THE MAPUTO BAY ECOSYSTEM

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Editors Salomão Bandeira | José Paula
THE MAPUTO BAY
ECOSYSTEM
Editors Salomão Bandeira | José Paula

Book title:
The Maputo Bay Ecosystem.
Editors:
Salomão Bandeira
José Paula
Assistant Editor:
Célia Macamo
Book citation:
Bandeira, S. and Paula, J. (eds.). 2014. The Maputo Bay Ecosystem.
WIOMSA, Zanzibar Town, 427 pp.
Chapter citation example:
Schleyer, M. and Pereira, M., 2014. Coral Reefs of Maputo Bay.
In: Bandeira, S. and Paula, J. (eds.), The Maputo Bay Ecosystem.
WIOMSA, Zanzibar Town, pp. 187-206.
ISBN: 978-9987-9559-3-0
© 2014 by Western Indian Ocean Marine Science Association
(WIOMSA)
Mizingani Street, House No. 13644/10
P.O. Box 3298, Zanzibar, Tanzania.
Website: www.wiomsa.org
E-mail: secretary@wiomsa.org
All rights of this publication are reserved to WIOMSA, editors and
authors of the respective chapters. No part of this publication
may be reproduced, stored in a retrieval system, or transmitted in
any form or by any means, electronic, mechanical, photocopying,
recording or otherwise, without the prior permission of the editors
and WIOMSA. The material can be used for scientic, educational
and informational purposes with the previous permission of the
editors and WIOMSA.
This publication is made possible by the generous support of
Sida (Swedish International Development Cooperation Agency)
through the Western Indian Ocean Marine Science Association
(WIOMSA). The contents do not necessarily reect the views of
Sida.
Design: Marco Nunes Correia | designer of comunication and
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Photographers: credits referred in respective legends.
Printed by: Guide – Artes Grácas, Lda. (www.guide.pt)
Printed in Portugal

The Maputo Bay Ecosystem XVII
TABLE OF CONTENTS
Foreword by the Rector of UEM
Foreword by the President of WIOMSA
Acknowledgements
List of contributors
PART I
ENVIRONMENTAL AND HUMAN SETTING
Chapter 1. AN INTRODUCTION TO THE MAPUTO BAY
José Paula and Salomão Bandeira
Chapter 2. GEOGRAPHICAL AND SOCIO-ECONOMIC SETTING OF MAPUTO BAY
Armindo da Silva and José Rafael
Case Study 2.1. Maputo Bay’s coastal habitats
Maria Adelaide Ferreira and Salomão Bandeira
Case Study 2.2. Main economic evaluation of Maputo Bay
Simião Nhabinde, Vera Julien and Carlos Bento
Chapter 3. GEOMORPHOLOGY AND EVOLUTION OF MAPUTO BAY
Mussa Achimo, João Alberto Mugabe, Fátima Momade and Sylvi Haldorsen
Case Study 3.1. Erosion in Maputo Bay
Elidio A. Massuanganhe
Chapter 4. HYDROLOGY AND CIRCULATION OF MAPUTO BAY
Sinibaldo Canhanga and João Miguel Dias
Case Study 4.1. Maputo Bay offshore circulation
Johan R.E. Lutjeharms† and Michael Roberts
Case Study 4.2. Ground water ow in/into Maputo Bay
Dinis Juízo
Chapter 5. HUMAN SETTINGS IN MAPUTO BAY
Yussuf Adam, Júlio Machele and Omar Saranga
1
3
11
21
25
31
39
45
55
61
67

