Academic literature on the topic 'Colonial gelatinous green algae'

Blue-green algae (Cyanobacteria) are imponant to the ecology of arid rangelands as sources of nitrogen and as soil stabilizers, yet have been the subject of little comment or investigation in Australia. To provide information on their distribution soil samples were collected from 136 locations in rangeland areas of southem Australia and cultured to permit the identification of the blue-green algae present. Blue-green algae were found in 134 of the samples. The species represented include several apparently capable of nitrogen fixation, and all produce a gelatinous sheath which can bind soil panicles to produce soil-surface crusts. It is likely that lichens and blue-green algae are important for the ecology of arid rangelands now, and if climatic change destroys the lichens which are very heat sensitive when wet, blue- greens may become even more significant in soil conservation and the maintenance of pasture productivity. Both lichens and blue-green algae merit inclusion in assessments of range condition.

We examined community impacts of phosphorus and mosquitofish (Gambusia affinis) in an experimental mesocosm study of factorial design in which two levels of phosphorus addition were cross-classified with two levels of fish. Total phosphorus (TP), chlorophyll, cryptomonads, unicellular green algae, unicellular blue-green algae, colonial blue-green algae, filamentous blue-green algae, chironomid tube length, cladocerans, fish density, and fish biomass were significantly enhanced in the presence of phosphorus addition. Total nitrogen (TN), TN:TP ratio, Secchi depth, chrysophytes, and periphytic diatoms were suppressed in the presence of phosphorus addition. Diatoms, filamentous blue-green algae, chrysophytes, periphytic unicellular and colonial green algae, periphytic filamentous blue-green algae, and rotifers were enhanced in the presence of mosquitofish. Secchi depth, TN:TP ratio, cyclopoid copepodids, nauplii, cladocerans, and chironomid tubes were suppressed in the presence of mosquitofish. We found significant phosphorus × mosquitofish interaction effects for TN:TP ratio, chrysophytes, dinoflagellates, periphytic colonial green algae, cladocerans, and chironomid tubes. These results show that nutrients and fish do not act as independent regulators of plankton communities but instead have effects which can only be predicted from an understanding of their combined impacts.

Abstract This article describes the morphological characteristics of the populations of green alga, Tetraspora gelatinosa, growing in the stressful Arctic conditions (77°00’22” N, 015°32’54.33” E). We present the first detailed morphological characteristics of this spe-cies from such a high latitude. Populations from both stagnant and flowing waters were studied. Depending on the type of habitat, their mucilaginous colonies (thalli) have differ-ent shapes, but the structure, size and the placement of the vegetative cells, akinetes and ameboid forms, as well as the pseudocilia morphology of both populations, were very simi-lar. Literature data on the distribution of T. gelatinosa indicate that it is a cosmopolitan spe-cies. Our data are compared with some characteristic features of this species growing in dif-ferent geographical and climatic zones. No significant differences were found in the morphology of the colonies compared, nor in the location and the inner structure of cells. How-ever, there were slight differences in cell size between the populations from warm and cold zones.

Eggs of the spotted salamander, Ambystoma maculatum, are usually green because of the presence of symbiotic, chlamydomonad algae which inhabit the envelope of each egg. An oxygen-sensitive electrode was used to measure the effect of algal photosynthesis on oxygen concentration inside eggs and within the gelatinous matrix surrounding them. During darkness, oxygen became severely depleted within the eggs, but upon exposure to light oxygen concentrations increased rapidly. Photosynthetic oxygen production by the chlamydomonads exceeded respiratory consumption by the embryo–algae complex and led to oxygen supersaturation inside eggs, even when water surrounding the egg mass was almost anoxic.

