Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Microcosms & Mesocosms

  1. Aquatic microcosms
  2. Aquatic mesocosms
  3. Sediment microcosms
  4. Soil microcosms

1. Aquatic microcosms

[ref. ID; 361]

Aquatic ecosystems

Green algae (Chlorella and Scenedesmus) + filamentous blue-green alga + ciliate protozoa (Cyclidium) + rotifers (Philodina + Lepadella) + aquatic oligochaetes + bacteria (five species or more)

Toxicants

Cu2+ (CuSO4/5H2O).

Test design

Measurements

Primary production, community respiration, biomass and population density.

[ref. ID; 1650]

Test system

Acidification in Emerald Lake (Sierra Nevada, California, U.S.A. 36 degrees 35'N, 118 degrees 40'W)

Toxicants

pH 6.3 (control), 5.8, 5.4, 5.3, 5.0, and 4.7. 0.5 N stock solution of nitric and sulphuric acid (1:1 by equivalents).

Test design of enclosures

Eighteen cylindrical enclosures made of clear polyethylene (4 mil) were suspended vertically through the water column from floating platforms anchored in the east-central part of the lake. Each enclosure was kept taut by hoops of PVC pipe (1.3 cm diameters) secured at 1 m intervals, and a circular frame of PVC pipe (2.5 cm diameters) at the base of the enclosures facilitated their insertion into the sediments. The enclosures were 1 m in diameter and extended from above the lake surface through the 9.7 m water column to the sediments, enclosing approximately 7.6 m3 of water. Each enclosure was randomly assigned an experimental treatment. There were six treatments, each with three enclosures. Experimental period 35 days.

Measurements/observations

Response of zooplankton and zoobenthos.

[ref. ID; 3588]

Test system

Test organisms

Organisms were collected from Patrick Brook in Hinesburg, Vermont, located in the Laplatte River watershed about 15 km south Burlington, Vermont, USA.

Toxicants

Atrazine.

Test design

Microcosm tank (L 100 x W 40 x D 20 cm). Exposure period 14 days.

Measurements/observations

Chlorophyll-a, invertebrate classification.

[ref. ID; 4573]

Test system

Toxicants

Pharmaceutical mixtures: ibuprofen (a nonsteroidal anti-inflammatory drug), fluoxetine (a selective serotonin reuptake inhibitor), ciprofloxacin (a DNA gyrase-inhibiting antibiotic).

Test design/concentrations

Microcosm had a surface area of 11.95 m2, a depth 1.05 m, and total volume of 12,000 L. Model aquatic ecosystems: sediment (1:1:1 mixture of sand, loam, and organic matter (mainly composted manure) - well water (deep 130 m): periphyton - phytoplankton - zooplankton - Fish (Lepomis gibbosus) - Aquatic plants (Myriophyllum spicatum and M. sibiricum) - Lemna gibba.

Measurements/observations

Mortality of fish, diversity of phytoplankton and zooplankton, abundance of phytoplankton and zooplankton.

Evaluations

Principal Response Curves (PRCs).

[ref. ID; 6701]

Test system

Single-species and multi-species toxicity test

Microcosm

Three trophic levels: producers (mixotrophic phytoflagellate Cryptomonas sp. (strain SAG 26.80 from the Experimental Phycology and Culture Collection of Algae, Gottingen, Germany)) - consumers (predatory ciliate Urotricha furcata (by Th. Weisse (Austrian Academy of Sciences, Mondsee, Austria) and originally derived from the mesotrophic Lake Mondsee, Austria) - decomposer (unspecified bacterial community (originated from the non-axenic stock cultures of flagellates and ciliates)).

Toxicants

Parathion-methyl, Prometryn.

Test design

Static test system in 300 ml Erlenmeyer flasks filled with 100-150 mL cell suspension and closed with air-permeable lids. Modified WC medium (final nitrate concentration of 0.2 mM).

Measurements/observations

Cell number.

Evaluations

NOEC.

