- Email: [email protected]
Detecting Vulnerable Marine Ecosystems in the Southern Ocean using research trawls and underwater imagery
Marine Policy 35 (2011) 732–736
Contents lists available at ScienceDirect
Marine Policy journal homepage: www.elsevier.com/locate/marpol
Short Communication
Detecting Vulnerable Marine Ecosystems in the Southern Ocean using research trawls and underwater imagery Christopher D. Jones n, Susanne J. Lockhart Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, NOAA National Marine Fisheries Service, 3333 N. Torrey Pines Court, La Jolla, CA 92037, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 December 2010 Received in revised form 31 January 2011 Accepted 3 February 2011 Available online 22 February 2011
To ensure that destructive bottom fishing activities do not have significant adverse impacts on Vulnerable Marine Ecosystems (VMEs) in high seas areas of the World Ocean, as required by United Nations General Assembly Resolution 61–105, knowledge of the locations of VMEs is required. Quantifying the occurrence and abundance of VME indicator taxa in research bottom-trawl samples, as well as from in situ observations with underwater photography, provides methods for detecting these ecosystems. A case study is presented in which a threshold density of indicator taxa was used as the basis for VME designation. In 2009, high densities of VME indicator taxa were encountered at 11 sites off th‘e South Orkney Islands in the Atlantic sector of the Southern Ocean. In most cases, thresholds were exceeded by a limited number of VME indicator taxa, primarily representatives of the class Demospongiae (siliceous sponges), Hexactinellida (glass sponges) and Ascidiacea (tunicates). In situ imagery further showed the importance of bryozoans (lace corals), scleractinians (stony corals) and stylastrids (hydrocorals) in the study region. The approach outlined here, which relies on widely used sampling techniques, could be employed throughout the World Ocean to detect and document the presence of VMEs from existing datasets. To illustrate this point, the method was applied to a separate dataset, collected in 2006, from a research cruise off the northern Antarctic Peninsula, which led to the detection of 17 VMEs. The VMEs from both the 2006 and 2009 data are now registered and influence the management of fisheries in the Southern Ocean. Published by Elsevier Ltd.
Keywords: Vulnerable Marine Ecosystems Antarctic benthic invertebrates Fisheries management
1. Introduction Protection of Vulnerable Marine Ecosystems (VMEs) is an important component of the management framework for bottom fisheries in high seas areas of the World Ocean. Requirements of the 2007 United Nations General Assembly (UNGA) Sustainable Fisheries Resolution (61/105) aim to ensure that destructive bottom fishing activities do not proceed unless conservation and management measures have been established to prevent significant adverse impacts to VMEs. The Commission for the Conservation of Marine Living Resources (CCAMLR), which manages commercial fishing activities in the Southern Ocean, has thus adopted conservation measures (CMs) aimed at minimizing adverse impacts on VMEs in the Southern Ocean. These measures include CM 22-06 [1] which, inter alia, includes a requirement to notify the Commission when VMEs are encountered during the course of scientific research. Another measure, CM 22-07 [2], is specifically designed to cover commercial fishing activities. In UNGA Resolution 61/105, VMEs are obliquely defined, and can include seamounts, hydrothermal vents, cold water corals and sponge
n
Corresponding author. Tel.: +1 858 546 5605; fax: + 1 858 546 5608. E-mail address: [email protected] (C.D. Jones).
0308-597X/$ - see front matter Published by Elsevier Ltd. doi:10.1016/j.marpol.2011.02.004
fields. In the Southern Ocean, CCAMLR has interpreted a VME to be consistent with an area that includes the presence of benthic invertebrates that significantly contribute to the creation of complex three-dimensional structure, cluster in high densities, change the structure of the substratum, provide substrata for other organisms or are rare or unique [3]. Currently, 27 taxonomic groups are recognized by CCAMLR as VME indicator taxa (Table 1). Based on a threshold density of VME indicator taxa, data collected during research cruises can lead to the designation of a VME and its inclusion in the CCAMLR VME Registry. Detection by commercial fishing vessels (as bycatch) can lead to the designation of a VME ‘‘Risk Area’’, which provisionally closes (until review) an area to bottom fishing when evidence of a VME is encountered. There are no established guidelines as to how a VME is quantitatively defined in the Southern Ocean. Currently the only guidelines set forth by CCAMLR to indicate a VME risk area pertain to indirect evidence of VME indicator taxa observed on commercial longline and pot fishing gear. In 2008, CCAMLR agreed that a minimum of 10 indicator units (¼10 kg or 10 l) of VME taxa [4] on a recovered section of line (1200 m section of bottom fishing gear) would be evidence of an encounter with a possible VME. No such guidelines are provided for research vessels. Research platforms can detect VMEs in several ways, including in situ photography and the presence of invertebrates in other
C.D. Jones, S.J. Lockhart / Marine Policy 35 (2011) 732–736
Table 1 Taxonomic groups currently recognized as indicators of vulnerable marine ecosystems in the Southern Ocean. Phylum
Taxon
Common name
Annelida Arthropoda Brachiopoda Bryozoan Chemosynthetic Chordata Cnidaria
Serpulidae (Family) Bathylasmatidae (Family) Brachiopoda (Phylum) Bryozoans (Phylum) Various groups Ascidiacea (Class) Actiniaria (Order) Alcyonacea (Order) Anthoathecatae (Family) Antipatharia (Order) Gorgonacea (Order)
Serpulid worms Goose and acorn barnacles Lamp shells Lace corals Chemosynthetic communities Sea squirts Anemones Soft corals Stylasterid hydrocorals Black corals Chrysogorgiidae (golden coral) Coralliidae (red/precious coral) Isididae (bamboo coral) Paragorgiidae (Bubblegum coral) Primnoidae (Bottle crush, sea fans) Hydroids Sea pens Stony corals Zoanthids Pencil spine urchins Basket and snake stars Sea lillies Acorn worms Antarctic scallop
Hydroidolina (Order) Pennatulacea (Order) Scleractinia (Order) Zoantharia (Order) Echinodermata Cidaroida (Order) Ophiurida (Order) Stalked crinoids (Orders) Hemichordata Pterobranchia (Class) Mullusca Adamussium colbecki (Species) Porifera Hexactinellida (Class) Demospongiae (Class) Xenophyophora Xenophyophora (Phylum)
Glass sponges Siliceous sponges Xenophyophores
samples. The U.S. Antarctic Marine Living Resources (AMLR) program has characterized benthic invertebrate catches from several research surveys originally developed to provide data on the status of finfish populations. These surveys also now aim to elucidate the factors that influence the distribution of epibenthic megafauna [5]. Research on factors that drive patterns in the distribution of benthic invertebrates has been previously pursued [6–8], but results from this work have not been used to inform of the presence of VMEs. Video footage off East Antarctica [9] has, however, been used to formally notify CCAMLR of two VMEs. Here, details of the VME indicator taxa encountered during the 2009 U.S. AMLR research survey of the South Orkney Islands is presented. The information on composition and density is then used as a basis for developing a threshold density at which a VME is considered to have been detected. In addition, direct evidence of VMEs using an underwater camera system is provided. This methodology was further applied to a dataset collected during a previous survey in another region of Antarctica. Results from this study formed the basis of VME notifications submitted to CCAMLR, the registration of several VMEs and subsequent management actions taken to minimize risk of adverse impacts from bottom fishing.
