434 



Fishery Bulletin 88(3), 1990 



There were no significant differences between sta- 

 tions in plasma calcium levels. The only seasonal varia- 

 tion was a significant difference between the spring 

 value of 4.43 + 0.10 mEq/L and the fall value of 

 3.49 + 0.11 mEq/L (Table 4). 



Overall, plasma osmolalities of fish collected from 

 Station 3 were significantly lower than those of fish 

 collected from Station 1 . When the data were separated 

 by season, the difference between Stations 1 and 3 for 

 each season was significant (Table 5). During the 

 winter, spring, and fall, plasma osmolalities from Sta- 

 tion 2 were also significantly lower than those from 

 Station 1. In general, the lowest plasma osmolalities 

 were found in the spring at each station; the highest, 

 in summer or fall. None of the season-to-season varia- 

 tions in plasma osmolality at Station 3 were significant. 



The mean salinity was 27.6"/(m at Station 1, 27.9"/m, 

 at Station 2, and 26.7"/(«i at Station 3. The total range 

 of salinity measured was 22.9-30.4"/.«i. The difference 

 between stations for a single month was rarely more 

 than 2"/(»i. Bottom temperatures are summarized in 

 Figure 2. In general, station-to-station differences were 

 slight. Dissolved oxygen concentrations are presented 

 in Figure 3. Station 3 tended to have a low oxygen con- 

 centration during the summer. During the cooler 

 months, differences between stations in dissolved 

 oxygen were less pronounced. Station 1 is 5.5 m deep; 

 Station 2, 15.2 m; and Station 3, 10.7 m. 



Discussion 



This investigation was undertaken in order to observe 

 windowpane flounder blood chemistry in the field and 

 to use a series of laboratory exposures in an attempt 

 to explain the inter-station differences. However, the 

 exposures actually provided only negative information 

 on the causes of differences in blood chemistry ob- 

 served in the field. The Interstate Sanitation Commis- 



sion (unpubl.) reported a median copper concentration 

 in the water column of western Long Island Sound of 

 12 Mg/L; the highest reported copper levels were above 

 60 fjg/L. This indicates that the exposure concentra- 

 tions of 10 and 20 ixgIL were realistic in terms of a 

 polluted environment. Few water column cadmium 

 concentrations were above 5 f^g/L and the median was 

 1.0 Mg/L. Therefore, the exposure concentrations of 

 cadmium were realistic to slightly high. Mercury levels 

 used in the exposures were high compared with those 

 measured in Long Island Sound waters; the highest 

 measured mercury concentration was 1.8 ^glL and the 

 median was <0.1 t^glL, compared with exposure levels 

 of 5.0 and 10.0 t^glL. The limited effects of mercury 

 at a high exposure level and the lack of effects of cad- 

 mium and copper at more environmentally relevant 

 water concentrations clearly demonstrated that the dif- 

 ferences between stations cannot be explained by the 

 effects of these metals. The lack of effects of the 

 exposures in the present study does not diminish the 

 possible usefulness of this type of approach. The ex- 

 posures performed here were by no means comprehen- 

 sive; a more extensive program of exposures might 

 mimic the inter-station differences. 



Bridges et al. (1976) reported changes in blood 

 chemistry and, specifically, the development of anemia 

 in winter flounder held in the laboratory for over 50 

 days. Anemia was not noted in such animals in the pres- 

 ent study; hematocrits and hemoglobin levels of labor- 

 atory-held fish were ty}3ical of those of animals collected 

 in the field during the same season. However, the 

 plasma potassium levels of windowpane flounder used 

 for the mercury exposure were somewhat higher than 

 those of fish sampled immediately after collection; this 

 may be the result of the length of time that the fish 

 were held in the laboratory. 



The geographical range of the field study was limited 

 to stations at which monthly sampling was feasible. 

 This limitation made it possible to describe seasonal 



