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Does Asellus Aquaticus Avoid Sediment Contaminated by the Insecticide Lufenuron?

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Does Asellus Aquaticus Avoid Sediment Contaminated by the Insecticide Lufenuron? DOES ASELLUS AQUATICUS AVOID SEDIMENT KOEN CONTAMINATED BY THE INSECTICIDE WORKEL LUFENURON? Aquatic Ecology and Water Quality Management Department Alterra – Environmental Risk Assessment Does Asellus aquaticus avoid sediment contaminated by the insecticide lufenuron? Master thesis for the attainment of the academic degree of MSc. Hydrology and Water Quality - Aquatic ecology Rapportnr. 010/2011 Koen Workel September 2011, Wageningen Supervisors: Dr. ir. Ivo Roessink Dr. Ir. Edwin Peeters MSc Jacqueline Augusiak Dr. Theo Brock Aquatic Ecology and Water Quality Management Department Alterra – Environmental Risk Assessment Niets uit deze uitgave mag worden verveelvoudigd en/of openbaar gemaakt door middel van druk, fotokopie, microfilm of op welke andere wijze ook zonder voorafgaande schriftelijke toestemming van Alterra Wageningen UR. Alterra B.V. aanvaardt geen aansprakelijkheid voor eventuele schade voortvloeiend uit het gebruik van de resultaten van dit onderzoek of de toepassing van de adviezen. Acknowledgment ‘Doing a thesis should be fun’, said Ivo in our first conversation. Giving the final touch to this report I realize that it was indeed fun! Did very nice experiments, learned many things about research and worked with pleasant people which that made me feel comfortable that really have great knowhow about aquatic ecology and risk assessment. In the first place many thanks to the ERA team of Alterra and Aquatic Ecology and Water Quality Management Department giving me the opportunity to do my master thesis under their supervision. Special thanks go to Ivo Roessink for his enthusiasm, always good mood and supervision. Many thanks to Jacqueline Augusiak for the nice practical cooperation and supervision and Theo Brock for his critical view and good ideas. Thanks to Edwin Peeters for his good supervision from the WU. Could not have done it without help from Hans Zweers, Arrienne Matser, Rene van Wijngaarden, Marie-Claire Boerwinkel, Laura Buijse and others from the ERA team. Thanks to John Beijer and Wendy Beekman for their support in the AEW labs. Summary In 2009 Brock and co-workers , conducted a study where in artificial ditch mesocosms the impact of a benzoylurea (lufenuron) on macroinvertebrates with sprayed and non-sprayed sections was assessed. Lufenuron inhibits the synthesis of chitin and affects the moulting and metamorphosis of arthropods. It was hypothesized that sensitive populations would recover faster from insecticide stress when non-contaminated refuges would be in close proximity. This was confirmed for macroinvertebrates related to the water column, however, sediment dwelling organisms were absent for a long time predominantly on the sprayed sections. It was reasoned that this could be due to (i) the poor ability of sediment bound organisms to migrate, (ii) the long lasting toxicity of lufenuron or (iii) avoidance behaviour. This research aimed to unravel whether one of these possible explanations caused the phenomenon. It was chosen to do a toxicity experiment with Asellus aquaticus, a sediment dwelling organism that has the ability to migrate, to investigate its sensitivity to lufenuron. Sediment was spiked with different concentrations and the specimens were exposed for 21 days. Due to turbid conditions caused by suspension of the sediment, 3 out of 5 replicates were sacrificed at day 5 and the remaining 2 at day 21. No treatment related effects were observed at any of the concentrations at day 5. At the end of the experiment however, pronounced effects were observed where all specimens died at the highest concentration. With the confirmation that A. aquaticus was affected by lufenuron, their avoidance behaviour was tested. In total 16 aquaria (50 x 30 x 30cm) were used divided into 8 controls and 8 treatments. Sediment was divided into a contaminated part, spiked with lufenuron and an uncontaminated part. 10 specimens of A. aquaticus were released in the middle and their positions were manually scored on hourly basis. The hypothesis that they would be more often observed on the uncontaminated part was rejected by the results. There was variation in between the aquaria but there was no avoidance observed. To test the general concept and the used methodology, also the species Anisoptera (Odonata), Zygoptera (Odonata) and Agrypnia sp. (Trichoptera) were tested on avoidance behaviour. For each species 4 aquaria were used each containing 5 specimens. For these species was no avoidance behaviour observed as well. Zygoptera, however, showed in all 4 aquaria a significant preference for one side of the aquaria which probably is caused by the fact that an uneven number of specimens were