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to record the swept area and contact with the seabed. For most stations, the trawl was on the seabed for 30 min at 2.2 knots, and the average sampling coverage of a station was 0.03 km2. Densities of megafaunal invertebrates at each station were standardized by prorating catches of VME indicator taxa to 1200 m2. The composition of each sample was analyzed by sorting catches into 61 feasible taxonomic groupings or operational taxonomic units (OTUs) that incorporate the VME indicator taxa adopted by CCAMLR (Table 1). Masses of each OTU were recorded and individuals counted where appropriate. Any dead or unsortable organic matter was also weighed and, for the latter, characterized (e.g. 60% demosponge, 30% irregular echinoid fragments, 10% organic matter). Weights were pooled within each taxonomic group to calculate the proportion each contributed to the total. Digital imagery was obtained using a custom-built (Sea Technology Services, Cape Town, South Africa) high resolution camera system on an open-frame towed sled that was deployed 17 times in the close vicinity ( 100 m) of trawl stations. Photographic transects ranged from 20 min to 1 h.
3. Designation of VMEs Indicator taxa can occur at a wide variety of densities, including at levels which would not warrant designation of a VME. To establish a density threshold that could be used to indicate a VME, the Z10 VME indicator unit/1200 m2 guideline, as set out in CCAMLR CM 22-07, was adopted. Using the density of indicator taxa observed in the trawl, standardized to 1200 m2 swept area, catches taken at each trawl station can be expressed in VME indicator units. Consistent with CM 22-07, a level of 10 VME indicator units was used as a threshold for detecting a VME, i.e. Z10 kg/1200 m2. This threshold formed the basis for VME notifications based on presence of indicator taxa in trawl samples. Photographic evidence from the camera deployments was also used to support trawl-based VME evidence, as well as to detect additional VMEs.
4. Results Indicator taxa were observed in the trawl catches at all but one station, with the number of VME indicator units ranging from o.01 to 63 (Fig. 1). Eleven of the 75 stations had sufficient densities to exceed the threshold: nine based on indicator units in
2. Methods Research trawling was conducted aboard the R/V Yuzhmorgeologiya in February–March 2009 around the South Orkney Islands as part of the U.S. AMLR Program field season [10]. Seventy five stations were sampled in a random, depth-stratified survey focused primarily on the continental shelf and slope (50–800 m). The sampling gear used was the ‘‘Hard Bottom Snapper Trawl’’ with vented V-Doors (Net Systems, Inc. Bainbridge Island, WA), a trawl designed for catching demersal finfish that also has demonstrated the capacity to sample sessile benthic invertebrates [5]. The headrope platform of the trawl was instrumented with a SimRad FS25 trawl sonar system
Fig. 1. Composition of VME indicator taxa at the South Orkney Islands. Sizes of pies indicate relative standardized densities of VME taxa. Inset figure shows the distribution of standardized VME density (kg/1200 m2 ¼ VME indicator units). A VME is declared for Z 10 indicator units.
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C.D. Jones, S.J. Lockhart / Marine Policy 35 (2011) 732–736
trawl catches and two based on underwater imagery alone. High densities of indicator taxa were relatively well clustered on the western and eastern shelf areas of the island chain (Fig. 1). The composition of indicator taxa demonstrated the significance of taxa in the phylum Porifera, specifically Demospongiae and Hexactinellida, as the primary indicator taxa (Table 1), accounting for seven of the nine VMEs. One VME was identified by the occurrence of a high density of Ascidiacea (colonial tunicates). In addition to Porifera, solitary and colonial tunicates and Actinarians contributed to high levels of VME indicator units. The communities of indicator taxa on the shelf of the South Orkney Islands showed some biogeographic patterning. The western stations were dominated by demosponges and hexactinellid sponges (Fig. 1), with colonial tunicates increasing in importance in the more inshore areas. The occurrence of indicator taxa on the southern South Orkney Island shelf, including the
shelf break, was well below the threshold, and thus no VMEs were detected in this region. There were associations among the VME taxa present in lesser densities. Sea pens were prominent components where anemones were abundant. Bryozoans, particularly foliose/filamentous species, increased in importance at the same locations that tunicates occurred. Hard reef-building bryozoan species (Fig. 2a) and primnoid gorgonians (Fig. 2b) formed dense communities in several regions. Direct evidence of VMEs was acquired from four of the 17 camera deployments. Two of these (Fig. 2c and d) confirmed high densities detected by the trawl; in the other two cases, the imagery provided direct evidence of a VME where there were insufficient indicator taxa in the trawl to exceed the threshold. The dominant indicator taxa at these two sites were scleractinians, stylasterids, bryozoans and primnoid gorgonians.