XVIII The Maputo Bay Ecosystem
Chapter 6. INHACA ISLAND: THE CRADLE OF MARINE RESEARCH IN MAPUTO BAY
AND MOZAMBIQUE
Salomão Bandeira, Lars Hernroth and Vando da Silva
Case Study 6.1. The role of SIDA/SAREC on research development in Maputo Bay during the
period 1983-2010
Almeida Guissamulo and Salomão Bandeira
Case Study 6.2. Inhaca and Portuguese islands reserves and their history
Salomão Bandeira, Tomás Muacanhia, Olavo Deniasse and Gabriel Albano
PART II
MAIN HABITATS AND ECOLOGICAL FUNCTIONING
Chapter 7. MANGROVES OF MAPUTO BAY
José Paula, Célia Macamo and Salomão Bandeira
Case Study 7.1. Incomati mangrove deforestation
Celia Macamo, Henriques Baliddy and Salomão Bandeira
Case Study 7.2. Saco da Inhaca mangrove vegetation mapping and change detection using very
high resolution satellite imagery and historic aerial photography
Griet Neukermans and Nico Koedam
Case Study 7.3. The mud crab Scylla serrata (Forskål) in Maputo Bay, Mozambique
Adriano Macia, Paula Santana Afonso, José Paula and Rui Paula e Silva
Case Study 7.4. Crab recruitment in mangroves of Maputo Bay
José Paula and Henrique Queiroga
Chapter 8. SEAGRASS MEADOWS IN MAPUTO BAY
Salomão Bandeira, Martin Gullström, Henriques Balidy, Davide Samussone and Damboia Cossa
Case Study 8.1. Zostera capensis – a vulnerable seagrass species
Salomão Bandeira
Case Study 8.2. Thalassodendron leptocaule – a new species of seagrass from rocky habitats
Maria Cristina Duarte, Salomão Bandeira and Maria Romeiras
Case Study 8.3. Morphological and physiological plasticity of the seagrass Halodule uninervis at
Inhaca Island, Mozambique
Meredith Muth and Salomão Bandeira
Chapter 9. CORAL REEFS OF MAPUTO BAY
Michael Schleyer and Marcos Pereira
87
99
101
107
109
127
131
135
141
147
171
175
181
187

XIX
The Maputo Bay Ecosystem
Table of Contents
Case Study 9.1. Shrimps in coral reefs and other habitats in the surrounding waters of Inhaca Island
Matz Berggren
Chapter 10. MARINE MAMMALS AND OTHER MARINE MEGAFAUNA OF MAPUTO BAY
Almeida Guissamulo
Case Study 10.1. Seagrass grazing by dugongs: Can habitat conservation help protect the dugong?
Stela Fernando, Salomão Bandeira and Almeida Guissamulo
Chapter 11. MARINE TURTLES IN MAPUTO BAY AND SURROUNDINGS
Cristina Louro
Chapter 12. THE TERRESTRIAL ENVIRONMENT ADJACENT TO MAPUTO BAY
Salomão Bandeira, Annae Senkoro, Filomena Barbosa, Dalmiro Mualassace and Estrela Figueiredo
Case Study 12.1. Inhaca Island within Maputaland centre of endemism
Annae Senkoro, Filomena Barbosa and Salomão Bandeira
Case Study 12.2. Uses of plant species from Inhaca Island
Filomena Barbosa, Annae Senkoro and Salomão Bandeira
Case Study 12.3. The avifauna of Maputo Bay
Carlos Bento
PART III
FISHERIES OF MAPUTO BAY
Chapter 13. SHALLOW-WATER SHRIMP FISHERIES IN MAPUTO BAY
Rui Paula e Silva and Zainabo Masquine
Case Study 13.1. Inuence of the precipitation and river runoff on the semi-industrial shrimp
catches in Maputo Bay
Carlos Bacaimane and Rui Paula e Silva
Case Study 13.2. Inuence of estuarine ow rates on the artisanal shrimp catches in Maputo Bay
Sónia Nordez
Case Study 13.3. Distribution and abundance of the shrimp Fanneropenaeus indicus in Maputo Bay
António Pegado and Zainabo Masquine
Case Study 13.4. By-catch in the artisanal and semi-industrial shrimp trawl sheries in Maputo Bay
Vanda Machava, Adriano Macia and Daniela de Abreu
207
215
223
229
239
255
259
265
275
277
285
287
289
291

