Undersokning av planktonsamhället i regionala referenssjöar i Skåne län,1969-2007.

Sammanfattning I Skane har sex sjoar valts ut som regionala referenssjoar. Referenssjoar for i forsta hand kalkade och forsurade sjoar ar Skaravattnet, Liasjon, Svanshalssjon, Faglasjon och Larkesholmssjon, alla belagna i norra Skane. Referenssjo till i forsta hand naringsrika slattsjoar ar Ellestadssjon som ar belagen i sodra Skane. Syftet med denna undersokning har varit att analysera artforekomst i insamlade prover och sammanstalla resultaten for att sakra 25 ars vaxtplanktondata fran regionala referenssjoar i Skane. Samtliga fem referenssjoar i norra Skane var, eller utvecklades under den studerade perioden till, ” Gonyostomum-sjoar”. Liasjon dominerades samtliga undersokta ar (1982, 1993-2007) av Gonyostemum semen, vaxtplanktonsamhallet var under hela perioden mycket artfattig och indikerade att vattnet var extremt surt. Skaravattnet dominerades hela undersokningsperioden(1982, 1993-2007) av Gonyostemum semen men med inslag av pansarflagellater fram till millennieskiftet. Darefter okade bade biomassan av vaxtplankton och dominansen av Gonyostemum semen. Tyvarr saknades prover fran 80-talet i Svanshalssjon. Fran 1993 och framat dominerade Gonyostemum semen men i Svanshalssjon utgjorde aven pansarflagellater en ganska stor del av biomassan under hela undersokningsperioden (1993-2007). Varken Faglasjon eller Larkesholmssjon var utpraglade Gonyostemum sjoar 1982 istallet dominerades sjoarna vid detta undersokningstillfalle av pansarflagellater. Darefter har det skett en forandring i artsammansattningen i sjoarna. Fran 1993 och framat dominerades Faglasjon av Gonyostemum semen och fran 2002 och framat dominerades Larkesholmssjon av Gonyostemum semen. Skillnaden mellan Ellestadssjon och de ovriga sjoarna var pataglig. Ellestadssjon dominerades av blagrona alger och/eller kiselalger. De hogsta biomassorna, som uppmattes i denna studie, registrerades i Ellestadssjon. Denna sjo ar en naringsrik slattsjo i sodra Skane. Det vaxtplankton, som patraffades, ar typiska for de naringsrika sjoarna pa sydskanska slatten. En dominans av Gonyostomum ar negativt for vattenkvaliteten, bade nar det galler rekreation och dricksvattenproduktion. Slemmet fran Gonyostomum kan klibba igen galarna pa fisk och kraftor och satta igen filtreringsorganen hos vattenloppor. Dessutom ar Gonyostomum-sjoar artfattigare an sjoar utan forekomst av Gonyostomum. Detta kan man tydligt se i Skaravattnet och Larkesholmssjon. Nar Gonyostomum okar i dessa sjoar, sa minskar antalet andra vaxtplanktonarter

Nitrate Reduction in a Groundwater Microcosm Determined by (15)N Gas Chromatography-Mass Spectrometry

Aerobic and anaerobic groundwater continuous-flow microcosms were designed to study nitrate reduction by the indigenous bacteria in intact saturated soil cores from a sandy aquifer with a concentration of 3.8 mg of NO(3)(−)-N liter(−1). Traces of (15)NO(3)(−) were added to filter-sterilized groundwater by using a Darcy flux of 4 cm day(−1). Both assimilatory and dissimilatory reduction rates were estimated from analyses of (15)N(2), (15)N(2)O, (15)NH(4)(+), and (15)N-labeled protein amino acids by capillary gas chromatography-mass spectrometry. N(2) and N(2)O were separated on a megabore fused-silica column and quantified by electron impact-selected ion monitoring. NO(3)(−) and NH(4)(+) were analyzed as pentafluorobenzoyl amides by multiple-ion monitoring and protein amino acids as their N-heptafluorobutyryl isobutyl ester derivatives by negative ion-chemical ionization. The numbers of bacteria and their [methyl-(3)H]thymidine incorporation rates were simultaneously measured. Nitrate was completely reduced in the microcosms at a rate of about 250 ng g(−1) day(−1). Of this nitrate, 80 to 90% was converted by aerobic denitrification to N(2), whereas only 35% was denitrified in the anaerobic microcosm, where more than 50% of NO(3)(−) was reduced to NH(4)(+). Assimilatory reduction was recorded only in the aerobic microcosm, where N appeared in alanine in the cells. The nitrate reduction rates estimated for the aquifer material were low in comparison with rates in eutrophic lakes and coastal sediments but sufficiently high to remove nitrate from an uncontaminated aquifer of the kind examined in less than 1 month

An experimental study of toxin production in Arthrospira fusiformis (Cyanophyceae) isolated from African waters

Arthrospira is one genus of cyanoprokaryota for which information on toxin production exists for only a few strains. The purpose of this study was to investigate whether strains of Arthrospira fusiformis produce intracellular toxic compounds such as microcystins and anatoxin-a. The study was based on three strains of Arthrospira, two strains isolated from wastewater ponds in Mozambique and one from Lake Nakuru, Kenya. These strains were cultivated experimentally in different light intensities and salinities. Microcystins were analysed by ELISA and HPLC and anatoxin-a by HPLC. Toxicity analysis of the three strains, following the growth cycle, detected neither microcystins nor anatoxin-a. The results indicated that the strains selected were not toxigenic under the experimental conditions applied. Thus, the strains of A. fusiformis tested in the present study could be considered candidates for use in different applications such as in food supplements and in aquaculture

Biotransfer of β-N-Methylamino-l-alanine (BMAA) in a Eutrophicated Freshwater Lake

β-N-Methylamino-l-alanine (BMAA), a neurotoxic non-protein amino acid, plays a significant role as an environmental risk factor in neurodegenerative diseases, such as amyotrophic lateral sclerosis. BMAA producers occur globally, colonizing almost all habitats and represent species from distinct phytoplanktonic groups, i.e., cyanobacteria, diatoms, and dinoflagellates. Bioaccumulation of BMAA in invertebrate and vertebrate organisms has also been registered around the globe. In the Baltic Sea, BMAA has been detected in several commercial fish species, raising the question of the bioaccumulation of BMAA in Swedish limnic systems. Here we find the presence of BMAA in water samples from Lake Finjasjön and identify its bioaccumulation patterns in both plankti-benthivorous and piscivorous fish, according to fish species, total weight, gender, and season of collection. For the first time, a large number of fish individuals were used in order to draw conclusions on BMAA bioaccumulation in a closed ecological community based on a statistical approach. We may, therefore, conclude that feeding patterns (plankti-benthivorous) and increased age of fish may lead to a higher tissue concentration of BMAA

Planktic cyanobacteria from freshwater localities in ThuaThien-Hue province, Vietnam. II. Algal biomass and microcystin production

A survey of cyanobacteria was carried out from February to August of 2004 along the Huong River and Hoamy Reservoir which supply part of the City of Hue, Vietnam with drinking water: also at some localities in the vicinity of the City of Hue. Quantitative analyses and screening for microcystin by ELISA and HPLC were done both in natural samples and in cultured cyanobacteria. The total biomass of cyanobacteria ranged from 0 to 3039 mg L-1 [wet weight (ww)] with Arthrospira massartii, Jaaginema sp., Merismopedia spp., Microcystis spp., Oscillatoria perornata, and Planktothrix zahidii as the dominating species. In the water samples, microcystins detected by ELISA varied between 0 and 76.2 mu g L-1. Concentrations above 1 mu g L-1, which is considered the safety limit for drinking water by WHO, were not found in the drinking water resources. Cultured strains of Microcystis aeruginosa, M. panniformis, M. botrys and Pseudanabaena cf. moniliformis were shown by ELISA to produce microcystins. The major microcystins produced were microcystin-LR and -RR, as detected by HPLC