DOCSLIB.ORG

Marine Geophysics Data Acquisition, Processing and Interpretation Guidance Notes

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Marine Geophysics Data Acquisition, Processing and Interpretation Guidance Notes 2013 Marine Geophysics Data Acquisition, Processing and Interpretation Guidance Notes 1 Contents List of acronyms ................................................................3 7 Processing and analysis of geophysical data ...............32 7.1 General data processing, presentation Preface ................................................................................4 and interpretation ......................................................32 7.1.1 General geophysical data processing ..........................32 Part I Standards for geophysical survey .....................4 7.1.2 General geophysical data presentation .......................33 7.1.3 General geophysical data interpretation .....................33 1 Legislation, existing standards and guidance ...............4 7.2 Side scan sonar processing, presentation and interpretation ......................................................34 2 Geophysics and maritime archaeology .........................6 7.2.1 General side scan sonar processing, presentation and interpretation ......................................................34 3 General guidance .........................................................6 7.2.2 Side scan sonar processing, presentation 3.1 Justification for a geophysical survey ...........................6 and interpretation for wreck sites ...............................35 3.2 Fieldwork .....................................................................7 7.2.3 Side scan sonar processing, presentation 3.3 General equipment statement ......................................8 and interpretation for submerged landscapes .............36 3.3.1 Navigation ....................................................................8 7.3 Bathymetry processing, presentation 3.3.2 Side scan survey ...........................................................8 and interpretation ......................................................36 3.3.3 Bathymetric survey .......................................................8 7.3.1 General bathymetry processing, presentation 3.3.4 Sub-bottom profiler survey ...........................................8 and interpretation ......................................................36 3.3.5 Magnetometer survey ...................................................8 7.3.2 Bathymetry processing, presentation and interpretation for wreck sites ...............................37 3.4 Data treatment .............................................................8 7.3.3 Bathymetry processing, presentation 3.5 Data interpretation .......................................................8 and interpretation for submerged landscapes .............38 3.6 The survey report .........................................................8 7.4 Sub-bottom profiler processing, presentation 3.7 Data archiving and dissemination ................................9 and interpretation ......................................................39 7.4.1 General sub-bottom profiler processing, Part II Planning and reporting for a marine presentation and interpretation ..................................39 archaeo-geophysical survey ...........................................9 7.4.2 Sub-bottom profiler processing, presentation and interpretation for wreck sites ...............................40 4 Archaeology and planning ............................................9 7.4.3 Sub-bottom profiler processing, presentation and interpretation for submerged landscapes .............40 5 MoRPHE – a project’s life cycle ....................................9 7.5 Magnetometer processing, presentation 5.1 Start-up and project proposal .......................................9 and interpretation ......................................................41 5.2 Initiation and project design .........................................9 5.3 Execution stages .........................................................10 References and further reading ..................................42 5.3.1 Desk-based assessment ...............................................10 5.3.2 Fieldwork ...................................................................10 Contacts and useful addresses ....................................47 5.3.3 Data processing and analysis ......................................11 5.3.4 Assessment of data potential for further analysis .......11 5.3.5 The survey report .......................................................11 5.3.6 The main project report ..............................................11 5.3.7 End of project report ..................................................11 5.3.8 Final (digital) archiving and dissemination ................11 Part III Practitioner’s guide – techniques and geophysical instrumentation ..............................12 6 Application of techniques ...........................................12 6.1 Navigation, positioning and datum ............................12 6.1.1 Navigation and positioning ........................................12 6.1.2 Datum, coordinate system and projections .................14 6.2 Side scan sonar survey ...............................................15 6.2.1 Instrumentation – side scan sonar ..............................15 6.2.2 Survey design – side scan sonar .................................17 6.3 Bathymetry survey ......................................................19 6.3.1 Instrumentation – bathymetry ....................................19 6.3.2 Survey design – bathymetry .......................................20 6.4 