Gretchen and Charles Lambert

12001 11th Ave. NW, Seattle, WA 98177

206-365-3734 or

home page:


Number 64                                                                                                     May 2009


   We greatly appreciate all the contributions for this issue. In addition to a number of Work in Progress articles and meetings abstracts, there are   thesis abstracts with significant new information, and 113 new publications listed at the end of this issue.   

   The next ascidian workshop will be June 4-18, 2009 at the Smithsonian Tropical Research Institute, Bocas del Toro, Panama, taught by Rosana Rocha and Gretchen and Charles Lambert. We will have a full class of 16, from many countries; we are looking forward to it. Rosana taught a workshop in Venezuela in April with 13 participants; see her report on this below.

   After the Panama workshop we will be at the Univ. of Washington Friday Harbor Labs July 1-Aug. 19, followed by a trip to Portland, Oregon for the 6th Intl. Bioinvasions meeting Aug. 24-27. In October we will teach a 5 day ascidian workshop in Quebec.


*Ascidian News is not part of the scientific literature and should not be cited as such.




1. From Mary Carman, Woods Hole Oceanog. Institution, Woods Hole, MA  

The next Intl. Invasive Sea Squirt Conference, IISSC3, will be held at WHOI, April 27-29, 2010. Oral and poster presentations will be considered for Taxonomy and Genetics, Biogeography, Ecology, Risk Assessment and Management. There will be another taxonomic workshop presented by Gretchen and Charley Lambert and a field trip to Martha's Vineyard. The journal Aquatic Invasions has agreed to publish the special issue of the IISSC-3 conference papers. They did a terrific job with the papers from IISSC-2 and we are most grateful for their willingness to take on this project again.


2. Dr. Nori Satoh retired from Kyoto University at the end of March 2009 and moved to Okinawa Institute of Science and Technology. His new email is  or


3. From Nori Satoh, Hiroki Nishida, and Euichi Hirose:

  We are very pleased to announce the 5th International Tunicate Meeting, which will be held on 21- 25 June 2009, at the hall of the Okinawa Industrial Supporting Center in Naha-city, Okinawa, Japan. Okinawa is a subtropical island, southwest of the main island of Japan, and you can access here easily by about 2-hrs flight from Tokyo or Osaka. Research of tunicate biology has become deeper and wider during the last several years. So, it is a good opportunity for everyone to come to Okinawa to discuss his or her research progress. Many beautiful corals surround Okinawa so that you may be relaxed for several days to refresh your head and body. We are looking forward to seeing you in Okinawa. Please find more information online:




1. From Mary Carman and Andrea Locke: The proceedings of the 2nd International Invasive Sea Squirt Conference, held at Prince Edward Island, Canada October 2-4, 2007, were peer reviewed for a special issue of Aquatic Invasions (Vol. 4, issue 1, January 2009) and are now available online ( ).  Edited by: Andrea Locke, Gulf Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5030, Moncton, New Brunswick, Canada, E1C 9B6  E-mail: and Mary Carman, Geology and Geophysics Dept., Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA




Andrea Locke and Mary Carman  An overview of the 2nd International Invasive Sea Squirt Conference: what we learned (pp 1-4)


Gretchen Lambert  Adventures of a sea squirt sleuth: unraveling the identity of Didemnum vexillum, a global ascidian invader (pp 5-28)


Lauren Stefaniak, Gretchen Lambert, Adriaan Gittenberger, Huan Zhang, Senjie Lin and Robert B. Whitlatch  Genetic conspecificity of the worldwide populations of Didemnum vexillum Kott, 2002 (pp 29-44)


Rodolfo C. Barros, Rosana M. da Rocha and Marcio R. Pie  Human-mediated global dispersion of Styela plicata (Tunicata, Ascidiacea) (pp 45-57)


Andrés Izquierdo-Muñoz, Marta Díaz-Valdés and Alfonso A. Ramos-Esplá
Recent non-indigenous ascidians in the Mediterranean Sea (pp 59-64)


Mary R. Carman, K. Elaine Hoagland, Emma Green-Beach and David W. Grunden  Tunicate faunas of two North Atlantic-New England islands: Martha’s Vineyard, Massachusetts and Block Island, Rhode Island (pp 65-70)


Andrea Locke  A screening procedure for potential tunicate invaders of Atlantic Canada (pp 71-79)


Erin K. Grey  Do we need to jump in? A comparison of two survey methods of exotic ascidians on docks (pp 81-86)


Emily Darbyson, Andrea Locke, John Mark Hanson and J. H. Martin Willison
Marine boating habits and the potential for spread of invasive species in the Gulf of St. Lawrence (pp 87-94)


Emily A. Darbyson, John Mark Hanson, Andrea Locke and J. H. Martin Willison  Settlement and potential for transport of clubbed tunicate (Styela clava) on boat hulls (pp 95-103)


Renée Y. Bernier, Andrea Locke and John Mark Hanson  Lobsters and crabs as potential vectors for tunicate dispersal in the southern Gulf of St. Lawrence, Canada (pp 105-110)

Following anecdotal reports of tunicates on the carapaces of rock crab (Cancer irroratus) and American lobster (Homarus americanus), we evaluated the role of these species and northern lady crab Ovalipes ocellatus as natural vectors for the spread of invasive tunicates in the southern Gulf of St. Lawrence. Several hundred adult specimens of crabs and lobster from two tunicate-infested estuaries and Northumberland Strait were examined for epibionts. Small patches of Botrylloides violaceus were found on rock crabs examined from Savage Harbour and a small colony of Botryllus schlosseri was found on one lobster from St. Peters Bay. Lobster and lady crab collected in Northumberland Strait had no attached colonial tunicates but small sea grapes (Molgula sp.) were found attached on the underside of 5.5% of the rock crab and on 2.5% of lobster collected in Northumberland Strait in August 2006. Lobster and rock crab clearly represent a vector for the spread of invasive tunicates regionally and wherever living crustaceans are shipped globally.



Anya Epelbaum, Thomas W. Therriault, Amber Paulson and Christopher M. Pearce  Botryllid tunicates: Culture techniques and experimental procedures (pp 111-120)


Robert B. Whitlatch and Richard W. Osman  Post-settlement predation on ascidian recruits: predator responses to changing prey density (pp 121- 131)


Jeffery M. Mercer, Robert B. Whitlatch and Richard W. Osman  Potential effects of the invasive colonial ascidian (Didemnum vexillum) on pebble-cobble bottom habitats in Long Island Sound, USA (pp 133-142)


Nicole L. Lengyel, Jeremy S. Collie and Page C. Valentine  The invasive colonial ascidian Didemnum vexillum on Georges Bank ― Ecological effects and genetic identification (pp 143-152)


Page C. Valentine, Mary R. Carman, Jennifer Dijkstra and Dann S. Blackwood  Larval recruitment of the invasive colonial ascidian Didemnum vexillum, seasonal water temperatures in New England coastal and offshore waters, and implications for spread of the species (pp 153-168)


Aaron Ramsay, Jeffrey Davidson, Daniel Bourque and Henrik Stryhn
Recruitment patterns and population development of the invasive ascidian Ciona intestinalis in Prince Edward Island, Canada (pp 169-176)


Rémi M. Daigle and Christophe M. Herbinger  Ecological interactions between the vase tunicate (Ciona intestinalis) and the farmed blue mussel (Mytilus edulis) in Nova Scotia, Canada (pp 177-187)


