As compared to their temperate counterparts, few toxicity tests have been conducted so far into the evaluation of the sensitivity of indigenous tropical species to pesticides. Especially mixture toxicity assessments appear to be scarce. To contribute to increase our knowledge in this arena, we evaluated the acute toxicity of diuron and carbofuran and their mixtures to the neotropical oligochaetes Allonais inaequalis and Dero furcatus, and the ostracod Strandesia trispinosa. Tests were performed with both the pure active ingredients, as well as their formulated products. The toxicity of the latter to the three test organisms was generally greater than that of the pure active ingredients, although absolute differences were rather small. The sensitivity of the indigenous species was slightly greater than temperate test species from the same taxonomic groups. The concentration addition conceptual model best described the results of the mixture toxicity data. Derived deviations of this model appeared to be dependent on the test organism and as to whether the pesticides were applied as active ingredients or their commercial products. Reported field concentrations of the two pesticides indicate risks to freshwater biota, especially if they are both present. The test species used in the present study are concluded to be suitable candidates as surrogate test organisms in local pesticide risk evaluations.

Codium fragile subsp. fragile (Suringar) Hariot is a large, dichotomously branched green alga that has invaded many temperate locations around the globe. Despite its wide distribution and pest status, there are few accounts of Codium fragile subsp. fragile that provide morphological descriptions, including illustrations, for comparison. In 2008, a seaweed sample suspected to be Codium fragile subsp. fragile was collected from Albany, Western Australia. As this taxon superficially resembles other local erect and dichotomously branching Codium species, a detailed morphological and molecular analysis of the suspect alga was conducted. Investigations confirmed the identity of this alga as the invasive subspecies Codium fragile subsp. fragile. This represents the first record of this species in Western Australia.

No abstract