Fig. 2. (a) Habitat consisting of large bryozoan reef structures; (b) hexactinellid and demosponges amongst sea whips, hydroids and bryozoans; (c) demosponges, anemones, sea pens and primnoid gorgonians among abundant scleractinian corals Flabellum spp.; (d) demosponges, compound ascidians, hydroids, bottle brush and other primnoid gorgonians amongst bryozoan reefs; (e) abundant hexactinellid sponges amongst demosponges, foliose bryozoans, solitary tunicates and pterobranch colonies; (f) assemblages of large demosponges and bryozoan reef supporting filamentous bryozoans, hydroids, compound ascidians and other invertebrates; (g) diverse assemblage of demosponges amongst foliose bryozoans, hydroids, solitary and compound ascidians, and a variety of primnoid gorgonians (also note the nototheniod finfish, Lepidonotothen nudifrons, toward the center of the image); (h) abundant brown hexactinellid sponges, stylasterid coral assemblages, diverse primnoid gorgonians, hydroids, basket stars and demosponges.
C.D. Jones, S.J. Lockhart / Marine Policy 35 (2011) 732–736
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5. Discussion A total of 11 VMEs, clustered on the eastern and western shelves of the South Orkney Islands (Fig. 3), were detected. The specific mechanisms that control the spatial distribution of such communities are, at present, poorly understood. Large scale shelf zonation of benthic invertebrate megafauna found along the northern Antarctic Peninsula and South Shetland Islands may be influenced by the interaction of the physical properties of the Antarctic Circumpolar Current and the Weddell Sea Bottom Water masses that meet in this region, as well as smaller scale disturbance regimes such as iceberg scouring and historical fishing [5]. The distributions of VME indicator taxa at the South Orkney Islands have likely been influenced by similar factors. This area is within the Scotia Sea-Weddell Sea Confluence where icebergs have keels that scour the seabed to 521 m [11]. This region was also impacted by bottom-trawl fisheries at various times from 1978 to 1989 [12,13]. There have been efforts to predict distributions of Antarctic benthos by applying physical modeling approaches [7,14,15], though these studies focused more on factors that lead to broad scale distribution of biodiversity and broadly grouped benthic communities [16], which cannot easily be related to VMEs. There have also been efforts to use surrogates like sediment composition and geomorphology to predict benthic habitats [17], including a framework for predicting the likelihood of encountering VMEs in East Antarctica based on depth, flow of bottom water, and location at the head of shelf cutting canyons [9]. No such relationship between geomorphic provinces and VMEs has been observed around the South Orkney Islands. There are numerous uncertainties that need to be resolved before relying on modeling approaches that make use of physical or geologic datasets as a means of predicting the locations of VMEs. More direct sampling is required to understand and characterize spatial distributions and community composition of VMEs and the factors that control them. The proposed density threshold as set out can provide compelling evidence of the presence of VMEs. The methodology described here is simple and can be applied to existing datasets from previous research cruises where quantitative data on
Fig. 3. Trawl and underwater camera stations for the South Orkney Islands, with VMEs detected through trawl sampling (Z 10 indicator unit trigger), VMEs directly observed through underwater imagery, and sites where no VMEs were detected. Squares demarcate the 12 blocks of the experimental harvest regime for the crab fishery around the South Orkney Islands. The three blocks with solid lines were closed to exploratory crab fishing as a result of the VMEs registered in these blocks.
Fig. 4. Trawl and in situ camera stations near the northern Antarctic Peninsula, with VMEs detected through trawl sampling ( Z10 indicator unit trigger).
benthic invertebrates have been recorded. To demonstrate this point, data from a previous U.S. AMLR survey were examined. In 2006, a trawl survey consisting of 67 stations was conducted off the northern Antarctic Peninsula using a similar survey design [18]. When the invertebrate catches from this survey were expressed in terms of VME indicator units, 17 of the 67 stations had densities exceeding the 10 kg/1200 m2 threshold. These were relatively well clustered on shallow shelf banks in a band along the lower and central Antarctic Peninsula (Fig. 4). Direct evidence of four of these VMEs is provided in Fig. 2e–h.
6. VME registration and management action In 2009, the evidence and thresholds presented in this paper were presented to the CCAMLR Scientific Committee and Commission as a basis and rationale for including 28 stations in the CCAMLR VME registry. The Commission agreed that there was compelling evidence of the existence of these VMEs and added all 28 to the CCAMLR Registry [19]. Once a VME has been registered, steps are then taken to minimize the risk of adverse impacts from any bottom fishing activities. In the case of the South Orkney Islands, there is currently an exploratory bottom fishery (using bottom pot gear) for Antarctic crabs (Order Decapoda, Suborder Reptantia). To participate in this fishery, vessels must undertake an experimental spatially explicit harvest regime (to collect data on the distribution of crabs) requiring that every vessel expend the first 200,000 pot hours within a total area delineated by 12 harvest blocks of 0.51 latitude by 1.01 longitude [20]. As a result of the VMEs now registered in this region, the CCAMLR Commission took a precautionary approach and prohibited the setting of pots in three experimental harvest blocks where the VMEs occur (Fig. 3). Thus, 9307 km2 of seabed were protected from disturbance by bottom fishing gear. At present, there are no bottom fisheries operating in the northern Antarctic Peninsula region, though historically there have been bottom-trawl fisheries here [12]. If there is future exploitation in this region using any gear that interacts with the seabed, it would be precautionary to combine the cluster of VMEs that form the long band running along the shelf area of the Trinity Peninsula (Fig. 4) and treat this cluster in a manner similar to how the clusters of VMEs were treated for managing the crab fishery, i.e. as a continuous block.
