. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AMMONIA TOXICITY TO LARVAL SHRIMP 21 300|- 200 < 100 z o CP E 50- 20- 10. _pH 8 34 12 24 48 72 96 TIME ( MRS) 120 144 FIGURE 1. The toxicity of total ammonia to larval -I/, rosenbergii exposed in solutions of different pH. Bars are ± one standard deviation. 1969). However, no such decrease in the slope of the pH toxicity curve had occurred, indicating longer tests were needed to estimate incipient concentrations. The time to death for larvae held in solutions of equal ammonia concentration hut different pH
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AMMONIA TOXICITY TO LARVAL SHRIMP 21 300|- 200 < 100 z o CP E 50- 20- 10. _pH 8 34 12 24 48 72 96 TIME ( MRS) 120 144 FIGURE 1. The toxicity of total ammonia to larval -I/, rosenbergii exposed in solutions of different pH. Bars are ± one standard deviation. 1969). However, no such decrease in the slope of the pH toxicity curve had occurred, indicating longer tests were needed to estimate incipient concentrations. The time to death for larvae held in solutions of equal ammonia concentration hut different pH is shown in Figure 2. In 100 ing ammonia/liter, 50% mortality of larvae in solutions of pH , , and occurred in about 9, 27, and 125 hr, respectively. Survival of larvae held in 32 mg/liter at pH and was nearly equal to that of controls. However, animals exposed to the same ammonia concentration at pH were all dead by 48 hr (Fig. 2). Un-ionized ammonia was not the exclusive toxic agent in these tests, and the XH4+ molecule apparently contributed to mortality also. When LCjo values were based on the concentration of XH3 only (, normalized with respect to pH), there was no equality of the levels found to be toxic at specific time intervals (Fig. 3). In fact, larvae exposed to the lowest levels of XH3 (pH = ) were the most susceptible to toxicity due to the concomitantly high levels of XH4+ present (Table I). The proportions of XH3 and XH4+ found to be toxic were inversely related as pH changed. Consequently, about five times less XH3 was lethal in a given period at low pH compared to the high, but it was accompanied by six times more XH4+ ion (Table I). The effect of XH4( on survival times of larvae is further demonstrated when the response of groups in equal XH3 concentrations at different pH values was compared. The LT00 values for larvae exposed to mg XH3/liter at pH Please note that these images are extracted from scanned page im
Size: 1521px × 1644px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
