Mangroves in the Northern Territory
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Mangroves in the Northern Territory Report Number 25/2003D i Mangroves in the Northern Territory. Edited and produced by Geraldine Lee. Published by Department of Infrastructure, Planning and Environment (DIPE) PO Box 30 Palmerston NT 0831 Tel: 08 8999 4455 Fax: 08 8999 4445 Website: http://www.ipe.nt.gov.au/ Northern Territory Government All rights reserved. No part of this publication may be reproduced, stored in any retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise for commercial purposes without the prior written permission of the publisher. The information in this publication has been published by DIPE to assist public knowledge of mangrove ecosystems. Publication data Lee, G.P. (2003), Mangroves in the Northern Territory, Department of Infrastructure, Planning and Environment, Darwin. Report Number 25/2003D Cover photograph shows a Rhizophora stylosa surrounded by Avicennia marina pneumatophores Funding provided by The Natural Heritage Trust and Department of Infrastructure, Planning and Environment. ii Northern Territory Mangrove Education Kit TABLE OF CONTENTS WHAT ARE MANGROVES? _______________________________________________________________ 1 WHERE DO MANGROVE COMMUNITIES OCCUR? __________________________________________ 1 MANGROVES IN AUSTRALIA 2 MANGROVES IN THE NORTHERN TERRITORY 2 MANGROVES IN DARWIN HARBOUR 2 HARSH CONDITIONS ____________________________________________________________________ 3 ADAPTATIONS TO SALT 3 Salt Exclusion 3 Salt Excretion 3 Storage 3 ADAPTATIONS TO INUNDATION AND WAVE ACTION 4 Stabilisation with Roots – Mangrove Balancing Acts 4 Aeration through Roots 5 Seed Dispersal and Establishment 6 MANGROVE PLANTS (FLORA)____________________________________________________________ 7 Aegialitis annulata (Club mangrove) 8 Avicennia marina (Grey mangrove) 9 Bruguiera exaristata (Orange mangrove) 10 Ceriops tagal (Yellow mangrove) 11 Excoecaria ovalis (Blind your eye) 12 Hibiscus tiliaceus (Beach hibiscus) 13 Lumnitzera racemosa (Black mangrove) 14 Rhizophora stylosa (Stilt rooted mangrove) 15 Sonneratia alba (Mangrove apple) 16 MANGROVE ZONATION ________________________________________________________________ 17 WHY DOES ZONATION OCCUR? 17 Environmental Variables 17 Propagule characteristics 17 WHAT ZONES OCCUR ? 18 The Seaward Zone 19 The Middle Zone 19 The Landward Zone 19 MANGROVE ANIMALS (FAUNA)_________________________________________________________ 20 VERTEBRATES 20 Mammals 20 Birds 20 Reptiles 20 Fish 21 INVERTEBRATES 21 Arthropods 21 Molluscs 22 MANGROVE SOILS _____________________________________________________________________ 23 WHAT’S THAT SMELL? 23 ACID SULPHATE SOILS 23 WHY ARE MANGROVES SO IMPORTANT? ________________________________________________ 24 ECOLOGICAL IMPORTANCE 24 Coastal Stabilisation 24 Sediment Traps 24 High Productivity 26 High Biodiversity 26 ECONOMIC IMPORTANCE 27 Tourism 27 Faunal Harvesting 27 Wood Harvesting 27 iii Northern Territory Mangrove Education Kit RECREATIONAL AND CULTURAL USES 27 Indigenous Harvest 27 Fishing 28 Other Recreational Pursuits 28 IMPACTS ON MANGROVES _____________________________________________________________ 29 COASTAL DEVELOPMENT 29 POLLUTION 29 SEDIMENTATION 29 WEED AND FERAL ANIMAL INVASION 30 Weeds 30 Feral Animals 30 Marine Pests 30 MANGROVE MONITORING AND PROTECTION ____________________________________________ 31 COMMUNITY MANGROVE MONITORING PROGRAM 32 NORTHERN TERRITORY UNIVERSITY / GOVERNMENT PROJECTS 32 REMOTE SENSING -A MANAGEMENT TOOL ______________________________________________ 33 LANDSAT SATELLITES 33 Mangrove Monitoring using Landsat 34 AERIAL PHOTOGRAPHY 34 MANGROVE MAPPING _________________________________________________________________ 35 MANGROVE VISITS ____________________________________________________________________ 36 CONTACT DETAILS ____________________________________________________________________ 36 REFERENCES __________________________________________________________________________ 42 INDEX ________________________________________________________________________________ 43 ACTIVITIES WHY ARE MANGROVES IMPORTANT? ___________________________________________________ 37 MANGROVE SNORKELS ________________________________________________________________ 38 REMOTE SENSING _____________________________________________________________________ 39 LIST OF FIGURES Figure 1: Schematic profile of mangrove zonation, topography and elevation in Darwin Harbour. ...............18 Figure 2: Coral Reefs in Darwin Harbour........................................................................................................25 Figure 3: Darwin Harbour mangrove communities .........................................................................................35 