We quantified the effects of planktivore biomass and planktivore type in an experimental mesocosm study of factorial design in which five levels of fish biomass (0–75 g/m3) were cross-classified with two plantivore types: filter-feeding gizzard shad (Dorosoma cepedianum) and visual-feeding bluegill (Lepomis macrochims). As fish biomass increased, cladocerans, cyclopoids, particulate phosphorus (PP) > 200 μm, and chironomids declined; conversely, rotifers, primary productivity, chlorophyll a, turbidity, unicellular flagellates, colonial and unicellular green algae, pennate diatoms, total phosphorus, and 20–200 and 12–20 μm PP were enhanced. In the presence of gizzard shad, as compared with bluegill, cyclopoids, turbidity, unicellular green algae, pennate diatoms, > 200 μm PP, and chironomid tubes were higher whereas colonial green algae and < 0.2 μm PP were lower. Fish biomass operated independently of planktivore type for most variables, except copepods, colonial green algae, turbidity, and 20–200 μm PP. Although gizzard shad and bluegill have different trophic cascade pathways, fish biomass was more important than planktivore type as a regulator of plankton communities and water quality.

This paper reports the discovery of endolithic algae from vertical limestone cliffs associated with the Niagara Escarpment, southern Ontario, Canada. The endolithic habitat forms a distinctive dark green layer 1–3 mm below the surface of the porous dolomitic limestone. Samples of the algal layer were isolated from freshly cleaved rock samples using sterile probes and grown on a solid (agarized) standard algal mineral medium supplemented with soil extract. A diverse assemblage of organisms grew on the agar plates, including bacteria, fungi, blue-green algae (cyanobacteria), green algae, yellow-green algae, and occasionally the protonemata of mosses. Isolated algae belong to unicellular, colonial, and filamentous morphological types. Algal genera that have been identified include seven blue-green algae (Cyanophyta or Cyanobacteria), six green algae (Chlorophyta), and one yellow-green alga (Xanthophyceae). Six of the algal genera found in Ontario rocks also occur inside rocks of the Colorado plateau in northern Arizona, and one genus also occurs inside Antarctic rocks. Key words: terrestrial algae, endolithic organisms, limestone cliffs, Niagara Escarpment, southern Ontario.

The results of investigation of the taxonomic diversity of the nonmotile unicellular and colonial green algae in the soils of Ellef Ringnes Island (Canadian Arctic Archipelago) are expounded. 49 genera and 88 species of algae belonging to the classes Chlamydophyceae and Chlorophyceae (Chlorophyta) are recorded. 64 species and 23 genera are new for the area of polar deserts.

The algae described in this paper appeared in enrichment culture from epiphytic mosses sample collected in southern Zabaikalie (Russia). This organism forms 2–8-celled and 3-dimensional packages of irregular shape. Vegetative cells are spherical, ellipsoidal and ovoid when solitary; cells with thin wall, thickening with age and occasionally with a unipolar manner. The cells and packages are devoid of a gelatinous matrix. There are akinete-like cells with sculptured cell wall. Sexual reproduction is ataktogamic. The results of morphologic and molecular phylogenetic studies allow us to attribute the alga to the genus Chlorosarcinopsis and show a high similarity with C. dissociata and C. bastropiensis. However, obtained data do not prove its identity to any known species of the genus.