XX The Maputo Bay Ecosystem
Chapter 14. THE MAGUMBA FISHERY OF MAPUTO BAY
Paula Santana Afonso and Zainabo Masquine
Chapter 15. ARTISANAL FISHERIES IN MAPUTO BAY
Alice Inácio, Eunice Leong, Kélvin Samucidine, Zainabo Masquine and José Paula
Case Study 15.1. Biology and current status of the Otolithes ruber population in Maputo Bay
Alice Inácio
Case Study 15.2. Aspects of the reproductive biology of saddle grunt (Pomadasys maculatus) and
silver sillago (Sillago sihama) in Maputo Bay
Isabel Chaúca
Case Study 15.3. Socio-economic aspects of gastropod and bivalve harvest from seagrass beds –
comparison between urban (disturbed) and rural (undisturbed) areas
Elisa Inguane Vicente and Salomão Bandeira
Case Study 15.4. The sea urchin Tripneustes gratilla: insight to an important food resource at Inhaca
Island
Stela Fernando and Salomão Bandeira
Case Study 15.5. Recreational and sport shing in Maputo Bay
Marcos Pereira and Rudy Van der Elst
PART IV
CROSS CUTTING ISSUES
Chapter 16. POLLUTION IN MAPUTO BAY
Maria Perpétua Scarlet and Salomão Bandeira
Case Study 16.1. Aerosols in Maputo Bay
António Queface
Case Study 16.2. Heavy metal contamination of penaeid shrimps from the artisanal and semi-
industrial sheries in Maputo Bay
Daniela de Abreu, David Samussone and Maria Perpétua Scarlet
Chapter 17. POTENCIAL CLIMATE CHANGE IMPACTS ON MAPUTO BAY
Alberto Mavume, Izidine Pinto and Elídio Massuanganhe
Chapter 18. MANAGEMENT OF MAPUTO BAY
Sérgio Rosendo, Louis Celiers and Micas Mechisso
297
303
321
325
329
335
341
345
347
373
377
383
399

XXI
The Maputo Bay Ecosystem
Table of Contents
Chapter 19. MAPUTO BAY: THE WAY FORWARD
José Paula and Salomão Bandeira
419

The Maputo Bay Ecosystem 223
In Mozambique, the Bazaruto Archipelago
region (in the southern central coast of Mozambique)
is the area with the highest dugong abundance esti-
mates, reaching 250 dugongs between 2007 and 2009
(see Table 1), as reported by Findlay et al. (2011). At
Inhaca Island, dugongs have long been reported but
even as late as the 1960s, populations were small and
already appeared to be declining (Smither and Lobão
Telo, 1976). Few individuals have been observed
since then, with aerial surveys counting only four
individuals in 2006 and a single animal in 2009. In
2006, 2010 and 2012 dugong feeding trails were doc-
umented at Inhaca Island, conrming their contin-
ued presence, though obviously in low abundance.
Dugongs are known to feed mainly on several
seagrass species (nine genera and 26 species) through
cropping (surface grazing) and or excavation (feeding
on both above and belowground plant parts) (Marsh
Stela Fernando, Salomão Bandeira and Almeida Guissamulo
Case Study_10.1
Seagrass grazing by dugongs:
Can habitat conservation
help protect the dugong?
Location Records of dugongs
(1992-2009) Recent Sur veys
Northern Quirimbas Archipelago no record Aerial surveys 2007
Southern Quirimbas Archipelago 1 Aerial surveys 2007
Pemba Bay no record --
Nacala no record Questionnaire 1998
Mozambique Island no record Questionnaire 1998
Angoche no record --
Bazaruto Archipelago 25-200 Aerial surveys 1992, 1995, 1999, 2001,
2003-2005, 2006-2007
Save – Bazaruto - São Sebastião Peninsula 250 Aerial sur veys 2001, 2006-2007
Pomene - Morrungulo 1 2001,
Inhambane Bay 1-8 1994, 2001 & 2007
Zavora 1 1994 (ORI)
Maputo Bay 1-4 Boat sur veys 1992, 1995-1997,
Aerial surveys 2005 & 2009
Table 1. Recent records of dugong distribution in Mozambique coastline.