Sub-bottom profiler survey .........................................23 6.4.1 Instrumentation – sub-bottom profiler .......................23 6.4.2 Survey design – sub-bottom profiler ...........................25 6.5 Magnetometer survey .................................................26 6.5.1 Instrumentation – magnetometer ...............................26 6.5.2 Survey design – magnetometer ..................................28 6.6 Integrated surveys ......................................................29 6.7 Other systems .............................................................30 2 List of acronyms ADS JNAPC UNESCO Archaeology Data Service Joint Nautical Archaeology Policy United Nations Educational, Scientific and ALSF Committee Cultural Organization Aggregate Levy Sustainability Fund JNCC UKHO BGS Joint Nature Conservation Committee UK Hydrographic Office British Geological Survey LBL UKOOA BMAPA Long Baseline United Kingdom Offshore Operators British Marine Aggregate Producers LINZ Association Association Land Information New Zealand USBL BODC MAG Ultra-short Baseline British Oceanographic Data Centre Maritime Affairs Group USGS CEFAS MBARI United States Geological Survey Centre for Environment, Fisheries and Monterey Bay Aquarium Research Institute US MMS Aquaculture Science MCA United States Minerals Management COWRIE Maritime and Coastguard Agency Service Collaborative Offshore Wind Research Into MEDIN UTM the Environment Marine Environmental Data Information Universal Transverse Mercator DBA Network VENUS Desk-based Assessment MESH Virtual Exploration of Underwater Sites DCLG Mapping European Seabed Habitats VORF Department for Communities and Local MEPF Vertical Offshore Reference Frame Government Marine Environment Protection Fund WGS84 DCMS MMO World Geodetic System 1984 Department for Culture Media and Sport Marine Management Organisation Defra MoRPHE Department for Environment, Food and Management of Research Projects in the Rural Affairs Historic Environment DGPS ms Differential Global Positioning System milliseconds DNH nT Department of National Heritage nanotesla DoE NIEA Department of the Environment Northern Ireland Environment Agency EH NOAA English Heritage National Oceanic and Atmospheric EIA Administration Environmental Impact Assessment OASIS ETRS89 Online AccesS to the Index of archaeological European Terrestrial Reference System investigationS 1989 PPK GEBCO Post-Processed Kinematic General Bathymetric Chart of the Oceans RCAHMS GPS Royal Commission on the Ancient and Global Positioning System Historic Monuments of Scotland GRS80 RCAHMW Geodetic Reference System 1980 Royal Commission on the Ancient and HER Historic Monuments of Wales Historic Environment Record REC HWTMA Regional Environmental Characterisation Hampshire and Wight Trust for Maritime ROV Archaeology Remotely Operated Vehicles Hz/kHz RTK hertz/kilohertz Real Time Kinematic ICOMOS SAR International Council on Monuments and Synthetic Aperture Radar Sites SAS IHO/IHB Synthetic Aperture Sonar International Hydrographic Organisation/ SBL Bureau Short Baseline IfA TWTT Institute for Archaeologists Two-way Travel Time 3 Preface We have tried to make these guidelines On a European scale, the UK govern- both practical and informative and able ment has ratified the European Convention These guidelines are part of the ALSF’s dis- to be used alongside other guidelines and on the Protection of the Archaeological semination of heritage information, which standards without major conflicts. It is Heritage (European Commission 1992) is managed by English Heritage. Previously impossible to produce fixed standards that and has signed the Charter on the the ALSF has funded studies of the potential can be used in all circumstances. Therefore, Protection and Management of Underwater and applicability of geophysical techniques the surveyor and researcher should have Cultural Heritage (ICOMOS 1996). Both for maritime archaeology, to provide basic some freedom to apply his or her own documents encourage the use of non- information for and characterisation
Load more

Recommended publications
  • Side Scan Sonar and the Management of Underwater Cultural Heritage Timmy Gambin
    259 CHAPTER 15 View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by OAR@UM Side Scan Sonar and the Management of Underwater Cultural Heritage Timmy Gambin Introduction Th is chapter deals with side scan sonar, not because I believe it is superior to other available technologies but rather because it is the tool that I have used in the context of a number of off shore surveys. It is therefore opportune to share an approach that I have developed and utilised in a number of projects around the Mediterranean. Th ese projects were conceptualised together with local partners that had a wealth of local experience in the countries of operation. Over time it became clear that before starting to plan a project it is always important to ask oneself the obvious question – but one that is oft en overlooked: “what is it that we are setting out to achieve”? All too oft en, researchers and scientists approach a potential research project with blinkers. Such an approach may prove to be a hindrance to cross-fertilisation of ideas as well as to inter-disciplinary cooperation. Th erefore, the aforementioned question should be followed up by a second query: “and who else can benefi t from this project?” Benefi ciaries may vary from individual researchers of the same fi eld such as archaeologists interested in other more clearly defi ned historic periods (World War II, Early Modern shipping etc) to other researchers who may be interested in specifi c studies (African amphora production for example).
