High density of the alien bryozoan Fenestrulina delicia in the fouling assemblage of a South American harbour (Argentina)

The non-indigenous cheilostome bryozoan Fenestrulina delicia Winston, Hayward and Craig has been recorded for the first time in the southern hemisphere. It was found on experimental substrata submersed to study the fouling assemblage of Quequén Harbour (Argentina, southwest Atlantic), an estuarine environment. Its density on experimental panels was very high, reaching almost 5,000 colonies.m −2 . The percentage of ovicellate colonies, however, was relatively low (mean ± SD: 5.2 ± 2.3 %, range: 1.6 – 9.9 %) due to the abundance of newly recruited zoaria. F. delicia was originally described for the Atlantic coast of the United States. It was later discovered in Alaska, Oregon and California, and has recently been reported as a highly invasive fouler along the Atlantic coasts of Europe. This species seems to have the potential to continue its dispersion by means of maritime traffic, or rafting on plastic debris, and become a stable component of this and neighbouring harbours in the area.