Biogeographical patterns of tunicates utilizing eelgrass as substrate in the western North Atlantic between 39o and 47o north latitude (New Jersey to Newfoundland)

Abstract

Amongst the most prominent driving factors behind this were the invasion of the Great Lakes by the zebra mussel Dreissena polymorpha Pallas, 1771 in the 1980s and reports of an average of one new species invading San Francisco Bay every 14 weeks between 1961 to 1995 (Cohen and Carlton 1998). At this time, scientists were becoming well aware of the growing number of introductions worldwide and their impacts on marine communities (Minchin 1996; Reise et al. 1998; Hewitt et al. 1999; Sliwa et al. 2009). Ascidians, commonly known as sea squirts, were quickly flagged as one of the most notorious and diverse group of fouling species being transported and introduced around the world (Shenkar and Swalla 2011). Indeed, in the late 1990s and early 2000s, invasive ascidians were identified as important players causing significant ecological and economic impacts to marine systems (Coles et al. 2002; Lambert 2002). As the twenty-first century enters its third decade, invasive ascidians continue to affect ecosystems (Carman et al. 2011; Shenkar 2012; Zhan et al. 2015), create problems for aquaculture (Muñoz and McDonald 2014; McKenzie et al. 2017), and frequently dominate coastal fouling communities (López-Legentil et al. 2015). The International Invasive Sea Squirt Conference (IISSC; https://web. whoi.edu/sea-squirt-conference/) began in 2005 to bring together diverse user groups concerned about invasive ascidians. The goal was to explore invasive ascidian biology, ecology, impacts and management options. The conference audience included marine biologists, shellfishery scientists and industry, governmental agencies concerned with coastal resources, representatives from sponsoring organizations and the media. The first IISSC was so successful that it became more or less a biennial event, with