Kaiho Super Science High School

Mangrove ecology: application of fatty acid biomarkers as trophic tracers in the

ecosystem

JSPS

Prosper Mfilinge

Advisor: Prof. Makoto Tsuchiya

Self Introduction

What are mangroves?

“Tropical & sub-tropical trees restricted to intertidal and adjacent communities” and adapted to live in salt water

Tropical:熱帯のIntertidal:潮間帯Adjacent:付近の

Mangal

Mangal “community (all animals and plants) that contains mangrove plants”

Mangrove ecology

“The study of interrelationships between living organisms and their environment”

Ecosystem “ecological system made up of various communities of organisms interacting with one another and influenced by the environment”

Interrelationships:相互関係Interact with:～と互いに影響し合う

Ecological significance of mangroves

Provide food, shelter, protection and nurseries for many species of fish

Sustain high biodiversity

Support aquatic and terrestrialfood webs

e.g. Birds, insects, reptiles which come to feed in mangroves

Terrestrial:陸生の

Source: ISME 1995

Ecological significance of mangroves

Mangrove assimilated energy and nutrients exported to surrounding coral reefs through export and food chain

Assimilate：吸収する nutrient：栄養分

Mangrove trophic ecology

Food chain/ food web(Energy transferred by feeding and nutrient recycled)

Examples of mangrove food chains in Okinawa mangroves

Example of food pyramid in Okinawa mangroves

Bacteria

3rd trophic level(Carnivores)

2nd trophic level(Herbivores)

1st trophic level(Primary producers)

In order to study trophic (food chains) relationships we need biomarkers

Trophic:栄養段階

What are biomarkers

Chemical compound/compounds characteristic of an organism, which can be used to indicate the presence of the organism/plant in the environment and to estimate its biomass

e.g. bacteria, diatoms, dinoflagellates, mangrove, algae

Estimate：推定する

Characteristic of a useful biomarker

Must be synthesized at low trophic levels e.g. mangrove and remain unchanged when transferred to higher trophic levels 3rd trophic level

(Carnivores)

2nd trophic level(Herbivores)

1st trophic level(Primary producers)

Why do we use biomarkers?

Because it is difficulty to identify types of food in stomachs once ingested

Or identify types of organic material in sediments after decay

To find links between ecosystems

Ingest:消化する decay：腐敗する

Sea-grasses Coral reefsMangroves

Examples of biomarkers used in marine ecology

Stable isotopes e.g. carbon (13C), nitrogen (15N), sulfur etc

Lipids e.g. fatty acids

fatty acids：脂肪酸 carbon:炭素 nitrogen：窒素

Classes of lipids

Phospholipids (Polar lipids), Sterols, Triacylglycerols, Free fatty acids, Waxes, Wax esters

What are fatty acids?

Major components of lipidsEssential components of all living cells and cell membrane lipids

Source of metabolic energy From http://www.oup.co.uk

Plant cell Animal cell

Fatty acids

cell membrane：細胞膜Metabolic: 代謝の

General features of a fatty acid structure

A long hydrocarbon chain ( 4-32 carbons), 14-30 is most common

A carboxylic acid group COOH

Hydrocarbon chain Carboxylicacid group

Classification of fatty acids

Based on the number of double bonds

CH3(CH2)14COOH

0 double bonds: Saturated fatty acids e.g. 16:0 (Palmitic acid)

One double bond: Monounsaturated fatty acids e.g. 16:1ω7 (Palmitoleic acid)

CH3(CH2)5CH=CH(CH2)7COOH

Palmitic acid：パルミチン酸 Monounsaturated：一価不飽和

Classification of fatty acids

2 or more double bonds: Polyunsaturated fatty acids e.g. 18:2ω6 (linoleic acid)

CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH

Branched fatty acids (odd and even number)

CH3CH2CH(CH2)10COOH

H3C

CH3CH2(CH2)11COOH

H3Ce.g. 15:0 iso

15:anteiso

Polyunsaturated：多価不飽和 Branched：分枝

Nomenclature of Fatty acids

There are 4 common naming systems

Palmitic acid Hexadecanoic acid 16:0 16:0

1) Trivial 2) IUPAC 3)Carboxylic reference 4) ω-reference

Oleic acid 9-Octadecenoic acid 18:1∆9 18:1ω9

Linoleic acid 9,12-Octadecenoic acid 18:2∆9,12 18:2ω6

Palmitic acid：パルミチン酸

ω & ∆ Designation

ω designated as X:YωZ Where X= number of carbon atoms Y= number of double bonds Z= Position of double bond from the terminal methyl group e.g. 16:0 and 18:2ω6

double bonds：二重結合 methyl：メチル基 CH3

CH3(CH2)4CH=CHCH2CH=CH(CH2)7COOH(∆designated)

CH3(CH2)14COOH 16:0

18:2ω6 (ωdesignated)

18:2 ∆9,12

Why two common designations?

