Toxicity of arsenite and arsenate to the marine macroalga Champia Parvula (rhodophyta)

A 2‐d exposure test using the marine red alga Champia parvula was developed to assess the toxic effects of pollutants entering the marine and estuarine environments. The initial exposure was followed by a 5‐ to 7‐d recovery period to allow the development of any cystocarps (evidence of sexual reproduction, the endpoint measured). The 2‐d exposure test was validated by comparison with a previously developed 2‐weed tests in which “no sexual reproduction” was used as the reproductive endpoint. The 2‐d procedure is intended for use in testing both single compounds and complex effluents. Complex effluents, however, cannot be accurately tested with the 2‐week test; therefore, only single compounds were used to compare the two procedures. Nine single compounds were tested. Concentrations that resulted in a 95% or greater decrease from the control response with the 2‐d exposure were considered the best estimate of the no sexual reproduction response from the 2‐week test. All of the single compounds tested, except cadmium, yielded essentially the same results with both tests.

Comparison of short‐and long‐term sexual reproduction tests with the marine red alga champia parvula

Thursby

Steele

1986

Laboratory culture of gametophytic stages of the marine macroalgae champia parvula (rhodophyta) and laminaria saccharina (phaeophyta)

Steele

Thursby

1988

Methods to help characterize the toxicity of effluent discharges within the National Pollutant Discharge Elimination System have been developed for the marine red alga Champia parvula and are currently being developed for the brown alga Laminaria saccharina. These methods require maintaining male and female gametophytes in laboratory cultures. Aseptic techniques are recommended even though the cultures are not intended to be axenic; the purpose is to guard against microalgal contamination. C. parvula can be grown at room temperature, but L. saccharina requires a controlled temperature chamber (12–15°C). Both species can be cultured successfully in either natural or artificial seawater.

Ecotoxicology of arsenic in the marine environment

Neff

1997

213

241

Arsenic has a complex marine biogeochemistry that has important implications for its toxicity to marine organisms and their consumers, including humans. The average concentration of total arsenic in the ocean is about 1.7 μg/L, about two orders of magnitude higher than the U.S Environmental Protection Agency's human health criterion (fish consumption) value of 0.0175 μg/L. The dominant form of arsenic in oxygenated marine and brackish waters is arsenate (As V). The more toxic and potentially carcinogenic arsenite (As III) rarely accounts for more than 20% of total arsenic in seawater. Uncontaminated marine sediments contain from 5 to about 40 μg/g dry weight total arsenic. Arsenate dominates in oxidized sediments and is associated primarily with iron oxyhydroxides. In reducing marine sediments, arsenate is reduced to arsenite and is associated primarily with sulfide minerals. Marine algae accumulate arsenate from seawater, reduce it to arsenite, and then oxidize the arsenite to a large number of organoarsenic compounds. The algae release arsenite, methylarsonic acid, and dimethylarsinic acid to seawater. Dissolved arsenite and arsenate are more toxic to marine phytoplankton than to marine invertebrates and fish. This may be due to the fact that marine animals have a limited ability to bioconcentrate inorganic arsenic from seawater but can bioaccumulate organoarsenic compounds from their food. Tissues of marine invertebrates and fish contain high concentrations of arsenic, usually in the range of about 1 to 100 μg/g dry weight, most of it in the form of organoarsenic compounds, particularly arsenobetaine. Organoarsenic compounds are bioaccumulated by human consumers of seafood products, but the arsenic is excreted rapidly, mostly as organoarsenic compounds. Arsenobetaine, the most abundant organoarsenic compound in seafoods, is not toxic or carcinogenic to mammals. Little of the organoarsenic accumulated by humans from seafood is converted to toxic inorganic arsenite. Therefore, marine arsenic represents a low risk to human consumers of fishery products.