The life cycle of Gonyostomum semen (Raphidophyceae)

Gonyostomum semen (Raphidophyceae) is today one of the most common flagellates in humic lakes ill Sweden and appears regularly in 30% of these lakes. The first mass development of this alga was recorded in 1948 in Lake Helgasjon, South Sweden. In this paper the life cycle of Gonyostomum is described for the first time. During the winter Gonyostomum survived as resting cysts on the surface of the bottom sediment. In spring (April to May) meiosis took place in the cysts, and on excystment two haploid gametes appeared. After a period of mobility, the gametes formed pairs. The gametes then fused, and a new diploid Gonyostomum cell developed. The vegetative stage of Gonyostomum, which was seen during the summer period (May-October), is thus the diploid phase. During this period normal, longitudinal cell division took place. Under unfavourable conditions, temporary cysts Could be formed. Cyst formation started from the centre of the cell, which swelled and became spherical. This was a thin-walled, temporary cyst, which was mobile and, like ordinary cells, had one flagellum protruding forward and one trailing behind. The temporary cysts could accumulate and settle in large clusters where the flagella were lost or had become invisible. When favourable conditions reappeared, the temporary cysts divided and formed two new gametes. In autumn, when the water temperature decreased to below about 10 degrees C, the temporary cysts went into dormancy and became resting cysts. The cyst wall thickened, and a brown body appeared within the cyst. Below 4-6 degrees C no vegetative cells were found

Mallomonas pseudocoronata Prescott (Synurophyceae), a recent arrival in Scania, southern Sweden?

Since the early 1960s, water chemistry and phytoplankton have been monitored in several lakes in Sweden. However, as early as 1900-1901, the German algologist Lemmermann investigated phytoplankton from lakes in Scania, southern Sweden. Several phytoplankton samples from these investigations were preserved and saved, and are deposited at the Department of Ecology in the University of Lund. These old samples have again been studied to assess potential changes in the phytoplankton community during the 20(th) century. Special emphasis has been focused on scaled chrysophytes. Since 1971 scaled chrysophytes from lakes and ponds in Scania have been investigated with SEM and/or TEM. This group of algae can at times be frequent in Scanian water bodies. Several scaled chrysophytes have endemic or restricted distribution. Mallomonas pseudocoronata Prescott, very common on the North American continent, has shown a restricted distribution outside the North American continent, only Japan, Russia and a subfossil record from Austria have been recorded. It had never been recorded from Sweden. In 2005, M. pseudocoronata was recorded for the first time in samples from Lake Borringesjon, Scania, and subsequently in eight more Scanian water bodies. Since M. pseudocoronata has not earlier been found in western and central Europe, it may be a new immigrant from America or Siberia, partially by transportation from migrating birds

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

Some nostocalean Cyanoprokaryotes from lentic habitats of Eastern and Southern Africa

The article comprises the second pari (Nostocales) of our study of little known planktie and metaphytic cyanoprokaryotes (cyanophytcs, cyanobacleria) from ponds, lakes and water reservoirs in East and Southern Africa. The morphology and Variation of 17 species was studied, and comments about their ccology and taxonomy are ineluded. Seven new spccies are defined: Anabaena austrocifricana, A, cannichaelii. A. bituri, A. maxima, A. nygaardii, Aphanizomenon capricorni and Cxlindwsper mopsix helicoidea. ln one tropical species, Cylindrospemiopsis africana, akinetefonnation was l'ound and dcscribed forlhe first time. These investigations of cyanoprokaryotic algae from Africa indicate the existcncc of a specific and unique tropical microflora. Based on our findings wc predicl thal many more taxa will be found in the future

