Standard Guide for Conducting Static Toxicity Tests With Lemna gibba G3

Importancia y uso:

5.1 The term duckweed commonly refers to members of the family Lemnaceae. This family has many species world-wide in 4 genera. This guide is designed for toxicity testing with one particular clone of one species of duckweed that has been extensively studied, Lemna gibba G3, although other species such as Lemna minor or Spirodela spp. can probably also be tested using the procedures described herein.

5.2 Duckweeds are widespread, free-floating aquatic plants, ranging in the world from tropical to temperate zones. Duckweeds are a source of food for waterfowl and small animals and provide food, shelter, and shade for fish. The plants also serve as physical support for a variety of small invertebrates. Duckweed is fast growing and reproduces rapidly compared with other vascular plants (1).3 Under conditions favorable for its growth, it can multiply quickly and form a dense mat in lakes, ponds, and canals, primarily in fresh water, but also in estuaries. It also grows well in effluents of wastewater treatment plants and has been suggested as a means of treating wastewaters (2). A dense mat of duckweed can block sunlight and aeration and cause fish kills (3).

5.3 Duckweed is small enough that large laboratory facilities are not necessary, but large enough that effects can be observed visually.

5.4 Because duckweed is a floating macrophyte, it might be particularly susceptible to surface active and hydrophobic chemicals that concentrate at the air-water interface. Results of duckweed tests on such chemicals, therefore, might be substantially different from those obtained with other aquatic species.

5.5 Results of toxicity tests with duckweed might be used to predict effects likely to occur on duckweed in field situations as a result of exposure under comparable conditions.

5.6 Results of tests with duckweed might be used to compare the toxicities of different materials and to study the effects of various environmental factors on results of such tests.

5.7 Results of tests with duckweed might be an important consideration when assessing the hazards of materials to aquatic organism (see Guide E1023) or when deriving water quality criteria for aquatic organisms (4).

5.8 Results of tests with duckweed might be useful for studying biological availability of, and structure-activity relationships between test materials.

5.9 Results of tests with duckweed will depend on temperature, composition of the growth medium, condition of the test organisms, and other factors. The growth media that are usually used for tests with duckweed contain concentrations of salts, minerals, and nutrients that greatly exceed those in most surface waters.

Subcomité:

E50.47

Referida por:

E1733-22, E1850-04R19, E2552-23, E1023-23

Volúmen:

11.09

Número ICS:

11.100.01 (Laboratory medicine in general)

Palabras clave:

aquatic plants; aquatic toxicity testing; duckweed; Lemna gibba;