Garth Arsenault, Jeff Davidson and Aaron Ramsay Temporal and spatial development of an infestation of Styela clava on mussel farms in Malpeque Bay, Prince Edward Island, Canada (pp 189-194)


Rosana M. Rocha, Laura P. Kremer, Mariah S. Baptista and Rafael Metri
Bivalve cultures provide habitat for exotic tunicates in southern Brazil (pp 195-205)


James A. Morris, Jr., Mary R. Carman, K. Elaine Hoagland, Emma R.M. Green-Beach and Richard C. Karney Impact of the invasive colonial tunicate Didemnum vexillum on the recruitment of the bay scallop (Argopecten irradians irradians) and implications for recruitment of the sea scallop (Placopecten magellanicus) on Georges Bank (pp 207-211)


Vanessa Lutz-Collins, Aaron Ramsay, Pedro A. Quijon and Jeffrey Davidson
Invasive tunicates fouling mussel lines: evidence of their impact on native tunicates and other epifaunal invertebrates (pp 213-220)


Andrea Locke, Kenneth G. Doe, Wayne L. Fairchild, Paula M. Jackman and Erica J. Reese  Preliminary evaluation of effects of invasive tunicate management with acetic acid and calcium hydroxide on non-target marine organisms in Prince Edward Island, Canada (pp 221-236)


Andrea Locke and John Mark Hanson  Rapid response to non-indigenous species. 1. Goals and history of rapid response in the marine environment (pp 237-247)


Andrea Locke, John Mark Hanson, Neil G. MacNair and Arthur H. Smith
Rapid response to non-indigenous species. 2. Case studies of invasive tunicates in Prince Edward Island (pp 249-258)


Andrea Locke and John Mark Hanson  Rapid response to non-indigenous species. 3. A proposed framework (pp 259-273)


Stephan G. Bullard and Robert B. Whitlatch  In situ growth of the colonial ascidian Didemnum vexillum under different environmental conditions (pp 275-278)


Adriaan Gittenberger  Invasive tunicates on Zeeland and Prince Edward Island mussels, and management practices in The Netherlands (pp 279-281)


Martin H. Davis and Mary E. Davis  Styela clava (Tunicata, Ascidiacea) – a new threat to the Mediterranean shellfish industry? (pp 283-289)


Mary R. Carman, Hannah M. Allen and Megan C. Tyrrell  Limited value of the common periwinkle snail Littorina littorea as a biological control for the invasive tunicate Didemnum vexillum (pp 291-294)


Richard C. Karney and Walter Y. Rhee  Market potential for Styela clava, a non-indigenous pest invading New England coastal waters (pp 295-297)


2. From Dr. M. Tamilselvi. V.V.Vanniaperumal College for Women, Virudhunagar, Tamilnadu, India.

Analyzing the food value of ascidians.  This is an ongoing two years minor project sponsored by University Grants Commission, Hyderabad. The main objective of this project is to find out the food value of ascidians and prepare pickles from selected ascidians from Tuticorin coast. [editors’ note: please send us the species names and recipes if they turn out well!]


3. From Mari Carmen Pineda Torres, Departamento de Biología Animal (Invertebrados), Facultad de Biología, Universidad de Barcelona, Spain

Biology, population genetics and stress responses of the cosmopolitan ascidian Styela plicata.

    This year I have started my PhD project focused on Styela plicata, under the supervision of Xavier Turon (Spanish Research Council) and Susanna López-Legentil (University of Barcelona).

At present, I am working on the global phylogeography of the solitary ascidian Styela plicata, in collaboration with Cynthia Riginos’ team from the University of Queensland, Australia. Our main goal is to infer the worldwide genetic patterns of S. plicata and the historical processes that had led to them. We are grateful to many Tunicata people that have contributed samples to this study. At a smaller scale, I would like to investigate the structure of Styela plicata populations within the Atlanto-Mediterranean area.

    I have also started studying the biology of Styela plicata and I’m performing a two-year monitoring of two populations from the Catalan coast (NW Mediterranean). The main goal of this study is to better understand the life cycle of this species in the Mediterranean Sea. The third part of my Ph.D. dissertation consists of analyzing the molecular responses of S. plicata to environmental perturbations. We are performing experiments with different pollutants and analysing HSP expression levels using Quantitative Real Time PCR.

    I hope to collaborate with other tunicate researchers in order to increase the general knowledge about this interesting species, determine its potential as a marine bio-indicator, predict its potential invasive role, or simply understand how this ascidian lives and where it comes from.


4. From Rosana Moreira da RochaUniversidade Federal do Paraná, Brazil.  

    a. Since July 2008, I have been working at Bocas del Toro Research Station, a facility of the Smithsonian Tropical Research Institute in Panama, as a fellowship researcher during my sabbatical year. I am developing the project “Distribution, reproduction and physiological tolerance of introduced and native tunicates in Bocas del Toro: a case study with Phlebobranchia”. Recent surveys show that Bocas del Toro is a region of high tunicate diversity, with many species shared with other Caribbean localities, but also many endemic species. It is one of the five more diverse sites in the Caribbean. In 2003, I made a first survey during the 1st Invertebrate Taxonomy Workshop at Bocas, which resulted in a list of 58 ascidian species, many of them new to science. (Rocha, R. M., Faria, S. B. & Moreno, T. R. 2005. Ascidians from Bocas del Toro, Panama. I. Biodiversity. Caribb. J. Sci. 41, 600-612; Collin, R. 2005. Ecological monitoring and biodiversity surveys at the Smithsonian Tropical Research Institute’s Bocas del Toro Research Station. Caribb. J. Sci. 41, 367-373; Collin, R., Diaz, M. C., Norenburg, J., Rocha, R. M., Sanchez, J. A., Schulze, A., Schwartz, M. & Valdes, A. 2005. Photographic identification guide to some common marine invertebrates of Bocas Del Toro, Panama. Caribb. J. Sci. 41, 638-707.) One of the things I am doing now is to re-collect these new species to have more material and mature individuals, to describe and publish their descriptions.

    This first survey did not differentiate artificial substrates and all possible exotic species that could be present on them. Artificial substrates are known to harbor more exotic species than the natural substrates. Bocas is growing fast and more and more artificial structures are being submerged. It is also passage for many ships that go to the Almirante port, and the incrustation on their hull is one of the most important vectors for sessile invertebrate transportation. Also some of the species in the list for Bocas are known for their wide distribution, which suggests human transportation. In my research I intend to address bioinvasion using tunicates as models, in a variety of approaches.

    The deployment of experimental plates in five different sites including one in Bocas town and four in mangrove habitats showed that species are very different between them, more diversity and more colonial species appearing in town. But Ascidia sydneiensis and Styela canopus, both probably introduced, are very common at all sites. On the other hand, species present on artificial substrates very close to natural mangrove sites are not that different between sites, indicating that these artificial substrates could function as stepping stones for introduced species to invade natural habitats.  There is also a seasonal pattern in colonization, with fewer recruits during the rainy season. 

