Bullard
Stephan G.
Bullard
Stephan G.
No Thumbnail Available
Search Results
Now showing
1 - 4 of 4
-
PreprintThe colonial ascidian Didemnum sp. A: Current distribution, basic biology and potential threat to marine communities of the northeast and west coasts of North America( 2006-10-09) Bullard, Stephan G. ; Lambert, Gretchen ; Carman, Mary R. ; Byrnes, J. ; Whitlatch, R. B. ; Ruiz, G. ; Miller, R. J. ; Harris, L. ; Valentine, Page C. ; Collie, Jeremy S. ; Pederson, J. ; McNaught, D. C. ; Cohen, A. N. ; Asch, Rebecca G. ; Dijkstra, Jennifer A. ; Heinonen, K.Didemnum sp. A is a colonial ascidian with rapidly expanding populations on the east and west coasts of North America. The origin of Didemum sp. A is unknown. Populations were first observed on the northeast coast of the U.S. in the late 1980s and on the west coast during the 1990s. It is currently undergoing a massive population explosion and is now a dominant member of many subtidal communities on both coasts. To determine Didemnum sp. A’s current distribution, we conducted surveys from Maine to Virginia on the east coast and from British Columbia to southern California on the west coast of the U.S. between 1998 and 2005. In nearshore locations Didemnum sp. A currently ranges from Eastport, Maine to Shinnecock Bay, New York on the east coast. On the west coast it has been recorded from Humboldt Bay to Port San Luis in California, several sites in Puget Sound, Washington, including a heavily fouled mussel culture facility, and several sites in southwestern British Columbia on and adjacent to oyster and mussel farms. The species also occurs at deeper subtidal sites (up to 81 m) off New England, including Georges, Stellwagen and Tillies Banks. On Georges Bank numerous sites within a 147 km2 area are 50-90% covered by Didemnum sp. A; large colonies cement the pebble gravel into nearly solid mats that may smother infaunal organisms. These observations suggest that Didemnum sp. A has the potential to alter marine communities and affect economically important activities such as fishing and aquaculture.
-
ArticleAbundance and diversity of ascidians in the southern Gulf of Chiriquí, Pacific Panama(Regional Euro-Asian Biological Invasions Centre (REABIC), 2011-07-04) Bullard, Stephan G. ; Carman, Mary R. ; Rocha, Rosana M. ; Dijkstra, Jennifer A. ; Goodwin, Anne M.Little is known about the ascidian fauna of Pacific Panama. Ascidian surveys were conducted in the southern Gulf of Chiriquí on the Pacific coast of Panama in January 2008 and 2009. Surveys along linear transects at 2-3 m depth (snorkel, 2008) and 5 and 12 m depth (SCUBA, 2009) were conducted at multiple sites within a chain of islands extending out from the mainland. Twelve different ascidian taxa were observed with mean densities of up to ~17 ascidians m-2. The most abundant species was Rhopalaea birkelandi. Two of the most abundant taxa (Ascidia sp., Pyura sp.) appear to represent previously undescribed species. Several species of didemnids were also abundant. Ascidians were most abundant near the coast of the mainland and were less abundant near the islands farthest offshore. These data on Panamanian ascidian communities provide a baseline of local biodiversity against which it will be possible to determine whether the communities change over time, if additional species become introduced to the region, or if native Panamanian species become invasive in other parts of the world.
-
ArticleAscidians at the Pacific and Atlantic entrances to the Panama Canal(Regional Euro-Asian Biological Invasions Centre (REABIC), 2011-08-12) Carman, Mary R. ; Bullard, Stephan G. ; Rocha, Rosana M. ; Lambert, Gretchen ; Dijkstra, Jennifer A. ; Roper, James J. ; Goodwin, Anne M. ; Carman, Mimi M. ; Vail, Elisabete M.The Panama Canal region is susceptible to non-native species introductions due to the heavy international shipping traffic through the area. Ascidian introductions are occurring worldwide but little is known about introductions at the Panama Canal. Surveys were conducted in 2002, 2008, and 2009 within the Pacific and Atlantic entrances to the canal. We found a high diversity of ascidians on both sides of the canal, dominated by non-native species; six species occurred at both Pacific and Atlantic Panama sites. This is the first report of Polyandrocarpa anguinea and P. sagamiensis in Atlantic Panama waters and Ascidia incrassata, Ascidia sydneiensis, Botrylloides nigrum, Botryllus planus, Didemnum perlucidum, Diplosoma listerianum, Microcosmus exasperatus, Polyandrocarpa zorritensis, Polyclinum constellatum, Symplegma brakenhielmi, Symplegma rubra, and Trididemnum orbiculatum in Pacific Panama waters. The canal may serve as a major invasion corridor for ascidians and should be monitored over time.
-
ArticleAll for one and one for all: research from the 6th International Invasive Sea Squirt Conference and the 10th International Conference on Marine Bioinvasions(Regional Euro-Asian Biological Invasions Centre, 2019-12-14) Dias, P. Joana ; Carman, Mary R. ; Bullard, Stephan G.It has been 20 years since the foundation of a dedicated International Conference on Marine Bioinvasions in 1999 (ICMB-I, Massachusetts Institute of Technology, Cambridge, MA, USA). 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).