[ref. ID; 6752]

Test system

Toxicity of a herbicide-insecticide mixture

Microcosm

Plankton-dominated shallow freshwater ecosystems (length and width 110 cm; depth 70 cm; water depth 50 cm; sediment depth 10 cm, constant temperature 19+/-2 degrees C; photoperiod 14 hr).

Toxicants

Atrazine (herbicide) and lindane (insecticide) mixture.

Test design

Six sets of two microcosms each were treated with 0, 0.01, 0.1, 0.5, 1 and 5 x EC50 of the most susceptible OECD standard test species for each of the two pesticides. All microcosms were investigated over a period of 14 weeks: a 3-week pre-treatment period, a 4-week treatment period and a 7-week post-treatment (restoration) period.

Measurements/observations

Community structure and number of macroinvertebrates, zooplankton, phytoplankton and periphyton. Dissolved oxygen, pH, conductivity, alkalinity.

Evaluations

NOEC(TU).

[ref. ID; 6828]

Test system

The effect of chronic low concentration for freshwater microcosms

Microcosms

Freshwater microcosms (Plankton and macro-invertebrate).

Toxicants

Chlorpyrifos (insecticide) and atrazine (herbicide).

Test design

7 weeks. Twelve microcosms. The mirocosms were situated in a climate room (constant temperature: 19+/-2 degrees C). Each cosm consisted of a glass aquarium (length 1.1 m, width 1.1 m, height 0.7 m, watervolume 600 L), filled with a 2 cm layer of lake sediment and a 50 cm water column. High pressure metal halide lamps (400 W) were used to provide artificial daylight (photoperiod 14 hr), resulting in an average light intensity of 120 uE.m-2.sec-1 at the water surface. All cosms were interconnected by tubes (internal diameter 2.6 cm) and the water was circulated using a pump with a flow rate of 3.5 L.min-1. Acclimation period is three month.

Measurements

Identification and counting of zooplankton, phytoplankton, and macro-invertebrates. DO, pH, electric conductivity, alkalinity, chlorophyll-a, soluble inorganic N and SRP (Soluble Reactive Phosphorous).

Evaluations

Univariate analyses (according to Dunnett, 1955) and Multivariate analysis (using the Redundancy Analysis).

[ref. ID; 6925]

Test system

Inherent variability and statistical detectability between replicates

Test microcosm

The microcosms are approximately 1.2 m deep with a water depth of 1 m, a diameter of 3.9 m and surface area of 11.95 m2 with a volume of approximately 12,000 L of water. n=15.

Measurements/observations

Zooplankton abundance and species richness, pH, DO, temperature, Chlorophyll-a.

Evaluations

Minimal detectable difference (MDD) using statistical power analysis.

[ref. ID; 7139]

Test system

Time-variable exposure regimes

Test microcosms

The experiment was performed in 16 outdoor microcosms (diameter 1.8 m, total depth 0.8 m, water depth 0.5 m, and total volume approximately 1,270 L). The microcosms were lined with a water-tight, non-toxic layer of black polyethylene to prevent exchange of water with the surroundings. Each microcosm contained an 8 cm sediment layer (fine clay), obtained from a mesotrophic Elodea nuttallii-dominated lake. The water was obtained from the station's water supply reservoir, which has low nutrient concentrations.

Toxicants

Chlorpyrifos.

Measurements/observations

Evaluations

Univariate analysis and Multivariate analysis.

[ref. ID; 7170]

Test system

Test microcosms

Translucent LDPE (low-density polyethylene) 22 L semirigid bags were used. Water volume 20-l (surface water of the Combani Reservoir dam). After treatment (inoculation with pesticide or not, nutrient enrichment), the bags were gently agitated by hand and distributed at random in an outdoor inflatable pool under a sunscreen (several layers of insect net). The system was designed to reduce fluctuations in light and temperature.

Toxicants/concentrations

Diuron (2.2 and 11 ug/l), Paraquat (10 and 40.5 ug/l), Fenitrothion (10 and 100 ug/l).

