Abstract:
Freshwater Calanoid copepods are a group of free-living fresh water crustaceans. They are planktonic
and limnetic and they occur in habitats varying from freshwater to seawater. We investigated detailed
morphology of Acaftia specr'es and some abundance details, possibly the first recording in Malala lagoon,
Bundala National Park. Attention was focused on population dynamics of Acartia specles with water
quality variations. When several other Caianiod copepods were abundant Acartia specles was reduced
to undetectable levels. Basic body measurements (mm) of Acaftia specles were observed as total body
length 1.36 t 0.07, width 0.19 t 0.07, prosome length 0.7310.1 and antennae length'1.16 r 0.11. The
species has a characteristics male 5th leg butwe could not finalize the species name due to some variations
in narrow and longer furcal ramus. There was a slight change in body measurernents (mm) [total length
up to caudal setae changed from 1.36t0.07 to 1.47t0.081 with changes in water quality, specially with a
slight increase in salinity (from 0.78 t 0.15 to 6.59 t 0.92 g/l)and slight decrease in Nitrate (from247 t
6.54 to 167 x 5.47 mg/l). However, no correlation was found with respect to body measurements of
Acartia specles and water quality parameters in Malala lagoon during our visits. Body measurements of
Acartia species and relationships to habitat-ecosystem functions have been emphasized elsewhere.
Therefore, further investigations of morphological variations of this species along with habitat quality
changes are being studied. We believe these ecological relationships are important in habitat management
practices of the Malala ecosystem.