THESIS APPROVAL

Table 10 Description of endpoints for short-term sediment toxicity test using
L. hoffmeisteri.
Mortality
Autotomy
Endpoint Description
Sediment avoidance
Reworking activity
Source: Meller et al. (1998)
4.5 Data Analysis
Animals were recorded as dead when they did not respond to a
gentle mechanical stimulus to the front end
Autotomy starts with a local constriction of the circular muscles,
which can be seen macroscopically. The segments behind the
constriction are completely autotomized (Kaster, 1979). Autotomy
was defined as all animals showing either constriction and/ or loss
of segments.
According to Keilty et al. (1988) a worm was considered
unburrowed if more than an estimated 75% of its body was visible
on the sediment surface.
The animals leave traces while digging through the sediment (socalled
galleries). To estimate the reworking activity, a qualitative
comparison on replicate level was performed. The reworking
activity of all animals in one test chamber was defined reduced
when the visible number of galleries was distinctly lower than in
the control chamber (Figure 12)
The effect rates in percentages of mortality, autotomy and sediment
avoidance for each concentration (i) and each test duration (j) were calculated
according to the following equations;
Mortality in ij = (Σ dead animals in ij) × 100 (1)
(Σ exposed animals in ij)
Autotomy in ij = (Σ dead animals in ij + Σ animals showing autotomy in ij) × 100 (2)
(Σ exposed animals in ij)
50