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Locating and minimizing risk of adverse impacts to VMEs in the Southern Ocean, as well as other high-sea areas of the World Ocean, is a high priority for global regional fishery management organizations and similar organizations, such as CCAMLR. The approach outlined here, which relies on a widely used sampling technique, could potentially be employed throughout the World Ocean to detect and document the presence of VMEs. Numerous scientific trawl surveys and sampling programs have been conducted by academic and governmental institutions throughout the world, and there is great potential for the data collected through these efforts to be used toward better understanding and protecting such ecosystems.
Acknowledgements The authors appreciate the hard work and skill of the captain and crew of the R/V Yuzhmorgeologiya during the 2006 and 2009 U.S. AMLR field seasons. We also thank the AMLR scientists who helped process samples, particularly Nerida Wilson, Eric LazoWasem, John Moore, Ryan Driscoll and Kim Dietrich and those who worked as underwater camera technicians, Andre Hoek and Anthony Cossio. We are also grateful for constructive comments provided by George Watters, as well as an anonymous reviewer. References [1] CCAMLR. Conservation Measure 22-06. Bottom fishing in the Convention Area. Schedule of Conservation Measure in Force 2009/10. 2009. CCAMLR, Hobart, Austalia. /http://www.ccamlr.org/pu/e/e_pubs/cm/09-10/22-06.pdfS. [2] CCAMLR. Conservation Measure 22-07. Interim measure for bottom fishing activities subject to Conservation Measure 22-06 encountering potential vulnerable marine ecosystems in the Convention Area. Schedule of Conservation Measure in Force 2009/10. 2009.CCAMLR, Hobart, Austalia. /http:// www.ccamlr.org/pu/e/e_pubs/cm/09-10/22-07.pdfS. [3] CCAMLR. Report of the Workshop on Vulnerable Marine Ecosystems. SCCAMLR-XXVIII/10. 2009. CCAMLR, Hobart, Australia. [4] CCAMLR. CCAMLR VME Taxa Identification Guide Version 2009. CCAMLR, Hobart, Australia. 2009. 4p. /http://www.ccamlr.org/pu/e/sc/obs/vme-guide. pdfS. [5] Lockhart SJ, Jones CD. Biogeographic patterns of benthic invertebrate megafauna on shelf areas within the Southern Ocean Atlantic sector. CCAMLR Science 2008;15:167–92.
[6] Clarke A, Griffiths HJ, Linse K, Barnes DKA, Crame JA. How well do we know the Antarctic marine fauna? A preliminary study of macroecological and biogeographical patterns in Southern Ocean gastropod and bivalve mollusks Diversity and Distributions 2007;13(5):620–37. [7] Barry JP, Grebmeier J, Smith J, Dunbar RB. Bathymetric versus seafloor-habitat control of benthic megafaunal patterns in the Ross Sea, Antarctica. Antarctic Research Series 2003;78:327–54. [8] Gutt J, Starmans A. Structure and biodiversity of megabenthos in the Weddell and Lazarev Seas (Antarctica): ecological role of physical parameters and biological interactions. Polar Biology 1998;20(4):229–47. [9] Post AL, O’Brien PE, Beaman RJ, Riddle MJ, De Santis L. Physical controls on coral communities on the George V Land Slope: East Antarctica. Antarctic Science 2010;22:371–8. [10] Lockhart SJ, Wilson N Lazo-Wasem E, Jones CD. Benthic invertebrate composition and characterization of the South Orkney Islands. U.S. AMLR 2008/09 Field Season Report 2009. Van Cise AM, editor. NOAA-TM-NMFSSWFSC-445. [11] Dowdeswell JA, Bamber JL. Keel depths of modern Antarctic icebergs and implications for sea-floor scouring in the geological record. Marine Geology 2007;243:120–31. [12] Kock K-H, Pshenichnov L, Jones CD, Shust K, Skora KE, Frolkina ZhA. Joinville– D’Urville Islands (Subarea 48.1) – a former fishing ground for the spiny icefish (Chaenodraco wilsoni), at the top of the Antarctic Peninsula – revisited. CCAMLR Science 2004;11:1–20. [13] Kock K-H, Jones CD. Fish stocks in the Southern Scotia Arc region—a review and prospects for future research. Reviews in Fisheries Science 2005;13:75–108. [14] Teixido´ N, Garrabou J, Arntz WE. Spatial pattern quantification of Antarctic benthic communities using landscape indices. Marine Ecology Progress Series 2002;242:1–14. [15] Thrush S, Dayton P, Cattaneo-Vietti R, Chiantore M, Cummings V, Andrew N, Hawes I, Kim S, et al. Broad-scale factors influencing the biodiversity of coastal benthic communities of the Ross Sea. Deep-Sea Research II 2006;53:959–71. [16] Gutt J. Antarctic macro-zoobenthic communities: a review and an ecological classification. Antarctic Science 2007;19:165–82. [17] Post AL, Wassenberg TJ, Passlow V. Physical surrogates for macrofaunal distributions and abundance in a tropical gulf. Marine and Freshwater Research 2006;57(5):469–83. [18] Lockhart SJ, Jones CD. Benthic invertebrate bycatch composition and characterization of the northern Antarctic Peninsula. U.S. AMLR 2005/06 Field Season Report. 2006. Lipsky JD, editor. NOAA-TM-NMFS-SWFSC-397. [19] CCAMLR. Report of the twenty-eighth meeting of the Commission. SC-CAMLR-XXVIII 2009. CCAMLR, Hobart, Australia. [20] CCAMLR. Conservation Measure 52-02. Limits on the exploratory fishery for crab in Statistical Subarea 48.2 in the 2009/10 season. Schedule of Conservation Measure in Force 2009/10. 2009. CCAMLR, Hobart, Austalia. /http:// www.ccamlr.org/pu/e/e_pubs/cm/09-10/52-02.pdfS.
