

Workload of School Educators. Performance of Duties.

2022

Maģistra darbs “Skolas pedagogu slodze. Pienākumu izpilde.” ir izstrādāts ar mērķi izstrādāt ieteikumus skolotājiem, darba pienākumu veikšanai nepieciešamā laika samazināšanai. Pētījuma laikā tika izmantotas tādas pētījuma metodes kā: literatūras analīze, diskusija, aptauja. Maģistra darba teorētiskajā daļā tiek aprakstīts skolas pedagoga pienakuma jēdziens un tas, kas tajos ietilpst. Liela teorētiskā pētījuma daļa ir veltīta skolas pedagogu slodzēm un algas likmēm Latvijā un citās Eiropas Savienības valstīs ar mērķi salīdzināt radītājus. Daļu no teorētiskā pētījuma aizņem pedagogu pārslodzes iemeslu un seku analīze, kā arī Covid-19 pendēmijas ietekmi uz to. Maģistra darba empīriskā daļā ve…

Preliminary data on the occurrence of alien macroalgae in the vermetid reef along the coasts of Favignana Island (Southern Tyrrhenian Sea)

2017

Intertidal vermetid reefs are highly diverse systems that provide numerous habitats for animal and vegetal species, leading to an increase of intertidal biodiversity. These habitats, particularly vulnerable to environmental changes and human activities, are now experiencing high mortality in several areas of the Mediterranean Sea. Since alien macroalgae are nowadays considered one of the most serious threats to biodiversity and natural ecosystem functioning, we provide a first baseline assessment of the occurrence of alien species in the vermetid reef along the coasts of the Island of Favignana (Egadi Islands Marine Protected Area). Surveyes carried out in 2015 revealed the only presence of…

A comparative study of silver amalgam and compomer as retrograde filling materials in periapical surgery

2008

Objective: A comparative study is made of the histological effects of silver amalgam versus compomer (Dyract®) 90 days after placement as retrograde filling materials in experimental animals. Method: Six Beagle dogs were used, with total pulpectomy and orthograde material filling followed by periapical surgery of the 6 upper and 6 lower incisors (for a total of 72 teeth). Thirty-six teeth corresponded to the right side and were filled with the control material (silver amalgam), while the 36 teeth on the left side were filled with the compomer study material (Dyract®). After three months the animals were sacrificed and the histological study was carried out, with evaluation of bone formation…

Historical Contaminant Records from Sclerochronological Archives

2015

A number of marine and freshwater organisms, including scleractinian and proteinacious corals, coralline algae, sclerosponges, and bivalve mollusks, secrete skeletons that grow larger over time and may record environmental contaminants over the lifespan of an individual. Most of these organisms also form periodic growth patterns (growth increments, lines or bands) that can be used to accurately date contaminant archives produced from chemical or physical analysis of sequential skeletal samples (termed sclerochronology). The majority of records produced from these organisms thus far have focused on paleoclimate reconstructions, but there is a vast potential for information on changes in cont…