Search results for "algae"
showing 10 items of 403 documents
Macroalgal responses to ocean acidification depend on nutrient and light levels
2015
Ocean acidification may benefit algae that are able to capitalize on increased carbon availability for photosynthesis, but it is expected to have adverse effects on calcified algae through dissolution. Shifts in dominance between primary producers will have knock-on effects on marine ecosystems and will likely vary regionally, depending on factors such as irradiance (light vs. shade) and nutrient levels (oligotrophic vs. eutrophic). Thus experiments are needed to evaluate interactive effects of combined stressors in the field. In this study, we investigated the physiological responses of macroalgae near a CO2 seep in oligotrophic waters off Vulcano (Italy). The algae were incubated in situ …
Sprectroradiometric characteristics of inland water bodies infestated by Oscillatoria rubescens algae
2010
In December 2006 blooms of Oscillatoria rubescens were found in the reservoir Prizzi in Sicily. Oscillatoria is a genus of filamentous alga comprising approximately 6 species, between these the O. rubescens is sadly famous since this organism produces microcystins which are powerful hepatotoxins. Firstly found in Europe in 1825 on Geneva lake, recently (2006) those algae has been find out in Pozzillo, Nicoletti e Ancipa reservoirs (Enna Province), as well as in Prizzi (Palermo Province) and Garcia reservoirs (Trapani Province). Toxins produced by those bacteria (usually called microcystine LR-1 and LR-2) are highly toxic since they can activate oncogenes cells causing cancer pathologies on …
Scaled chrysophytes (Chrysophyceae and Synurophyceae) from national park lakes in southern and central Finland
1989
A total of 34 scaled chrysophyte taxa (18 Mallomonas spp., 6 Synura spp., 2 Chrysosphaerella spp., 6 Spiniferomonas spp. and 2 Paraphysomonas spp.) were recorded by SEM techniques in 61 samples from 59 lakes locating in 8 national parks of southern and central Finland in July 1987. Most of the lakes were small forest and peat bog lakes with acid (pH 4.6–7.2) and soft-water and with variable water colour (10–350 mg Pt/l). The number of taxa per lake varied from 0 to 15 and it correlated very significantly with the water pH. The species structure was rather typical for the oligotrophic and acid lakes. Besides the eurytypic and common species like Mallomonus caudata (fr. 72.1% of lakes), M. cr…
Effects of Nile Tilapia (Oreochromis niloticus) on phytoplankton community structure and water quality: A short-term mesocosm study
2022
Nile tilapia is a highly invasive fish species, deliberately introduced into many lakes and reservoirs worldwide, sometimes resulting in significant ecosystem alterations. A short-term mesocosm experiment with and without Nile tilapia (Oreochromis niloticus) was designed to test the hypotheses that the presence of tilapia may affect phytoplankton community structure, increase nutrients availability in water column and deteriorate water quality. Nutrients, total suspended solids (TSS) and biomass of phytoplankton in different size classes (as Chl a) were measured. We found that tilapia increased the total nitrogen (TN), total dissolved nitrogen (TDN), NH4 + and TSS concentrations, deteriorat…
Filtration and ingestion rates of brachionus calyciflorus after exposure to endosulfan and diazinon
1992
Abstract 1. Rotifers Brachionus calyciflorus were exposed to endosulfan and diazinon to determine the effect on nitration and ingestion rates. 2. The experiments were carried out with the algae Nannochloris oculata in a density of 5 × 105 cell/ml. 3. Rates of filtration and ingestion were decreased significantly at sublethal concentrations of pesticide tested after 5 hr exposure. 4. The effective concentration at which filtration and ingestion rates were reduced to 50% of those in controls ( ec 50) were calculated for both toxicants.
Study of the antioedema activity of some seaweed and sponge extracts from the mediterranean coast in mice
1993
Chloroform and methanol extracts of ten marine species, seven seaweeds and three sponges, have been studied for possible, antioedema activities. The extracts were administered either topically or orally on TPA-induced mouse ear oedema and on carrageenan mouse paw oedema, respectively. The most interesting seaweed extracts were found to be from Corallina elongata, Galaxaura oblongata, Laurencia obtusa and Udotea petiolata, where both extracts of each species induced a large antioedema effect in both models employed. None of the sponges assayed demonstrated antiinflammatory effects on carrageenan mouse paw oedema, however, some extracts elicited an inhibition of the oedema developed by TPA.
Photosynthesis of the red alga Gracilaria chilensis under natural solar radiation in an estuary in southern Chile
2005
The photosynthetic performance and pigment content of Gracilaria chilensis Bird, McLachlan, and Oliveira were measured under natural solar radiation in the Quempillen river estuary (southern Chile) in order to assess the short-term acclimation of this species to the current levels of ultraviolet (UV) radiation during midsummer. The effect of the tidal fluctuation was evaluated in algae exposed for 3 days to two light climates in cages suspended at two depths (0.5 and 1.5 m from the bottom). Responses to high solar radiation at noon were also assessed to gain insights into rapid photochemical kinetics and the degree of photoinhibition. Results indicated that G. chilensis is a shade-adapted s…
Ancient recruitment by chromists of green algal genes encoding enzymes for carotenoid biosynthesis.
2008
Chromist algae (stramenopiles, cryptophytes, and haptophytes) are major contributors to marine primary productivity. These eukaryotes acquired their plastid via secondary endosymbiosis, whereby an early-diverging red alga was engulfed by a protist and the plastid was retained and its associated nuclear-encoded genes were transferred to the host genome. Current data suggest, however, that chromists are paraphyletic; therefore, it remains unclear whether their plastids trace back to a single secondary endosymbiosis or, alternatively, this organelle has resulted from multiple independent events in the different chromist lineages. Both scenarios, however, predict that plastid-targeted, nucleus-…
Application of algae in active biomonitoring of the selected holding reservoirs in swietokrzyskie province
2016
Abstract During the years 2014-2015, biomonitoring studies were carried out at three holding reservoirs located in Swietokrzyskie Province (central Poland): Kielce artificial lake, Chancza reservoir and Sielpia reservoir. In sea water algae Palmaria palmata (Linnaeus) Weber & Mohr, exposed in the analysed waters, the increases of concentrations were determined by the atomic absorption spectrometry method (AAS), of the following: Mn, Fe, Cu, Zn, Cd and Pb. Conductivity and pH were also determined in the reservoirs waters. The differences between the increases of heavy metal concentrations in the samples of algae found along the coastline were indicated; they result from different distanc…
Algae utilization in assessment of the large Turawa Lake (Poland) pollution with heavy metals.
2011
This investigation was undertaken to determine the applicability of algae for the assessment of contamination level of water reservoirs with heavy metals. The alga Spirogyra sp. collected in the littoral zone of the Large Turawa Lake (artificial lake in Southern Poland) was used for the study. The concentrations of heavy metals accumulated in the alga inhabiting a flow-through water basin of the Large Turawa Lake were found to correlate with sources of these metals, such as benthic sediments and contaminated watercourses. The highest concentrations of metals were found in alga samples collected at the outlet of the lake: c (Mn) = 12330 mg/kg dry mass, c (Fe) = 15059 mg/kg d.m., c (Cu) = 47.…