J. Phycol. 42, 139–141 (2005) r 2005 Phycological Society of America DOI: 10.1111/j.1529-8817.2005.00160.x

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GRACILARIA VERMICULOPHYLLA (RHODOPHYTA, ) IN HOG ISLAND BAY, VIRGINIA: A CRYPTIC ALIEN AND INVASIVE MACROALGA AND TAXONOMIC CORRECTION1

Mads Solgaard Thomsen2 Department of Applied Sciences, Auckland University of Technology, Auckland, New Zealand Carlos Frederico Deluqui Gurgel, Suzanne Fredericq Department of Biology, University of Louisiana at Lafayette, P.O. Box 42451, Lafayette, Louisiana 70504-2451, USA and Karen J. McGlathery Department of Environmental Sciences, Clark Hall, University of Virginia, Charlottesville, Virginia 22903, USA

Gracilaria in Virginia, USA, is abundant and Lachlan and Bird 1986). Unfortunately, in many cases, composed of thalli either having relatively flat or Gracilaria species are difficult to identify based on mor- cylindrical branches. These two morphologies were phological features (Oliveira et al. 2000, Gurgel and referred to previously as G. foliifera (Forsska˚l) Fredericq 2004). Given these difficulties and new pos- Bgesen and G. verrucosa (Hudson) Papenfuss. sibilities of accurate identification by molecular biology However, G. verrucosa is regarded an invalid techniques, Gracilaria sensu lato species are regularly name, and the flat specimens are now referred to as changing taxonomic status (Bird and Rice 1990, Bell- G. tikvahiae McLachlan. This has created confusion orin et al. 2002, Gurgel and Fredericq 2004, Gurgel about the nomenclature of Gracilaria from this re- et al. 2004). gion. Here we document that the cylindrical form Gracilaria is a particularly important genus in Vir- that dominates Hog Island Bay, Virginia, is ginia, USA, where it is abundant in lagoons and estu- G. vermiculophylla (Ohmi) Papenfuss, an alien mac- aries (Humm 1979, Thomsen 2004a). In Virginia, roalga from the West Pacific. Most of the ecological cylindrical Gracilaria specimens have been referred to studies performed at the Long Term Ecological Re- traditionally as G. verrucosa (Hudson) Papenfuss, search (LTER) site in Hog Island Bay used this cy- whereas flat specimens have been referred to as G. lindrical species. The present study clarifies the foliifera (Forsska˚l) Bgesen (1932) or G. foliifera var. taxonomical status of this species, and we identify angustissima Taylor (1937) (Zaneveld and Barnes 1965, attributes that make this alien successful in turbid Mangum et al. 1968, Rhodes 1970, Humm 1979, Con- coastal lagoons. nor 1980, Parker et al. 2001), based on the work of Key word index: alien macroalgae; cryptic inva- Taylor (1957, 1960) and Humm (1979), who cited sion; Gracilaria vermiculophylla; phylogeography; these species for the western Atlantic. This taxonomy Virginia has been used in several recent studies from Hog Is- land Bay, Virginia (Thomsen 2004a, b, Thomsen and Abbreviations: cox, cytochrome oxidase; ITS, inter- McGlathery 2005). However, Steentoft et al. (1991) nal transcribed spacer; rbcL, large subunit of the and Irvine and Steentoft (1995) have shown that the RUBISCO gene G. verrucosa epithet is taxonomically invalid. In addi- tion, based on DNA analysis of nuclear ITS rDNA and the chloroplast rbcL gene, the species identified as G. The genus Gracilaria (Gracilariales, Rhodophyta) foliifera is known today as G. tikvahiae McLachlan (Bird has a worldwide distribution, comprising more than and Rice 1990, Gurgel and Fredericq 2004, Gurgel 110 species (Gurgel and Fredericq 2004), of which et al. 2004). This has led several Hog Island Bay stud- many are important economically (Oliveira and Plas- ies to refer to all Gracilaria material as G. tikvahiae tino 1994, Oliveira et al. 2000) and ecologically (Mc (McGlathery et al. 2001, Tyler et al. 2001, Tyler 2002, Anderson et al. 2003, Tyler and McGlathery 2003). It is noteworthy that most material in these studies was 1Received 16 May 2005. Accepted 7 September 2005. composed of cylindrical Gracilaria specimens. Still, the 2Author for correspondence: e-mail [email protected]. cylindrical forms from Virginia remain a taxonomic

