G. Verriopoulos

Some effects of sub-lethal concentrations of copper on a marine copepod☆

Abstract Laboratory experiments were carried out to the influence of different concentrations of copper in feeding and respiratory rates, fecundity and longevity of the marine planktonic copepod Acartia clausi, taken from a polluted and a clean area of the Saronic gulf (Greece). In the range of copper concentrations 0.001 to 0.01 mg l.−1, all tested activities of the animals coming from the clean region seem affected. Feeding acitity, longevity and fecundity showed a progressive reduction from 0.001 to 0.01 mg l.−1 On the other hand oxygen consumption rates showed a continuous increase at the same range of concentrations. The pollution-adapted population of Acartia seems more resistant to sub-lethal copper stress. Although longevity and respiration were affected in all concentrations used (the reaction was of the same kind as for the animals from the clean region), ingestion rate was not affected at 0.001 mg l.−1 decreasing at higher concentrations. The fecundity of the pollution-adapted population is higher than that of the clean area, shows a slight increase at 0.001 and 0.0025 mg l.−1 dropping about to the control animals fecundity level at 0.01 mg l.−1

Differentiation of the sensitivity to copper and cadmium in different life stages of a copepod

Copper is more toxic to all life stages of the copepod Tisbe than cadmium. The most sensitive life stage of Tisbe to both copper and cadmium is the one-day-old nauplius. The resistance of larval stages of Tisbe increases with age (one-day-old nauplii 48h lc50=0.3142 mg Cu l−1. and 0.5384 mg Cd l−1, 0.3415 mg Cu l−1. and 0.645 mg Cd l−1. for five-days-old nauplii and 0.5289 mg Cu l−1. and 0.9061 mg Cd l−1. for ten-days-old nauplii. The two reproductive stages of Tisbe tested (females with ovigerous bands and females bearing the first ovigerous sac) demonstrated an increased sensitivity to metals and proved more sensitive than the ten-days-old copepodids (only females with ovigerous bands had a similar sensitivity to copper with the ten-days-old copepodids).

Combined toxicity of copper, cadmium, zinc, lead, nickel, and chrome to the copepod Tisbe holothuriae

In recent years much work has been concerned with the determination of various contaminants in the environment and with the establishment of the toxicity of these compounds to marine animals. Heavy metals are of increasing concern as pollutants of marine and especially coastal environments. Mixtures of heavy metals may produce unexpected effects. The purpose of this study was to determine the acute toxicity of six heavy metals (Cu, Cd, Zn, Pb, Ni and Cr) to the marine copepod Tisbe holothuriae Humes and to see whether there is any interaction between these metals, when applied jointly.

Effects of sublethal concentrations of cadmium as possible indicators of cadmium pollution for two populations of Acartia clausi (Copepoda) living at two differently polluted areas.

Toxicity of heavy metals to marine organisms is a subject of interest because, due to technological development, the sea receives an increasing amount of heavy metals. Acute toxicity studies have played a major role in estimating the effects of heavy metals to marine organisms because survival is considered the best index of a pollutant stress, being in general the least variable. However, long term exposure to sublethal concentration of a pollutant may markedly alter the normal functioning of organisms and thus destroy a population as effectively as lethal doses. Therefore, the study of the effects of sublethal doses is indispensable if we want to set realistic standards of water qualtiy criteria. The purpose of this study was twofold: first to establish and characterize the sublethal effects of cadmium on different physiological processes (longevity, feeding, respiratory rates), and second to verify whether there exist differences in the effects of sublethal concentrations of cadmium between the two populations of Acartia adapted to differently polluted areas.

Analysis of the biological cycle of Acartia clausi (Copepoda) in a meso-oligotrophic coastal area of the eastern Mediterranean Sea using time-series analysis

We evaluated the duration of Copepodite Stages C1 to C6, the biological cycle and the number of annual generations of the planktonic copepod Acartia clausi in a meso-oligotrophic area of the eastern Mediterranean Sea (Saronikos Gulf, Greece). The results were based on 95 zooplankton samples collected during the period November 1988 through June 1990, at intervals of 1, 2, 7 and 15 d, the sampling intervals being dependent on the abundance of A. clausi. Time-series analysis (cross-correlation) of fluctuations in the comparative abundance (percentages) of the copepodite stages present was used to determine the duration of the development stages and generation length. This methodology could significantly contribute to the identification of cohorts, and hence to the estimation of stage duration, from field data for a given copepod species. The development of A. clausi stages was not isochronal; duration of the first copepodite stage was shorter than that of the last three stages. The mean generation length estimated (28.6 d) is among the highest recorded in the literature for A. clausi at the range of temperatures prevailing in the area (13 to 25°C). Throughout the year there were four or five generations. The possible limiting role of food availability on the duration of each stage and hence on generation length is also discussed.

