N19 2018 Northeastern Naturalist Notes Vol. 25, No. 3 K.L. Osborne and W.A. Hubbard Underwater Video Mapping of Benthic Habitats in Buzzards Bay, Massachusetts Records the Pelagic Colonial Pyrosome Tunicate Pyrosoma atlanticum Kristin L. Osborne1 and William A. Hubbard1,* Abstract - High-definition underwater-video mapping of Buzzards Bay, MA, photographed a pyrosome tunicate. Positive identification to the species level was not possible because to do so requires a live, undamaged specimen. However, the most probable species is Pyrosoma atlanticum, a common species in temperate waters worldwide, which has not been docum ented in Buzzards Bay until now. Introduction. Massachusetts Maritime Academy (MMA) had been conducting highdefinition (HD) underwater video transects in Buzzards Bay under a grant from the Massachusetts Environmental Trust. This funding has enabled MMA to conduct at-sea mapping of Buzzards Bay substrates focusing on extensive seafloor areas covered with Crepidula fornicata L. (Common Slipper Shell). In June 2016, a pyrosome was photographed at the edge of one of one of these shell reefs (Fig. 1). Consultations with regional experts have not identified any previous records of this colonial tunicate in bays or sounds of New England. The pyrosomes are an interactive group of small animals that form together as a holoplanktonic colony, which filters water into their tube-like colony structure as it maintains 1 direction of movement and passively migrates at the mercy of currents. These organisms are often found offshore in temperate waters, drifting in the pelagic zones. Pyrosomes are members of the Tunicata (previously the Urochordata), a sub-phylum within the phylum Chordata. Hallmark traits of this phylum include a post-anal tail, 1Massachusetts Maritime Academy, Buzzards Bay, MA 02532. *Corresponding author - WHubbard@maritime.edu. Manuscript Editor: Melisa Wong Notes of the Northeastern Naturalist, Issue 25/3, 2018 Figure 1. A Pyrosome filmed with the Massachusetts Maritime Academy towed high-definition video camera. (Photograph © Massachusetts Maritime Academy). 2018 Northeastern Naturalist Notes Vol. 25, No. 3 N20 K.L. Osborne and W.A. Hubbard pharyngeal gill slits; a dorsal, hollow nerve cord; and a notochord. The tunicates are a unique subphylum of the chordates because they revert to a more simplistic body plan by the eventual loss of these features during their metamorphosis from the embryonic stages to their adult forms (Lemaire et al. 2008). Interestingly, molecular analyses indicate that the Tunicata are the closest invertebrate relatives of the sub-phylum Vertebrata (Delsuc et al. 2006, Vienne and Pontarotti 2006). The class Thaliacea (within the Tunicata), is a group of ~72 pelagic species (Govindarajan et al. 2011). The pyrosomes are classified within the order Pyrosomatida. In this paper, we describe the first known record of a pyrosome in New England. Field-site description. Buzzards Bay is a 650-km2 temperate estuary characterized by semi-diurnal tides and broad seasonal climate and water-temperature variations. Substrates are diverse, ranging from boulder and rock to sand and silt/clay. Water temperatures vary from 22 °C in summer to 1 °C in winter (BBCCMP 2013). In 2012 and 2013, maximum annual temperatures of 25.57 °C in August 2012 and 26.11 °C in July 2013 were recorded 0.5 m off the bottom at a station 6.5-km east of where the pyrosome was discovered (CAF East) (Hubbard 2016). Methods. The MMA 30-foot RV Liberty used a SIMRAD® NSS-2 navigation-chart plotter to conduct benthic mapping transects from 2016 through 2017. High-definition underwater video transects were recorded as part of the Common Slipper Shell reef (hereafter, C-reef) mapping on a Seaviewer® underwater video-camera system. The unit paired a Seadrop 5500 HD camera with a surface-recording unit. The Seadrop 5550 camera was installed in a vertical tow tube with laser pointers for a 10-cm scale in all recorded video (Fig. 2). The surface-recording display system was programmed to continuously overlay latitude, longitude, date, time (UTC), and course over ground (COG) on all video. This overlay on high-definition video was accomplished by running the video signal through a Videologic® PROTEUS II unit. The images were captured on a HDMI H.264 recorder while simultaneously being displayed on the recording console and research-vessel navigationchart plotter. Commercially available software (PowerDirector14®) was used for post-processing which allowed the capture of still images (with location and time data overlaid). Thousands of C-reef images were analyzed and classified by ecological function according to the national Coastal and Marine Ecological Classification System (CMECS 2010). This review of individual video frames captured for classification allowed the team to identify the pyrosome on the edge of a C-reef adhered to the sandy/shell substrate at an 8-m depth in upper Buzzards Bay, MA (Fig. 3). Results and discussion. We identified the organism photographed in Figure 1 (video clip is avaialable at https://youtu.be/0U-LSDyCaaA) as a member of the family Pyrosomatidae, according to the taxonomic descriptions of Kott (2005) and upon consultation with pelagic tunicate experts (e.g., M. Corrales-Ugalde, University of Oregon, Eugene, OR; pers. comm.). The Pyrosomatidae is the only family within the order Pyrosomatida and contains 8 species (van Soest 1981). In 1981, van Soest discussed a benthic pyrosome species identified as Pyrosoma benthica (Monniot and Monniot 1966)—an organism at the mercy of currents, with motion in only 1 direction. Logically, a pelagic colony caught on the substrate would be exposed to benthic predators and therefore could not survive. The most common pelagic North Atlantic species is Pyrosoma atlanticum Péron. The specimen depicted in Figure 1 was found in shallow waters adjacent to the open-ocean native range of P. atlanticum. P. atlanticum colonies can range in color from clear to a translucent white, grey, pink, or blue-green (Palma and Apablaza 2004). Colonies can reach up to 60 cm in length, with N21 2018 Northeastern Naturalist Notes Vol. 25, No. 3 K.L. Osborne and W.A. Hubbard Figure 2. Massachusetts Maritime Academy 2016 underwater video high-definition camera system. Figure 3. Pyrosome located just west of Stony Point Dike along Hog Island Channel—the entrance to Cape Cod Canal. Base chart provided by NOAA office of Coast Survey; nauticalcharts. noaa.gov. 2018 Northeastern Naturalist Notes Vol. 25, No. 3 N22 K.L. Osborne and W.A. Hubbard individual blastozooids measuring ~8–9 mm each (Palma and Apablaza 2004). The specimen captured in this dataset presents characteristics (e.g., outside colonial-wall morphology) consistent with P. atlanticum. With a live specimen, siphon orientation, bud-growth direction, and zooid-row formation could also be used to provide additional taxonomic support for identification (Esnal 1996, Kott 2005), but the size, color, geographic location, and expert consultations support the high likelihood of this being a P. atlanticum colony. Identification to the species level is impossible with only a video and frame capture; it requires a live, undamaged specimen. The 10-cm laser-pointer scale in the video output allowed us to estimate the size of this colony as 8 x 40 cm. Various post-processing and photographic magnifications showed some details, but not enough structural components to positively identify the species. Further, it is important to note that although it is likely that this organism is P. atlanticum, additional surveys and collection are needed to substantiate the observations of the present study. We communicated our putative discovery via email to both the Benthic and Pelagic Working Groups of the Northeast Regional Association of Coastal and Ocean Observing Systems (NERACOOS) and other academic, governmental, and private organizations. None of these organizations had previously documented a pyrosome in New England. P. atlanticum is a temperate, cosmopolitan, pelagic species. In this case, the pyrosome was likely pushed downward by currents and thus adhered to the ocean floor despite not being a benthic species. It is plausible that there are other pyrosomes in New England bays, and the high-definition technology being deployed by research teams such as those operating at Massachusetts Maritime Academy is just now allowing for their discovery. This specimen may have been swept into Buzzards Bay from a warm core breaking off the North Atlantic Gulf Stream current; as our oceans warm, we may expect to observe more exotic visitors such as this colonial pelagic tunicate. Acknowledgments. The Massachusetts Environmental Trust has financially supported this effort. Literature Cited Buzzards Bay Comprehensive Conservation and Management Plan (BBCCMP). 2013. US Environmental Protection Agency, Buzzards Bay National Estuary Program. Available online at http:// buzzardsbay.org/newccmp.htm. Accessed 17 January 2018. Coastal and Marine Ecological Classification System of the Federal Geographic Data Committee (CMECS). 2012. Coastal and Marine Ecological Classification Standard. FGDC-STD-018-2012. Available online at https://www.fgdc.gov/standards/projects/FGDC-standards-projects/cmecsfolder/ CMECS_Version_06-2012_FINAL.pdf. Accessed 20 March 2017. Delsuc, F., H. Brinkmann, D. Chourrout, and H. Philippe. 2006. Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature 439:965 –968. Esnal, G. 1996. Thaliacea y Appendicularia. (R. Gasca & E. Suárez, Eds.). Introducción al Estudio del Zooplancton Marino México. El Colegio de la Frontera Sur (ECOSUR)/El Consejo Nacional de Ciencia y Tecnología (CONACYT), Chetumal, Mexico. 711 pp. Govindarajan, A.F., A. Bucklin, and L.P. Madin. 2011. A molecular phylogeny of the Thaliacea. Journal of Plankton Research 33:843–853. Hubbard, W.A. 2016. Benthic studies in upper Buzzards Bay, Massachusetts: 2011/12 as compared to 1955. Marine Ecology 37:532–554. Kott, P. 2005. Catalogue of Tunicata in Australian Waters. Australian Biological Resources Study, Department of the Environment and Heritage, Canberra, Australia. 301 pp. Lemaire, P., W.C. Smith, and H. Nishida. 2008. Ascidians and the plasticity of the chordate developmental program. Current Biology 18:R620–R631. Monniot, C., and F. Monniot. 1966. Un pyrosome benthique: Pyrosoma benthica n. sp. Comptes rendus des séances del’Académie des Sciences 263:368–370. N23 2018 Northeastern Naturalist Notes Vol. 25, No. 3 K.L. Osborne and W.A. Hubbard Palma, S., and P. Apablaza. 2004. Primer registro de Pyrosoma atlanticum Péron, 1804 en aguas costeras del Sistema de la Corriente de Humboldt (Tunicata, Thaliacea, Pyrosomatidae). Investigaciones Marinas 32:133–136. Van Soest, R.W.M. 1981. A monograph of the order Pyrosomatida (Tunicata, Thaliacea). Journal of Plankton Research. 3:6036–3031. Vienne, A., and P. Pontarotti. 2006. Metaphylogeny of 82 gene families sheds a new light on chordate evolution. 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