Gulf of Maine Ecosystem Overview Report East Coast Aquatics Ecosystem Management Branch Maritimes Region Fisheries and Oceans Canada PO Box 1006 Dartmouth, NS B2Y 4A2 2011 Canadian Technical Report of Fisheries and Aquatic Sciences 2946 1 Canadian Technical Report of Fisheries and Aquatic Sciences Technical reports contain scientific and technical information that contributes to existing knowledge but which is not normally appropriate for primary literature. Technical reports are directed primarily toward a worldwide audience and have an international distribution. No restriction is placed on subject matter and the series reflects the broad interests and policies of Fisheries and Oceans Canada, namely, fisheries and aquatic sciences. Technical reports may be cited as full publications. The correct citation appears above the abstract of each report. Each report is abstracted in the data base Aquatic Sciences and Fisheries Abstracts. 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Canadian Technical Report of Fisheries and Aquatic Sciences 2946 2011 Gulf of Maine Ecosystem Overview Prepared by: East Coast Aquatics1 With contributions from: Northeast Fisheries Science Center, National Marine Fisheries Service, National Oceanographic and Atmospheric Administration St. Andrews Biological Station and Bedford Institute of Oceanography, Fisheries and Oceans Canada Atlantic Cooperative Wildlife Ecology Research Network Canadian Wildlife Service University of New Brunswick Oceans and Coastal Management Division Ecosystem Management Branch, Maritimes Region Fisheries and Oceans Canada PO Box 1006 Dartmouth, Nova Scotia B2Y 4A2 1 PO Box 129, 402 Granville Street, Bridgetown, Nova Scotia, Canada B0S 1C0 © Her Majesty the Queen in Right of Canada, 2011. Cat No. Fs 97-6/2946E ISSN 0706-6457 Correct citation for this publication: East Coast Aquatics. 2011. Gulf of Maine Ecosystem Overview. Can. Tech. Rep. Fish. Aquat. Sci. 2946: xvi + 203 p. ii TABLE OF CONTENTS ACKNOWLEDGEMENTS ............................................................................................... vi LIST OF FIGURES ........................................................................................................... vii LIST OF TABLES .............................................................................................................. xi LIST OF ACRONYMS AND ABBREVIATIONS ........................................................ xiii ABSTRACT....................................................................................................................... xiv RÉSUMÉ .............................................................................................................................xv INTRODUCTION 1. PROJECT DEFINITION............................................................................................1 1.1 Context and Purpose of Report.............................................................................1 1.2 Boundaries of Study Area and General Features..................................................1 2. METHODOLOGY OF STUDY .................................................................................6 2.1 Sources of Information .........................................................................................6 2.2 Information Use and Reliability............................................................................7 PART A – GEOLOGICAL SYSTEM 3. MARINE GEOLOGY .................................................................................................8 4. GEOMORPHOLOGY ................................................................................................9 4.1 Inner Shelf Bathymetry and Seascapes...............................................................15 4.2 Central Shelf Bathymetry and Seascapes ...........................................................18 4.3 Outer Shelf Bathymetry and Seascapes ..............................................................20 5. SEDIMENTOLOGY .................................................................................................23 5.1 Nature and Characterization of Surface Sediments ............................................25 5.2 Habitat classification and physical–biological relationships ..............................28 PART B – OCEANOGRAPHIC SYSTEM 6. SEASONAL CLIMATIC PATTERNS....................................................................31 6.1 Air Temperature..................................................................................................31 6.2 Precipitation ........................................................................................................35 6.3 Prevailing Wind and Storm Tracks.....................................................................39 7. PHYSICAL OCEANOGRAPHY.............................................................................42 7.1 Freshwater Inputs................................................................................................42 iii 7.2 Sea Level and Tides............................................................................................46 7.3 Water Currents and Masses ................................................................................49 7.4 Stratification and Mixing (Fronts, Gyres and Upwellings) ................................56 7.4.1 A Stratified Western Gulf .......................................................................58 7.4.2 A Vertically Mixed Eastern Gulf............................................................59 7.5 Waves and Turbulence (Influence on Mixing) ...................................................61 7.6 Ice (Seasonal Coverage) .....................................................................................61 8. SEAWATER TEMPERATURE, SALINITY AND DENSITY.............................64 8.1 Temperature ........................................................................................................64 8.2 Salinity ................................................................................................................69 8.3 Nutrients..............................................................................................................71 8.4 Seasonality ..........................................................................................................73 8.4.1 Winter Observations ...............................................................................73 8.4.2 Spring Observations................................................................................75 8.4.3 Summer Observations.............................................................................76 8.4.4 Autumn Observations .............................................................................80 8.5 Major spatial patterns..........................................................................................80 8.6 Long-term trends.................................................................................................82 PART C – MAJOR ECOSYSTEM COMPONENTS 9. FLORA AND FAUNA...............................................................................................85 9.1 Planktonic Communities.....................................................................................85 9.1.1 Bacterioplankton.....................................................................................87 9.1.2