Length, weight and condition factor of Acartia clausi (Copepoda) in the eastern Mediterranean

Cephalothorax length and dry weight of copepodite stages and adults of the planktonic copepod Acartia clausi Giesbrecht in the Saronikos Gulf, Greece, were measured. Length-weight relationships and condition factor were also determined. The results were based on 17 zooplankton samples collected between November 1989 and June 1990, a period in which the abundance of A. clausi is significant. There was an inverse relationship between temperature and length, a pattern shown by many copepods. Temperature had the most significant effect on length, which was also affected by chlorophyll level. This strong temporal variation in length might possibly be considered as an adaptation of A. clausi to a continuously fluctuating environment. Length-weight regressions displayed high coefficients of determination ( r 2 =0.98 ). Food, expressed as chlorophyll, affected the size and condition factor, and could act as a limiting factor on length and weight of A. clausi in the study area.

Individual and combined toxicity of three heavy metals, Cu, Cd and Cr for the marine copepod Tisbe holothuriae

The acute toxicity of Cu, Cd and Cr to the marine copepod Tisbe holothuriae, Humes, was estimated by static bioassays and the LCinf50su48h(in mg/l) was calculated. Copper proved to be the most toxic (LCinf50su48h= 0,08 ± 0,01 mg/l) and chromium the least toxic (LCinf50su48h= 8,14 ± 0,05 mg/l), while cadmium showed an intermediate toxicity (LCinf50su48h= 0,97 ± 0,04 mg/l).In mixtures of the two metals an obvious synergism of the effects was observed in all cases. In all three combinations with two metals (Cu + Cd, Cu + Cr, and Cd + Cr) the mortality was higher than that expected on a purely additive basis. The mixture of the three metals presented a higher toxicity than that of the individual metals acting separately, but lower than that of all two metals mixture.

Combined toxicity of four toxicants (Cu, Cr, oil, oil dispersant) to Artemia salina.

In sea waters multicontaminant pollution appears to be the rule rather than the exception. For a realistic approach to pollution effects it is essential to estimate the combined toxicity of two or more chemicals. There is a need to understand the mechanisms of quantify the effects of multiple toxicity in order to provide responsible authorities with rational estimate of the effects of chemical mixtures. Thus the potential toxic effects of mixtures of toxicants has recently become a subject of growing scientific interest. In this paper the authors have tried to estimate the joint toxicity of some pollutants commonly found in nearshore polluted waters: two metals, copper and chromium; an oil (Tunesian crude oil zarzaitine type); and an oil dispersant (Finasol OSR-2).

Spatial and seasonal variations in size, body volume and body proportion (prosome:urosome ratio) of the copepod Acartia tonsa in a semi-closed ecosystem (Berre lagoon, western Mediterranean)

Variations in size (prosome), body volume and proportion (prosome:urosome ratio) of female Acartia tonsa copepods were studied during three different seasons (June, October and November) in a network of 13 stations distributed throughout the Berre Lagoon, near Marseille. Strong morphological differences were found between the populations collected through the different seasonal surveys, but also between the different stations or groups of stations. They were related to the variations of environmental parameters (temperature, salinity, chlorophyll, particulate seston) according to the season and to the location of the stations (submitted to the marine influence in the south and to the intake of fresh water in the north of the lagoon). Considering all seasonal data, the size and body volume were inversely related to temperature. Body volume also showed a negative correlation with chlorophyll and carbon and a positive one with the C:N ratio of particles. The body proportion was positively correlated with temperature, chlorophyll and carbon. For each seasonal survey, the relationship between morphological features and environmental factors did not reach the significant level except in October when body proportion and volume were positively correlated to chlorophyll.Nevertheless, for each season, significant spatial changes in size or body proportion appeared in parts of the population of Acartia tonsa, in relation with local specific conditions of environmental factors, especially chlorophyll. These biometric differences suggest that individuals must develop in situ for at least the final period of larval growth, despite the dispersion effect caused by hydrodynamic movements. This stability in horizontal distribution may result from the diurnal vertical migrations of copepods between the surface and the bottom, two layers displaying currents of opposite directions. These results justify the use of somatic features (size and body proportion) to discriminate sets of individuals belonging to the same population. %

Effects of sublethal concentration of zinc on survival and fertility in four successive generations of Tisbe

Abstract In this study we determined the survival and fertility of successive generations of the harpacticoid copepod Tisbe holothuriae, after exposure to three sublethal concentrations of zinc (0.07; 0.01 and 0.007 ppm Zn). A direct relationship between mortality, exposure time and zinc concentration was observed. For the 0.07 ppm Zn concentration, equal to 1 10 of the 48 h LC50 population size is reduced to zero after the first generation whereas the population size of the fourth generation is not affected by a concentration of 0.007 ppm Zn.