Contents lists available at ScienceDirect
Marine Policy journal homepage: www.elsevier.com/locate/marpol
Short Communication
Detecting Vulnerable Marine Ecosystems in the Southern Ocean using research trawls and underwater imagery Christopher D. Jones n, Susanne J. Lockhart Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, NOAA National Marine Fisheries Service, 3333 N. Torrey Pines Court, La Jolla, CA 92037, USA
a r t i c l e i n f o
a b s t r a c t
Article history: Received 6 December 2010 Received in revised form 31 January 2011 Accepted 3 February 2011 Available online 22 February 2011
To ensure that destructive bottom fishing activities do not have significant adverse impacts on Vulnerable Marine Ecosystems (VMEs) in high seas areas of the World Ocean, as required by United Nations General Assembly Resolution 61–105, knowledge of the locations of VMEs is required. Quantifying the occurrence and abundance of VME indicator taxa in research bottom-trawl samples, as well as from in situ observations with underwater photography, provides methods for detecting these ecosystems. A case study is presented in which a threshold density of indicator taxa was used as the basis for VME designation. In 2009, high densities of VME indicator taxa were encountered at 11 sites off th‘e South Orkney Islands in the Atlantic sector of the Southern Ocean. In most cases, thresholds were exceeded by a limited number of VME indicator taxa, primarily representatives of the class Demospongiae (siliceous sponges), Hexactinellida (glass sponges) and Ascidiacea (tunicates). In situ imagery further showed the importance of bryozoans (lace corals), scleractinians (stony corals) and stylastrids (hydrocorals) in the study region. The approach outlined here, which relies on widely used sampling techniques, could be employed throughout the World Ocean to detect and document the presence of VMEs from existing datasets. To illustrate this point, the method was applied to a separate dataset, collected in 2006, from a research cruise off the northern Antarctic Peninsula, which led to the detection of 17 VMEs. The VMEs from both the 2006 and 2009 data are now registered and influence the management of fisheries in the Southern Ocean. Published by Elsevier Ltd.
Keywords: Vulnerable Marine Ecosystems Antarctic benthic invertebrates Fisheries management
1. Introduction Protection of Vulnerable Marine Ecosystems (VMEs) is an important component of the management framework for bottom fisheries in high seas areas of the World Ocean. Requirements of the 2007 United Nations General Assembly (UNGA) Sustainable Fisheries Resolution (61/105) aim to ensure that destructive bottom fishing activities do not proceed unless conservation and management measures have been established to prevent significant adverse impacts to VMEs. The Commission for the Conservation of Marine Living Resources (CCAMLR), which manages commercial fishing activities in the Southern Ocean, has thus adopted conservation measures (CMs) aimed at minimizing adverse impacts on VMEs in the Southern Ocean. These measures include CM 22-06 [1] which, inter alia, includes a requirement to notify the Commission when VMEs are encountered during the course of scientific research. Another measure, CM 22-07 [2], is specifically designed to cover commercial fishing activities. In UNGA Resolution 61/105, VMEs are obliquely defined, and can include seamounts, hydrothermal vents, cold water corals and sponge
n
Corresponding author. Tel.: +1 858 546 5605; fax: + 1 858 546 5608. E-mail address: [email protected] (C.D. Jones).
0308-597X/$ - see front matter Published by Elsevier Ltd. doi:10.1016/j.marpol.2011.02.004
fields. In the Southern Ocean, CCAMLR has interpreted a VME to be consistent with an area that includes the presence of benthic invertebrates that significantly contribute to the creation of complex three-dimensional structure, cluster in high densities, change the structure of the substratum, provide substrata for other organisms or are rare or unique [3]. Currently, 27 taxonomic groups are recognized by CCAMLR as VME indicator taxa (Table 1). Based on a threshold density of VME indicator taxa, data collected during research cruises can lead to the designation of a VME and its inclusion in the CCAMLR VME Registry. Detection by commercial fishing vessels (as bycatch) can lead to the designation of a VME ‘‘Risk Area’’, which provisionally closes (until review) an area to bottom fishing when evidence of a VME is encountered. There are no established guidelines as to how a VME is quantitatively defined in the Southern Ocean. Currently the only guidelines set forth by CCAMLR to indicate a VME risk area pertain to indirect evidence of VME indicator taxa observed on commercial longline and pot fishing gear. In 2008, CCAMLR agreed that a minimum of 10 indicator units (¼10 kg or 10 l) of VME taxa [4] on a recovered section of line (1200 m section of bottom fishing gear) would be evidence of an encounter with a possible VME. No such guidelines are provided for research vessels. Research platforms can detect VMEs in several ways, including in situ photography and the presence of invertebrates in other
C.D. Jones, S.J. Lockhart / Marine Policy 35 (2011) 732–736
Table 1 Taxonomic groups currently recognized as indicators of vulnerable marine ecosystems in the Southern Ocean. Phylum
Taxon
Common name
Annelida Arthropoda Brachiopoda Bryozoan Chemosynthetic Chordata Cnidaria
Serpulidae (Family) Bathylasmatidae (Family) Brachiopoda (Phylum) Bryozoans (Phylum) Various groups Ascidiacea (Class) Actiniaria (Order) Alcyonacea (Order) Anthoathecatae (Family) Antipatharia (Order) Gorgonacea (Order)
Serpulid worms Goose and acorn barnacles Lamp shells Lace corals Chemosynthetic communities Sea squirts Anemones Soft corals Stylasterid hydrocorals Black corals Chrysogorgiidae (golden coral) Coralliidae (red/precious coral) Isididae (bamboo coral) Paragorgiidae (Bubblegum coral) Primnoidae (Bottle crush, sea fans) Hydroids Sea pens Stony corals Zoanthids Pencil spine urchins Basket and snake stars Sea lillies Acorn worms Antarctic scallop
Hydroidolina (Order) Pennatulacea (Order) Scleractinia (Order) Zoantharia (Order) Echinodermata Cidaroida (Order) Ophiurida (Order) Stalked crinoids (Orders) Hemichordata Pterobranchia (Class) Mullusca Adamussium colbecki (Species) Porifera Hexactinellida (Class) Demospongiae (Class) Xenophyophora Xenophyophora (Phylum)
Glass sponges Siliceous sponges Xenophyophores
samples. The U.S. Antarctic Marine Living Resources (AMLR) program has characterized benthic invertebrate catches from several research surveys originally developed to provide data on the status of finfish populations. These surveys also now aim to elucidate the factors that influence the distribution of epibenthic megafauna [5]. Research on factors that drive patterns in the distribution of benthic invertebrates has been previously pursued [6–8], but results from this work have not been used to inform of the presence of VMEs. Video footage off East Antarctica [9] has, however, been used to formally notify CCAMLR of two VMEs. Here, details of the VME indicator taxa encountered during the 2009 U.S. AMLR research survey of the South Orkney Islands is presented. The information on composition and density is then used as a basis for developing a threshold density at which a VME is considered to have been detected. In addition, direct evidence of VMEs using an underwater camera system is provided. This methodology was further applied to a dataset collected during a previous survey in another region of Antarctica. Results from this study formed the basis of VME notifications submitted to CCAMLR, the registration of several VMEs and subsequent management actions taken to minimize risk of adverse impacts from bottom fishing.