used (5) and ones they were distributed, their natural ‘sit and wait’ ambush behaviour made that they hardly moved causing a preference for one side. To address both avoidance behaviour as toxicity in a field environment, sediment spiked with different concentrations lufenuron placed in small containers were inserted in an artificial mesocosm ditch. It was expected that colonization by macroinvertebrates would be negatively related to an increasing lufenuron concentration. After an incubation period of 55 days, the containers were removed from the ditch. The found macroinvertebrates were sorted on taxa per container and their dry weight was determined. The results show that there was no significant treatment related response which indicate that there was again no avoidance behaviour observed. Since A. aquaticus has abilities to migrate under water and midges are able to recolonize through the air via egg deposition by adults, it is reasonable that a poor ability to migrate did not caused the phenomenon. Although food avoidance could possibly have taken place, no avoidance behaviour has been observed. Toxicity has been observed by Brock and co- workers and in the toxicity experiment but not in the colonization experiment which might be caused by a constant inflow of new macroinvertebrates or external input of clean food source. Taking into account that there is no avoidance behaviour observed and a poor ability to migrate is probably not an issue as well, it is reasonable that the toxicity of lufenuron possibly caused the long lasting absence of sediment dwelling organisms. Table of Contents 1 Introduction .................................................................................................................. 2 1.1 Research aim ............................................................................................................. 3 1.2 Research question and hypotheses ................................................................................ 4 2 Method ......................................................................................................................... 6 2.1 Toxicity experiment .................................................................................................... 6 2.2 Avoidance behaviour experiment ................................................................................. 12 2.3 Colonization experiment ............................................................................................. 17 3 Results ........................................................................................................................ 19 3.1 Toxicity experiment ................................................................................................... 19 3.2 Avoidance behaviour experiment ................................................................................. 20 3.3 Colonization experiment ............................................................................................. 31 4 Discussion and conclusion .............................................................................................. 35 4.1 Discussion ................................................................................................................ 35 4.2 Conclusion ................................................................................................................ 37 5 References ................................................................................................................... 38 6 Appendix ..................................................................................................................... 40 1 1 Introduction The yield of agricultural farmers has increased worldwide since the use of pesticides, new seed varieties and fertilizers. However, pesticides do not only affect the target organisms but other exposed species as well. This in turn negatively affects biodiversity (McLaughlin and Mineau 1995; Geiger, Bengtsson et al. 2010). Agricultural land in the Netherlands is commonly boarded by small ditches for drainage and with the application of pesticides on agricultural fields, pesticide fractions enter adjacent water bodies through spray drift, runoff, and drainage. Depending on the hydrophobicity of the pesticide, the water column and/or the sediment compartment in the drainage ditch may become contaminated. To assess potential negative effects of pesticides on the environment, experiments are performed on a set of aquatic standard test species such as Oncorhynchus mykiss (rainbouw trout) (Li, Zlabek et al. 2010), Daphnia magna (water flea), Lemna minor L (duckweed) (Singh, Chandra et al. 2008) and Pseudokirchneriella subcapitata (algae) (Perez, Loureiro et al. 2010). Most of such experiments are performed on organisms that live in the water column like fish, Lemna and algae. Due to the high hydrophobicity of some
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