Sammanställning och utvärdering av planktonsamhället i nio skånska sjöar

Växtplanktonsamhället utgör basen i det akvatiska ekosystemet och speglar näringsstatusen i sjöar; näringsrika (eutrofa) sjöar har ett helt annat växtplanktonsamhälle än näringsfattiga (oligotrofa) sjöar. Eutrofa sjöar domineras av höga biomassor och en hög andel cyanobakterier i biomassan under sommaren medan oligotrofa sjöar har låga biomassor och låg andel cyanobakterier. Planktonsamhället, både växt – och djurplankton, svarar snabbt på vattenkvalitetsförändringar eftersom organismernas generationstider är korta och är därför goda indikatorer på förändringar i miljön, vilket gör dem användbara i miljöövervakning. I Skåne finns naturligt näringsrika sjöar och algblomningar i dessa sjöar har varit ett naturligt och återkommande fenomen varma somrar. Men i takt med den ökande eutrofieringen av våra sjöar förekommer nu blomningar av cyanobakterier i allt fler sjöar, under allt längre tidsperioder och med allt större biomassor. Sjöarna i denna undersökning ligger i jordbruksområden och är stark påverkade av sin omgivning. De är näringsrika (eutrofa) till mycket näringsrika (hypertrofa) och algblomningar uppträder i allmänhet regelbundet. Algblomningar av cyanobakterier kan vara giftiga då vissa arter kan producera potenta toxiner (se faktaruta). I denna undersökning har växt- och djurplanktondata från nio skånska sjöar analyserats och utvärderats. Sjöarna som undersökts är: Börringesjön, Ellestadsssjön, Fjällfotasjön, Snogeholmssjön, Svaneholmssjön, Sövdeborgssjön, Sövdesjön, Yddingen och Östra Ringsjön. Studien utförs inom ramen för länets regionala miljöövervakning med koppling till miljökvalitetsmålen ”Levande sjör och vattendrag”, ”Ingen öergöning”. Resultaten utgör ett viktigt underlag i arbetet med att nå målen i EU:s ramdirektiv för vatten

Some chroococcalean and oscillatorialean Cyanoprokaryotes from southern African lakes, ponds and pools

This article is the first part (Chroococcales and Oscillatoriales) of a study of little known planktic and metaphytic cyanoprokaryotes (cyanophytes, cyanobacteria) from ponds, lakes and water reservoirs in southern Africa. Thirty-three species were observed, of which 24 are presented with comments. Ten new species are defined, and one species, originally described as a taxonomic form, is recombined to the specific level. Our results demonstrate the specificity of southern African cyanobacterial microflora

New species of Uroglena and Ochromonas (Chromulinales, Chrysophyceae) from Estonia

During the spring of 2003 ninety-five water bodies in southeastern Estonia were surveyed for chrysophytes. The sampling was carried out as the ice broke up, when, within two weeks, the water temperature rose from 3 degrees C to 13 degrees C. Large lakes to small pools of different water chemistry were investigated. The plankton collected was studied alive within a few hours after sampling. Preparations for scanning electron microscopy (SEM) were made from fresh samples and later also from material preserved in Lugol's solution. About 95% of the water bodies contained chrysophytes. Species belonging to the genera Chrysosphaerella, Dinobryon, Mallonionas, Synura, Ochromonas, Paraphysomonas, Spiniferomonas, Uroglena and Uroglenopsis were recorded. The genus Uroglena was frequent and recorded in 30% of the localities studied. Mass development of different Uroglena species was found in several waterbodies. Many populations had developed stomatocysts (statospores, cysts) of different morphology, and, using LM, smooth stomatocysts and stomatocysts with long spines could be recognised. However, using SEM, it was shown that also the smooth stomatocysts had short spines. Four new species of Uroglena were found and are described here. Uroglena estonica and U. spinosa had long spines while U. kukkii and U. pikamae had very short spines. In addition, mass development of stomatocysts of an Ochromonas was recorded in two lakes. This species had similarities with Ochromonas stellaris, but differed in stomatocyst ornamentation, and is also described as a new species, O. magnifica

Kiselalgernas egendomliga evolutionshistoria

Kiselalger finns över nästan hela jorden och står för en stor del av jordens samlade fotosyntes. Deras kloroplaster härstammar från rödalger, men resten av deras celler kommer från andra håll. Kiselalgerna har många gener vilkas närmaste släktingar återfinns hos djur, svampar, grönalger eller olika bakterier