    [Show full text]
  • IMCA D033 Limitations in the Use of Scuba Offshore
    AB The International Marine Contractors Association Limitations in the Use of SCUBA Offshore IMCA D 033 www.imca-int.com October 2003 AB The International Marine Contractors Association (IMCA) is the international trade association representing offshore, marine and underwater engineering companies. IMCA promotes improvements in quality, health, safety, environmental and technical standards through the publication of information notes, codes of practice and by other appropriate means. Members are self-regulating through the adoption of IMCA guidelines as appropriate. They commit to act as responsible members by following relevant guidelines and being willing to be audited against compliance with them by their clients. There are two core committees that relate to all members: Safety, Environment & Legislation Training, Certification & Personnel Competence The Association is organised through four distinct divisions, each covering a specific area of members’ interests: Diving, Marine, Offshore Survey, Remote Systems & ROV. There are also four regional sections which facilitate work on issues affecting members in their local geographic area – Americas Deepwater, Asia-Pacific, Europe & Africa and Middle East & India. IMCA D 033 This guidance document was prepared for IMCA under the direction of its Diving Division Management Committee, enhancing and extending guidance formerly available via guidance note AODC 065, which is now withdrawn. www.imca-int.com/diving The information contained herein is given for guidance only and endeavours to reflect best industry practice. For the avoidance of doubt no legal liability shall attach to any guidance and/or recommendation and/or statement herein contained. Limitations in the Use of SCUBA Offshore 1 BACKGROUND SCUBA – self-contained underwater breathing apparatus – was first developed in the 1940s and has since become widely used for recreational and amateur diving.
    [Show full text]
  • Information Synthesis on the Potential for Bat Interactions with Offshore Wind Facilities
    _______________ OCS Study BOEM 2013-01163 Information Synthesis on the Potential for Bat Interactions with Offshore Wind Facilities Final Report U.S. Department of the Interior Bureau of Ocean Energy Management Office of Renewable Energy Programs www.boem.gov OCS Study BOEM 2013-01163 Information Synthesis on the Potential for Bat Interactions with Offshore Wind Facilities Final Report Authors Steven K. Pelletier Kristian S. Omland Kristen S. Watrous Trevor S. Peterson Prepared under BOEM Contract M11PD00212 by Stantec Consulting Services Inc. 30 Park Drive Topsham, ME 04086 Published by U.S. Department of the Interior Bureau of Ocean Energy Management Herndon, VA Office of Renewable Energy Programs June 2013 DISCLAIMER This report was prepared under contract between the Bureau of Ocean Energy Management (BOEM) and Stantec Consulting Services Inc. This report has been technically reviewed by BOEM, and it has been approved for publication. Approval does not signify that the contents necessarily reflect the views and policies of BOEM, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. It is, however, exempt from review and compliance with BOEM editorial standards. REPORT AVAILABILITY The report may be downloaded from the boem.gov website through the Environmental Studies Program Information System (ESPIS). You will be able to obtain this report from BOEM or the National Technical Information Service. U.S. Department of the Interior U.S. Department of Commerce Bureau of Ocean Energy Management National Technical Information Service Office of Renewable Energy Programs 5285 Port Royal Road 381 Elden Street, HM-1328 Springfield, Virginia 22161 Herndon, VA 20170 Phone: (703) 605-6040 Fax: (703) 605-6900 Email: [email protected] CITATION Pelletier, S.K., K.
    [Show full text]
  • Overview of Geophysical and Geotechnical Marine Surveys for Offshore Wind Transmission Cables in the UK September 2015
    Overview of geophysical and geotechnical marine surveys for offshore wind transmission cables in the UK September 2015 Overview of geophysical and geotechnical marine surveys for offshore wind transmission cables in the UK Disclaimer Whilst the information contained in this report has been prepared and collated in good faith, the Offshore Wind Programme Board (OWPB) makes no representation or warranty (express or implied) as to the accuracy or completeness of the information contained in this report (including any enclosures and attachments) nor shall be liable for any loss or damage, whether direct or consequential, arising from reliance on this report by any person. In particular, but without limitation, the OWPB accepts no responsibility for accuracy and completeness for any comments on, or opinions regarding the functional and technical capabilities of any software, equipment or other products mentioned in the report. The OWPB is not responsible in any way in connection with erroneous information or data contained or referred to in this document. It is up to those who use the information in this report to satisfy themselves as to its accuracy. This report and its contents do not constitute professional advice. Specific advice should be sought about your specific circumstances. The information contained in this report has been produced by a working group of industry professionals and has not been subject to independent verification. The OWPB has not sought to independently corroborate this information. The OWPB accepts no responsibility for accuracy and completeness for any comments on, or opinions regarding the functional and technical capabilities of any software, equipment or other products mentioned.
    [Show full text]
  • Norway/UK Regulatory Guidance for Offshore Diving
    AB The International Marine Contractors Association Norway/UK Regulatory Guidance for Offshore Diving (NURGOD) IMCA D 034 www.imca-int.com December 2003 AB The International Marine Contractors Association (IMCA) is the international trade association representing offshore, marine and underwater engineering companies. IMCA promotes improvements in quality, health, safety, environmental and technical standards through the publication of information notes, codes of practice and by other appropriate means. Members are self-regulating through the adoption of IMCA guidelines as appropriate. They commit to act as responsible members by following relevant guidelines and being willing to be audited against compliance with them by their clients. There are two core activities that relate to all members: Safety, Environment & Legislation Training, Certification & Personnel Competence The Association is organised through four distinct divisions, each covering a specific area of members’ interests: Diving, Marine, Offshore Survey, Remote Systems & ROV. There are also four regional sections which facilitate work on issues affecting members in their local geographic area – Americas Deepwater, Asia-Pacific, Europe & Africa and Middle East & India. IMCA D 034 The Norway/UK Regulatory Guidance for Offshore Diving (NURGOD) has been developed jointly by IMCA, under the direction of its Diving Division Management Committee, and OLF (Oljeindustriens Landsforening – The Norwegian Oil Industry Association). www.imca-int.com/diving The information contained herein is given for guidance only and endeavours to reflect best industry practice. For the avoidance of doubt no legal liability shall attach to any guidance and/or recommendation and/or statement herein contained. Norway/UK Regulatory Guidance for Offshore Diving IMCA D 034 – December 2003 1 Introduction and Scope...................................................................................................
    [Show full text]
  • To Download Psdiver Monthly Issue
    Greetings safety diving. That is a topic we can discuss this year. For now let’s stick with the expectation we should have of the skills a Each issue of PSDiver Monthly has included a short editorial or Professional Diver performing public safety diving should have. commentary that I have felt compelled to share. The topic is usually something that is either a personal pet peeve of mine or If we are not Recreational Divers and hold ourselves above my opinion or concern about something that is relevant at the them, then the skill sets we possess and use should be above a time. I am privileged to have the opportunity to share these recreational diver level as well. If not, what exactly can we use editorials with such a dedicated audience. as a defense that we are Professional Divers? Recreational divers can buy all of the gear we use and commercial and This last year my focus was on something I now believe is scientific divers use the same types of gear we us. We cannot epidemic within our genre of diving. Over the last thirty years I use visibility as our measure, all the above dive in zero visibility have been part of or put together a number of groups with the as well as contaminated waters. The ONLY thing that sets us specific intention of developing a PSD Standard. I was certainly apart is our skill sets. not the first and actually have a box of letters and documents from a group who tried to do the same thing years before I While we do employ some techniques that may be unique to started.