139 140 MADS SOLGAARD THOMSEN ET AL. problem, and when only character-poor specimens are ments, overall gonimoblast mass with a triangular available, molecular analysis remains the most reliable shape and lobed contour, carposporangia organized species identifier. in distinct chains with progressively maturing stages In 1999, a single cylindrical Gracilaria specimen toward the apice) corresponded exactly to the ones from Hog Island Bay was rbcL-analyzed (GenBank observed in these two works. Gracilaria vermiculophylla AY049312, Gurgel and Fredericq 2004), and subse- probably arrived in Virginia attached to transplanted quent phylogenetic analyses by Rueness (2005) indi- oysters, because it is an efficient recruiter onto bivalve cated that this specimen could be G. vermiculophylla shells and man-made structures, and has a high ability (Ohmi) Papenfuss, a species of Northwestern Pacific to recover from fragmentation (Thomsen 2004a, b). It origin, which is an invader in the east Pacific (Bellorin is unlikely to have drifted over long distances because et al. 2004) and in several European countries (Rue- of its negative buoyancy. In Hog Island Bay, G. vermi- ness 2005). The goal of the present study was to con- culophylla has been the dominant macroalga at least firm the status of the cylindrical Hog Island Bay since 1998 (Thomsen 2004a) when our intensive LTER Gracilaria species. Cylindrical Gracilaria samples were studies began. Now that we have established that the collected on 8 December 2004 from three key localities taxonomical status of the cylindrical Gracilaria in Hog used to study the ecology of Hog Island Bay: Little Island Bay is G. vermiculophylla, our previous work pro- Cobb Island (37118.2620N, 75147.5690W), Oyster Har- vides insights into its success as an invader. Hog Island bor (37117.3060N, 75155.3990W), and South end of Bay is a turbid shallow lagoon, where G. vermiculophylla Hog Island (37123.2180N, 75143.3220W). Algal sam- represents 480% of the submerged macrophyte bio- ples were freeze dried and stored in plastic bags with mass. We suggest that its dominance in the lagoon is silica gel. Vouchers were fixed in 4% formalin/seawater related to the following: (1) its association with the solution and herbarium pressed. Exsiccate were de- ubiquitous polychaete, Diopatra cuprea, (2) its efficient posited in the herbarium of the University of Louisiana recruitment on hard substratum, (3) its high tolerance at Lafayette. The DNA was extracted with a Plant of desiccation, grazing, burial by sediment, low light, Dneasy MiniKit (Qiagen, Valencia, CA, USA) following and low and high temperatures, and (4) its long-term the manufacturer’s protocol. The cox2–cox3 mito- persistence as both small and large vegetative frag- chondrial DNA spacer region was amplified follow- ments (as G. verrucosa, Thomsen 2004a, b, Thomsen ing protocol and primers as described by Zuccarello and McGlathery 2005, in press). et al. (1999). The PCR amplifications were cleaned To avoid future taxonomic confusion, we encourage with ExoSAP-ITs (USB Corp., Cleveland, OH, USA) researchers to create silica-gel, air-dried, and/or her- following the manufacturer’s protocol. Both strands of barium presses as voucher specimens so that the cor- the cox2–cox3 spacer were sequenced using the same rect identification can be confirmed using PCR primers and BigDye Terminator chemistry (Ap- morphological and molecular analysis. Such precau- plied Biosystems, Foster City, CA, USA) following the tions need to be undertaken to avoid similar cryptic manufacturer’s protocol. The DNA sequences were as- invasions, such as that which also occurred with Codium sembled with a Sequencher (Gene Codes Corp., Ann fragile ssp. tomentosoides (Trowbridge 1998). Arbor, MI, USA) and aligned manually in a nexus file together with the published cox2–cox3 DNA sequences We would like to thank Dr. Art Schwartzchild, site Director for the Virginia Coast Reserve Long Term Ecological Research from GenBank. program for Gracilaria collections. All three samples provided identical cox2–cox3 spacer mitochondrial DNA sequences (Genbank Anderson, I. C., McGlathery, K. J. & Tyler, A. C. 2003. Microbial DQ173302, DQ173303, DQ173304). This single ha- mediation of ‘reactive nitrogen’ transformations in a temper- plotype was also 100% identical to the single haplotype ate lagoon. Mar. Ecol. Prog. Ser. 246:73–84. sequenced for 22 specimens studied by Rueness (2005) Bellorin, A. M., Oliveira, M. C. & Oliveira, E. C. 2002. Phylogeny and systematics of the marine algal family Gracilariaceae in northern Europe (France AY725141 and AY725152- (Gracilariales, Rhodophyta) based on small subunit rDNA and 63), Sweden (AY725147), Spain (AY725143), Portugal its sequences of Atlantic and Pacific species. J. Phycol. 38:551–63. (AY725146), and the Netherlands (AY725142), includ- Bellorin, A. M., Oliveira, M. C. & Oliveira, E. C. 2004. Gracilaria ing one sample from South Korea (AY725144), and vermiculophylla. A Western Pacific species of Gracilariaceae (Rhodophyta) first recorded from the Eastern Pacific. Phycol. one from Japan (AY725145). This confirmed that the Res. 52:69–79. cylindrical Gracilaria that dominates Hog Island Bay is Bird, C. J. & Rice, E. L. 1990. Recent approaches to the taxonomy indeed G. vermiculophylla, and that all samples from the of the Gracilariaceae (Gracilariales, Rhodophyta) and the northern Atlantic analyzed so far present no genetic Gracilaria verrucosa problem. 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