DOCSLIB.ORG

An Ecosystem Approach to Management of Seamounts in the Southern Indian Ocean Volume 1 – Overview of Seamount Ecosystems and Biodiversity

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

An Ecosystem Approach to Management of Seamounts in the Southern Indian Ocean Volume 1 – Overview of Seamount Ecosystems and Biodiversity Alex D. Rogers IUCN GLOBAL MARINE AND POLAR PROGRAMME The designation of geographical entities in this publication, and the presentation of the material, do not imply the expression of any opinion whatsoever on the part of IUCN concerning the legal status of any country, territory, or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The views expressed in this publication do not necessarily reflect those of IUCN. Published by: IUCN, Gland, Switzerland Copyright: © 2012 International Union for Conservation of Nature and Natural Resources Reproduction of this publication for educational or other non-commercial purposes is authorized without prior written permission from the copyright holder provided the source is fully acknowledged. Reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder. Citation: Rogers, A.D. (2012). An Ecosystem Approach to Management of Seamounts in the Southern Indian Ocean. Volume 1 – Overview of Seamount Ecosystems and Biodiversity. Gland, Switzerland: IUCN. 18 + iipp. This paper is to be read in conjunction with two others: one on threats to seamount ecosystems (Volume 2) and one on a legal and instituional gap analysis (Volume 3). ISBN: 978-2-8317-1561-2 Cover photos: Front: Unidentified octopus, South West Indian Ocean, R/V Fridtjof Nansen Cruise, Nov-Dec 2009. Back: Chaunacidae – Sea toads, South West Indian Ocean, R/V Fridtjof Nansen Cruise, Nov-Dec 2009. Layout by: Tim Davis, DJEnvironmental, UK Available from: IUCN (International Union for Conservation of Nature) Publications Services Rue Mauverney 28 1196 Gland Switzerland Tel +41 22 999 0000 Fax +41 22 999 0020 [email protected] www.iucn.org/publications An Ecosystem Approach to Management of Seamounts in the Southern Indian Ocean Volume 1 – Overview of Seamount Ecosystems and Biodiversity Alex D. Rogers IUCN SIO Seamount Governance i TABLE OF CONTENTS I. General: About Seamount Ecosystems....................................................................................1 II. Specific: The Southern Indian Ocean and its Seamounts.......................................................5 A. Biology of seamounts in the Indian Ocean.............................................................................6 B. Deep-sea fisheries on seamounts in the Indian Ocean...........................................................9 C. Management of deep-water fisheries on the high seas of the Indian Ocean...........................9 III. Knowledge Gaps .....................................................................................................................11 IV. References...............................................................................................................................12 I. G ENERAL : A BOUT SEAMOUNT ECOSYSTEMS eamounts are topographic rises of the demersal fish are important as spawning sites seabed with a limited extent across the (e.g., Pankhurst et al., 1987; Boehlert and Sasaki, Ssummit. Originally this definition held that 1988; Pankhurst, 1988; Tsukamoto et al., 2003; seamounts had an elevation of ≥1,000 m and that Tsukamoto, 2006). they were intraplate features, reflecting a contrasting geological origin to those associated To date (July 2010), 798 species of fish have with mid-ocean ridges and other settings been listed as occurring at seamounts (Morato et (Staudigel et al., 2010). However, smaller al., 2004). Deep-sea fisheries target a relatively submarine knolls (elevation 500-1,000 m) and hills small fraction of these that aggregate around (elevation >500 m) share many of the seamounts. Most of these species have been environmental characteristics of larger features, identified as forming a specific guild of robust- and given that the size distribution of such bodied demersal fish species, generally elevations are continuous, the term seamount is characterized by a strong swimming ability, high used interchangeably for most features >100 m in food consumption and energy expenditure, and elevation (Wessel, 2007; Staudigel et al., 2010). low rates of growth and productivity (e.g., Koslow Large seamounts usually originate as volcanoes, et al., 2000). These species include orange although some, such as Atlantis Bank in the roughy (Hoplostethus atlanticus), pelagic South West Indian Ocean, are formed by tectonic armourhead ( Pseudopentaceros wheeleri; uplift, or even from serpentinite mud (e.g., Fryer et Pseudopentaceros richardsoni ), rockfish al., 1992). Most large seamounts are associated (Sebastes spp., Helicolenus spp.), oreos with intraplate hotspots, mid-ocean ridges or (Oreosomatidae), cardinal fish ( Epigonus spp.) island arcs. There may be up to 100,000- roundnose grenadier ( Coryphaenoides rupestris ), 200,000 large seamounts in the oceans, with Patagonian toothfish ( Dissostichus eleginoides ) perhaps >25 million (with a range of error of 8-80 and alfonsinos ( Beryx splendens, Beryx million) with an elevation ≥100 m (Wessel, 2007; decadactylus ). These fish are specifically Wessel et al., 2010). Most seamounts are located associated with seamounts, although they also in the Pacific Ocean, with lower numbers in the occur on continental slopes and the slopes of Indian, Atlantic, Arctic and Southern Oceans oceanic islands. (Wessel, 2007). Overall this adds up to a globally significant area of habitat with an estimate of Why seamounts host abundant populations of fish nearly 10 million km 2, comparable with tropical and other pelagic and aquatic predators is still humid forest, temperate broad-leafed forest or all uncertain. Early observations suggested that the world’s wetlands (Etnoyer et al., 2010). chlorophyll concentrations may be higher above seamounts than in non-seamount locations There is evidence that seamounts form hotspots (Bezrukov and Natarov, 1976; Lophukin, 1986; of biological activity in the oceans. Over large Boehlert and Genin, 1987; Dower et al., 1992; geographic scales ocean predators appear to be Mouriño et al., 2001). This gave some support to associated with seamounts and other features. a hypothesis of enhanced primary productivity Tuna, billfish, sharks, cetaceans, pinnipeds, turtles above seamounts, resulting from nutrient and seabirds may all be associated with enrichment of the euphotic zone by localized seamounts, and high biomass and abundance of upwelling induced by current-topography such predators have been observed in the vicinity interactions, especially the formation of Taylor of seamounts (Holland and Grubs, 2007; columns. Seamounts may also be associated Kaschner, 2007; Litvinov, 2007; Santos et al., with turbulent mixing caused by internal or 2007; Thompson, 2007). This is thought to be baroclinic waves that can also induce upwelling of because of enhanced levels of prey or feeding nutrients (Kunze and Sanford, 1997; Toole et al., opportunities for these species. Seamounts may 1997). However, it has been argued more recently also act as ‘navigational waypoints’ for oceanic that evidence for enhancement of primary species that undergo large-scale annual or production, beyond sporadic and temporary ontogenetic migrations (e.g., Holland and Grubs, blooms of phytoplankton, are lacking (Genin and 2007) and for some species of catadromous and Dower, 2007; Clark et al., 2010). Although such SIO Seamount Ecosystems and Biodiversity 1 GENERAL : A BOUT SEAMOUNT ECOSYSTEMS phenomena may enhance patchiness of micronekton (Rogers, 1994; Genin and Dower, phytoplankton downstream of seamounts, they 2007; Porteiro and Sutton, 2007). These layers, are unlikely to significantly enhance the known as the deep-scattering layer (DSL) productivity of the seamounts themselves. because it is seen as a layer of acoustic reflectivity in echosounders, undergo migrations towards the It is now recognized that several other physical surface at dusk and then back down into deeper processes associated with seamounts may waters at dawn. During the night the DSL may be enhance productivity or food supply in their advected over a seamount and at dawn, when vicinity. These include tidal rectification (generation the organisms descend, their passage is of mean residual currents by tidal flow), flow obstructed by the raised topography and they are acceleration and the formation of internal waves, preyed on by fish and other planktivores living on and can enhance vertical mixing around a the seamount (Genin and Dower, 2007). The DSL seamount, causing upwelling of nutrient-rich deep may be enhanced by organisms that are water and enhancement of primary production associated with the seabed on the seamount but (White et al., 2007; Lavelle and Mohn, 2010). The which undertake migrations into the water column water above a seamount may become stabilized to feed at night (Boehlert and Seki, 1984; by high-density stratification, promoting Vereshaka, 1995). Evidence that the DSL is an productivity (Comeau et al., 1995). Seamounts important food source for seamount-resident or may also interact with eddies shed from frontal visiting species of predators has been observed zones, or Meddies, lenses of warm salty water through analyses of stomach contents for released from the Mediterranean into the colder demersal and pelagic species (Genin et al., 1988; waters of the Atlantic which can interact with Seki and Somerton, 1994; Fock et al., 2002; seamounts. Eddies have been observed
Recommended publications
  • Identity Crisis Or Split Personality? Trans-Ocean Distances and Not Within Individual Regions

    Identity Crisis Or Split Personality? Trans-Ocean Distances and Not Within Individual Regions

    Journal of Biogeography (J. Biogeogr.) (2007) 34, 2001–2008 GUEST Seamounts: identity crisis or split EDITORIAL personality? Craig R. McClain* Monterey Bay Aquarium Research Institute, ABSTRACT 7700 Sandholdt Road, Moss Landing, CA At present, researchers propose that over 14,000 seamounts exist and, like their 95039, USA terrestrial analogues, function like islands. In addition, seamounts are described as oases, biodiversity hotspots, and lush coral/sponge gardens. Here I discuss the extent to which these tenets regarding seamounts may be inappropriate, suffer from a lack of support, and be over-generalizations of a broad range of envi- ronmental types encountered on seamounts. Ultimately, for seamount science to progress, we need to challenge our conventional wisdom on these habitats and the extent to which all seamounts function in a similar manner. *Correspondence: Craig R. McClain, Monterey Bay Aquarium Research Institute, 7700 Keywords Sandholdt Road, Moss Landing, CA, 95039, USA. Biodiversity, conservation, coral, deep sea, ecological oasis, endemism, hotspot, E-mail: [email protected] island biogeography, isolation, seamount. biological communities that support highly unique and INTRODUCTION endemic faunas’. In ‘Toward a strategy for high seas marine There is no such things as mountains and valleys on the deep-sea protected areas’, Gjerde & Breide (2003) notes that ‘Sea- bottom. mounts are areas of high endemic biodiversity with little Mosely (1880), p. 343 overlap in community composition between seamount Less than 100 years after Mosely’s statement, Hubbs (1959) clusters’. contemplated the ‘scientific interests, particularly in respect Alternatively, others suggest that seamounts are unique to zoogeography and speciation’ of recently discovered habitats for reasons not related to their ‘islandness’.
  • Cnidaria, Hydrozoa) from the Vema and Valdivia Seamounts (SE Atlantic)

    Cnidaria, Hydrozoa) from the Vema and Valdivia Seamounts (SE Atlantic)

    European Journal of Taxonomy 758: 49–96 ISSN 2118-9773 https://doi.org/10.5852/ejt.2021.758.1425 www.europeanjournaloftaxonomy.eu 2021 · Gil M. & Ramil F. This work is licensed under a Creative Commons Attribution License (CC BY 4.0). Research article urn:lsid:zoobank.org:pub:7CA6D8AC-2312-47F9-8C17-528B94E4C8A7 Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic) Marta GIL 1,* & Fran RAMIL 2 1,2 CIM-UVigo – Centro de Investigación Mariña, Facultade de Ciencias do Mar, Universidade de Vigo, Spain. 1 Instituto Español de Oceanografía, Centro Oceanográfi co de Vigo, Spain. * Corresponding author: [email protected] 2 Email: [email protected] 1 urn:lsid:zoobank.org:author:FFF187EB-84CE-4A54-9A01-4E4326B5CD26 2 urn:lsid:zoobank.org:author:67BAF0B6-E4D5-4A2D-8C03-D2D40D522196 Abstract. In this report, we analyse the benthic hydroids collected on the Vema and Valdivia seamounts during a survey conducted in 2015 in the SEAFO Convention Area, focused on mapping and analysing the occurrence and abundance of benthopelagic fi sh and vulnerable marine ecosystem (VMEs) indicators on selected Southeast Atlantic seamounts. A total of 27 hydroid species were identifi ed, of which 22 belong to Leptothecata and only fi ve to Anthoathecata. Monostaechoides gen. nov. was erected within the family Halopterididae to accommodate Plumularia providentiae Jarvis, 1922, and a new species, Monotheca bergstadi sp. nov., is also described. Campanularia africana is recorded for the fi rst time from the Atlantic Ocean, and the Northeast Atlantic species Amphinema biscayana, Stegopoma giganteum and Clytia gigantea are also recorded from the South Atlantic.
  • Inferences on Potential Seamount Locations from Mid-Resolution

    Inferences on Potential Seamount Locations from Mid-Resolution

    T. Morato and D. Pauly (eds.), Seamounts: Biodiversity and Fisheries, Page 7 INFERENCES ON POTENTIAL SEAMOUNT LOCATIONS FROM MID- RESOLUTION BATHYMETRIC DATA Adrian Kitchingman and Sherman Lai Fisheries Centre, The University of British Columbia. 2259 Lower Mall, Vancouver, B.C., V6T 1Z4, Canada [email protected]; [email protected] ABSTRACT Seamounts are underwater volcanoes that did not grow tall enough to break to the sea surface and turn into islands. Once formed, seamounts tend to gradually sink under their own weight and the subsidence of the lithosphere. The ocean floor is littered with these former seamounts, here called ‘seamounds’. Seamounts occur throughout the world's oceans, but their number (which may surpass 50,000) is difficult to estimate, even roughly, because it depends on the resolution of the bathymetric map used and the specific definition of a seamount used, i.e., the limits used to distinguish between seamounts and seamounds. Here, the locations of a subset of the seamounts of the world were identified using two algorithms relying on the depth differences between adjacent cells of a digital global elevation map distributed by the U.S. National Oceanographic and Atmospheric Agency (NOAA). The overlap of both algorithms resulted in a set of about 14,000 seamounts, but a different number would have been found had we used different thresholds. Known seamount locations supplied by NOAA and SeamountsOnline (http://seamounts.sdsc.edu) were compared against the corresponding seamounts located by the study, which led to some degree of ground-truthing. The coordinates of the seamounts identified in this study are available on the CD-ROM attached to this report, and on http://www.seaaroundus.org.
  • Vulnerable Marine Ecosystems – Processes and Practices in the High Seas Vulnerable Marine Ecosystems Processes and Practices in the High Seas

    Vulnerable Marine Ecosystems – Processes and Practices in the High Seas Vulnerable Marine Ecosystems Processes and Practices in the High Seas

    ISSN 2070-7010 FAO 595 FISHERIES AND AQUACULTURE TECHNICAL PAPER 595 Vulnerable marine ecosystems – Processes and practices in the high seas Vulnerable marine ecosystems Processes and practices in the high seas This publication, Vulnerable Marine Ecosystems: processes and practices in the high seas, provides regional fisheries management bodies, States, and other interested parties with a summary of existing regional measures to protect vulnerable marine ecosystems from significant adverse impacts caused by deep-sea fisheries using bottom contact gears in the high seas. This publication compiles and summarizes information on the processes and practices of the regional fishery management bodies, with mandates to manage deep-sea fisheries in the high seas, to protect vulnerable marine ecosystems. ISBN 978-92-5-109340-5 ISSN 2070-7010 FAO 9 789251 093405 I5952E/2/03.17 Cover photo credits: Photo descriptions clockwise from top-left: Acanthagorgia spp., Paragorgia arborea, Vase sponges (images courtesy of Fisheries and Oceans, Canada); and Callogorgia spp. (image courtesy of Kirsty Kemp, the Zoological Society of London). FAO FISHERIES AND Vulnerable marine ecosystems AQUACULTURE TECHNICAL Processes and practices in the high seas PAPER 595 Edited by Anthony Thompson FAO Consultant Rome, Italy Jessica Sanders Fisheries Officer FAO Fisheries and Aquaculture Department Rome, Italy Merete Tandstad Fisheries Resources Officer FAO Fisheries and Aquaculture Department Rome, Italy Fabio Carocci Fishery Information Assistant FAO Fisheries and Aquaculture Department Rome, Italy and Jessica Fuller FAO Consultant Rome, Italy FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS Rome, 2016 The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations (FAO) concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
  • Roadmap to Recovery: a Global Network of Marine Reserves

    Roadmap to Recovery: a Global Network of Marine Reserves

    © Greenpeace/Åslund Roadmap to Recovery: A global network of marine reserves Callum M. Roberts, Leanne Mason and Julie P. Hawkins Contributing authors: Elizabeth Masden, Gwilym Rowlands, Jenny Storey and Anna Swift Environment Department, University of York, York, YO10 5DD, UK Correspondence to: [email protected] 3 4 Roadmap to Recovery: A global network of marine reserves content 1. Summary 7 2. Introduction 9 3. Aims of this report 11 4. Life on the high seas 11 4.1 The pelagic realm 11 4.2 The deep sea 13 5. History of exploitation of the high seas 16 6. Present status and threats to life on the high seas 17 6.1 Fishing 17 6.2 Global warming 18 6.3 Disposal of CO2 18 6.4 Oil and mineral exploitation 18 6.5 Bioprospecting 20 6.6 Noise 20 7. Designing a global marine reserve network for the high seas 20 7.1 Marine reserves and why they are needed 20 7.2 Will marine reserves protect species on the high seas? 21 7.3 Identifying candidate sites for protection 23 7.4 The grid 25 8. Principles of marine reserve networking 25 8.1 Site selection 25 8.2 Networking and connectivity 26 8.3 Level of replication 26 8.4 Spacing of marine reserves 26 8.5 Size of marine reserves 26 8.6 Coverage of marine reserves 27 9. Procedure used for computer-assisted design of a network 28 of marine reserves 9.1 Features and targets used for Marxan analyses 29 Oceanographic Features 29 Physical features 29 Biological data 29 Expert consultation 31 10.
  • Importance of Seamount-Like Features for Conserving Mediterranean Marine Habitats and Threatened Species

    Importance of Seamount-Like Features for Conserving Mediterranean Marine Habitats and Threatened Species

    Nº. 1105 IMPORTANCE OF SEAMOUNT-LIKE FEATURES FOR CONSERVING MEDITERRANEAN MARINE HABITATS AND THREATENED SPECIES Ricardo Aguilar, Xavier Pastor, Silvia García & Pilar Marín Oceana. Leganitos, 47 - 28013 Madrid. Spain - *[email protected] INTRODUCTION HABITAT LOCATION MAIN SPECIES 16 of the more than 200 seamount‑like peaks in the Mediterranean1 have been observed using ROV. Coral reefs 4, 5, 6, 7 Lophelia pertusa, Madrepora oculata Desmophyllum dianthus, Stenocyathus vermiformis, The findings, which include carnivorous sponges, elasmobranches, coral gardens, sponge aggregations, Cold water corals All sites Caryophyllia spp. Pourtalosmilia anthophyllites, Javania caileti, coralligenous beds, as well as species new to science like the giant foraminifera Spiculosiphon oceana, Anomocora fecunda, Dendrophyllia spp. Paramuricea spp., Eunicella spp., Viminella flagellum, or new to the Mediterranean, like the scleractinian Anomocora fecunda, underscore the importance of 1, 2, 3, 4, 5, Callogorgia verticillata, Acanthogorgia spp., Placogorgia these geological features as hotspots and shelters/refuges species and habitats that are threatened, in Gorgonian/coral gardens: 6, 7, 8, 9, 11, coronata, Swiftia pallida, Muriceides lepida, Villogorgia regression, or rare in other Mediterranean areas. 12, 13, 14 bebrycoides, Bebryce mollis, Nicella granifera 1, 4, 5, 6, 7, Leiopathes glaberrima, Antipathes dichotoma, Antipathella METHODOLOGY Black corals Since 2006, Oceana has carried out six expeditions in the Mediterranean performing 129 ROV’s dives 9, 11, 15, 16 subpinnata, Parantipathes larix Isidella elongata, Pennatula spp., Pteroeides griseum, 2, 3, 4, 7, 8, over 16 seamounts, between ‑37 and ‑638 meters deep. Soft bottoms’ octocorals Virgularia mirabilis, Veretillun cynomorium, Kophobelemnon 9, 11, 14, 16 RESULTS stelliferum, Funiculina quadrangularis 2 3, 4, 5, 6, 7, Asconema setubalense, Phakellia spp., Axinella spp.
  • Chapter 51. Biological Communities on Seamounts and Other Submarine Features Potentially Threatened by Disturbance

    Chapter 51. Biological Communities on Seamounts and Other Submarine Features Potentially Threatened by Disturbance

    Chapter 51. Biological Communities on Seamounts and Other Submarine Features Potentially Threatened by Disturbance Contributors: J. Anthony Koslow, Peter Auster, Odd Aksel Bergstad, J. Murray Roberts, Alex Rogers, Michael Vecchione, Peter Harris, Jake Rice, Patricio Bernal (Co-Lead members) 1. Physical, chemical, and ecological characteristics 1.1 Seamounts Seamounts are predominantly submerged volcanoes, mostly extinct, rising hundreds to thousands of metres above the surrounding seafloor. Some also arise through tectonic uplift. The conventional geological definition includes only features greater than 1000 m in height, with the term “knoll” often used to refer to features 100 – 1000 m in height (Yesson et al., 2011). However, seamounts and knolls do not appear to differ much ecologically, and human activity, such as fishing, focuses on both. We therefore include here all such features with heights > 100 m. Only 6.5 per cent of the deep seafloor has been mapped, so the global number of seamounts must be estimated, usually from a combination of satellite altimetry and multibeam data as well as extrapolation based on size-frequency relationships of seamounts for smaller features. Estimates have varied widely as a result of differences in methodologies as well as changes in the resolution of data. Yesson et al. (2011) identified 33,452 seamount and guyot features > 1000 m in height and 138,412 knolls (100 – 1000 m), whereas Harris et al. (2014) identified 10,234 seamount and guyot features, based on a stricter definition that restricted seamounts to conical forms. Estimates of total abundance range to >100,000 seamounts and to 25 million for features > 100 m in height (Smith 1991; Wessel et al., 2010).
  • Microbiology of Seamounts Is Still in Its Infancy

    Microbiology of Seamounts Is Still in Its Infancy

    or collective redistirbution of any portion of this article by photocopy machine, reposting, or other means is permitted only with the approval of The approval portionthe ofwith any articlepermitted only photocopy by is of machine, reposting, this means or collective or other redistirbution This article has This been published in MOUNTAINS IN THE SEA Oceanography MICROBIOLOGY journal of The 23, Number 1, a quarterly , Volume OF SEAMOUNTS Common Patterns Observed in Community Structure O ceanography ceanography S BY DAVID EmERSON AND CRAIG L. MOYER ociety. © 2010 by The 2010 by O ceanography ceanography O ceanography ceanography ABSTRACT. Much interest has been generated by the discoveries of biodiversity InTRODUCTION S ociety. ociety. associated with seamounts. The volcanically active portion of these undersea Microbial life is remarkable for its resil- A mountains hosts a remarkably diverse range of unusual microbial habitats, from ience to extremes of temperature, pH, article for use and research. this copy in teaching to granted ll rights reserved. is Permission S ociety. ociety. black smokers rich in sulfur to cooler, diffuse, iron-rich hydrothermal vents. As and pressure, as well its ability to persist S such, seamounts potentially represent hotspots of microbial diversity, yet our and thrive using an amazing number or Th e [email protected] to: correspondence all end understanding of the microbiology of seamounts is still in its infancy. Here, we of organic or inorganic food sources. discuss recent work on the detection of seamount microbial communities and the Nowhere are these traits more evident observation that specific community groups may be indicative of specific geochemical than in the deep ocean.
  • A Review of the Effects of Seamounts on Biological Processes

    A Review of the Effects of Seamounts on Biological Processes

    A REVIEW OF THE EFFECTS OF SEAMOUNTS ON BIOLOGICAL PROCESSES George W. Boehlert Southwest Fisheries Center Honolulu Laboratory, National Marine Fisheries Service. NOAA. 2570 Dole St., Honolulu, HI 96822-2396 Amatzia Genin Scripps Institution of Oceanography, A-008, University of California, La Jolla, CA 92093 Abstract. Seamounts interacting with oceanic continental shelf or slope counterparts at similar currents create flow complexities which depend water depths [Hubbs, 19591. In the open ocean, upon current speed, stratification. latitude, and seamounts interact with ocean currents and create seamount morphology. Seamount effects. which variability in the physical flow field. Several include internal wave generation. eddy formation. studies have described these effects on the Gulf local upwelling. and closed circulation patterns Stream [Vastano and Warren, 19761 and the Kuroshio called Taylor columns. have important effects upon [Roden et al.. 1982; Roden. 19871. The physical pelagic and benthic ecosystems over seamounts. effects include local small- and mesosca7.e phe- The biological effects of these current-topography nomena including the shedding of mesoscale eddies interactions are poorly understood. Flow accel- which alter flow patterns for significant dis- eration on upper flanks of seamounts may lead to tances downstream of the seamounts [Royer. 19781. low sedimentation but areas of high standing Biological effects of these physical complexities stocks of benthic fauna, particularly filter feed- are not well understood [Genin and Boehlert 1985; ers. Other effects extend into the water column: Boehlert, 19861. Discovery of seamount fishery nutrient enrichment and enhanced primary produc- [Uchida and Tagami. 19841 and mineral resources tivity occur over some seamounts. Longer observa- [Manheim, 19861, however, has caused increased tional periods will be necessary to understand the interest in seamount oceanography and its effects time-varying nature of such enhanced productivity on biota [Darnitsky et al.
  • Joint Geological Survey/University of Cape Town MARINE GEOSCIENCE UNIT TECHNICAL ^REPORT NO. 13 PROGRESS REPORTS for the YEARS 1

    Joint Geological Survey/University of Cape Town MARINE GEOSCIENCE UNIT TECHNICAL ^REPORT NO. 13 PROGRESS REPORTS for the YEARS 1

    Joint Geological Survey/University of Cape Town MARINE GEOSCIENCE UNIT TECHNICAL ^REPORT NO. 13 PROGRESS REPORTS FOR THE YEARS 1981-1982 Marine Geoscience Group Department of Geology University of Cape Town December 1982 NGU-Tfc—Kh JOINT GEOLOGICAL SURVEY/UNIVERSITY OF CAPE TOWN MARINE GEOSCIENCE UNIT TECHNICAL REPORT NO. 13 PROGRESS REPORTS FOR THE YEARS 1981-1982 Marine Geoscience Group Department of Geology University of Cape Town December 1982 The Joint Geological Survey/University of Cape Town Marine Geoscience Unit is jointly funded by the two parent organizations to promote marine geoscientific activity in South Africa. The Geological Survey Director, Mr L.N.J. Engelbrecht, and the University Research Committee are thanked for their continued generous financial and technical support for this work. The Unit was established in 1975 by the amalgamation of the Marine Geology Programme (funded by SANCOR until 1972) and the Marine Geophysical Unit. Financial ?nd technical assistance from the South African National Committee for Oceanographic Research, and the National Research Institute for Oceanology (Stellenbosch) are also gratefully acknowledged. It is the policy of the Geological Survey and the University of Cape Town that the data obtained may be presented in the form of theses for higher degrees and that completed projects shall be published without delay in appropriate media. The data and conclusions contained in this report are made available for the information of the international scientific community with tl~e request that they be not published in any manner without written permission. CONTENTS Page INTRODUCTION by R.V.Dingle i PRELIMINARY REPORT ON THE BATHYMETRY OF PART OF 1 THE TRANSKEI BASIN by S.H.
  • High Seas Deep-Sea Fishing Grounds in the South East Atlantic Ocean 51