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to record the swept area and contact with the seabed. For most stations, the trawl was on the seabed for 30 min at 2.2 knots, and the average sampling coverage of a station was 0.03 km2. Densities of megafaunal invertebrates at each station were standardized by prorating catches of VME indicator taxa to 1200 m2. The composition of each sample was analyzed by sorting catches into 61 feasible taxonomic groupings or operational taxonomic units (OTUs) that incorporate the VME indicator taxa adopted by CCAMLR (Table 1). Masses of each OTU were recorded and individuals counted where appropriate. Any dead or unsortable organic matter was also weighed and, for the latter, characterized (e.g. 60% demosponge, 30% irregular echinoid fragments, 10% organic matter). Weights were pooled within each taxonomic group to calculate the proportion each contributed to the total. Digital imagery was obtained using a custom-built (Sea Technology Services, Cape Town, South Africa) high resolution camera system on an open-frame towed sled that was deployed 17 times in the close vicinity ( 100 m) of trawl stations. Photographic transects ranged from 20 min to 1 h.
3. Designation of VMEs Indicator taxa can occur at a wide variety of densities, including at levels which would not warrant designation of a VME. To establish a density threshold that could be used to indicate a VME, the Z10 VME indicator unit/1200 m2 guideline, as set out in CCAMLR CM 22-07, was adopted. Using the density of indicator taxa observed in the trawl, standardized to 1200 m2 swept area, catches taken at each trawl station can be expressed in VME indicator units. Consistent with CM 22-07, a level of 10 VME indicator units was used as a threshold for detecting a VME, i.e. Z10 kg/1200 m2. This threshold formed the basis for VME notifications based on presence of indicator taxa in trawl samples. Photographic evidence from the camera deployments was also used to support trawl-based VME evidence, as well as to detect additional VMEs.
4. Results Indicator taxa were observed in the trawl catches at all but one station, with the number of VME indicator units ranging from o.01 to 63 (Fig. 1). Eleven of the 75 stations had sufficient densities to exceed the threshold: nine based on indicator units in
2. Methods Research trawling was conducted aboard the R/V Yuzhmorgeologiya in February–March 2009 around the South Orkney Islands as part of the U.S. AMLR Program field season [10]. Seventy five stations were sampled in a random, depth-stratified survey focused primarily on the continental shelf and slope (50–800 m). The sampling gear used was the ‘‘Hard Bottom Snapper Trawl’’ with vented V-Doors (Net Systems, Inc. Bainbridge Island, WA), a trawl designed for catching demersal finfish that also has demonstrated the capacity to sample sessile benthic invertebrates [5]. The headrope platform of the trawl was instrumented with a SimRad FS25 trawl sonar system
Fig. 1. Composition of VME indicator taxa at the South Orkney Islands. Sizes of pies indicate relative standardized densities of VME taxa. Inset figure shows the distribution of standardized VME density (kg/1200 m2 ¼ VME indicator units). A VME is declared for Z 10 indicator units.
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trawl catches and two based on underwater imagery alone. High densities of indicator taxa were relatively well clustered on the western and eastern shelf areas of the island chain (Fig. 1). The composition of indicator taxa demonstrated the significance of taxa in the phylum Porifera, specifically Demospongiae and Hexactinellida, as the primary indicator taxa (Table 1), accounting for seven of the nine VMEs. One VME was identified by the occurrence of a high density of Ascidiacea (colonial tunicates). In addition to Porifera, solitary and colonial tunicates and Actinarians contributed to high levels of VME indicator units. The communities of indicator taxa on the shelf of the South Orkney Islands showed some biogeographic patterning. The western stations were dominated by demosponges and hexactinellid sponges (Fig. 1), with colonial tunicates increasing in importance in the more inshore areas. The occurrence of indicator taxa on the southern South Orkney Island shelf, including the
shelf break, was well below the threshold, and thus no VMEs were detected in this region. There were associations among the VME taxa present in lesser densities. Sea pens were prominent components where anemones were abundant. Bryozoans, particularly foliose/filamentous species, increased in importance at the same locations that tunicates occurred. Hard reef-building bryozoan species (Fig. 2a) and primnoid gorgonians (Fig. 2b) formed dense communities in several regions. Direct evidence of VMEs was acquired from four of the 17 camera deployments. Two of these (Fig. 2c and d) confirmed high densities detected by the trawl; in the other two cases, the imagery provided direct evidence of a VME where there were insufficient indicator taxa in the trawl to exceed the threshold. The dominant indicator taxa at these two sites were scleractinians, stylasterids, bryozoans and primnoid gorgonians.