    [Show full text]
  • Dreamer's Bay Underwater Survey, 2019
    Ancient Akrotiri Project Dreamer’s Bay Underwater Survey, 2019 Interim Report Lucy Blue 1 Contents Introduction .......................................................................................................................................... 3 The Landscape and Geological context of Dreamer’s Bay - M. Polidorou .............................. 5 Previous work at Dreamer’s Bay ................................................................................................... 8 Underwater Survey of Dreamer’s Bay 2019: Approach and Objectives ...................................... 9 Methodology ..................................................................................................................................... 9 The Breakwater Survey – L. Blue and M. Polidorou ..................................................................... 10 Investigation of the rubble to the west and east of the breakwater ........................................ 12 Estimation of the energy and height of the wave that caused the destruction of the breakwater…………………………………………………………………………………………17 Investigation of the different types of breakwater construction ............................................. 19 Erosion and biological development of the breakwater ........................................................... 20 Further detail of the breakwater………………………………………………………………...20 Conclusions ..................................................................................................................................... 21 Extended area and
    [Show full text]
  • Competence Assurance and Assessment: Offshore Survey Division
    Guidance on Competence Assurance and Assessment Offshore Survey Division IMCA C 004 Rev. 3.1 June 2020 The International Marine Contractors Association (IMCA) is the international trade association representing offshore, marine and underwater engineering companies. IMCA promotes improvements in quality, health, safety, environmental and technical standards through the publication of information notes, codes of practice and by other appropriate means. Members are self-regulating through the adoption of IMCA guidelines as appropriate. They commit to act as responsible members by following relevant guidelines and being willing to be audited against compliance with them by their clients. There are five core committees that relate to all members: ◆ Competence & Training ◆ Contracts & Insurance ◆ Health, Safety, Security & Environment ◆ Lifting & Rigging ◆ Marine Policy & Regulatory Affairs The Association is organised through four distinct divisions, each covering a specific area of members’ interests – Diving, Marine, Offshore Survey and Remote Systems & ROV. There are also five regions which facilitate work on issues affecting members in their local geographic area – Asia-Pacific, Europe & Africa, Middle East & India, North America and South America. IMCA C 004 Rev. 3.1 This guidance was produced under the direction of the IMCA Competence & Training committee. Separate volumes exist for each of the IMCA technical divisions – Diving (IMCA C 003), Marine (IMCA C 002), Offshore Survey and Remote Systems & ROV (IMCA C 005). www.imca-int.com/competence If you have any comments on this document, please click the feedback button below: [email protected] Date Reason Revision January 1999 Initial publication July 2003 To include additional safety-critical positions Rev. 1 November 2009 To include client representative tables Rev.
    [Show full text]
  • Draft Guidelines for Consideration of Bats in Wind Farm Projects – Revision 2014
    Doc.EUROBATS.MoP7.13.Annex Draft Guidelines for consideration of bats in wind farm projects – revision 2014 Notes: - Comments may be sent to Luisa Rodrigues ([email protected]; [email protected]) - Additional data on studies (annex 1) and mortality (annex 2) may still be incorporated. - Sentences/words highlighted in yellow are still missing or need to will be revised after 7MoP. - Suren will check if all references are referred in the text, and uniform the references - Suren will highlight in the text all terms that are included in the Glossary - Authors: Luísa Rodrigues (Portugal), Lothar Bach (Germany), Marie-Jo Dubourg-Savage (SFEPM, France), Branko Karapandža (Serbia), Dina Kovač (Croatia), Thierry Kervyn (Belgium), Jasja Dekker (BatLife Europe, The Netherlands), Andrzej Kepel (Poland), Petra Bach (Germany), Jan Collins (BCT, United Kingdom), Christine Harbusch (NABU, Germany), Kirsty Park (Stirling University, United Kingdom), Branko Micevski (FYR Macedonia), Jeroen Minderman (Stirling University, United Kingdom) Foreword Comment [LR1]: At the end we need to 1 Introduction discuss the level of detail of the index 2 General aspects of the planning process 2.1 Site selection phase 2.2 Construction phase 2.3 Operation phase 2.4 Decommissioning phase 3 Carrying out impact assessments Goals of the impact assessment in relation to bats (EXTRA BOX - Collision risk level for European bat species) 3.1 Pre-survey assessment Collation and review of existing information 3.2 Survey 3.2.1 Survey design 3.2.2 Survey methods 3.2.2.1
    [Show full text]
  • Aeromedical Evacuation Springer New York Berlin Heidelberg Hong Kong London Milan Paris Tokyo William W
    Aeromedical Evacuation Springer New York Berlin Heidelberg Hong Kong London Milan Paris Tokyo William W. Hurd, MD, MS, FACOG Nicholas J. Thompson Professor and Chair, Department of Obstetrics and Gynecology, Wright State University School of Medicine, Dayton, Ohio; Col, USAFR, MC, FS, Commander, 445th Aeromedical Staging Squadron, Wright-Patterson AFB, Dayton, Ohio John G. Jernigan, MD Brig Gen, USAF, CFS (ret), Formerly Commander, Human Systems Center, Brooks AFB, San Antonio, Texas Editors Aeromedical Evacuation Management of Acute and Stabilized Patients Foreword by Paul K. Carlton, Jr., MD Lt Gen, USAF, MC, CFS USAF Surgeon General With 122 Illustrations 1 3 William W. Hurd, MD, MS John G. Jernigan, MD Nicholas J. Thompson Professor and Chair Brig Gen, USAF, CFS (ret) Department of Obstetrics and Gynecology Formerly Commander Wright State University School of Medicine Human Systems Center Dayton, OH, USA Brooks AFB Col, USAFR, MC, FS San Antonio, TX, USA Commander 445th Aeromedical Staging Squadron Wright-Patterson AFB Dayton, OH, USA Cover illustration: Litter bearers carry a patient up the ramp of a C-9 Nightingale medical transport aircraft. (US Air Force photo by Staff Sgt. Gary R. Coppage). (Figure 7.4 in text) Library of Congress Cataloging-in-Publication Data Aeromedical evacuation : management of acute and stabilized patients / [edited by] William W. Hurd, John G. Jernigan. p. ; cm Includes bibliographical references and index. ISBN 0-387-98604-9 (h/c : alk. paper) 1. Airplane ambulances. 2. Emergency medical services. I. Hurd, William W. II. Jernigan, John J. [DNLM: 1. Air Ambulances. 2. Emergency Medical Services. 3. Rescue Work. WX 215 A252 2002] RA996.5 .A325 2002 616.02¢5—dc21 2002021045 ISBN 0-387-98604-9 Printed on acid-free paper.