    High Seas Deep-Sea Fishing Grounds in the South East Atlantic Ocean 51

    50 Worldwide review of bottom fisheries in the high seas MAP 1 High seas deep-sea fishing grounds in the South East Atlantic Ocean 51 South East Atlantic Ocean FAO Statistical Area 47 (and a portion of 34) GEOGRAPHIC DESCRIPTION OF THE REGION Angola, Namibia and South Africa are the three countries bordering the South East Atlantic Region (FAO Statistical Area 47) along the African coast. This region extends from the Central Atlantic in the north at 6°S to the Southern Ocean in the south at 50°S. The western limit of the South East Atlantic is the 20°W meridian, which means that the southern Mid-Atlantic Ridge is within the region, at around 15°W, and extends over the entire region from north to south. Other important bottom topographic features in this region are the Walvis Ridge and the Valdivia Bank, joining the exclusive economic zone (EEZ) of Tristan da Cunha on the northern part of the Namibian continental shelf at around 18°S, and in the southern part, the Meteor Rise and the Agulhas Ridge. These are the areas largely targeted in the deep-sea bottom fisheries in the region, together with associated or isolated seamounts areas such as Ewing and Molloy Seamounts, Vema Seamount and those in SEAFO Subdivision A1 (SEAFO, 2007a). It is important to note that in the South East Atlantic, the continental shelf along the coasts does not extend beyond the EEZs of the coastal states. MANAGEMENT REGIME APPLICABLE TO DEEP-SEA BOTTOM FISHERIES IN THE HIGH SEAS Regional Fisheries Management Organization/Arrangement The South East Atlantic Fisheries Organisation (SEAFO) was established in 2003 with the entry into force of the Convention on the conservation and management of fisheries resources in the South East Atlantic Ocean.
  • Mount Vema-H.S.)

    Mount Vema-H.S.)

    Friday, August 7, 2020 Not for Sale. The Sanctity of Seamount Treasures (Mount Vema-H.S.) - 12 November 2019 Greenpeace Germany oceans campaigner Thilo Maack encounters a Tristan Rock Lobster (Jasus tristani) on one of Mount Vema’s summits. Credit © Richard Barnden / Greenpeace The Mount Vema seamount is 1000km out to sea in the southeast Atlantic Ocean. It is out of reach except by industrial fishing fleets or passing ships. But finding a lobster cage there has alarmed Greenpeace which has reiterated that seamounts must be protected from being exploited. This week Greenpeace reported that its ship, Arctic Sunrise, visited the area as part of the “Protect the Oceans” tour, a year-long pole-to-pole expedition. On board are a group of activists, divers and scientists who took the opportunity to explore the secrets of the Vema seamount which rises from the seabed at 4600m to just 26m below the surface of the ocean. Indian ocean seamounts Seamounts are not exactly a secret to the commercial fishing fleets of South Africa and Namibia. Some 25 years have passed since the first seamounts were discovered in the south west Indian ocean. Then in 2010, a South African-led exploration of eight seamounts including Atlantis, “Middle of What” and Coral was successfully concluded. This was made possible by the United Nations, the International Union for the Conservation of Nature (IUCN), and the Global Environmental Facility. There was also support from the Norwegians who provided the research ship. Fish finds On board the Fridtjof Nansen, amongst the group of scientists, was a phytoplankton specialist, researchers, marine biologists and seamount specialist Dr Alex Rogers from the Zoological Society of London.