Sublethal Toxicity Tests Research Articles

Evaluation of metabolic responses of Artemia salina to oil and oil dispersant as a potential indicator of toxicant stress.

Insight into the impact of a pollutant on marine organisms may be gained from four types of biological and chemical investigations: a) short-term acute toxicity tests,b)organism-environment transfer studies,c)physiological studies and d)field studies.In the case of oil pollution,field studies have limited value for the estimation of the impact of oil on natural communities since results are often confused with the effects of "detergents"used in cleanup processes. Both types of laboratory studies(acute toxicity and sublethal toxicity tests)provide valuable information for the toxicity of oils and oil dispersants.Since in the case of oil pollution treatment, oils and detergents are acting in combination,a realistic approach of laboratory studies must also include the combined action of these substances on marine organisms.Although acute toxicity studies which measure the mortality due to a toxicant are very useful for the determination of the range of animal tolerance,other effects causing physiological alterations may be detrimental to a population's survival. This paper concerns research on the effects of an oil,an oil dispersant and of the mixture of oil and dispersant on a physiological process;the respiration of the brine shrimp Artemia salina. MATERIAL AND METHODS Adults of Artemia hatched from commercially available cysts(New Technology Artemia salina Revolution)were used as test animals.The hatching of the cysts and rearing of Artemia was performed in constant temperature rooms at 22+0,5~ in synthetic sea water (Synthetica). The three toxic solutions tested were a crude oil(tunesian crude oil zarzaitine type),anoil dispersant(Finasol-OSR2)and their mixture. The type of oil/water mixture tested was oil-water dispersion(OWD).

The influence of biorhythms on sensitivity of Nerita to pollutants at sublethal levels

Intrinsic rhythmic activity of Nerita (Melanerita) atramentosa melanotragus was assessed under constant laboratory conditions. Activity proved to be a sensitive indicator of toxicity, and was affected by low levels of a relatively new oil dispersing agent, Shell SD LTX. How the state of activity influenced animal sensitivity to Shell SD LTX and to an oil, Maui Condensate, was investigated using short-term recovery experiments. Nerita were most sensitive during their active phase, and results during this period differed significantly from tests carried out during the inactive phase of the animal. Dispersant/oil mixture proved to be highly toxic. These findings have ecological implications and permit comment relating to the design of sublethal toxicity tests. These subjects are discussed.

Effects of Kuwait oils on feeding rates of copepods

Sub-lethal toxicity and recovery tests were made on feeding rates of 4 species of copepods using Kuwait oils kept in suspension on a slowly rotating wheel. Counts of faecal pellets from individuals fed on standard algal suspension were made after 20 h at 12°C. This exposure produced only marginal effects at 1 and 2 ppm, but 10 ppm produced definite effects on planktonic species. Recoveries were generally quite good from ‘weathered’ oil treatments. Oils emulsified alone did not produce significantly different effects in these experiments from oils emulsified with dispersants.