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

O2

O2

To proproot

O2

Concentration

time

apply grease to root

48 h

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

Aerobic mud

Anaerobic mud

Pneumatophores(air root)

Radial rootAnchor root

Structure of the Black Mangrove

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 orjust respond to deposition?

MANGROVE ZONATION PATTERNS

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

1. Land building

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

3. Physico- Chemical Gradients

Two hypotheses

1. Land building2. Geomorphology

Gradient

Different optima for each species leads to zonation

a. Distinct preference

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

3. Physico- Chemical Gradients

Two hypotheses

1. Land building2. Geomorphology

b. No preference

Gradient

a. Distinct preference

Optimum range for all species

Zonation is determined by other factors (competition, predation)

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

3. Physico- Chemical Gradients

1. Land building2. Geomorphology

e.g. Tidal inundation

<10 ppt

35 ppt

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

3. Physico- Chemical Gradients

1. Land building2. Geomorphology

SeedlingSurvival (%)

100

50

0

Salinity

0 20 30 40 50 60 70 80

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

3. Physico- Chemical Gradients

1. Land building2. Geomorphology

Salinity

0 20 30 40 50 60 70 80

Ceriops tagal

Ceriops australis

Optimum salinity for germination - 15 ppt

(lab)

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical

4. Propagule dispersion

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical4. Propagule dispersion

5. Propagule predation

Grapsid crabs

Dominance 1/predation

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical4. Propagule dispersion

5. Propagule predation

Avicennia marina

Normal distribution

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical4. Propagule dispersion

5. Propagule predation

Normal distribution

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical4. Propagule dispersion

5. Propagule predation

Normal distribution

MANGROVE ZONATION PATTERNS

HYPOTHESES FOR ZONATION

1. Land building2. Geomorphology3. Physico-chemical4. Propagule dispersion5. Propagule predation

6. Competition

?

MANGROVE ZONATION PATTERNS

Structure of Mangroves

MANGROVES AS NURSERIESLutjanus griseus(Gray snapper)

Spawn on ocean side of

reef

Postlarva moves to Thalassia beds

Juveniles live in mangroves & move to Thalassia at night

to feed

Mangrove Reproduction - Red Mangrove

Wind Pollinated

Mangrove Reproduction - Black Mangrove

Wind Pollinated

Mangrove Reproduction - White Mangrove

Insect Pollinated

Mangrove Food Chain

Direct grazing by crabs

Leaf particles colonized by bacteria and fungi

Bacterial and fungal recolonization

fish

prawn

Particulate organic matter

Small fish

Small crustacea

detritus

protozoa

bacteria

algae

Absorbed by sediment

Eaten by mud whelks

Dissolved organic substances

MANGROVE LEAF

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.