FISHERY BULLETIN: VOL. 76, NO. 2 



Sebastiao water. At 15°, 25°, and 30°C, metabolic 

 rates were not significantly different over the 

 range of 15-45%o. The rates varied from a 

 minimum of 4.32 to a maximum of 19.17 ix\/mg h ' 

 dry weight (Figure 1). 



DISCUSSION 



In Brazilian waters, populations of £■. acutifrons 

 thrive over a wide range of salinities and variable 

 salinity alone does not seem to be a limiting factor 

 in their distributional patterns (Tundisi 1972; 

 Moreira and Yamashita 1975). Indeed, of the vari- 

 ous environmental variables tested, temperature 

 alone significantly affected the metabolic rates of 

 these copepods. The present data demonstrate 

 that specimens of copepods from the unpolluted 

 Sao Sebastiao Channel have the capability of 

 metabolic regulation over a wide range of 

 salinities when tested using Sao Sebastiao water. 

 On the other hand, marked diminution in the 

 capability to regulate metabolically at salinity ex- 

 tremes was noted in E. acutifrons from the Santos 

 population and specimens from Sao Sebastiao 

 maintained in Santos water. For both groups of 

 animals salinity, as well as temperature, proved to 

 exert a statistically significant effect at the 5% 

 level (or less) on their oxygen uptake rates. These 

 marked changes in metabolic control in the 

 copepods taken from or exposed to Santos water 

 compared with that of copepods from Sao Sebas- 

 tiao are depicted in Figure 2. 



While we did not measure population densities 

 of the E. acutifrons in our two study areas (Santos 

 Bay and Sao Sebastiao Channel), there is some 

 indication in the literature that population size is 

 sensitive to polluted waters. Gabriel et al. (1975) 

 reported a decrease in abundance of this species 

 in the Milford Haven Estuary following its de- 

 velopment into the largest oil port in the United 

 Kingdom in the 1960's, and there are several 

 examples that indicate that pollutants can affect 

 the survival of copepods and planktonic larvae. 

 Barnes and Stanbury ( 1948) have studied the toxic 

 action of copper and mercury salts on the copepod 

 Nitocra spinipes and verified that mercuric 

 chloride is a very effective poison; in contrast, 

 these animals are very resistant to copper. 

 D'Agostino and Finney (1974) have found that 

 copper and cadmium inhibit growth and develop- 

 ment of the copepod Tigriopus Japonicus at 0.064 

 mg/1 and 0.044 mg/1, respectively. Heinle (1969) 



suggested that the high mortality rate ofAcartia 

 tonsa in a power plant effluent was due to the 

 chlorination of the cooling water, correlating the 

 apparent periodicity in the mortality rate with the 

 chlorination schedule. Latimer et al. (1975) 

 studied the toxicity of 30-min exposures of re- 

 sidual chlorine to two species of copepods, Lim- 

 nocalanus macrurus and Cyclops bicuspidatus 

 thomasi. The predicted "safe" concentrations were 

 0.9 mg/1 for L. macrurus and 0.5 mg/1 for C. b. 

 thomasi. Roberts et al. (1975) studied the acute 

 toxicity of chlorine to some estuarine species, in- 

 cluding molluscan larvae, copepods, shrimps, and 

 fishes. They found that molluscan larvae and 

 Acartia tonsa were the most sensitive species 

 tested, with 48-h TLg,, values at chlorine levels 

 <0.005 ppm. Gray (1974) demonstrated that lead 

 (Pb(N03)2) at 0.3 ppm reduced the growth rate of 

 the marine ciliate protozoan Cristigera by 11.7% 

 and at 0.15 ppm by 8.46%. Mercury was found to 

 have an effect on survival, metabolism, and be- 

 havior of the planktonic larvae of Uca pugilator 

 (DeCoursey and Vernberg 1972; Vernberg et al. 

 1973). Generally, larvae are much more sensitive 

 to toxicants than are adults and very low concen- 

 trations of a toxicant can interact with environ- 

 mental factors to cause increased mortalities 

 among larvae (Vernberg 1975). 



Detailed chemical analyses of Santos water ob- 

 viously are needed, but the very high concentra- 

 tion of lead and nickel which were found in one 

 sample, plus the oil and other industrial effluents 

 that are being discharged, leave little doubt that 

 the Santos Estuary is highly polluted. Data pre- 

 sented in this paper strongly suggest that speci- 

 mens living in the Santos Estuary do so at a high 

 cost energetically. This high metabolic cost for 

 survival following exposure to salinity extremes 

 would almost certainly be a factor limiting the 

 distribution of £. acutifrons in polluted estuaries, 

 since fluctuating salinity regimes are characteris- 

 tic of this environment. Results obtained in this 

 study highlight the fact that the physiological re- 

 sponses of marine organisms may be markedly 

 modified if test animals are taken from or exposed 

 to polluted waters. 



LITERATURE CITED 



Barnes, H., and F. A. Stanbury. 



1948. The toxic action of copper and mercury salts both 

 separately and when mixed on the harpacticid copepod, 

 Nitocra spinipes (Boeck). J. Exp. Biol. 25:270-275. 



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