The ω -designation is useful because it allows nutritionists and ecologists to track families of fatty acids or link diet with tissue fatty acid composition

The ∆-designation is useful to describe the biochemical reactions

Fatty acid metabolism

Synthesis in plants..where? in chloroplast

Synthesis:生合成Chloroplast：葉緑体

From http://www.oup.co.uk/oxed/children/oise/pictures/nature/plantcell/

Fatty acid metabolism

Smooth ER

Rough ER

Synthesis in animalsWhere? Phospholipids of smooth

endoplasmic reticullum(ER)

endoplasmic reticullum：小胞体

http://www.oup.co.uk/oxed/children/oise/pictures/nature/animalcell/From

Fatty acid metabolism

Fatty acids are synthesized from acetyl-CoA

First products of biosynthesis16:0

Subsequent metabolism and modification occur in endoplasmic reticulum

From http://www.oup.co.uk/oxed/children/oise/pictures/nature/plantcell/

Subsequent:次のModification:変化 Endoplasmic:小胞体 Reticulum：網状組織

Why do we use fatty acids as biomarkers

High structural diversity

High taxonomic specificity e.g.

Specificity：特異性

Terebralia palustris Terebralia sulcata

FA distributions in green and yellow leaves

Green leaves

16:0

16:1ω

717

:0

18:0

22:0

18:1ω

9 18:2ω

6

18:3ω

320

:0

24:0

28:0

26:0

23:0

14:0

% o

f tot

al F

As

Yellow leaves

16:0

16:1ω

717

:018

:0

22:0

18:1ω

918

:2ω

618

:3ω

320

:0 24:0

28:0

26:023:0

14:0

30:0

% o

f tot

al F

As

Even-Long chain FAs

FA distributions in decayed leaves and mangrove sediment

After 132 days

Mangrove sediments

18:0

18:2ω

6

16:0

16:1ω

717

:0

22:018

:3ω

3

23:0

14:0 28

:026:0

30:0

22:6ω

3

18:1ω

9/7

20:0

24:0

20:3ω

6

16:1ω

717

:0

22:0

23:0

14:0 28

:026:0

30:0

18:1ω

9/7

20:0

24:0

20:3ω

6

18:0

16:0

% o

f tot

al F

As

% o

f tot

al F

As

Even-Long chain FAsSediment：底質

FA should be transferred unchanged to high trophic level

26:028:030:032:0

15:0 iso; 15:0 anteiso; 17:0 iso17:0 anteiso; 18:1ω7

20:5ω3

18:4ω322:6ω3Bacteria

18:2ω618:3ω618:3ω3

Diet composition of gastropods

26:028:030:032:0

26:028:030:032:0

26:028:030:032:0

Diatoms (20:5ω3)

Algae 18:2ω618:3ω618:3ω3

Dinoflaggelates18:4ω322:6ω3

Bacteria 15:0 iso; 15:0 anteiso; 17:0 iso17:0 anteiso; 18:1ω70

2

4

6

Oura Okukubi Nagura Komi Urauchi

Dinoflagellates Bacteria 18:1ω7

18:2ω618:3ω618:3ω320:5ω3

18:4ω322:6ω3

15:0 iso15:0 anteiso17:0 iso17:0 anteiso; 18:1ω7

0

4

8

12

Oura Okukubi Nagura Komi Urauchi

Mangrove Macroalgae Diatoms

%

High

Low

Low

High

%

Fatty acid as indicators of sources & fate of organic matter

Mfilinge et al., (2005) Estuarine Coastal and Shelf Science, Vol. 63, 301-313

mangrove

Sand flat

Sand flat

Mud flat

Remarks and conclusions

Vascular plants (mangrove and terrestrial plants) share common fatty acid markers (even long chain FAs). Therefore it is impossible to distinguish between mangrove and terrestrial plants organic matter inputs.

Ongoing research: Find new fatty acid biomarkers that can distinguish between mangrove and terrestrial plants.

Vascular plants:維管束植物

Fungi:菌類

Acknowledgements

Prof. Makoto Tsuchiya

For his kind advice throughout my studies in Japan

Japan Society for the Promotion of Science (JSPS)

For the post-doctoral fellowship

THANK YOU