Phytoplankter sind die bedeutendsten Primärproduzenten in aquatischen Ökosystemen und leisten ca. 45 % der globalen Primärproduktion. Sie weisen eine hohe taxonomische Diversität mit vielfältigen morphologischen und physiologischen Eigenschaften auf. Funktionelle Eigenschaften, die das licht-, temperatur- und nährstoffabhängige Wachstum sowie Verlustgrößen (Fraß, Sedimentation) beschreiben, sind eine Möglichkeit Phytoplankter zu klassifizieren. Diese Einteilung gewinnt für das Verständnis und die Modellierung der Phytoplanktonsukzession (z.B. in Wassergütemodellen) immer mehr an Bedeutung, da nicht taxonomische, sondern funktionelle Eigenschaften das Vorkommen der Phytoplankter im Gewässer bestimmen. Das Wassergütemodell SALMO ist ein mechanistisches, dynamisches, vertikales 1D-Modell, welches Nährstoffe, Sauerstoff, Detritus, 4 funktionelle Phytoplanktontypen und eine Zooplanktonmischgruppe simuliert. Bei der Modellanwendung wurde ersichtlich, dass die vorhandenen funktionellen Typgruppen teilweise nicht ausreichen, um die funktionelle Diversität der realen Phytoplanktongemeinschaften adäquat widerzuspiegeln. Deshalb wird eine Erweiterung der funktionellen Typgruppen in SALMO angestrebt. Eine empirische Freilanddatenanalyse an zwei morphologisch und trophisch verschiedenen Talsperren ergab insgesamt 10 funktionelle Phytoplanktontypen (Typgruppen 1, 2 und 4 bereits in SALMO vorhanden). Die bestehenden funktionellen Eigenschaften wurden erweitert und teilweise verändert (insgesamt 10 funktionelle Eigenschaften). Die neue funktionelle Typgruppe 6 (unbewegliche, koloniale, gelatinöse Chlorophyceen) wurde in lichtabhängigen Wachstumsversuchen und Fraßversuchen mit Daphnia galeata × hyalina genauer untersucht. Als stellvertretende Art für diese Typgruppe wurde Sphaerocystis schroeteri gewählt. Die Wachstumsversuche bei 20 °C kennzeichneten Sphaerocystis als Starklichtart mit einer relativ hohen Wachstumsrate (Iopt = 250 µmol m-2 s-1; µmax = 0.96 d-1; 12:12 h Hell-Dunkelzyklus). Eigene Nährmediumsversuche wiesen auf eine Abhängigkeit von freiem CO2 hin. Dies bietet eine Erklärung für ihr häufiges Auftreten in oligo- bis mesotrophen Gewässern. Bei Anwesenheit von Daphnia konnte nach 96 h Versuchsdauer eine signifikante Erhöhung der Koloniegröße (Anteil nicht fressbarer Kolonien 3-74 %), im Vergleich zur Kontrolle (Anteil nicht fressbarer Kolonien 0-5 %), festgestellt werden. Dies stellt einen effektiven Fraßschutz gegen größenselektiv filtrierendes Zooplankton wie z.B. Daphnia dar und kann bei hohem Fraßdruck zur Dominanz der Typgruppe führen (z.B. Klarwasserphase in eutrophen Gewässern). Der Effekt war nicht durch Infochemikalien induzierbar. Aus Literaturdaten wurde eine relativ hohes Topt von 27 °C, eine nur mäßige Konkurrentstärke um Phosphor (mittlerer KP-Wert) sowie eine Brutto-Sinkgeschwindigkeit von 1.5 m d-1 entnommen werden
Phytoplankter are the most important primary producer in aquatic ecosystems and contribute about 45 % to global primary production. Phytoplankton communities usually show an enormous taxonomical diversity. However, besides taxonomical diversity, a phytoplankton can also be characterised by its functional diversity by means of functional traits like resource-dependent growth characteristics (e.g. KI-, KP-, KN-values) or sensitivity to zooplankton grazing and sedimentation. Since functional, and not taxonomic, traits drive the phytoplankton succession, a functional classification of phytoplankton is recognised to be increasingly important for the ecological understanding and modelling of plankton succession (e.g. in water quality models). The mechanistic, dynamic, vertical 1D water quality model SALMO simulates the dynamics of nutrient concentrations (P, N), oxygen, detritus, 4 functional phytoplankton types and 1 mixed zooplankton group. Different model applications showed that the number of phytoplankton types in SALMO was sometimes not sufficient for accounting for the observed functional diversity in phytoplankton communities. Therefore, the aim of this thesis is to extend the functional diversity of phytoplankton types in SALMO. After careful evaluation of empirical data from two reservoirs with different morphology and trophic state 10 functional phytoplankton types are proposed (types 1, 2 and 4 remained unchanged). Existing functional traits in SALMO were extended and partly changed (in total 10 functional traits). For the new functional phytoplankton type 6 (non motile, colonial gelatinous green algae) light-dependent growth rates were measured and grazing experiments with Daphnia galeata × hyalina were carried out in the laboratory. For these experiments, Sphaerocystis schroeteri was chosen as representative species for this group. It is characterised by high light demand and relative high growth rates at 20 °C (µmax = 0.96 d-1, Iopt = 250 µmol m-2 s-1, 12:12 h light-dark cycle). Their growth depends on the availability of free CO2. This explains the common occurrence in oligo-mesotrophic water bodies. The range of the colony sizes of Sphaerocystis increased in the presence of Daphnia significantly (portion of inedible colonies 3-74 %) in contrast to the control (portion of inedible colonies 0-5 %). This was induced by direct size-selective grazing and not by infochemicals. Thus, Sphaerocystis has evolved an effective defence mechanism against size-selective filter-feeding zooplankton and is competitive superior at high zooplankton grazing pressure (e.g. clear water stage in eutrophic waters). The lack of experimentally derived parameters for temperature- and phosphorus-depending growth (Tmin, Topt, KP-value) as well as gross sinking velocity was complemented with literature data. The alga is only moderately competitive for phosphorus and exhibits relatively high minimal and optimal growth temperatures (Tmin = 7 °C, Topt = 27 °C). Since type 6 consists of large, non motile species, gross sinking velocity was estimated to be about 1.5 m d-1

