de Matos et al. (2014). First record of Antipathella subpinnata (Anthozoa, Antipatharia) in the Azores (NE Atlantic), with description of the first monotypic garden for this species. Deep-Sea Research Pt. II, 99: 113-121. (original) (raw)

First record of Antipathella subpinnata (Anthozoa, Antipatharia) in the Azores (NE Atlantic), with description of the first monotypic garden for this species

Valentina de Matos*, José N. Gomes-Pereira, Fernando Tempera, Pedro A. Ribeiro, Andreia Braga-Henriques, Filipe Porteiro

IMMI/DOPOJAc LARSyS Associate Laboratory, Department of Oceanography and Fisheries of the University of the Azores, 9901-862 Horta, Portugal

A R T I C L E I N F O

Keywords:
Black coral garden
Benthic habitat
ROV surveys
Taxonomy
Distribution records

A B S T R A C T

The first record of Antipathella subpinnata (Ellis and Solander, 1786) for the Azores archipelago is presented based on bottom longline by-catch analysis and ROV seafloor surveys, extending the species western-most boundary of distribution in the NE Atlantic. The species was determined using classic taxonomy and molecular analysis targeting nuclear DNA. Although maximum spine height on Azorean colonies branchlets is slightly smaller than that reported from Mediterranean colonies ( 0.12 vs 0.16 mm ), the analysis of partial 18S rDNA, complete ITS1, 5.8S, ITS2 and partial 28S rDNA suggests that the Azorean and Mediterranean specimens belong to the same species. Video surveys of an A. subpinnata garden detected near Pico Island are used to provide the first in situ description of the species habitat in the region and the first detailed description of a black coral garden in the NE Atlantic. With A. subpinnata being the only coral found between 150 and 196 m depths, this is the deepest black coral garden recorded in the NE Atlantic and the first one to be monospecific. The species exhibited a maximum density of 2.64 colonies /m2/ \mathrm{m}^{2} and occurred across a surface area estimated at 67,333 m267,333 \mathrm{~m}^{2}, yielding a local population estimate of 50,500 colonies.
© 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Antipatharians, commonly known as black corals, are colonial hexacorals that usually present a slow growth and can reach remarkable longevities of a few millennia (e.g. Carreiro-Silva et al., 2013; Grange, 1985). They can be found in all oceans from polar to tropical regions and present a wide range of depth distributions ( 2 to 8600 m ), colony sizes (few cm to several m ) and morphologies (Wagner, 2011).

While only isolated colonies occur in many locations, in lowlight environments with hard substrates, increased current, low sedimentation and enhanced suspended or re-suspended organic matter supply, antipatharians can form dense monotypic aggregations, or coral beds, that extend over large areas (Wagner, 2011).

Black coral aggregations are currently classified as “Coral Gardens” (ICES, 2007), which are defined as relatively dense aggregation of colonies or individuals of one or more coral species occurring on a wide range of soft and hard seabed substrata and are currently designated as under threat and/or in decline in OSPAR Regions I, II, IV and V (OSPAR, 2008).

[1]Antipatharians achieve higher abundances in tropical and subtropical environments (Wagner, 2011) with dense ( ≥0.5\geq 0.5 colonies /m2/ \mathrm{m}^{2} ) populations recorded in the Mediterranean sea (Bo et al., 2009) NW Atlantic (Goenaga, 1977; Padilla and Lara, 2003; Sánchez 1999; Sánchez et al., 1998; Warner, 2005), NE and central Pacific (Grigg, 2001; Opresko and Genin, 1990; Wagner et al., 2011) and Indo-Pacific Oceans (Tazioli et al., 2007). In these environments, several species form colonies that can grow over 50 cm above the sea floor and create dense 3D aggregations that serve as substrate, feeding area and shelter for invertebrates, fish and even mammals such as Hawaiian monk seals (Boland and Parrish, 2005; Parrish et al., 2002; Tazioli et al., 2007).

In temperate and polar waters, antipatharians are usually less abundant (Wagner, 2011), with only 2 species known to form dense aggregations in a few locations. The first coldwater black coral gardens discovered were dense monotypic assemblages of Antipathella fiordensis (Grange, 1985) at 4−40 m4-40 \mathrm{~m} depth, in the exceptional conditions of the New Zealand fiords (Grange, 1985; Grange and Singleton, 1988).

