Almut Gerhardt

Monitoring behavioural responses to metals inGammarus pulex (L.) (Crustacea) with impedance conversion.

An impedance conversion technique was used to study the behaviour ofGammarus pulex (L.) exposed to acutely toxic concentrations of Pb (0.01, 0.05, 0.1 and 0.5 mg Pb l−1) and to field concentrations of Cu ( ≤ 0.05 mg Cu l−1). Initial stress responses were studied during short-term exposure (1 h) and sublethal toxic effects were monitored during 7 (Pb) and 35 days (Cu), respectively.Exposure to Pb caused 30 % mortality and resulted in a bioconcentration factor (BCF) of 2700 at 0.5 mg Pb l−1 after 168 h. Exposure to Cu polluted stream water caused no mortality within 35 days and uptake was low (BCF 5.8).Gammarus pulex reacted with initial stress responses to metal exposure within 30 min. (Cu) or 1 h (Pb). The reactions consisted of increased ventilation and decreased locomotion.Sublethal concentrations of Pb and Cu caused toxic effects on the behaviour of G.pulex after several days of exposure, consisting of increased ventilation and decreased locomotion.Impedance conversion is an appropriate method for detecting stress responses to metals and can be used in “early warning” biomonitoring systems as well as for acute and chronic behavioural toxicity testing.

Behavioural early warning responses to polluted water : Performance ofGammarus pulex L. (Crustacea) andHydropsyche angustipennis (Curtis) (Insecta) to a complex industrial effluent.

Behavioural early warning responses to polluted surface water from an industrial effluent have been measured in two freshwater macroinvertebrate species using the four electrode impedance conversion technique. Specimens ofGammarus pulex (L.) andHydropsycho angustipennis (Curtis) were caught from reference streams and exposed to water from above and below the factory and to reference water for about 1 h with different kinds of behaviour being registered on-line every 10 min, such as time spent on locomotion, number of “high swimming peaks”, number of activity phases, cleaning, time spent on ventilation, ventilation frequency and netspinning. Additionally, G.pulex was exposedin situ above and 100 m, 500 m and 1000 m below the factory for 24 h.G.pulex reacted to water pollution within 1 h with less time spent on locomotion, fewer “high swimming peaks” and lower number of activity phases (p < 0.01). The same results were found after thein situ exposure (p < 0.05) and the pollution gradient mirrored survival and behavioural performance of the organisms.H. angustipennis reacted to water pollution within 1 h with decreased time spent on ventilation (p < 0.001), no change in locomotion and netspinning during daytime. During the night, exposure to water pollution resulted in increased locomotion (p < 0.0001).Simultaneous multispecies on-line biomonitoring of industrial effluents is recommended for reliable risk assessment.

Short-term responses of Oryzias latipes (Pisces: Adrianichthyidae) and Macrobrachium nipponense (Crustacea: Palaemonidae) to municipal and pharmaceutical waste water in Beijing, China: survival, behaviour, biochemical biomarkers.

Whole effluent toxicity was assessed for the fish Oryzias latipes and the prawn Macrobrachium nipponense for 18 h in a dilution series (0-66%) of the inflow and effluent of a municipal waste water treatment plant as well as waste water from a teramycin producing pharmaceutical industry, before, during and after a pilot laboratory purification process. The waste waters caused acute toxicity as measured by inhibition of light emission in the luminiscent bacterium Vibrio qingaiensis sp. nov. (Q67). EROD and aryl hydrocarbon hydroxylase activity in in vitro carp liver-cells showed a dose-dependent toxic response to the municipal waste water. Behavioural responses and time-to-death of fish and prawn, recorded online with the Multispecies Freshwater Biomonitor proved to be concentration- and time-dependent sensitive toxicity indicators in both types of waste water. Behaviour changed stepwise from normal activity to (increased or decreased) activity to more time spent on ventilation and finally to increased morbidity at higher concentration and time of exposure. The municipal waste water treatment plant managed to reduce toxicity to bacteria (Q67), prawn and fish. The pharmaceutical waste water treatment process still has to be improved, in order to reduce toxicity for fish and prawn.

Chironomidae larvae as bioindicators of an acid mine drainage in Portugal

The abandoned São Domingos mine in South Portugal discharges acid metal pollution in the drainage system. A dynamic pH- and metal-gradient (pH 3.3–6.8) modulated by rainfall at the confluence of a tributary with the acid mine drainage (AMD)-channel, and a small reservoir contaminated with arsenic were sampled for Chironomidae in three different seasons and compared with a control river, to test whether this insect family is sensitive to AMD-pollution and arsenic. The AMD sites contained 18–22 taxa, compared to 22 taxa in the reservoir and 25 taxa in the control site. The chironomid fauna in the AMD was characterised by a high proportion of Chironominae and predatory Tanypodinae, and a low proportion of Orthocladiinae, these subfamilies being useful and easy bioindicators for AMD. The presence of morphological deformities in Ablabesmyia monilis and Procladius sp. is a potential bioindication of AMD but due to low numbers of larvae, it was of limited use. Despite high arsenic levels in the water, the small reservoir contained many taxa forming a typical lentic community.

