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Investigations on marine biological invasions have become an important field of
study due to its enormous effect on ecology, economy and human health. Fouling
on ship hulls considered to be one of the most common pathways of introducing
non indigenous species (NIS) across the oceans.The present study was conducted in
eight sampling locations within Colombo Port. Biofouling aggregates were collected
using artificial settlement plates (10cm x 10cm) submerged in four depths. The first
set was lm below the water surface and others settled in lm increments. Monthly
samples were collected from October 2014 to July 2015 from both replacing and
permanently settled collectors. Species were identified microscopically, observing
their fine morphological features using stereomicroscopes. Eight morphologically
dissimilar encrusting bryozoans were recorded. The most promising finding is the
first record of highly invasive encrusting bryozoan, Watersipora subtorquata. They
were recorded in two of the sampling locations. In New Pilot Station (NPS), they
were recorded at 2m depth covering 12.5% of the panel area and Bandaranayake
Quay (BQ) at lm depth covering 2.19% of the panel area. W. Subtorquata is an encrusting foliaceous colonial bryozoans affiliated to the family Watersiporidae belong
to the suborder Ascophora. The colony is dark or black with bright orange outer
growing edge. The colony consists with comparatively large and distinct zooecia
with numerous pores and distinct mushroom shaped operculum. This species is well
recognized as highly invasive in many parts of the world and they facilitate the dispersion of other invasive organisms via providing non toxic substrates to settle in,
compete with native bryozoans and other fouling organisms subsequently altering