LIST OF PLATES Plate 1: Mangroves, Channel Island................................................................................................................1 Plate 2: Sonneratia alba (Mangrove apple).....................................................................................................3 Plate 3: Salt crystals on the leaf of Aegialitis annulata (Club mangrove).......................................................3 Plate 4: Leaf fall in Bruguiera exaristata (Orange mangrove)........................................................................3 Plate 5: Rhizophora stylosa (Stilt rooted mangrove) roots..............................................................................4 Plate 6: Ceriops tagal (Yellow mangrove) base..............................................................................................4 Plate 7: Avicennia marina (Grey mangrove) base...........................................................................................4 Plate 8: Sonneratia alba (Mangrove apple) pneumatophores at low tide........................................................5 Plate 9: Sonneratia alba (Mangrove apple) pneumatophores at high tide.......................................................5 Plate 10: Bruguiera exaristata (Orange mangrove) knee roots.........................................................................6 Plate 11: Developing propagule of Rhizophora stylosa (Stilt rooted mangrove) ..............................................6 Plate 12: Acrostichum speciosum (Mangrove fern)...........................................................................................7 Plate 13: Base of Ceriops tagal (Yellow mangrove) Avicennia marina (Grey mangrove)...............................7 Plate 14: Aegialitis annulata (Club mangrove) at Dundee beach......................................................................8 Plate 15: Club shaped base of Aegialitis annulata (Club mangrove) ................................................................8 Plate 16: Salt crystals on the leaf of Aegialitis annulata (Club mangrove).......................................................8 Plate 17: Developing propagules of Aegialitis annulata (Club mangrove).......................................................8 Plate 18: Avicennia marina (Grey mangrove) at Nightcliff Beach....................................................................9 Plate 19: Pencil like pneumatophores................................................................................................................9 iv Northern Territory Mangrove Education Kit Plate 20: Avicennia marina (Grey mangrove) base...........................................................................................9 Plate 21: Avicennia marina (Grey mangrove) leaf (pale underside showing salt excretion).............................9 Plate 22: Bruguiera exaristata (Orange mangrove) flowers ...........................................................................10 Plate 23: Bruguiera exaristata (Orange mangrove) knee roots.......................................................................10 Plate 24: Bruguiera exaristata (Orange mangrove) base ................................................................................10 Plate 25: Bruguiera exaristata (Orange mangrove) calyx...............................................................................10 Plate 26: Buttress roots of Ceriops tagal (Yellow mangrove) showing close up of bark................................11 Plate 27: Ceriops tagal (Yellow mangrove) fruit............................................................................................11 Plate 28: Ceriops tagal (Yellow mangrove) form...........................................................................................11 Plate 29: Oval shaped leaves and white latex of Excoecaria ovalis (Blind your eye).....................................12 Plate 30: Excoecaria ovalis (Blind your eye) tree...........................................................................................12 Plate 31: Excoecaria ovalis (Blind your eye) leaves.......................................................................................12 Plate 32: Hibiscus tiliaceus (Beach hibiscus) flower .....................................................................................13 Plate 33: Hibiscus tiliaceus (Beach hibiscus) heart shaped leaf......................................................................13 Plate 34: Hibiscus tiliaceus (Beach hibiscus) form.........................................................................................13 Plate 35: Stunted growth form of Lumnitzera racemosa (Black mangrove) and close up of bark..................14 Plate 36: Heart shaped leaves of Lumnitzera