Phytoplankter sind die bedeutendsten Primärproduzenten in aquatischen Ökosystemen und leisten ca. 45 % der globalen Primärproduktion. Sie weisen eine hohe taxonomische Diversität mit vielfältigen morphologischen und physiologischen Eigenschaften auf. Funktionelle Eigenschaften, die das licht-, temperatur- und nährstoffabhängige Wachstum sowie Verlustgrößen (Fraß, Sedimentation) beschreiben, sind eine Möglichkeit Phytoplankter zu klassifizieren. Diese Einteilung gewinnt für das Verständnis und die Modellierung der Phytoplanktonsukzession (z.B. in Wassergütemodellen) immer mehr an Bedeutung, da nicht taxonomische, sondern funktionelle Eigenschaften das Vorkommen der Phytoplankter im Gewässer bestimmen. Das Wassergütemodell SALMO ist ein mechanistisches, dynamisches, vertikales 1D-Modell, welches Nährstoffe, Sauerstoff, Detritus, 4 funktionelle Phytoplanktontypen und eine Zooplanktonmischgruppe simuliert. Bei der Modellanwendung wurde ersichtlich, dass die vorhandenen funktionellen Typgruppen teilweise nicht ausreichen, um die funktionelle Diversität der realen Phytoplanktongemeinschaften adäquat widerzuspiegeln. Deshalb wird eine Erweiterung der funktionellen Typgruppen in SALMO angestrebt. Eine empirische Freilanddatenanalyse an zwei morphologisch und trophisch verschiedenen Talsperren ergab insgesamt 10 funktionelle Phytoplanktontypen (Typgruppen 1, 2 und 4 bereits in SALMO vorhanden). Die bestehenden funktionellen Eigenschaften wurden erweitert und teilweise verändert (insgesamt 10 funktionelle Eigenschaften). Die neue funktionelle Typgruppe 6 (unbewegliche, koloniale, gelatinöse Chlorophyceen) wurde in lichtabhängigen Wachstumsversuchen und Fraßversuchen mit Daphnia galeata × hyalina genauer untersucht. Als stellvertretende Art für diese Typgruppe wurde Sphaerocystis schroeteri gewählt. Die Wachstumsversuche bei 20 °C kennzeichneten Sphaerocystis als Starklichtart mit einer relativ hohen Wachstumsrate (Iopt = 250 µmol m-2 s-1; µmax = 0.96 d-1; 12:12 h Hell-Dunkelzyklus). Eigene Nährmediumsversuche wiesen auf eine Abhängigkeit von freiem CO2 hin. Dies bietet eine Erklärung für ihr häufiges Auftreten in oligo- bis mesotrophen Gewässern. Bei Anwesenheit von Daphnia konnte nach 96 h Versuchsdauer eine signifikante Erhöhung der Koloniegröße (Anteil nicht fressbarer Kolonien 3-74 %), im Vergleich zur Kontrolle (Anteil nicht fressbarer Kolonien 0-5 %), festgestellt werden. Dies stellt einen effektiven Fraßschutz gegen größenselektiv filtrierendes Zooplankton wie z.B. Daphnia dar und kann bei hohem Fraßdruck zur Dominanz der Typgruppe führen (z.B. Klarwasserphase in eutrophen Gewässern). Der Effekt war nicht durch Infochemikalien induzierbar. Aus Literaturdaten wurde eine relativ hohes Topt von 27 °C, eine nur mäßige Konkurrentstärke um Phosphor (mittlerer KP-Wert) sowie eine Brutto-Sinkgeschwindigkeit von 1.5 m d-1 entnommen werden.