Almost 25 years later, Antipathella subpinnata (Ellis and Solander, 1786) was found to also form dense assemblages of mixed antipatharian and gorgonian colonies at 50−100 m50-100 \mathrm{~m} depth in the Tyrrhenian Sea (Bo et al., 2009). More recently, mixed assemblages of A. subpinnata were reported at 57−105 m57-105 \mathrm{~m} depth

[2]

  2. 0967-0645/š-see front matter © 2013 Elsevier Ltd. All rights reserved.
    http://dx.doi.org/10.1016/j.dsr2.2013.07.003 ↩︎

in the Bay of Biscay, Galicia and Southwestern Portugal and at 100-143 m depth in the Gorringe Bank (OCEANA, 2011) but these gardens were not individually described and no quantitative data are available for them.
A. subpinnata was first recorded in the Mediterranean Sea (Ellis and Solander, 1786), where it is now confirmed to be a common component of deep circulartoral environments (Bo et al., 2008), but can also be found in the NE Atlantic Ocean from the English Channel to the southern coast of Portugal as well as on the Gorringe Ridge, Josephine and Great Meteor Seamounts, between 50 and 500 m of depth (see Bo et al., 2008).

The diverse seafloor habitats of the Azores EEZ (NE Atlantic) constitute a hotspot for cold-water corals, with the most recent review accounting for 164 species, including 18 antipatharians (Braga-Henriques et al., 2013). While numerous cold-water coral communities were recorded on hard bottom areas on island slopes and seamounts (Braga-Henriques et al., 2012; Braga-Henriques et al., 2013; CNEXO, 1972; Tempera et al., 2012), no dense aggregations of antipatharians were found in the region, except for Antipathella wollastoni which forms patches of colonies on some highly hydrodynamic vertical bedrock facies (Tempera et al., 2001).

This study presents the first record of A. subpinnata for the Azores and provides a detailed description of the colonies forming the first black coral garden recorded in the Azores. This information sets a baseline for the protection of the coral garden.

2. Materials and methods

2.1. Study area

The Azores is a northeast Atlantic archipelago composed by nine islands of recent volcanic origin. The offshore topography is rich and extends to more than 5000 m depth, including 63 large and 398 small seamount-like features (Morato et al., 2008).

The study area (Cabeço do Luís) is a small volcanic elevation located one nautical mile away from the southwestern coast of Pico Island, on the southern flank of the Faial-Pico Passage. The hill has a conical shape and rises from depths of 400 m in the north and 700 m in the south, culminating in a shallow peak at approximately -150 m . The bottom is rough and blocky, with medium and largesized boulders. Small coarse sediment patches occur in areas with a less pronounced slope (Fig. 1).

2.2. Taxonomy

In order to provide a detailed description of the morphology of Azorean A. subpinnata, samples of fourteen different colonies (eleven of which were undamaged), collected between 115 and 430 m depth in 10 locations in the Azores EEZ, including one of the largest colonies on Cabeço do Luís (collected for ground truthing), were used in this study (Table 1). All specimens are deposited at the Reference Collection (COLETA) of IMAR-DOP/UAc. Previous records were also compiled from literature (Table 2) in order to estimate the species distribution in the NE Atlantic.

All specimens were identified based on the general shape of the corallum as well as the size, shape and distribution of the branchlets, polyps and spines, following Opresko (2001) and Bo et al. (2008). Measurements of structures discernible by the naked eye were taken using a vernier calliper, while the microscopic structures were measured from images obtained by a digital camera attached to a vertical light microscope (Leica DM6000) using ImageJ 1.43.

The identity of the Azorean specimens was also confirmed using molecular tools. The sequence variation of a nuclear genomic DNA region encompassing partial 18S rDNA, complete ITS1, 5.8S, ITS2 and partial 28 S rDNA was assessed from four specimens (DOP-2151, DOP-7462, DOP-7466, DOP-7479), and compared with a previously published sequence of Mediterranean A. subpinnata (GenBank accession number AM404329).
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Fig. 1. Bathymetric map of Cabeço do Luís hill with geomorphological context (grid interval 500 m ).