Rapid Assessment Survey of introduced ascidians in a region with many marinas in the southwest Atlantic Ocean, Brazil

In August 2014, we performed Rapid Assessment Surveys (RAS) in seven marinas along circa 70 km of the coastline of Ilha Grande Bay (IGB), southeastern Brazil to evaluate diversity in the Ascidiacea and of introduced species. This region is very important for marine biodiversity and includes many protected areas. However, urbanization, tourism and economic development (aquaculture, fisheries, commercial ports and nuclear energy generation) are some of the impacts and drivers of species introduction. Our survey found 16 species, only one native, two introduced and eleven cryptogenic. Two species could not be identified precisely. The most species-rich marina had 11 species and the most polluted three marinas had only six species each. Comparisons with literature indicated that marinas in the IGB had fewer species and fewer introductions than marinas in the Sao Sebastiao Channel (Sao Paulo), in the same biogeographic region. Future monitoring should consider complementary methods such as passive collectors deployed during summer time and RAS in at least two different times of the year.