Nutrient enrichment experiment

Each day, the nutrients were added just after sampling to achieve daily semicontinuous enrichment of 2.50 uM ammonium (NH4Cl), 1.25 uM nitrate (NaNO3), and 0.25 uM phosphate (NaH2PO4). The nutrient concentration in Cambani Reservoir water was low, with typical nitrate concentrations of 0.1-0.7 uM, ammonium concentrations of 0.2-1 uM, and soluble reactive phosphorus of 0.1-0.7 uM in surface water.

Measurements/observations

Density and biomass of bacterioplantkon, phytoplankton, heterotrophic flagellates and zooplankton. Thymidine incorporation rate. Shannon index H'. Biovolume.

2. Aquatic mesocosms

[ref. ID; 1852]

Test system

Freshwater plankton community succession (75 days)

Environmental stress

Acidification.

Experimental site

Lake O'Woods is a small impoundment in Preston Country, West Varginia that was formed in 1940 for recreationla use by daming Patterson Run, which is now the major inflow to the lake. The lake has a surface area of 29 ha, a mean depth of 3.4 m, and a maximum depth 6 m.

Enclosure system

Eight clear polyethylene bags (1mm thick) were suspended from a wooden raft over the deepest point in the lake. The bags were sealed at the bottom, but open at the top to allow gas exchange with the atomosphere. When filled (by immersing tops to 2 m, and then drawing the bags up through the water) they enclosed approximately 2.0 m3 of lakewater, and presumably also the indigenous plankton. The bags were suspended from the raft with their openings 0.5 m above the water surface, to prevent lakewater intrusion.

Experimental design

Measurements/observations

Water chemistory, Phytoplankton, Zooplankton.

[ref. ID; 4956]

Test systems

Seasonal variation in planktonic community response to PCP (20 days)

Toxicants/concentrations

Pentachlorophenol (PCP): 0, 4, 10, 24, 36, 54, 81, and 121 ug/l.

Test design/concentrations

Four separate seasonal mesocosms (860 l) using enclosures in a small pond.

Measurements

Species diversity and abundance.

Evaluations

The Principal Response Curves (PCR) method (PRC is based on the Redundancy Analysis ordination technique, the constrained form of PCA (Principal Components Analysis).

[ref. ID; 6105]

Test system

Effect on a natural zooplankton, especially predator-prey relationship (39 days)

Toxicants/concentrations

Lindane (0, 2, 6, 12, 18, 24, and 50 ug/l).

Test design

Natural pond (15x15 m, 0.8 m deep), enclosures (1000 litres).

Measurements

Abundance of cyclopoid larvae, Chaoborus flavicans larvae, Asplanchna priodonta and Keratella quadrata.

Evaluations

Population dynamics.

[ref. ID; 7227]

Test system

Effects on the plankton size spectrum (7 days)

Toxicants

Acidification.

Test design

Triplicate in situ enclosures (East Twin Lake) containing plankton from a small glacial lake were either untreated (pH >8) or were acidified to pH 6.5, 5.5 and 4.5 over 7 days using H2SO4.

Experimental design

Twelve transparent bags were filled with 60 L of surface water, which was first passed throuh a 200 um mesh to remove large crustaceans. Crustacean zooplankton were collected from the entire 6 m water column at the site with vetical tows of a 200 um net. The content of each tow were added to bag. The bags were tied closed and suspended at mid-epilmnion (2 m) for surface floats.

Measurements

Particle size distribution, phytoplankton and zooplankton biomass, and plankton taxonomic composition.

Evaluations

Mean phytoplankton size, mean zooplankton size, and phytoplankton-zooplankton size difference.

3. Sediment microcosms

[ref. ID; 4448]

Test system

Microcosms (indoor microcosms: length and width 110 cm; depth 70 cm; water depth 50 cm; sediment depth 10 cm)

Toxicants

Chlorpyrifos (commercial formulation Dursban 4E), lindane (commercial formulation Lindafor flo).