Phytoplankter are the most important primary producer in aquatic ecosystems and contribute about 45 % to global primary production. Phytoplankton communities usually show an enormous taxonomical diversity. However, besides taxonomical diversity, a phytoplankton can also be characterised by its functional diversity by means of functional traits like resource-dependent growth characteristics (e.g. KI-, KP-, KN-values) or sensitivity to zooplankton grazing and sedimentation. Since functional, and not taxonomic, traits drive the phytoplankton succession, a functional classification of phytoplankton is recognised to be increasingly important for the ecological understanding and modelling of plankton succession (e.g. in water quality models). The mechanistic, dynamic, vertical 1D water quality model SALMO simulates the dynamics of nutrient concentrations (P, N), oxygen, detritus, 4 functional phytoplankton types and 1 mixed zooplankton group. Different model applications showed that the number of phytoplankton types in SALMO was sometimes not sufficient for accounting for the observed functional diversity in phytoplankton communities. Therefore, the aim of this thesis is to extend the functional diversity of phytoplankton types in SALMO. After careful evaluation of empirical data from two reservoirs with different morphology and trophic state 10 functional phytoplankton types are proposed (types 1, 2 and 4 remained unchanged). Existing functional traits in SALMO were extended and partly changed (in total 10 functional traits). For the new functional phytoplankton type 6 (non motile, colonial gelatinous green algae) light-dependent growth rates were measured and grazing experiments with Daphnia galeata × hyalina were carried out in the laboratory. For these experiments, Sphaerocystis schroeteri was chosen as representative species for this group. It is characterised by high light demand and relative high growth rates at 20 °C (µmax = 0.96 d-1, Iopt = 250 µmol m-2 s-1, 12:12 h light-dark cycle). Their growth depends on the availability of free CO2. This explains the common occurrence in oligo-mesotrophic water bodies. The range of the colony sizes of Sphaerocystis increased in the presence of Daphnia significantly (portion of inedible colonies 3-74 %) in contrast to the control (portion of inedible colonies 0-5 %). This was induced by direct size-selective grazing and not by infochemicals. Thus, Sphaerocystis has evolved an effective defence mechanism against size-selective filter-feeding zooplankton and is competitive superior at high zooplankton grazing pressure (e.g. clear water stage in eutrophic waters). The lack of experimentally derived parameters for temperature- and phosphorus-depending growth (Tmin, Topt, KP-value) as well as gross sinking velocity was complemented with literature data. The alga is only moderately competitive for phosphorus and exhibits relatively high minimal and optimal growth temperatures (Tmin = 7 °C, Topt = 27 °C). Since type 6 consists of large, non motile species, gross sinking velocity was estimated to be about 1.5 m d-1.

This chapter gives a broad overview of freshwater algae in standing (lentic) and flowing (lotic) waters, with information on their morphological and taxonomic diversity. Algal communities are considered in relation to phytoplankton, substrate-attached and biofilm organisms. Methods are given for their collection, sample processing, enumeration, and biomass estimation in different aquatic situations. The relevance of these algae to human activities is considered particularly in relation to eutrophication of standing waters and the occurrence of harmful algal blooms. Control strategies to limit the growth of colonial blue-green algae are discussed within the context of an integrated management policy