The recent arrival of the non-indigenous oyster Saccostrea cucullata (Bivalvia: Ostreidae in Southeast Brazilian coast

Abstract

Rock oysters of the genus Saccostrea are widely distributed in tropical and subtropical regions around the world. Saccostrea cuccullata (Born, 1778) is categorized as indigenous from the Indo-Pacific, south and east coasts of Africa and has been introduced in Hawaii, in the Mediterranean Sea, the Suez Canal and Panama (Atlantic coast). In Arraial do Cabo, an upwelling region in southeastern Brazilian coast, the non-indigenous (NI) oyster S. cucullata has been the subject of investigation in a port area (Forno Port). The examined material matches the morphological characteristics to S. cucullata from the Pacific Ocean. The NI oysters S. cucculata are confined to shallow waters at Forno Port, well-established in the pillars and breakwater as the most prominent taxon among the fouling community, growing with the native oysters along the midlittoral zone. S. cucculata is also cohabiting with an NI associated fauna including: Eualetes tulipa (Rousseau in Chenu 1843) and Isognomon bicolor (Adams, 1845); and the following native fauna: the vermetid Petaloconchus varians (d’Orbigny 1839), the oysters Crassostrea brasiliana (Lamarck 1819) and Ostrea sp., the balanid Tetraclita stalactifera (Lamarck 1818), micromolluscs and small spirorbid polychaetes. The impact to the native benthic community is unknown, but our initial results suggest that this recent introduction could compete with the native equivalent mollusks species. Considering the connectivity of shipping vessels, S. cucullata may have been introduced at Arraial do Cabo by commercial vessels and would be easily spread. We predict the increase of its population densities to surrounding rocky shores due to intensive domestic recreational traffic boats in the region, and by natural dispersion of larvae. Future steps include efforts on monitoring this newly arrived population; elucidate some of the ecological aspects and also the potential of spread.