Test design/concentrations

Concentrations (0, 0.005, 0.01, 0.05, 0.1, and 0.5 x LC50 of the most sensitive standard test species for each of the two insecticides). Temperature 19+/-2 degrees C, photoperiod 14 hr.

Measurements/observations

Chlorophyll-a Zooplankton, Phytoplankton, and Periphyton.

[ref. ID; 6958]

Test system

All sediment and meiofauna samples were collected in south-west England.

Toxicants

TBT (Tributyltin) chloride.

Test design

Microcosms consisted of 570 ml narrow-mouthed glass bottles, stoppered with a rubber bung with two holes and aerated via an air-stone diffuser. The microcosms were kept in the dark, at 20 degrees C, for 2 months. Four replicate microcosms for each TBT-contaminated treatment and eight uncontaminated controls which were randomly located spatially within crates.

Measurements/observations

Identification of Nematodes and counting number.

Evaluations

Multivariate data analysis was by non-metric multi-dimensional scaling ordination.

[ref. ID; 6960]

Test system

Pollutant transport

Strains

Tubificid worms (>90% Limnodrilus hoffmeisteri, <10% Tuifex tubifex) were collected with their native sediment (largely fecal material) from Calls Creek, a small north Georgia stream draining predominantly undeveloped rural lands.

Toxicants

Pentachlorobenzene, Hexachlorobenzene, and Trifluoralin.

Microcosm

4-L flat-bottomed glass bottles (~~ 250-cm2 cross-sectional area). The microcosms were equipped with glass frits and resin traps and air purge initiated. Air purge (~~ 0.8 L/min, directed upward so as not resuspended bottom sediment. Sediment layer 2-5 cm). Tubificid populations be maintained at population levels of 10E4-10E5 individuals/m2 for a 90-100-day experimental period (with no added nutrients).

4. Soil microcosms

[ref. ID; 4959]

Test system

Testing for integrated soil microcosm (ISM) test protocol (56 days)

Test organisms

Lumbricus rubellus, Enchytraeus albidus.

Toxicants/concentrations

Carbendazim: 1 x PEC (the predicted environmental concentration: 0.76 mg a.i./kg soil dry weight), 3 x PEC, 9 x PEC, 27 x PEC, and 81 x PEC.

Test protocol

Microcosms, set up in a greenhouse, consisted of cylinders made from high-density polyethylene pipe, 7.5 cm (i.d.) x 15 cm high. A fine nylon mesh was placed across the bottom of each microcosm for leachate collection. Field soil, (silty clay loam), collected from Florsheim, Germany, was sieved through a 5 mm screen and mixed thoroughly. Earthworms, enchytraeids, and microarthropods were added to each microcosm. Each microcosm contained five wheat seedlings, and was maintained at a 12-12 hr light-dark cycle. Artificial rainwater was used to water microcosms as required. Five replicates.

Measurements/observations

Basal respiration rate (modified version of a method for long-term measurement of carbon dioxide evolution rates in the field (Anderson 1982)), soil ammonium and nitrate concentration, leachate ammonium and nitrate concentration, soil dehydrogenase enzyme activity, invertebrate feeding activity, organic matter decomposition, number of nematode.

Evaluations

LC50, EC50 (the trimmed Spearman-Karber method).

[ref. ID; 6768]

Test system

Experimental site

A spruce forest, Piceetum nudum, in Oberhaag near Aigen (Bohmerwald, Upper Austria, 860 m above sea level).

Toxicants

Mancozeb, lindane.

Experimental design

The plots were arranged in six comletely randomized blocks. Each block contained five plots each 1 m2 (four treatments, one control).

Measurements/observations

Ciliates, Testaceans, Nematoda and Rotifer numbers at 1, 15, 40 and 90 days after the pesticide applications.

Evaluations

Jaccard's species similarity and the species-abundance index of Bray-Curtis (dissimilarity type), were performed with the unweighted pair-group method using arithmetic averages. Shannon-Weaver's diversity.