Abstract

A non harmful chemical method aiming to control crayfish (Procambarus clarkii) populations physiological activity by decreasing gill hematosis is presently under development. The aims of this approach are to assist rice farming and, simultaneously, to allow crayfish production in rice fields, taking profit of both activities without affecting significantly other animal populations. In order to assess potential implications to the ecosystem, the effects of a selected surfactant formulated by HOECHST ( GENAPOL OX-080) on three non target aquatic species were studied in parallel to their effects on crayfish. The non target species, respectively Gambusia affinis (Pisces), Physa acuta (Gastropoda), and Daphnia magna (Cladocera), were selected as representative organisms in the study area, the Lower Mondego River Valley, in Portugal, given that these species also represent different trophic levels. The concentration of GENAPOL OX-080 found to be effective in decreasing gill hematosis of crayfish, was 0.005%. In order to evaluate crayfish and non target organisms tolerance to this concentration, 96-h LC₅₀ tests were carried out. The LC₅₀ values ranged from 1.9 to 2.8 times higher than the concentration decreasing gill hematosis in crayfish, and between 6.2 and 27.8 times lower than this concentration for the three selected non target species. Although at a concentration of 0.005%, GENAPOL OX- 080 might be considered as a non harmful chemical regarding crayfish populations, it may cause significant damage to non target organisms. Nevertheless, GENAPOL OX-080 is biodegradable and presents low toxicity when compared to pesticides ( e.g. parathion) commonly used, although illegally, by farmers to prevent crayfish activity in rice fields.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: