Spatial and temporal diversity of non-native biofouling species associated with marinas in two Angolan bays.
Artificial structures in coastal areas provide substrates which facilitate the spread of non-native species. Published records of introduced benthic species in the coastal waters of Angola are scarce, and so far these have numbered 29 non-native species and seven cryptogenic species. This study aimed to describe the spatial and temporal diversity of non-native biofouling species (Cnidaria, Annelida, Cirripedia, Bryozoa and Ascidiacea) in marinas in Luanda and Lobito bays. Settlement plates were employed for three months to enable development of the sessile community. We then identified all organisms retreived and compared the composition of introduced species between the sites and seasons (dry and wet). Species composition varied between seasons and sites, and 13 taxa (11 introduced) were recorded for the first time for Angolan waters, including nuisance species, such as the bryozoans Watersipora subtorquata and Amathia verticillata. Of the 35 taxa recorded, 21 were introduced species, 10 were not identified to species level, and only two species were native to the Angolan coast-corroborating the role of marinas and ports as main pathways for introductions, and the need for studies in Angola and on the tropical west coast of Africa in general. Our study expands, from 36 to 49, the number of introduced sessile animals recorded for the Angolan coast. Species known to cause harmful effects on coastal facilities elsewhere were among those most frequently recorded in the studied marinas. The findings indicate that monitoring initiatives and comparisons of biological communities between artificial and natural habitats are essential for the management of bioinvasions, to prevent both ecological and economic losses.