Fig. 2. (a) Habitat consisting of large bryozoan reef structures; (b) hexactinellid and demosponges amongst sea whips, hydroids and bryozoans; (c) demosponges, anemones, sea pens and primnoid gorgonians among abundant scleractinian corals Flabellum spp.; (d) demosponges, compound ascidians, hydroids, bottle brush and other primnoid gorgonians amongst bryozoan reefs; (e) abundant hexactinellid sponges amongst demosponges, foliose bryozoans, solitary tunicates and pterobranch colonies; (f) assemblages of large demosponges and bryozoan reef supporting filamentous bryozoans, hydroids, compound ascidians and other invertebrates; (g) diverse assemblage of demosponges amongst foliose bryozoans, hydroids, solitary and compound ascidians, and a variety of primnoid gorgonians (also note the nototheniod finfish, Lepidonotothen nudifrons, toward the center of the image); (h) abundant brown hexactinellid sponges, stylasterid coral assemblages, diverse primnoid gorgonians, hydroids, basket stars and demosponges.
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5. Discussion A total of 11 VMEs, clustered on the eastern and western shelves of the South Orkney Islands (Fig. 3), were detected. The specific mechanisms that control the spatial distribution of such communities are, at present, poorly understood. Large scale shelf zonation of benthic invertebrate megafauna found along the northern Antarctic Peninsula and South Shetland Islands may be influenced by the interaction of the physical properties of the Antarctic Circumpolar Current and the Weddell Sea Bottom Water masses that meet in this region, as well as smaller scale disturbance regimes such as iceberg scouring and historical fishing [5]. The distributions of VME indicator taxa at the South Orkney Islands have likely been influenced by similar factors. This area is within the Scotia Sea-Weddell Sea Confluence where icebergs have keels that scour the seabed to 521 m [11]. This region was also impacted by bottom-trawl fisheries at various times from 1978 to 1989 [12,13]. There have been efforts to predict distributions of Antarctic benthos by applying physical modeling approaches [7,14,15], though these studies focused more on factors that lead to broad scale distribution of biodiversity and broadly grouped benthic communities [16], which cannot easily be related to VMEs. There have also been efforts to use surrogates like sediment composition and geomorphology to predict benthic habitats [17], including a framework for predicting the likelihood of encountering VMEs in East Antarctica based on depth, flow of bottom water, and location at the head of shelf cutting canyons [9]. No such relationship between geomorphic provinces and VMEs has been observed around the South Orkney Islands. There are numerous uncertainties that need to be resolved before relying on modeling approaches that make use of physical or geologic datasets as a means of predicting the locations of VMEs. More direct sampling is required to understand and characterize spatial distributions and community composition of VMEs and the factors that control them. The proposed density threshold as set out can provide compelling evidence of the presence of VMEs. The methodology described here is simple and can be applied to existing datasets from previous research cruises where quantitative data on
Fig. 3. Trawl and underwater camera stations for the South Orkney Islands, with VMEs detected through trawl sampling (Z 10 indicator unit trigger), VMEs directly observed through underwater imagery, and sites where no VMEs were detected. Squares demarcate the 12 blocks of the experimental harvest regime for the crab fishery around the South Orkney Islands. The three blocks with solid lines were closed to exploratory crab fishing as a result of the VMEs registered in these blocks.
Fig. 4. Trawl and in situ camera stations near the northern Antarctic Peninsula, with VMEs detected through trawl sampling ( Z10 indicator unit trigger).
benthic invertebrates have been recorded. To demonstrate this point, data from a previous U.S. AMLR survey were examined. In 2006, a trawl survey consisting of 67 stations was conducted off the northern Antarctic Peninsula using a similar survey design [18]. When the invertebrate catches from this survey were expressed in terms of VME indicator units, 17 of the 67 stations had densities exceeding the 10 kg/1200 m2 threshold. These were relatively well clustered on shallow shelf banks in a band along the lower and central Antarctic Peninsula (Fig. 4). Direct evidence of four of these VMEs is provided in Fig. 2e–h.
6. VME registration and management action In 2009, the evidence and thresholds presented in this paper were presented to the CCAMLR Scientific Committee and Commission as a basis and rationale for including 28 stations in the CCAMLR VME registry. The Commission agreed that there was compelling evidence of the existence of these VMEs and added all 28 to the CCAMLR Registry [19]. Once a VME has been registered, steps are then taken to minimize the risk of adverse impacts from any bottom fishing activities. In the case of the South Orkney Islands, there is currently an exploratory bottom fishery (using bottom pot gear) for Antarctic crabs (Order Decapoda, Suborder Reptantia). To participate in this fishery, vessels must undertake an experimental spatially explicit harvest regime (to collect data on the distribution of crabs) requiring that every vessel expend the first 200,000 pot hours within a total area delineated by 12 harvest blocks of 0.51 latitude by 1.01 longitude [20]. As a result of the VMEs now registered in this region, the CCAMLR Commission took a precautionary approach and prohibited the setting of pots in three experimental harvest blocks where the VMEs occur (Fig. 3). Thus, 9307 km2 of seabed were protected from disturbance by bottom fishing gear. At present, there are no bottom fisheries operating in the northern Antarctic Peninsula region, though historically there have been bottom-trawl fisheries here [12]. If there is future exploitation in this region using any gear that interacts with the seabed, it would be precautionary to combine the cluster of VMEs that form the long band running along the shelf area of the Trinity Peninsula (Fig. 4) and treat this cluster in a manner similar to how the clusters of VMEs were treated for managing the crab fishery, i.e. as a continuous block.