    First results of physiological tolerances to salinity variation of some species in the Order Phlebobranchia showed some capacity for ion control and cellular volume control in salinities as low as 15‰. This indicates potential for these species to travel into waters of different salinity conditions.  Some experiments on the role of predation and monitoring of species growth rate are going on to help understand differences between native and introduced species. 


    b. Ascidian Workshop in Venezuela

    In April 20-24 I taught an ascidian workshop on Margarita Island, Venezuela. The objective of the workshop was both to train new taxonomists and ecologists willing to be able to identify ascidians, as well as to know the fauna of La Restinga Nacional Park. This is a beautiful hypersaline lagoon lined by healthy mangrove forest with an amazing biomass and diversity of ascidians growing on the roots. In two mornings of snorkeling, we visited four sites and collected and identified around 30 species, three possibly new. I thank the hard-working organizers and participants for a very successful workshop!


5. From Mary Carman. Geology and Geophysics Dept., Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA

    In January 2008 we conducted exploratory surveys at the Pacific Panama Canal and on the Pacific coast of Panama between the islands of Isla Canales de Tierra (ICT) and Isla de Coiba (IC).  During these surveys, ascidian species were observed at the canal and in the island chain; species identifications are pending.  The apparent low diversity and abundance of ascidians in Pacific Panama waters is in stark contrast to the high diversity of ascidians in the Atlantic-Caribbean waters at Bocas del Toro, Panama (Rocha et al. 2005).  The unique nature of the Panama Canal and its potential role in the movement of invasive species warrants additional study of the ascidian fauna of the Pacific coast of Panama.  In this context, Carman, Bullard, Jennifer Dijkstra, and Rosana Rocha returned to Panama in January 2009 to address the specific questions: 1) How abundant and diverse are the ascidians occurring at the Pacific entrance to the Panama Canal and in the chain of islands from ICT to IC (Panama’s largest national preserve)?  2) Does the composition of the ascidian fauna differ with the degree of shoreline development? 3) Are the ascidians currently residing in Pacific Panama waters considered native or invasive species?   A manuscript is in preparation.


6.  From Christine Paetzold. Dept. of Health Management, Univ. of Prince Edward Island, 550 Univ. Ave., Charlottetown, PEI, Canada

    Mortality Model. We are in the process of determining how tunicates die, naturally and as effect of mitigation treatments, by describing their chemical and protein fingerprints and pathohistological changes occurring at the cellular level.  So far, the focus is on two solitary species, Ciona intestinalis and Styela clava.  To date, chemical fingerprints (HPLC/MS) of live and dead animals did not identify a particular chemical that gave a strong enough signal to distinguish between healthy and dying tunicates.  This summer, protein fingerprinting and histopathological descriptions of both healthy and dying/dead animals will be performed.


7.  From Marcos Tatian, Ecología Marina, Facultad de Ciencias Exactas, Físicas y Naturales, Univ. nacional de Córdoba, Argentina.

Colonization of Patagonian harbors (SW Atlantic) by invasive sea squirts.  Marcos Tatián,  Evangelina Schwindt, Cristian Lagger & María M. Varela.

   In spite of the poorly studied biodiversity of the Southwestern Atlantic, several exotic species have already been detected. We follow the distribution and estimate the abundance of invasive ascidians in the SW Atlantic and review its historical records. For this purpose, we examined ascidians from argentine museum collections dated as from 1914 and inspected randomly sampled natural biota collections as well as colonization on plates deployed in situ for two years throughout six major harbors along Patagonia Argentina coast. Museum collections revealed a sudden presence of the species Ascidiella aspersa early in the 1960’s. The species is actually distributed over 10 latitudinal degrees in harbors and subtidal areas along the SW Atlantic. Together, results suggest that this species, an exotic for the SW Atlantic, is able to colonize new areas. Further studies are needed to assess invasion impacts on biodiversity in the study area.


8. From Francoise Monniot, Museum national histoire naturelle, 57 rue Cuvier, 75231 cedex 05 FR Paris.

– The CAML “Census of Antarctic Marine Life “ is a five year international program involving several ships. During the summer of 2007-2008  in Terre Adelie and Geoge V Land (eastern Antarctic)  the objective was a comprehensive survey of the plankton, fish, benthos and oceanography, driving to a better knowledge of the diversity and evolution of the current biota, in order to evaluate the effects of climatic change in the future. During this program numerous ascidians were photographed and collected by trawl aboard the N.O. Aurora Australis.  The study of this material is in progress.


9. From Billie J. Swalla and Noa Shenkar, Biology Dept., Univ. of Washington, Seattle, WA.

   We are currently working on using molecular tools to solve cases of synonym in the ascidian literature. By using two nuclear genes, 18S rDNA and 28S rDNA, we were able to clarify a case of synonym in the Molgulidae family, Molgula citrina and Molgula echinosiphonica. In addition, we are working on COI sequences provided by a collaboration with the Smithsonian Barcoding of Life project  based on the Shenkar extensive collection of Mediterranean and Red Sea ascidians (National Collections of Natural History at Tel-Aviv University These sequences include several species that do not appear in Genbank and represent a diverse range of ascidian families. Enlarging the number of species sequenced and the number of genes amplified from ascidians will assist us in a better understanding of ascidian phylogeny and evolution. If anyone would like to send specimens for museum voucher and also in ethanol for DNA analysis, please contact us.




1. International Conference on Aquatic Invasive Species, April 19-23, 2009, Montreal.

First occurrence of the invasive colonial ascidian Didemnum vexillum to utilize eelgrass Zostera marina as substrate. Mary R. Carmana and David W. Grundenb.       aGeology and Geophysics Department, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543; bOak Bluffs Shellfish Dept., PO Box 1327, Oak Bluffs, MA 02557

    The invasive colonial ascidian Didemnum vexillum Kott, 2002 has adapted to utilizing eelgrass Zostera marina (Linnaeus, 1753) as substrate in Atlantic coastal waters at Massachusetts.  Usually associated with artificial and rocky substrates, we found D. vexillum attached to Z. marina at Lake Tashmoo, Martha’s Vineyard, Massachusetts in fall 2008.  Several non-endemic species of ascidians including D. vexillum were introduced to New England in the 1980s and are now common in subtidal communities and at shellfish aquaculture sites, marinas and harbors.  The bay scallop Argopecten irradians irradians (Lamarck, 1819), a cultured shellfish that is also placed out as part of shellfish restoration efforts on the Vineyard, is a valuable coastal resource on the Vineyard and elsewhere in New England.  Eelgrass serves as a habitat for bay scallops and juvenile fish and threats to it are of concern by coastal managers and the fishing industry.  We surveyed Lake Tashmoo, a protected marine pond with shellfish aquaculture operations and restored bay scallops.  We found the invasive colonial ascidians D. vexillum, Botrylloides violaceus Okra, 1927, Botryllus schlosseri (Pallas, 1774), Diplosoma listerianum (Milne-Edwards, 1841) and the native solitary ascidian Molgula manhattensis (Dekay, 1843) growing on eelgrass in patches scattered throughout the mid pond area, encompassing about one fourth of the pond.  These ascidians, including D. vexillum, were attached to the stalk and blade of live in situ eelgrass and to floating pieces of eelgrass.  Rafting of ascidians on floating eelgrass blades or pieces of the plant is a recognized dispersal mechanism for some ascidians and should now be considered as a dispersal mechanism for D. vexillum too.  Botrylloides violaceus, B. schlosseri, D. listerianum and M. manhattensis have been previously recorded as attached to eelgrass, but D. vexillum has not been previously recorded attached to eelgrass. Perhaps because of lack of available space, D. vexillum has spread to utilize eelgrass as habitable space.  Other eelgrass sites in North American Atlantic and Pacific waters should be examined for epibiotic ascidians and the impact of D. vexillum and other invasive species of ascidians on eelgrass should be assessed.