224 The Maputo Bay Ecosystem
II . Main Habitats and Ecological Functioning
et al., 2012). Incidentally, they also consume algae
and invertebrates, especially when there is seagrass
shortage (Marsh et al., 2012). The two feeding modes
make it difcult for a dugong to feed on a single sea-
grass species, especially a morphologically small spe-
cies when present in a mixed species seagrass
meadow (Marsh et al., 2012). The depth of dive and
tides also inuence access to seagrass species, with
tides in particular restricting access to intertidal spe-
cies.
At Inhaca, dugong feeding trails have been
observed in the areas depicted in Figure 1, in the
Saco da Inhaca bay area and close to Portuguese
island, areas that coincide with seagrass beds of Hal-
odule uninervis and Halophila ovalis. These seagrass
species are part of the dugong diet at Inhaca, and
dominate the intertidal zone mostly close to the
coastline or surrounding sand banks, in areas of ne
sediment (silt and clay) and low rates of sedimenta-
tion. The dugong trails (that remain visible over sev-
eral days) were observed near the small intertidal
channels, in restricted areas with 30 to 698 m2 of sea-
grass cover (Table 2). These feeding trails suggest
the existence of a small population of dugongs around
Figure 1. Areas of dominance by Halodule uninervis and Halophila ovalis beds (in green) and of dugong grazing trials (red spots) around
Inhaca Island.
0 3
km
1.5
N
490000000000 492000000000 494000000000 496000000000 498000000000 500000000000
490000000000 492000000000 494000000000 496000000000 498000000000 500000000000
7116000000000 7118000000000 7120000000000 7122000000000 7124000000000 7128000000000
7126000000000
7116000000000 7118000000000 7120000000000 7122000000000 7124000000000 7128000000000
7126000000000
Inhaca Island
Portuguese
Island
Saco
da Inhaca
INDIAN OCEAN
INDIAN OCEAN
MAPUTO BAY

225
The Maputo Bay Ecosystem
Case Study 10.1. Seagrass Grazing by Dugongs: Can habitat conservation help protect the dugong?
the seagrass beds of Inhaca preferring to eat mostly at
Saco (the southern bay of Inhaca). Feeding trails
(Figure 2) are also indicative that dugongs employ
excavating mode in these meadows, because the
above ground biomass of these seagrass species is
low.
In the vicinity of natural grazing areas, experi-
mental trails that replicate grazing by dugongs were
articially excavated, to help further understand the
seagrass growth dynamics and recovery (method fol-
lowing Supanwanid et al., 2001) (Figure 3). The
recovery time of seagrass after dugong grazing do not
differ statistically between stations, seasons and sea-
grass form (ANOVA, p>0.05).
The study suggests that biomass is closely related
with percentage cover during wet the season where
the gradual increase of above ground biomass (leaves
and shoots) was reected by an increase of seagrass
percentage cover. During the dry season, the main
growth occurred belowground (roots and rhizome)
with few leaves emerging until the end of the sam-
pling time, with coverage never exceeding 10%
(Table 3).
The seasonal variation in biomass of seagrasses at
Inhaca is similar to that reported by Hossain et al.
(2010) in Australia, and Dawes et al. (1985) in Florida.
In both these cases there was greater mean biomass
during the dry season than during the wet season,
because the belowground biomass was higher. Sea-
sonal variation indicates that productivity increases
in response to favourable growing conditions (Hill-
man et al., 1989). In the dry season, the aboveground
biomass was lower, which favoured the development
of roots and rhizomes. Tomlinson (1974), cited by
Kuo and Hartog (2006), considered that vegetative
propagation of rhizomes is probably of greater impor-
tance in the maintenance and spread of seagrass than
seed production. Thus during the dry season, when
Trail characteristics Saco Portuguese Island Barreira Vermelha
Seagrass form Narrow Medium Medium
Depth 0.01 – 0.05 m 0.02 -0.04 m 0.02 – 0.05 m
Length 1.1 -7.7m 1.0 – 5.1 m 1.0 – 5.1 m
Width 0.12 – 0.28 m 0.05 -0.20 m 0.14 – 0.22 m
Area 698 m2123 m230m2
Table 2. Trail characteristics of dugong grazing over the main feeding areas at Inhaca Island (Halodule uninervis).
Figure 2. Seagrass trails at: (A) Saco and (B) Barreira Vermelha. Photographs by Salomão Bandeira.
AB