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Locating and minimizing risk of adverse impacts to VMEs in the Southern Ocean, as well as other high-sea areas of the World Ocean, is a high priority for global regional fishery management organizations and similar organizations, such as CCAMLR. The approach outlined here, which relies on a widely used sampling technique, could potentially be employed throughout the World Ocean to detect and document the presence of VMEs. Numerous scientific trawl surveys and sampling programs have been conducted by academic and governmental institutions throughout the world, and there is great potential for the data collected through these efforts to be used toward better understanding and protecting such ecosystems.
Acknowledgements The authors appreciate the hard work and skill of the captain and crew of the R/V Yuzhmorgeologiya during the 2006 and 2009 U.S. AMLR field seasons. We also thank the AMLR scientists who helped process samples, particularly Nerida Wilson, Eric LazoWasem, John Moore, Ryan Driscoll and Kim Dietrich and those who worked as underwater camera technicians, Andre Hoek and Anthony Cossio. We are also grateful for constructive comments provided by George Watters, as well as an anonymous reviewer. References [1] CCAMLR. Conservation Measure 22-06. Bottom fishing in the Convention Area. Schedule of Conservation Measure in Force 2009/10. 2009. CCAMLR, Hobart, Austalia. /http://www.ccamlr.org/pu/e/e_pubs/cm/09-10/22-06.pdfS. [2] CCAMLR. Conservation Measure 22-07. Interim measure for bottom fishing activities subject to Conservation Measure 22-06 encountering potential vulnerable marine ecosystems in the Convention Area. Schedule of Conservation Measure in Force 2009/10. 2009.CCAMLR, Hobart, Austalia. /http:// www.ccamlr.org/pu/e/e_pubs/cm/09-10/22-07.pdfS. [3] CCAMLR. Report of the Workshop on Vulnerable Marine Ecosystems. SCCAMLR-XXVIII/10. 2009. CCAMLR, Hobart, Australia. [4] CCAMLR. CCAMLR VME Taxa Identification Guide Version 2009. CCAMLR, Hobart, Australia. 2009. 4p. /http://www.ccamlr.org/pu/e/sc/obs/vme-guide. pdfS. [5] Lockhart SJ, Jones CD. Biogeographic patterns of benthic invertebrate megafauna on shelf areas within the Southern Ocean Atlantic sector. CCAMLR Science 2008;15:167–92.
[6] Clarke A, Griffiths HJ, Linse K, Barnes DKA, Crame JA. How well do we know the Antarctic marine fauna? A preliminary study of macroecological and biogeographical patterns in Southern Ocean gastropod and bivalve mollusks Diversity and Distributions 2007;13(5):620–37. [7] Barry JP, Grebmeier J, Smith J, Dunbar RB. Bathymetric versus seafloor-habitat control of benthic megafaunal patterns in the Ross Sea, Antarctica. Antarctic Research Series 2003;78:327–54. [8] Gutt J, Starmans A. Structure and biodiversity of megabenthos in the Weddell and Lazarev Seas (Antarctica): ecological role of physical parameters and biological interactions. Polar Biology 1998;20(4):229–47. [9] Post AL, O’Brien PE, Beaman RJ, Riddle MJ, De Santis L. Physical controls on coral communities on the George V Land Slope: East Antarctica. Antarctic Science 2010;22:371–8. [10] Lockhart SJ, Wilson N Lazo-Wasem E, Jones CD. Benthic invertebrate composition and characterization of the South Orkney Islands. U.S. AMLR 2008/09 Field Season Report 2009. Van Cise AM, editor. NOAA-TM-NMFSSWFSC-445. [11] Dowdeswell JA, Bamber JL. Keel depths of modern Antarctic icebergs and implications for sea-floor scouring in the geological record. Marine Geology 2007;243:120–31. [12] Kock K-H, Pshenichnov L, Jones CD, Shust K, Skora KE, Frolkina ZhA. Joinville– D’Urville Islands (Subarea 48.1) – a former fishing ground for the spiny icefish (Chaenodraco wilsoni), at the top of the Antarctic Peninsula – revisited. CCAMLR Science 2004;11:1–20. [13] Kock K-H, Jones CD. Fish stocks in the Southern Scotia Arc region—a review and prospects for future research. Reviews in Fisheries Science 2005;13:75–108. [14] Teixido´ N, Garrabou J, Arntz WE. Spatial pattern quantification of Antarctic benthic communities using landscape indices. Marine Ecology Progress Series 2002;242:1–14. [15] Thrush S, Dayton P, Cattaneo-Vietti R, Chiantore M, Cummings V, Andrew N, Hawes I, Kim S, et al. Broad-scale factors influencing the biodiversity of coastal benthic communities of the Ross Sea. Deep-Sea Research II 2006;53:959–71. [16] Gutt J. Antarctic macro-zoobenthic communities: a review and an ecological classification. Antarctic Science 2007;19:165–82. [17] Post AL, Wassenberg TJ, Passlow V. Physical surrogates for macrofaunal distributions and abundance in a tropical gulf. Marine and Freshwater Research 2006;57(5):469–83. [18] Lockhart SJ, Jones CD. Benthic invertebrate bycatch composition and characterization of the northern Antarctic Peninsula. U.S. AMLR 2005/06 Field Season Report. 2006. Lipsky JD, editor. NOAA-TM-NMFS-SWFSC-397. [19] CCAMLR. Report of the twenty-eighth meeting of the Commission. SC-CAMLR-XXVIII 2009. CCAMLR, Hobart, Australia. [20] CCAMLR. Conservation Measure 52-02. Limits on the exploratory fishery for crab in Statistical Subarea 48.2 in the 2009/10 season. Schedule of Conservation Measure in Force 2009/10. 2009. CCAMLR, Hobart, Austalia. /http:// www.ccamlr.org/pu/e/e_pubs/cm/09-10/52-02.pdfS.