2. Benthic Ecology Meeting March 4-7, 2009, Corpus Christi, Texas.
The effects of Didemnum vexillum overgrowth on Mytilus edulis growth and reproduction.
Auker, Linda A., and Harris, Larry G. Dept. of Biol. Sci., Univ. of New Hampshire, Durham, NH 03824
   Didemnum vexillum is an invasive tunicate that has been observed overgrowing several species of sessile marine animals, including the common blue mussel Mytilus edulis. It is clear that the overgrowth negatively affects the retrieval and processing of farmed mussels. However, it is not known specifically what aspects of mussel biology and ecology are affected. Therefore, this study aims to compare growth, reproduction, and predator preference for mussels not covered by D. vexillum, and those that are. Mussels were maintained in triplicate cages at the University of New Hampshire pier in Newcastle, NH, where D. vexillum is a dominant fouling species. Each month, thirty mussels from each set of cages are randomly measured for height, length, and width. Every three months for a year, a set of each clean and overgrown mussels are retrieved and measured in the lab to calculate shell thickness index, tissue index, lip thickness, and reproductive output (measured by gonad weight and from histology samples). This presentation will cover the first six months of data and some conclusions that can tentatively be made.


3. National seminar on Pollution Hazards and Marine Fishery Resources Management organized by Fisheries College and Research Institute, Tamilnadu Veterinary and Animal Sciences Univeristy, Tuticorin, India. 

Heavy metals accumulation in tunicates Didemnum psammathodes (colonial ascidian) and Herdmania pallida (simple ascidian) from Tuticorin Coast, India. M. Tamilselvi1, V. Sivakumar2, H. Abdul Jaffar Ali3, and  R.D.Thilaga4.  1Dept. of Zool., V.V.Vanniaperumal College for Women, Virudhunagar. 2Dept. of Zool., V.O.Chidambaram College, Tuticorin.  3Dept. of Zool., Muslim Arts College, Thiruvithancode. 4Dept. of Zool., St. Mary’s College, Tuticorin.

   The concentrations of Cd, Pb, V and Hg have been measured in the tunicates Didemnum psammathodes and Herdmania pallida inhabiting two areas (Station 1 and Station 2), situated along the Tuticorin coast. These two stations are vulnerable to the mixing of industrial and urban wastes from adjacent factories and township. The accumulation of heavy metals in the body tissues of D. psammathodes and H. pallida exhibited seasonal variation. Higher metal accumulation was observed in both the tunicates during premonsoon season at Station 1 (harbour area) and monsoon season at Station 2 (coastal area). The load, source and effect of these metals are discussed.


4. ICAIS 2009  (16th Intl. Conference on Aquatic Invasive Species). Fairmont Queen Elizabeth, Montreal, Quebec, Canada, April 19 – 23, 2009.

New mitigation options against Ciona intestinalis. Christine Paetzold, Jeff Davidson, Aaron Ramsay, Dept. of Health Management, Atlantic Veterinary College, Univ. of Prince Edward Island, Charlottetown, PEI, Canada

    Over the past decade, the fouling of mussels and aquaculture gear by invasive tunicates has decreased the profitability of the mussel industry in Prince Edward Island (PEI).  Tunicates settle in such abundance on mussel gear and crop that regular maintenance requires more time, manpower and cost due to the increased weight of the gear.  In addition, mussel growth and meat yields may be negatively impacted on leases heavily infested with tunicates resulting in longer time to reach market size.  Lastly, either chemical or mechanical treatments are necessary to remove the tunicates from mussel gear throughout the season and prior to harvest, adding more expenses to a mussel farming operation.

    Currently, the most detrimental tunicate around PEI is the vase tunicate, Ciona intestinalis.  Consisting mostly of water, C. intestinalis adds considerable weight to the mussel lines.  Previously, a variety of C. intestinalis mitigation treatments were tested and high-pressure water proved to be most effective.  Our current focus is on developing a more practical and efficient mitigation method.  New treatments under consideration include the biocide Virkon Aquatic®, electro-chlorination (hypochlorous acid), ultrasound, laser and water siltation.  In addition, the cellulose-degrading enzyme cellulase was tested since tunicates contain a cellulose-like compound in the tissue surrounding their internal organs.  Treatment trials were conducted in the laboratory at the Atlantic Veterinary College and in a portable aquatic laboratory (PAL), which is a flow-through system using estuarine water.  Virkon® Aquatic was the most effective treatment, reducing up to 100% of C. intestinalis from experimental plates.  Electro-chlorination and ultrasound showed potential as mitigation agents, but treatment application needs to be optimized for more effective results.  Cellulase and water siltation had no effect on C. intestinalis in the laboratory.  Based on these results, future trials in the laboratory and field are planned to further evaluate the potential of Virkon® Aquatic, electro-chlorination and ultrasound to reduce C. intestinalis fouling on mussel gear on PEI.


5. State level seminar on conserved bio resources – 29-30 December, 2008.
Study on food value of marine ascidians from the Tuticorin coast.  H.A. Jaffar Ali and V. Sivakumar, Dept. of Zoology, Dr. Zakir Hussain College, Ilangudi - 63072, Tn, India.   [No abstract available.]




1. Presence and localization of the hormones TRH, TSH, T4, GnRH, FSH and LH in the reproductive cycle of Styela plicata: immunohistochemical investigation. Ph.D. thesis.

Annunziata Laurenza, Dept. of Life Sciences, Fac. of Sci., II Univ. of Naples, 43 Vivaldi road, 81100 Caserta, Italy.  Faculty advisor Dr. Lucio Botte.

   Historically, morphological homologies have been used to support a phylogenetic relationship between Hemichordata (Pterobranchia and Enteropneusta) with Echinodermata and Chordata.

