SYNERGISTIC EFFECTS OF ENVIRONMENTAL VARIABLES ON 



THE METABOLISM OF THE COPEPOD EUTERPINA ACUTIFRONS 



FROM TWO DIFFERENT AREAS OFF THE COAST OF THE 



STATE OF SAO PAULO, BRAZIL^ 



G. Scares Moreira^ and W. B. Vernberg^ 



ABSTRACT 



The combined efFects of temperature and salinity on the respiratory rate of two populations of the 

 copepod Euterpina acutifrons have been determined. One population was taken from a nonpolluted 

 area, Sao Sebastiao Channel, and the other from a polluted area, Santos Bay, both off the coast of the 

 State of Sao Paulo, Brazil. Four groups of copepods were used in the experiments: 1) Sao Sebastiao 

 animals kept in Sao Sebastiao water (35%« salinity); 2 1 Santos animals kept in Santos water (28%o 

 salinity); 3) Sao Sebastiao animals kept in Santos water; and 4) Sao Sebastiao animals kept in diluted 

 Sao Sebastiao water (28%o salinity). Results showed that Sao Sebastiao copepods in either full strength 

 seawater (35%«) or lower salinity seawater (28%o) could metabolically regulate over a wider range of 

 salinities than could Santos copepods in Santos water or Sao Sebastiao copepods maintained in Santos 

 water. It was concluded that the water quality of the Santos Bay was responsible for changes in the 

 metabolic regulatory capacity of the copepods exposed to Santos water. 



The planktonic harpacticoid Euterpina acutifrons 

 (Dana) is distributed in the warm waters of the 

 world between lat. 66°N and 40°S (Haq 1972). It is 

 a euryhaline species and has been reported in 

 salinities ranging from 8%o (Cananeia Estuary, 

 southern Brazil, Tundisi 1972) to 39%o (Mediter- 

 ranean Sea, El-Maghraby 1965). Laboratory 

 studies have shown that reproduction can occur 

 over a salinity range of 15 to 45%o (Moreira and 

 Yamashita 1975). Euterpina acutifrons is an im- 

 portant link in the marine trophic web serving as 

 food source for both adult and larval fishes 

 (Pouchet and de Guerne 1887; Lebour 1918; Blin 

 1923; Carvalho 1945; Marques 1951; Thayer et al. 

 1974). 



In an earlier paper, Moreira (1975) reported 

 that salinity tolerances for Brazilian populations 

 of £. acutifrons from Santos were very different 

 from those of populations of this species from Sao 

 Sebastiao. This in itself is not surprising since the 

 salinity regimes of the two areas are different. The 

 salinity in the Santos Estuary varies widely from 

 17 to 30%o depending on the tide and season of the 



'Contribution no. 214 of the Belle W. Baruch Institute for 

 Marine Biology and Coastal Research. 



^Physiology Department, Institute of Biosciences, and Insti- 

 tute of Marine Biology, University of Sao Paulo, Brazil. 



^School of Pubhc Health, Belle W. Baruch Institute for Marine 

 Biology and Coastal Research and Department of Biology, Uni- 

 versity of South Carolina, Columbia, SC 29208. 



Manuscript accepted September 1977. 

 FISHERY BULLETIN: VOL. 76, NO. 2, 1978. 



year, while in Sao Sebastiao Channel the salinity 

 is approximately 35%o throughout the year. Water 

 temperatures in both areas are essentially the 

 same, ranging from 19° to 30°C depending upon 

 season. It was not determined, however, if the 

 observed differences in salinity tolerances of the 

 two populations were genetically or environmen- 

 tally induced. Subsequently, a study was initiated 

 to resolve this question by measuring metabolic 

 response patterns of specimens from both popula- 

 tions to different thermal-salinity regimes. It soon 

 became apparent that environmental parameters 

 other than temperature and salinity were factors 

 in determining the metabolic response patterns of 

 these copepods. 



A detailed chemical analysis of the water in 

 Santos Bay is not available, but great numbers of 

 tankers and other vessels continuously operate 

 near shore, discharging ballast water and con- 

 taminating seawater and adjacent regions with 

 petroleum. In addition, there are a large number 

 of industries that discharge wastes directly into 

 the water. One sample analysis of Santos Bay 

 seawater was found to contain 270 ppb lead and 

 200 ppb nickel (unpublished data). Furthermore, 

 to minimize the effects of human waste or degra- 

 dation products, approximately 400 tons of 

 chlorine are added monthly near shore. The data 

 presented in this paper demonstrate that 



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