Behavioural, developmental and morphological responses of Chironomus gr. thummi larvae (Diptera, Nematocera) to aquatic pollution

Populations of Chironomus gr. thummi larvae from two differently polluted lowland streams (Dommei, high cadmium and zinc; Ijse, medium copper and organic xenobiotics) were screened for behavioural and morphological responses to pollution. Behaviours such as locomotion (swimming and looping), respiration movements (ventilation) and inactivity were quantified with impedance conversion technique. Chironomids from the Dommel were more active than larvae from Ijse. In Ijse, deformed larvae showed less emergence, less locomotion and more ventilation than non-deformed larvae. In Dommel, deformed and normal larvae were equally fit (behaviour, emergence).

CHIRONOMIDAE (DIPTERA, NEMATOCERA) FAUNA IN THREE SMALL STREAMS OF SKANIA, SWEDEN

Two unpolluted streams and one chemically and thermally pollutedstream in Skania, Sweden, were investigated in summer 1995 for their temporary chironomid fauna and the occurrence of buccal deformities. The unpolluted streams `Övedsan and `Skäralidbäcken each contained, respectively, 13 and 16 taxa, with a dominance of Microtendipes pedellus group andMicropsectra spp., respectively. Most taxa were found in thepebbles and the submerged vegetation. Deformities were insignificant. The degraded stream Ybbarpsan in Perstorp contained 5 taxa, dominated by Procladius choreus. This species had 14% deformed larvae, interpreted as an effect of thechemical pollution. Shannon H and equitability J reflected thedifferences in chironomid community structure between the two unpolluted and the polluted sites. The Belgian Biotic Index scored maximally `10 in Skäralid, however only `6 in Öved and `5 in Perstorp. The combination of rapid assessmentof macrobenthos and description of communities of Chironomidae,with mention of deformed larvae, adds a bonus of information about the temporary state of a stream.

Automated recording of vertical negative phototactic behaviour in Daphnia magna Straus (Crustacea)

Diurnal vertical migration is a well-known phenomenon in the circadian activity rhythms of zooplankton. Our goal was to test whether negative phototaxis in Daphnia magna clone BEAK (provoked by artificially induced light stress, alternating light and dark phases in 2xa0h intervals), and its interference with the endogenous rhythm of diurnal vertical migration, can be automatically registered with a biomonitor. For the first time the vertical swimming behaviour of D. magna was recorded quantitatively based on non-optical data recording in a fully automated biotest system, the Multispecies Freshwater Biomonitor in a new experimental setup consisting of a column of three recording units (3-level chambers). Circadian vertical migration was clearly recorded in the 3-level chambers and the rhythm was more clear with 5 than with 1 organism per chamber. The organisms clearly responded to induced light stress with negative phototaxis, however best in larger chambers. The artificially induced rhythm was influenced by the endogenous rhythm. This approach may facilitate long-term observations of vertical swimming activity of zooplankton in the future.

Quality Control of Drinking Water from the River Rhine with the Multispecies Freshwater Biomonitor

The Multispecies Freshwater Biomonitor (MFB) based on quadropole impedance conversion technique is a biological early warning system (BEWS) for online water quality biomonitoring. The aim of this study was to test the MFB with two crustaceans (Gammarus pulex and Daphnia magna) in a drinking water processing plant at the River Rhine: 1) Sensitivity of the test species to short-term acid pulses and alarm-responses in the MFB were studied in the laboratory. 2) Long-term monitoring with Gammarus pulex and Daphnia magna in the MFB was performed in situ . A decrease in pH, especially below pH 6.8, resulted in a significant behavioural response of both species according to the Stepwise Stress Model. After a first escape response of D. magna , both species reacted similarly with decreased activity and G. pulex additionally with increased ventilation. G. pulex survived better than D. magna . The behavioural effects remained in the recovery phase. Long-term monitoring showed stable locomotory behaviour and better survival of G. pulex when compared to D. magna . The MFB can be recommended for drinking water control using G. pulex as test species.

Effects of subacute doses of cadmium on pH-stressed leptophlebia marginata (L.) and baetis rhodani pictet (insecta: ephemeroptera)

Cd uptake, emergence, survival and locomotory activity at two pH levels were studied in a 27-day experiment with Leptophlebia marginata and in a 19-day experiment with Baetis rhodani. Model ecosystems containing recirculating stream water, patches of sediment and leaves, simulated a natural stream. During the experiments, concentrations of Al, Cd, Fe and Zn increased in the water at pH 5, while conductivity decreased. Cd was taken up by both species at a rate which indicated linear uptake kinetics. No steady state of Cd in the animals was observed. The larvae of B. rhodani contained significantly more Cd than the adults (p<0.001). Uptake of Cd by Baetis rhodani was higher at pH 7 than at pH 5 (p<0.05). The survivial of L. marginata was not influenced by pH and Cd stress, but emergence was significantly reduced (p<0.05). The survival and the emergence of B. rhodani were reduced by low pH and also by Cd addition (p<0.01). At pH 7, Cd had no significant adverse effect on survival. Locomotory activity of Baetis rhodani was reduced by low pH and additionally by Cd stress.