In the present Ph.D. thesis I have examined the functional morphology between neural gland complex, endostyle and ovary in the ascidian Styela plicata by means of morphological and immunohistochemical techniques. The morphostructural, cytochemical and immunocytochemical evidence displayed in this thesis confirm, in agreement with previous findings, that the endostyle is homologous to the follicle of the thyroid gland of vertebrate. Moreover, this thesis provides also in Styela plicata, hormonal evidence that a partial imitation of the hypothalamus- hypophysis- thyroid- ovary of vertebrate axis can be observed.  The presence of endostylar variations in morphology and in number is constantly observed in our experiments. The activity of the gonads is controlled by the neural complex; morever the endostyle could play an important role in the maturation of these.
   In order to verify the hypothetical functional relationship between neural complex and endostyle similar to that already seen in vertebrates, I have tested immunohistochemically for the presence and location of T4 hormone, given the importance of thyroid hormones in energy metabolism and   in metamorphosis of some ascidians (Patricolo, 2001). For the same purpose I also studied TRH and TSH at the level of neural complex, thus verifying the regulation of the synthesis of T4 on the basis of these two hormones; GnRH, LH and FSH hormones. Morphological analysis of Styela plicata’s endostyle, confirm the classic v shape reported in the literature for all classes of ascidians. This morphology has no structural links with the equivalent human thyroid gland, since it is composed of closed follicles. However, an important report with morphological thyroid follicles was found by examining sections of whole animals in which the presence of closed endostylar structure, or endostyles in whose terminal (zones 6 and 7) are joined at the top to close the endostylar lumen was found.
From an immunohistochemical viewpoint, it is confirmed in Styela plicata, as in Ciona intestinalis, the presence of a TSH similar to that found in vertebrates at the cerebral ganglion and neural gland; at the level of cells that constitute the terminals endostylar cellular zones and  in areas 4 and 5, in haemolymphatic cells and in the ovotestis. Positivity increases for all components in the period of sexual maturity, showing the role of this hormone in the maturation of the gonads. The increased hormonal activity during the period of sexual maturity confirms the biochemical data in the literature for Ciona intestinalis. Immunohistochemical investigations have revealed the presence of the T4 hormone in zone 6 and in the endostylar terminal zones in the period April to July increased activity of T4 to load all endostylar zones and in the epithelium surroundings. During several months of the year (including the period of sexual maturity), we can ascribe a clear positive to T4 component of the neural (cortical area of the ganglion) and a moderate activity of the medullary component and glandular component. In this period there is also an increased activity of a TSH level of the complex neural and in the endostyle.
   The presence of TSH in haemolymphatic cells can be interpreted as storage and transport of this hormone to the districts and their tissue distribution primarily due to the lack of a closed circulatory system. Differently to vertebrates it is likely that in ascidians the production of TSH is not only dependent on the neural gland, but relies on several sites. The same cellular components also show a clear positive at T4 hormone and TSH in the same period; this would suggest that in ascidians as in vertebrates there is a negative feedback regulation of the neural complex on the endostyle. This suggests a functional relationship between the two structures in the ascidian class, similar to what happens in vertebrates: pituitary-thyroid. The hypothesis of this feedback mechanism comes from immunohistochemical investigations which showed that in the spawning period of the same tissue components also of TRH and GnRH, FSH and LH to a corresponding increase of TRH in the same districts, and concomitant increase in TSH and T4. This suggests that these different hormones work together for a regulatory mechanism similar to that known in vertebrates involving the neural complex and the endostyle.




Ali, H. A. J., Tamilselvi, M. and Sivakumar, V. 2008. Antibacterial activity of the marine ascidians Phallusia nigra and Herdmania pallida from the Tuticorin coast, India. J. Biol. Res. -Thessaloniki 10: 71-179.

Arsenault, G., Davidson, J. and Ramsay, A. 2009. Temporal and spatial development of an infestation of Styela clava on mussel farms in Malpeque Bay, Prince Edward Island, Canada. Aquatic Invasions 4: 189-194.

Auger, H., Lamy, C., Haeussler, M., Khoueiry, P., Lemaire, P. and Joly, J. S. 2009. Similar regulatory logic in Ciona intestinalis for two Wnt pathway modulators, ROR and SFRP-1/5. Dev.  Biol. 329: 364-373.

Belmiro, C. L., Castelo-Branco, M. T., Melim, L. M., Schanaider, A., Elia, C., Madi, K., Pavao, M. S. and de Souza, H. S. 2009. Unfractionated heparin and new heparin analogues from ascidians (chordate-tunicate) ameliorate colitis in rats. J. Biol. Chem. 284: 11267-11278.

Bernier, R. Y., Locke, A. and Hanson, J. M. 2009. Lobsters and crabs as potential vectors for tunicate dispersal in the southern Gulf of St. Lawrence, Canada. Aquatic Invasions 4: 105-110.

Bitar, G., Ocaña, O. and Ramos-Esplá, A. A. 2007. Contribution of the Red Sea alien species to structuring some benthic biocenosis in the Lebanon coast (eastern Mediterranean). Rapp. Comm. int. Mer. Medit. 38: (one page)

Brunetti, R. 2009. Pseudodistoma valeriae a new species of aplousobranch ascidian from Mediterranean Sea (Tunicata, Ascidiacea). Boll. Mus. civ. St. nat. Venezia 59: 75-79.

Brunetti, R. and Zaniolo, G. 2009. Phallusia ingeria Traustedt, 1883: morphology and development (Ascidiacea, Tunicata). Societa Veneziana di Scienze Naturali Lavori 34: 33-46.

Bullard, S. G. and Whitlatch, R. B. 2009. In situ growth of the colonial ascidian Didemnum vexillum under different environmental conditions. Aquatic Invasions 4: 275-278.

Cannon, J. T., Rychel, A. L., Eccleston, H., Halanych, K. M. and Swalla, B. J. 2009. Molecular phylogeny of Hemichordata, with updated status of deep-sea enteropneusts. Molec. Phylogen. & Evol. 52: 7-24.

Carman, M., Hoagland, K. E., Green-Beach, E. and Grunden, D. W. 2009. Tunicate faunas of two North Atlantic-New England islands: Martha’s Vineyard, Massachusetts and Block Island, Rhode Island. Aquatic Invasions 4: 65-70.

Carman, M. R., Allen, H. M. and Tyrrell, M. C. 2009. Limited value of the common periwinkle snail Littorina littorea as a biological control for the invasive tunicate Didemnum vexillum. Aquatic Invasions 4: 291-294.

Chavanich, S., Viyakarn, V., Piyatiratitivorakul, P., Suwanborirux, K. and Bussarawit, S. 2009. Two introduced tunicate species, Ecteinascidia thurstoni Herdman, 1891 and Clavelina cyclus Tokioka & Nishikawa, 1975, in Thailand. Aquatic Invasions 4: epub.

Choe, B. L., Qi, H. and Rho, B. J. 2000. Karyotypes of three ascidians (Chordata; Ascidiacea) from Korea. Korean J. Biol. Sci. 4: 105-107.

Cima, F. and Ballarin, L. 2009. Apoptosis and pattern of Bcl-2 and Bax expression in the alimentary tract during the colonial blastogenetic cycle of Botryllus schlosseri (Urochordata, Ascidiacea). Ital. J. Zool. 76: 28-42.

Clement, J. A., Kitagaki, J., Yang, Y., Saucedo, C. J., O'Keefe, B. R., Weissman, A. M., McKee, T. C. and McMahon, J. B. 2008. Discovery of new pyridoacridine alkaloids from Lissoclinum cf. badium that inhibit the ubiquitin ligase activity of Hdm2 and stabilize p53. Bioorg. & Med. Chem. 16: 10022-10028.

Cuevas, C. and Francesch, A. 2009. Development of Yondelis (trabectedin, ET-743). A semisynthetic process solves the supply problem. Nat. Prod. Rep. 26: 322-337.

Dahlberg, C., Auger, H., Dupont, S., Sasakura, Y., Thorndyke, M. and Joly, J. S. 2009. Refining the Ciona intestinalis model of central nervous system regeneration. PLoS ONE 4: e4458.

Daigle, R. M. and Herbinger, C. M. 2009. Ecological interactions between the vase tunicate (Ciona intestinalis) and the farmed blue mussel (Mytilus edulis) in Nova Scotia, Canada. Aquatic Invasions 4: 177-187.

Darbyson, E., Locke, A., Hanson, J. M. and Willison, J. H. M. 2009. Marine boating habits and the potential for spread of invasive species in the Gulf of St. Lawrence. Aquatic Invasions 4: 87-94.

