Effect of unionized ammonia, viscosity and
protozoan contamination on reproduction and enzyme activity of the rotifer
Brachionus rotundiformis
A. Belem de Araujo, A. Hagiwara, T.W. Snell-2001
Hydrobiologia, 446/447: 363-368
Abstract:
We determined the effect of environmental stressors on the physiological
condition of Brachionus rotundiformis. For two morphologically distinct B.
rotundiformis strains: Hawaii (average lorica length = 222 mm) and Langkawi
strains (average lorica length 180 mm), neonates hatched from resting eggs
were exposed to different levels of unionized ammonia (0.7–9.8 mg l^−1),
viscosity (relative viscosity against natural seawater = 1–1.17) and
Euplotes sp. (protozoan) contamination (1–40 cells ml^−1). Increasing
stress decreased fecundity and lifespan of both rotifer strains. Glucosidase
and phospholipase activities were correlated with reproductive responses of
both the strains exposed to unionized ammonia. When culture water viscosity
was changed, the activity of esterase and phospholipase was correlated with
reproductive responses of the Hawaiian strain, and glucosidase activity was
correlated with those of Langkawi strain.With the protozoan contamination,
esterase and glucosidase activities were correlated only with reproductive
responses of the Hawaiian strain, while activity of all three enzymes was
correlated to those of the Langkawi strain. Glucosidase activity proved to
be a reliable indicator of stress for cultured B. rotundiformis.