Chlorpyrifos and Dichlorvos in Combined Exposure Reveals Antagonistic Interaction to Freshwater Fish Mrigal, Cirrhinus mrigala

Abstract Toxicity imposed by organophosphate pesticides to the freshwater cultivable fish species mrigal (Cirrhinus mrigala) was assessed under laboratory conditions. Healthy juveniles were exposed to chlorpyrifos, dichlorvos, and their equitoxic mixture in geometric series. Median lethal concentrations of chlorpyrifos were found to be 0.906 (0.689–1.179), 0.527 (0.433–0.633), 0.435 (0.366–0.517) and 0.380 (0.319–0.450) mg/L and dichlorvos were found to be 38.432 (33.625–47.866), 22.477 (19.047–26.646), 12.442 (9.619–14.196) and 11.367 (9.496–13.536) mg/L after 24 h, 48 h, 72 h and 96 h of exposure respectively. Surprisingly, the joint toxicity of these organophosphates in the binary mixture was less than additive during most of the exposure periods. Behavioral changes exhibited by pesticide exposed fish were elevated opercular beatings, loss of equilibrium, loss of schooling behavior, aggregating at corners of the test chamber, slight color changes, surplus mucus secretion, and sudden and rapid body movements before death. Such behavioral studies can be applied as a non-invasive bio-monitoring tool for water quality assessment for fish growth and development. Despite the same mode of action of both pesticides, the antagonistic action in the binary mixture is an interesting outcome of this research that requires further investigation for a lucid understanding of the joint toxicity mechanism of such pesticides.

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Improvement of a test-chamber for behavioral studies on adult females of Aedes aegypti (Linnaeus) (Diptera, Culicidae)

Revista Brasileira de Entomologia ◽

10.1590/s0085-56262007000200018 ◽

2007 ◽

Vol 51 (2) ◽

pp. 252-254 ◽

Cited By ~ 3

Author(s):

Isaías Cabrini ◽

Carlos Fernando S. Andrade

Keyword(s):

Aedes Aegypti ◽

Test Chamber ◽

Adult Females ◽

Behavioral Studies

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IMPACT OF HEAVY METALS CONTAMINATION ON SPRING ABUNDANCE OF AQUATIC MACRO-INVERTEBRATES INHABITING LAKE TIMSAH, EGYPT

Journal of Water Security ◽

10.15544/jws.2017.003 ◽

2017 ◽

Vol 3 (1) ◽

Author(s):

Marwa Ibrahim Saad El-Din ◽

Heba Nageh Gad El-HaK

Keyword(s):

Heavy Metals ◽

Marine Pollution ◽

Important Determinant ◽

Water Quality Assessment ◽

Life Cycles ◽

Aquatic Food Chain ◽

Bio Monitoring ◽

Aquatic Food ◽

High Concentrations ◽

Important Position

Lake Timsah, Egypt receives several kinds of pollutants coming from domestic sewage of unconnected areas adjoining the shore and possibly marine pollution. During the last decades heavy metals have become common contami-nants of aquatic and wetland environments throughout the world because of human activity and technological develop-ment. Increasing attention has been given during the last decade to the protection of marine and freshwater aquatic envi-ronment against pollution, both nationally and internationally. Macro-benthoses are the most commonly organisms used as bio-indicators water quality assessment. All of the aquatic macro-invertebrates that were collected from El-Taween station, Lake Timsah, Egypt fell into three major groups that were fairly easy to identify. They were annelids (Polychaeta and Oligochaeta), molluscs (Bivalvia and Gastropoda) and arthropods (Crustacea). The small sized crustacean Sphaeroma. serratum are considered suitable species for aquatic bio-monitoring because they hold an important position in the aquatic food chain responds to many pollutants, easy to culture and has short life cycles. Iron was most important determinant; it appears in high concentrations in both water sample and the tissue of crustacean sample (S. serratum).

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Focusing of Visuospatial Attention

Journal of Psychophysiology ◽

10.1027//0269-8803.15.4.256 ◽

2001 ◽

Vol 15 (4) ◽

pp. 256-274 ◽

Cited By ~ 13

Author(s):

Caterina Pesce ◽

Rainer Bösel

Keyword(s):

Reaction Times ◽

Visual Space ◽

Spatial Relation ◽

Stimulus Onset ◽

Visuospatial Attention ◽

Task Demands ◽

Time Interval ◽

Behavioral Studies ◽

Task Conditions ◽

Simple Rt

Abstract In the present study we explored the focusing of visuospatial attention in subjects practicing and not practicing activities with high attentional demands. Similar to the studies of Castiello and Umiltà (e. g., 1990) , our experimental procedure was a variation of Posner's (1980) basic paradigm for exploring covert orienting of visuospatial attention. In a simple RT-task, a peripheral cue of varying size was presented unilaterally or bilaterally from a central fixation point and followed by a target at different stimulus-onset-asynchronies (SOAs). The target could occur validly inside the cue or invalidly outside the cue with varying spatial relation to its boundary. Event-related brain potentials (ERPs) and reaction times (RTs) were recorded to target stimuli under the different task conditions. RT and ERP findings showed converging aspects as well as dissociations. Electrophysiological results revealed an amplitude modulation of the ERPs in the early and late Nd time interval at both anterior and posterior scalp sites, which seems to be related to the effects of peripheral informative cues as well as to the attentional expertise. Results were: (1) shorter latency effects confirm the positive-going amplitude enhancement elicited by unilateral peripheral cues and strengthen the criticism against the neutrality of spatially nonpredictive peripheral cueing of all possible target locations which is often presumed in behavioral studies. (2) Longer latency effects show that subjects with attentional expertise modulate the distribution of the attentional resources in the visual space differently than nonexperienced subjects. Skilled practice may lead to minimizing attentional costs by automatizing the use of a span of attention that is adapted to the most frequent task demands and endogenously increases the allocation of resources to cope with less usual attending conditions.

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