Darbyson, E. A., Hanson, J. M., Locke, A. and Willison, J. H. M. 2009. Settlement and potential for transport of clubbed tunicate (Styela clava) on boat hulls. Aquatic Invasions 4: 95-103.

Davis, M. H. and Davis, M. E. 2009. Styela clava (Tunicata, Ascidiacea) – a new threat to the Mediterranean shellfish industry? Aquatic Invasions 4: 283-289.

de Barros, R. C., da Rocha, R. M. and Pie, M. R. 2009. Human-mediated global dispersion of Styela plicata (Tunicata, Ascidiacea). Aquatic Invasions 4: 45-57.

De Santis, R., Marino, R. and Pinto, M. R. 2001. Further observations on the molecular bases of gamete self-discrimination in Ciona intestinalis: seasonal variation of self sterility rate. In: Sawada, H., Yokosawa, H. and Lambert , C. C. (ed.), The Biology of Ascidians. Tokyo, Springer, pp. 14-17.

Dias, G. M., Abreu, A. G., Morais e Silva, F. and Solferini, V. N. 2009. Microgeographical differentiation between morphotypes of Trididemnum orbiculatum (Tunicata: Ascidiacea) in southeastern Brazil. Aquat. Biol. 4: 243-252.

Dong, B., Horie, T., Denker, E., Kusakabe, T., Tsuda, M., Smith, W. C. and Jiang, D. 2009. Tube formation by complex cellular processes in Ciona intestinalis notochord.  Dev.  Biol. 330 (2): 237-249.

Dunn, M. P. and Di Gregorio, A. 2009. The evolutionarily conserved leprecan gene: its regulation by Brachyury and its role in the developing Ciona notochord. Dev.  Biol. 328: 561-574.

Dupont, L., Viard, F., Dowell, M. J., Wood, C. and Bishop, J. D. 2009. Fine- and regional-scale genetic structure of the exotic ascidian Styela clava (Tunicata) in southwest England, 50 years after its introduction. Molec. Ecol. 18: 442-453.

Emara, A. M. and Belal, A. B. 2004. Marine fouling in Suez Canal, Egypt. Egyptian J. Aquatic Res. 30: 189-206.

Epelbaum, A., Herborg, L. M., Therriault, T. W. and Pearce, C. M. 2009. Temperature and salinity effects on growth, survival, reproduction, and potential distribution of two non-indigenous botryllid ascidians in British Columbia. J. Exp. Mar. Biol. Ecol. 369: 43-52.

Epelbaum, A., Pearce, C. M., Barker, D. J., Paulson, A. and Therriault, T. W. 2009. Susceptibility of non-indigenous ascidian species in British Columbia (Canada) to invertebrate predation. Mar. Biol. 156: 1311-1320.

Epelbaum, A., Therriault, T. W., Paulson, A. and Pearce, C. M. 2009. Botryllid tunicates: Culture techniques and experimental procedures. Aquatic Invasions 4: 111-120.

Erives, A. 2009. Non-homologous structured CRMs from the Ciona genome. J. Comput. Biol. 16: 369-377.

Forrest, B. M., Gardner, J. P. A. and Taylor, M. D. 2009. Internal borders for managing invasive marine species. J. Applied Ecol. 46: 46–54.

Galinier, R., Roger, E., Sautiere, P.-E., Aumelas, A., Banaigs, B. and Mitta, G. 2009. Halocyntin and papillosin, two new antimicrobial peptides isolated from hemocytes of the solitary tunicate, Halocynthia papillosa.  J. Peptide Sci. 15: 48-55.

Gittenberger, A. 2009. Invasive tunicates on Zeeland and Prince Edward Island mussels, and management practices in The Netherlands. Aquatic Invasions 4: 279-281.

Gotto, V. 2004. Footprints in the Sea--Tales of a Marine Biologist. Ballyhay Books, Donaghadee, N. Ireland. 127 pp.

Grey, E. K. 2009. Do we need to jump in? A comparison of two survey methods of exotic ascidians on docks. Aquatic Invasions 4: 81-86.

Herborg, L.-M., O'Hara, P. and Therriault, T. W. 2009. Forecasting the potential distribution of the invasive tunicate Didemnum vexillum. J. Applied Ecol. 46: 64 - 72.

Hess, J. E., Swalla, B. J. and Moran, P. 2009. New molecular markers to genetically differentiate populations of Didemnum vexillum Kott, 2002 - an invasive ascidian species. Aquatic Invasions 4: 299-310.

Hill, A. S., Nishino, A., Nakajo, K., Zhang, G., Fineman, J. R., Selzer, M. E., Okamura, Y. and Cooper, E. C. 2008. Ion channel clustering at the axon initial segment and node of Ranvier evolved sequentially in early chordates. PLoS Genetics 4: 15 pp.

Hirose, E. 2009. Ascidian tunic cells: morphology and functional diversity of free cells outside the epidermis. Invert. Biol. 128: 83–96.

Hirose, E. and Nakabayashi, S. 2008. Algal symbionts in the larval tunic lamellae of thecolonial ascidian Lissoclinum timorense (Ascidiacea, Didemnidae). Zool. Sci. 25: 1205–1211.

Hirose, E., Ohtake, S.-I. and Azumi, K. 2009. Morphological characterization of the tunic in the edible ascidian, Halocynthia roretzi (Drasche), with remarks on 'soft tunic syndrome' in aquaculture. J. Fish Diseases 32: 433–445.

Hirose, E. and Oka, A. T. 2008. A new species of photosymbiotic ascidian from the Ryukyu Archipelago, Japan, with remarks on the stability of stigma number in photosymbiotic Diplosoma species. Zool. Sci. 25: 1261–1267.

Hirose, E., Oka, A. T. and Hirose, M. 2009. Two new species of photosymbiotic ascidians of the genus Diplosoma from the Ryukyu Archipelago, with partial sequences of the COI gene. Zool. Sci. 26: 362–368.

Hirose, M., Yokobori, S. and Hirose, E. 2009. Potential speciation of morphotypes in the photosymbiotic ascidian Didemnum molle in the Ryukyu Archipelago, Japan. Coral Reefs 28: 119-126.

Hodson, S. L., Burke, C. M. and Bissett, A. P. 2000. Biofouling of fish-cage netting: the efficacy of a silicone coating and the effect of netting colour. Aquaculture 184: 277-290.

Holland, P. W. and Wada, H. 2008. Protochordates. Methods in Molec. Biol. 461: 563-566.

Honegger, T. G. and Füglister, M. 2001. Structural and molecular investigations on the egg coat in Phallusia mammillata. In: Sawada, H., Yokosawa, H. and Lambert , C. C. (ed.), The Biology of Ascidians. Tokyo, Springer, pp. 3-8.

Horie, T., Nakagawa, M., Sasakura, Y. and Kusakabe, T. G. 2009. Cell type and function of neurons in the ascidian nervous system. Dev. Growth & Differ. 51: 207-220.

Imai, K. S., Stolfi, A., Levine, M. and Satou, Y. 2009. Gene regulatory networks underlying the compartmentalization of the Ciona central nervous system. Development 136: 285-293.

