THESIS APPROVAL

Table 14 Lethal and sublethal effects of naphthalene associated with sediment on
L. hoffmeisteri.
Endpoint Data analysis Exposure time (h)
24 48 72 96
Mortality LC50 >100 >100 85.11 60.26
95% CI 83.92-86.30 58.83-61.69
NOEC 50 25 25 25
LOEC 100 50 50 50
Autotomy EC50 >100 83.17 46.77 35.48
95% CI 82.00-84.34 45.14-48.40 33.51-37.45
NOEC 25 25 25 12.5
LOEC 50 50 50 25
Sediment EC50 >100 >100 97.72 58.88
avoidance 95% CI 96.74-98.70 57.37-60.39
NOEC 50 25 25 25
LOEC 100 50 50 50
Reworking EC50
activity 95% CI
NOEC 50 25 25 12.5
LOEC 100 50 50 25
Sediment avoidance of the worms was observed within 48 h from a value
of 50 µg/g wwt onward. The EC50 values were 97.72 and 58.88 µg/g wwt for 72 and
96 h, respectively. To describe this behavioral change, in negative control and solvent
control, the worms were vertically distributed throughout the whole sediment. By
contrast, the animals in the treatments with naphthalene did not burrow immediately
throughout the whole contaminated sediment. These worms remained in a group on
the surface of the contaminated sediment (Figure 31), and then burrowed just into the
surface. The observation also demonstrated that most animals initially burrowed into
the spiked sediment and then some of them returned to the sediment surface during
the following 96 h. The body part of these worms became white, with disintegration.
The color of the worms was paler than of worms in clean sediment.
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