Transcript Soft Substrates

Lecture 16 MANGALS
Mangal: a tropical shoreline community in which
various species of MANGROVE are the
dominant plant species
Conditions for Mangal Formation
1. Protection from strong wave action
2. Availability and accumulation of sediment
3. Periodic flooding by salt water
Mangal = Tropical Salt Marsh
Mangals - Tropical Salt Marshes
World Distribution
Mangrove Succession
Mangrove Succession -Red Mangrove - Rhizophora mangle
Tolerating Anaerobic Mud
Lenticels
Aerobic mud
Anaerobic mud
lenticel
apply grease to root
O2
O2
Concentration
O2
To prop
root
48 h
time
Red Mangrove - basis of community
1. Provide substrate for growth of other species
Red Mangrove - basis of community
2. Trap sediment and stabilize shore
Black Mangrove (Avicenna) - second stage of succession
Structure of the Black Mangrove
Pneumatophores
(air root)
Aerobic mud
Anaerobic mud
Anchor root
Radial root
Pneumatophores
Pneumatophores
Coping with salt
Salt secreting glands on leaf
Final Successional Stage - White Mangrove - Laguncularia racemosa
-least tolerant of salt and aerobic muds
Mangrove Succession and Zonation
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
1. Plant succession due to land building
- plant zonation - a successional sequence
But do mangroves cause different patterns of sediment deposition or
just respond to deposition?
MANGROVE ZONATION PATTERNS
1. Land building
HYPOTHESES FOR ZONATION
2. Geomorphological influences
-mangroves response to changes in geomorphology but
don’t cause them
Patterns depend on abiotic patterns of sediment deposition
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
3. Physico- Chemical Gradients
Two hypotheses
a. Distinct preference
Gradient
Different optima for each species leads to zonation
1.
2.
Land building
Geomorphology
MANGROVE ZONATION PATTERNS
1.
2.
HYPOTHESES FOR ZONATION
3. Physico- Chemical Gradients
Two hypotheses
a. Distinct preference
b. No preference
Gradient
Optimum range for all species
Zonation is determined by other factors (competition, predation)
Land building
Geomorphology
1.
2.
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
3. Physico- Chemical Gradients
e.g. Tidal inundation
35 ppt
<10 ppt
Land building
Geomorphology
1.
2.
MANGROVE ZONATION PATTERNS
Land building
Geomorphology
HYPOTHESES FOR ZONATION
3. Physico- Chemical Gradients
100
Seedling
Survival (%)
50
0
0
20
30
40
Salinity
50
60
70
80
1.
2.
MANGROVE ZONATION PATTERNS
Land building
Geomorphology
HYPOTHESES FOR ZONATION
3. Physico- Chemical Gradients
Ceriops tagal
Ceriops australis
Optimum salinity for
germination - 15 ppt
(lab)
0
20
30
40
Salinity
50
60
70
80
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
4. Propagule dispersion
1.
2.
3.
Land building
Geomorphology
Physico-chemical
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
1.
2.
3.
4.
Land building
Geomorphology
Physico-chemical
Propagule dispersion
5. Propagule predation
Dominance  1/predation
Grapsid crabs
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
1.
2.
3.
4.
Land building
Geomorphology
Physico-chemical
Propagule dispersion
5. Propagule predation
Normal distribution
Avicennia marina
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
5. Propagule predation
Normal distribution
1.
2.
3.
4.
Land building
Geomorphology
Physico-chemical
Propagule dispersion
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
5. Propagule predation
Normal distribution
1.
2.
3.
4.
Land building
Geomorphology
Physico-chemical
Propagule dispersion
MANGROVE ZONATION PATTERNS
HYPOTHESES FOR ZONATION
6. Competition
?
1.
2.
3.
4.
5.
Land building
Geomorphology
Physico-chemical
Propagule dispersion
Propagule predation
MANGROVE ZONATION PATTERNS
Structure of Mangroves
MANGROVES AS NURSERIES
Lutjanus griseus
(Gray snapper)
Juveniles live in mangroves
& move to Thalassia at night
to feed
Spawn on
ocean side of
reef
Postlarva moves to
Thalassia beds
Mangrove Reproduction - Red Mangrove
Wind Pollinated
Mangrove Reproduction - Black Mangrove
Wind Pollinated
Mangrove Reproduction - White Mangrove
Insect Pollinated
Mangrove Food Chain
Bacterial and fungal
recolonization
Leaf particles colonized
by bacteria and fungi
fish
Particulate
organic matter
prawn
Direct grazing by
crabs
Small fish
MANGROVE
LEAF
detritus
Dissolved organic substances
Absorbed by
sediment
Small crustacea
bacteria
protozoa
algae
Eaten by mud whelks
algae
Hurricanes and Mangroves
Hurricanes and Mangroves
Hurricanes and Mangroves
Hurricanes and Mangroves
Hurricanes and Mangroves
Costanza et al, 2008. AMBIO 37(4):241-248.