Izquierdo-Muñoz, A., Díaz-Valdés, M. and Ramos-Esplá, A. A. 2009. Recent non-indigenous ascidians in the Mediterranean Sea. Aquatic Invasions 4: 59-64.

Karney, R. C. and Rhee, W. Y. 2009. Market potential for Styela clava, a non-indigenous pest invading New England coastal waters. Aquatic Invasions 4: 295-297.

Kawakami, N., Ueki, T., Amata, Y., Kanamori, K., Matsuo, K., Gekko, K. and Michibata, H. 2009. A novel vanadium reductase, Vanabin2, forms a possible cascade involved in electron transfer. Biochim. Biophys. Acta 1794: 674-679.

Keduka, E., Kaiho, A., Hamada, M., Watanabe-Takano, H., Takano, K., Ogasawara, M., Satou, Y., Satoh, N. and Endo, T. 2009. M-Ras evolved independently of R-Ras and its neural function is conserved between mammalian and ascidian, which lacks classical Ras. Gene 429: 49-58.

Kossuga, M. H., Lira, S. P., McHugh, S., Torres, Y. R., Lima, B. A., Gonçalves, R., Veloso, K., Ferreira, A. G., Rocha, R. M. and Berlinck, R. G. S. 2009. Antibacterial modified diketopiperazines from two ascidians of the genus Didemnum. J. Braz. Chem. Soc. 20: 704-711.

Kumano, G. and Nishida, H. 2009. Patterning of an ascidian embryo along the anterior-posterior axis through spatial regulation of competence and induction ability by maternally localized PEM. Dev.  Biol. epub:

Lebrato, M. and Jones, D. O. B. 2009. Mass deposition event of Pyrosoma atlanticum carcasses off Ivory Coast (West Africa). Limnol. Oceanog. 54: 1197-1209.

Lengyel, N. L., Collie, J. S. and Valentine, P. C. 2009. The invasive colonial ascidian Didemnum vexillum on Georges Bank--Ecological effects and genetic identification. Aquatic Invasions 4: 143-152.

Locke, A. 2009. A screening procedure for potential tunicate invaders of Atlantic Canada. Aquatic Invasions 4: 71-79.

Locke, A., Doe, K. G., Fairchild, W. L., Jackman, P. M. and Reese, E. J. 2009. Preliminary evaluation of effects of invasive tunicate management with acetic acid and calcium hydroxide on non-target marine organisms in Prince Edward Island, Canada. Aquatic Invasions 4: 221-236.

Locke, A. and Hanson, J. M. 2009. Rapid response to non-indigenous species. 3. A proposed framework. Aquatic Invasions 4: 259-273.

Locke, A. and Hanson, J. M. 2009. Rapid response to non-indigenous species. 1. Goals and history of rapid response in the marine environment. Aquatic Invasions 4: 237-247.

Locke, A., Hanson, J. M., MacNair, N. G. and Smith, A. H. 2009. Rapid response to non-indigenous species. 2. Case studies of invasive tunicates in Prince Edward Island. Aquatic Invasions 4: 249-258.

Lutz-Collins, V., Ramsay, A., Quijón, P. A. and Davidson, J. 2009. Invasive tunicates fouling mussel lines: evidence of their impact on native tunicates and other epifaunal invertebrates. Aquatic Invasions 4: 213-220.

Marins, F., Oliveira, C., Maciel, N. M. V. and Skinner, L. F. 2009. Reinclusion of Ciona intestinalis (Ascidiacea: Cionidae) in Brazil—a methodological view. JMBA2 - Biodiversity Records.

Mercer, J. M., Whitlatch, R. B. and Osman, R. W. 2009. Potential effects of the invasive colonial ascidian (Didemnum vexillum Kott, 2002) on pebble-cobble bottom habitats in Long Island Sound, USA. Aquatic Invasions 4: 133-142.

Miyakawa, H., Kumano, M., Hoshi, M., Takeda, N. and Matsumoto, M. 2008. A chloride ion channel in Halocynthia roretzi hemocytes is associated with PO activity but not pigmentation during the contact reaction. Zool. Sci. 25: 1130-1138.

Monniot, F. 2009. A new species of Monandrocarpa (Ascidiacea, Styelidae) from Vanuatu I. (South Pacific Ocean). Zootaxa 2044: 65–68.

Monniot, F. 2009. Some ascidians from Indonesian marine lakes (Raja Ampat Islands, West Papua). Zootaxa 2106: 13–40.

Monniot, F. and Monniot, C. 2008. Compléments sur la diversité des ascidies (Ascidiacea, Tunicata) de l’ouest Pacifique tropical. Zoosystema 30: 799-872.

Morris, J. A. J., Carman, M. R., Hoagland, K. E., Green-Beach, E. R. M. and Karney, R. C. 2009. Impact of the invasive colonial tunicate Didemnum vexillum on the recruitment of the bay scallop (Argopecten irradians irradians) and implications for

recruitment of the sea scallop (Placopecten magellanicus) on Georges Bank. Aquatic Invasions 4: 207-211.

Nakayama-Ishimura, A., Chambon, J. P., Horie, T., Satoh, N. and Sasakura, Y. 2009. Delineating metamorphic pathways in the ascidian Ciona intestinalis. Dev.  Biol. 326: 357-367.

Nomura, M., Nakajima, A. and Inaba, K. 2009. Proteomic profiles of embryonic development in the ascidian Ciona intestinalis. Dev.  Biol. 325: 468-481.

Ooishi, S. 2008. Female and male Mychophilus roseus (Crustacea: Copepoda: Cyclopoida: Ascidicolidae) living in the compound ascidian Botryllus schlosseri. Proc. Biol. Soc. Wash. 121: 512-530.

Ooishi, S. 2008. Female Enteropsis roscoffensis Chatton & Brément (Crustacea: Copepoda: Cyclopoida: Ascidicolidae) living in the solitary ascidian Dendrodoa grossularia. Proc. Biol. Soc. Wash. 121: 501-511.

Paetzold, S. C., Davidson, J. and Giberson, D. 2008. Responses of Mitrella lunata and Caprella spp., potential tunicate micropredators, in Prince Edward Island estuaries to acetic acid anti-fouling treatments. Aquaculture 285: 96-101.

Pennati, R., Groppelli, S., De Bernardi, F., Mastrototaro, F. and Zega, G. 2009. Immunohistochemical analysis of adhesive papillae of Clavelina lepadiformis (Muller, 1776) and Clavelina phlegraea (Salfi, 1929) (Tunicata, Ascidiacea). Europ. J. Histochem. 53: 25-34.

Pla, D., Albericio, F. and Alvarez, M. 2008. Recent advances in lamellarin alkaloids: isolation, synthesis and activity. Anticancer Agents in Med. Chem. 8: 746-760.

Prodon, F., Hanawa, K. and Nishida, H. 2009. Actin microfilaments guide the polarized transport of nuclear pore complexes and the cytoplasmic dispersal of Vasa mRNA during GVBD in the ascidian Halocynthia roretzi.  Dev. Biol. 330 (2): 377-388.

Ramadan, S. E., Kheirallah, A. M. and Abdel-Salam, K. M. 2006. Marine fouling community in the Eastern harbour of Alexandria, Egypt compared with four decades of previous studies. Medit. Mar. Sci. 7: 19-29.