226 The Maputo Bay Ecosystem
II . Main Habitats and Ecological Functioning
the environmental conditions are not ideal, seagrass
plants prioritize the development of rhizomes, and
only after that produce leaves and seeds.
Fast growing leaves of seagrasses Halodule unin-
ervis and Halophila ovalis will yield a higher nutri-
tional quality that slower growing ones (Cymodocea
rotundata, Thalassia hemprichii and Zostera capricorni)
according to De Iongh et al. (1995) and Preen and
Marsh (1995), due to a low content of indigestible
bber (i.e. lignin) and a high carbohydrate content,
all of which combined are good indicators of the
nutritional value of the plants (see Cebrian and
Duarte, 1998).
Dugong decline in Mozambique is due mainly to
direct entanglement by netting operations and hunt-
ing as reported in the media. Fish catches appear to
be reducing and, as suggested by Provancha and Sto-
len (2008), an anticipated local reduction of the
inshore shery and resulting reduced productivity
(catches) may result in a revival of human harvest of
dugongs for local subsistence, specially around
Bazaruto Archipelago, the most densely populated
dugong area in Mozambique. However, this is con-
sidered unlikely to happen as ofcially the species
has a protection status and a large national park
(Bazaruto Archipelago National Park) has been estab-
lished to conserve it. Seagrass depletion around
Inhaca Island appears relatively minor and its possi-
ble impact on dugong population is unknown. The
loss of seagrass was associated with disturbance,
trampling and possible small-scale pollution from the
main small harbour at Inhaca, as well as from sand
accretion impacting the southwestern coast of Inhaca
(between Ponta Rasa and Ponta Ponduine) (see Ban-
deira and Gell, 2003; Chapter 8). The present study
of dugong grazing trails could contribute towards ini-
tiatives aimed at dugong population monitoring
around Inhaca Island and other areas in Mozambique
and eastern Africa, improving the understanding of
dugong movements, such as those related to tides,
day/night periods, and their relationships with shing
activities, therefore potentially contributing towards
future management of the region’s relatively small
dugong populations.
25
20
15
10
5
00 2 4 6
Biomass (g m-2)
sampling time (weeks)
Dry season 25
20
15
10
5
00 2 4 6
sampling time (weeks)
Wet season
Station 2 Station 3Station 1
Figure 3. Variation of biomass recovery over time in dry and wet season experimental trials.
Wet season Dry season
Species Hu Ho Hu Ho
Percentage cover (%) 10-50 5-10 5-10 <5
Shoot density 37.5 ± 35.6 29.2 ± 45.8 35.5 ± 27.6 9.2 ± 7.8
Biomass (g m-2) 10.1±11.2 2.8±2.5 14.1±14.1 1.4±3.6
Table 3. Percentage cover, shoot density, biomass related with season and seagrass species (Hu - Halodule uninervis; Ho - Halophila ovalis).

227
The Maputo Bay Ecosystem
Case Study 10.1. Seagrass Grazing by Dugongs: Can habitat conservation help protect the dugong?
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