    [Show full text]
  • 2018 September;48(3):132−140
    Diving and Hyperbaric Medicine The Journal of the South Pacific Underwater Medicine Society and the European Underwater and Baromedical Society Volume 48 No. 3 September 2018 Subclavian Doppler bubble monitoring Australian snorkelling and diving fatalities 2012 Inner ear barotrauma – a tool for diagnosis Which tooth restoration for divers? HBOT for large bowel anastomosis problems ISSN 2209-1491 (online); ISSN 1833-3516 (print) ABN 29 299 823 713 CONTENTS Diving and Hyperbaric Medicine Volume 48 No.3 September 2018 Editorials 198 Baltic Symposium on Diving and Hyperbaric Medicine 2018 129 The Editor’s offering Fiona Sharp 130 Decompression sickness, fatness and active hydrophobic spots Pieter Jan AM van Ooij Book review 199 Gas bubble dynamics in the human body Original articles John Fitz-Clarke 132 Reliability of venous gas embolism detection in the subclavian area for decompression stress assessment following scuba diving Julien Hugon, Asya Metelkina, Axel Barbaud, Ron Nishi, Fethi Bouak, SPUMS notices and news Jean-Eric Blatteau, Emmanuel Gempp 141 Provisional report on diving-related fatalities in Australian 201 ANZ Hyperbaric Medicine Group waters in 2011 Introductory Course in Diving John Lippmann, Chris Lawrence, Andrew Fock, Scott Jamieson and Hyperbaric Medicine 2019 168 Impact of various pressures on fracture resistance and 201 Australian and New Zealand microleakage of amalgam and composite restorations College of Anaesthetists Diving Elnaz Shafigh, Reza Fekrazad, Amir Reza Beglou and Hyperbaric Medicine Special 173 Meta-analysis
    [Show full text]
  • Distribution and Retention of Larval Fishes Near Reefs in the Gulf of California
    MARINE ECOLOGY PROGRESS SERIES Vol. 115: 1-13,1994 Published December 1 1 Mar. Ecol. Prog. Ser. 1 Distribution and retention of larval fishes near reefs in the Gulf of California Michael W. Brogan* Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA ABSTRACT. I conducted a study of larval fishes in the Gulf of California, Mexico, with 3 objectives: identify the families that utilize the near-reef habitat throughout development; evaluate distributions of reef fishes for evidence of larval retention; and relate larval distributions of reef fishes to egg type and morphology of hatchlings. Analyses were based on 165 light-trap and plankton-net samples collected -1, 20, and 100 m off reefs during the summers of 1989 and 1990, and on previous offshore surveys. Six- teen families accounted for >93 % of all larvae collected near reefs, and only these families were con- sidered further. At least 11 families, including epipelagic, sandy-bottom, and reef fishes, appeared to utilize the near-reef habitat throughout development. In addition, larval retention may have occurred in at least 5 of the reef fish families (Bythitidae, Chaenopsidae, Gobiesocidae, Labrisomidae, Triptery- giidae). Evidence for this included the presence of all larval size classes over reefs, high concentrations of larvae at 1 m and/or 20 m stations that decreased by 72.0 to 99.9 O/o at 100 m stations, and absence or rarity in offshore surveys. Larvae of some gobiids may also have been retained, but distributions varied within the family. Larvae of other reef fish families (Balistidae,Blenniidae, Pomacentridae, and perhaps Haemulidae) appeared to disperse away from reefs.
    [Show full text]