Ramsay, A., Davidson, J., Bourque, D. and Stryhn, H. 2009. Recruitment patterns and population development of the invasive ascidian Ciona intestinalis in Prince Edward Island, Canada. Aquatic Invasions 4: 169-176.

Ramsay, A., Davidson, J., Landry, T. and Arsenault, G. 2008. Process of invasiveness among exotic tunicates in Prince Edward Island, Canada. Biol. Invasions 10: 1311-1316.

Rinkevich, Y., Rinkevich, B. and Reshef, R. 2008. Cell signaling and transcription factor genes expressed during whole body regeneration in a colonial chordate. BMC Dev. Biol. 8: 100.

Rius, M., Turon, X. and Marshall, D. J. 2009. Non-lethal effects of an invasive species in the marine environment: the importance of early life-history stages. Oecologia 159 (4): in press.

Rocha, R. M., Kremer, L. P., Baptista, M. S. and Metri, R. 2009. Bivalve cultures provide habitat for exotic tunicates in southern Brazil. Aquatic Invasions 4: 195-205.

Sanamyan, K. and Gleason, D. F. 2009. Ascidians of the genus Aplidium collected on shallow hard-bottom reefs of coastal Georgia (Atlantic coast of N America, U.S.A.). Zootaxa 2066: 50–58.

Sanamyan, K., Gleason, D. F. and Sanamyan, N. 2009. A new species of Polyzoa (Ascidiacea: Styelidae) from the Atlantic coast of N. America, U.S.A. Zootaxa 2088: 65–68.

Sanamyan, K. and Schories, D. 2004. Ascidians from Peru. Spixiana 27: 193-197.

Santalova, E. A., Denisenko, V. A., Berdyshev, D. V., Aminin, D. L. and Sanamyan, K. E. 2008. 6-Bromo-5-hydroxyindolyI-3-g!yoxylate from the far eastern ascidian Syncarpa oviformis. NPC I Natural Product Communications 3: 1617-1620.

Satoh, N. 2008. An aboral-dorsalization hypothesis for chordate origin. Genesis 46: 614-622.

Satoh, N. 2009. An advanced filter-feeder hypothesis for urochordate evolution. Zool. Sci. 26: 97-111.

Shi, W., Hendrix, D., Levine, M. and Haley, B. 2009. A distinct class of small RNAs arises from pre-miRNA-proximal regions in a simple chordate. Nat. Struct. Mol. Biol. 16: 183-9.

Shi, W., Peyrot, S. M., Munro, E. and Levine, M. 2009. FGF3 in the floor plate directs notochord convergent extension in the Ciona tadpole. Development 136: 23-28.

Shiba, K., Baba, S. A., Inoue, T. and Yoshida, M. 2008. Ca2+ bursts occur around a local minimal concentration of attractant and trigger sperm chemotactic response. Proc. Natl. Acad. Sci. 105: 19312-19317.

Shimai, K., Hirano, A., Kitaura, Y., Kitano, Y., Itoh, A., Kiuchi, A., Sasaki, N. and Nishikata, T. 2008. Novel ubiquitous promoters and expression-vector optimization in ascidian embryos. Invert. Repro. & Dev. 51: 103-110.

Sielfeld, W. 2000. Subphylum Tunicata Guías de Identificación y Biodiversidad Fauna Chilena. In: (ed.), Apuntes de Zoología. Universidad Arturo Prat, Iquique, Chile, pp. 10 pp.

Sierro, N., Li, S., Suzuki, Y., Yamashita, R. and Nakai, K. 2009. Spatial and temporal preferences for trans-splicing in Ciona intestinalis revealed by EST-based gene expression analysis. Gene 430: 44-49.

Tiozzo, S. and De Tomaso, A. W. 2009. Functional analysis of Pitx during asexual regeneration in a basal chordate. Evol. & Dev. 11: 152-162.

Ueki, T., Furuno, N., Xu, Q., Nitta, Y., Kanamori, K. and Michibata, H. 2009. Identification and biochemical analysis of a homolog of a sulfate transporter from a vanadium-rich ascidian Ascidia sydneiensis samea. Biochim. Biophys. Acta epub:

Valentine, P. C., Carman, M. R., Dijkstra, J. and Blackwood, D. S. 2009. Larval recruitment of the invasive colonial ascidian Didemnum vexillum, seasonal water temperatures in New England coastal and offshore waters, and implications for spread of the species. Aquatic Invasions 4: 153-168.

Voskoboynik, A., Soen, Y., Rinkevich, Y., Rosner, A., Ueno, H., Reshef, R., Ishizuka, K. J., Palmeri, K. J., Moiseeva, E., Rinkevich, B. and Weissman, I. L. 2008. Identification of the endostyle as a stem cell niche in a colonial chordate. Cell Stem Cell 3: 456-464.

Whitlatch, R. B. and Osman, R. W. 2009. Post-settlement predation on ascidian recruits: predator responses to changing prey density. Aquatic Invasions 4: 121-131.

Whitson, E. L., Ratnayake, A. S., Bugni, T. S., Harper, M. K. and Ireland, C. M. 2009. Isolation, structure elucidation, and synthesis of eudistomides A and B, lipopeptides from a Fijian ascidian Eudistoma sp. J. Org. Chem. 74: 1156-1162.

Yahel, G., Marie, D. and Genin, A. 2005. InEx—a direct in situ method to measure filtration rates, nutrition, and metabolism of active suspension feeders. Limnol. Oceanogr.: Methods 3: 46–58.

Yakovis, E. L., Artemieva, A. V. and Fokin, M. V. 2004. Spatial pattern indicates an influence of barnacle and ascidian aggregations on the surrounding benthic assemblage. J. Exp. Mar. Biol. Ecol. 309: 155– 172.

Yakovis, E. L., Artemieva, A. V., Fokin, M. V., Grishankov, A. V. and Shunatova, N. N. 2005. Patches of barnacles and ascidians in soft bottoms: Associated motile fauna in relation to the surrounding assemblage. J. Exp. Mar. Biol. Ecol. 327: 210– 224.

Yakovis, E. L., Artemieva, A. V., Fokin, M. V., Varfolomeeva, M. and Shunatova, N. N. 2007. Effect of habitat architecture on mobile benthic macrofauna associated with patches of barnacles and ascidians. Mar. Ecol. Prog. Ser. 348: 117-124.

Yamada, L., Saito, T., Taniguchi, H., Sawada, H. and Harada, Y. 2009. Comprehensive egg coat proteome of the ascidian Ciona intestinalis reveals gamete recognition molecules involved in self-sterility. J. Biol. Chem. 284: 9402-9410.

York, A., Gallager, S., Taylor, R., Vine, N. and Lerner, S. 2008. Using a towed optical habitat mapping system to monitor the invasive tunicate species Didemnum sp along Georges Bank. J. Shellfish Res. 27: 1066-1067.

Zega, G., De Bernardi, F., Groppelli, S. and Pennati, R. 2009. Effects of the azole fungicide Imazalil on the development of the ascidian Ciona intestinalis (Chordata, Tunicata): morphological and molecular characterization of the induced phenotype. Aquatic Toxicol. 91: 255-261.

Zega, G., Pennati, R., Candiani, S., Pestarino, M. and De Bernardi, F. 2009. Solitary ascidians embryos (Chordata, Tunicata) as model organisms for testing coastal pollutant toxicity. ISJ 6: S29-S34.