THE EFFECT OF DIET ON THE EFFECT OF DIET ON DMSP ACCUMULATION AND DMSP ACCUMULATION AND TASTE IN SOUTH AFRICAN TASTE IN SOUTH AFRICAN ABALONE (ABALONE (Haliotis midaeHaliotis midae))

Deborah Robertson-Andersson1; A. J.

Smit2; S. Peall3 and Bolton J. J1

1Botany Department, UCT

2School of Biological and Conservation Sciences,

UKZN

3Hearshaw and Kinnes Analytical Laboratory, UCT,

Deborah Robertson-Andersson1; A. J.

Smit2; S. Peall3 and Bolton J. J1

1Botany Department, UCT

2School of Biological and Conservation Sciences,

UKZN

3Hearshaw and Kinnes Analytical Laboratory, UCT,

What do DMSP and abalone taste have What do DMSP and abalone taste have to do with each other?to do with each other?What do DMSP and abalone taste have What do DMSP and abalone taste have to do with each other?to do with each other?

Abalone farming and the importance of macroalgal feeds

The effect of macroalgae on abalone growth

The problem

DMSP

Our studies

Work in progress and the future

Abalone farming and the importance of macroalgal feeds

The effect of macroalgae on abalone growth

The problem

DMSP

Our studies

Work in progress and the future

Integrated abalone-macroalgal Integrated abalone-macroalgal cultivationcultivationIntegrated abalone-macroalgal Integrated abalone-macroalgal cultivationcultivation

number of benefits:

Increased growth rates,

Improved vigor

and stress resistance

number of benefits:

Increased growth rates,

Improved vigor

and stress resistance

6

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28

30

Aug-02

Sep-0

2

Oct-0

2

Nov-02

Dec-0

2

Jan-

03

Feb-0

3

Mar

-03

Apr-03

May

-03

Mea

n w

et w

eig

ht

(g)

Mixed diet

Rotation

Fresh Kelp

Fresh Kelp + formulated feed

Formulated feed

(Naidoo et al., in press)

Benefits of a mixed algal diet

KELP ONLY DIET

MIXED ALGAL DIET

However…..However…..However…..However…..

Two farms which feed Ulva and Gracilaria exclusively experienced that their abalone developed an ‘off’ taste and sulphur-like smell after the canning process

Two farms which feed Ulva and Gracilaria exclusively experienced that their abalone developed an ‘off’ taste and sulphur-like smell after the canning process

Abalone Mariculture Operations in South AfricaAbalone Mariculture Operations in South Africa

Durban

Port ElizabethCape Town

I&J Abalone Atlantic FishingSea Plant Products

Roman Bay

Marine Growers

HIK Farm

AbagoldAquafarm Development

Avuca AbaloneFish Bay Mariculture

Jacobsbaai Sea Products

West Coast Abalone

Port Nolloth Sea Farms

Wild Coast Abalone

Abaseed

Questions…Questions…Questions…Questions…

What is the cause of the problem?

What can be done about it?

What is the cause of the problem?

What can be done about it?

Preliminary investigations Preliminary investigations Preliminary investigations Preliminary investigations

Methionine (mg.g-1 protein)

Cysteine (mg.g-1 protein)

Ecklonia 18.5 29.1

Ulva 15.7 13.3

Gracilaria 16.8 28.1

Methionine, cysteine? No…

Hill et al. (2000; 2004) mentioned a similar problem in tridacnid clams and implicated DMS (produced from DMSP)…

Do abalone receive DMSP in their diet?

Methionine, cysteine? No…

Hill et al. (2000; 2004) mentioned a similar problem in tridacnid clams and implicated DMS (produced from DMSP)…

Do abalone receive DMSP in their diet?

Preliminary investigations Preliminary investigations Preliminary investigations Preliminary investigations

Methionine (mg.g-1 protein)

Cysteine (mg.g-1 protein)

DMSP (μg.g-1 fresh mass)

Ecklonia 18.5 29.1 0.5 - 46.1

Ulva 15.7 13.3 4101 - 7961

Gracilaria 16.8 28.1 1.6 - 48.6

Do abalone receive DMSP from their feed?

Van Alstyne et al. (2003) - Ulva… yes!

Do abalone receive DMSP from their feed?

Van Alstyne et al. (2003) - Ulva… yes!

Background: DMSP and DMS in algaeBackground: DMSP and DMS in algaeBackground: DMSP and DMS in algaeBackground: DMSP and DMS in algae

Some algal species contain high concentrations of intercellular DMSP

Produced in response to freezing temperatures and fluctuating salinity

hypothesised function as osmolyte

DMSP is oxidised in the presence of OH-, O3- or H2O2

reaction with reactive oxygen species implies role as antioxidant

Enzymatic cleavage of DMSP leads to DMS and acrylate

Some algal species contain high concentrations of intercellular DMSP

Produced in response to freezing temperatures and fluctuating salinity

hypothesised function as osmolyte

DMSP is oxidised in the presence of OH-, O3- or H2O2

reaction with reactive oxygen species implies role as antioxidant

Enzymatic cleavage of DMSP leads to DMS and acrylate

DMSP and DMSDMSP and DMSDMSP and DMSDMSP and DMS

COO-

CH3

CH3

S+

DMSP lyase

CH3

CH3

S COO-

H

CH2

H++ +

Dimethylsulphoniopropionate Dimethylsulphide Acrylate

• Produced by algal or bacterial DMSP lyase

• Thermal decomposition of DMSP

• Highly volatile• Distinct taste and

odor• Noticeable at 0.03 -

0.045 μg.ml-1 in water

• Produced by algae• Accumulated by

grazers

• Taste - and odorless

Do abalone contain

DMSP?

Do abalone contain

DMSP?

If they contain DMSP, where is it If they contain DMSP, where is it accumulated?accumulated?If they contain DMSP, where is it If they contain DMSP, where is it accumulated?accumulated?

Top of foot

foot

Epipodial frill

Epipodial frill

AM

BF F

TF

0

5

10

15

20

25

30

35D

MS

P (

g

.g-1)

DMSP values from various tissue types in mixed diet cultivated

abalone diet (25% Ulva; 1 year)

DMSP values from various tissue types in mixed diet cultivated

abalone diet (25% Ulva; 1 year)

Preliminary investigations Preliminary investigations Preliminary investigations Preliminary investigations

AM Abductor muscle

BF Bottom of foot

F Epipodial frill

TF Top of foot

In Tridacnidae, siphonal mantle not abductor muscle had high

concentrations (Hill et al. 2000)

Oysters and mussles have highest concentrations in abductor

muscle (Iida et al. 1986)

In Tridacnidae, siphonal mantle not abductor muscle had high

concentrations (Hill et al. 2000)

Oysters and mussles have highest concentrations in abductor

muscle (Iida et al. 1986)

Abductor muscle preparationAbductor muscle preparationAbductor muscle preparationAbductor muscle preparation

Step 1

Step 4Step 3

Step 2

DMSP diet experimentDMSP diet experimentDMSP diet experimentDMSP diet experiment

Values for fish, crustaceans and other molluscs usually below 1800 μg.g-1 (Hill et al. 2000)

Previous recorded highest DMSP accumulation in tridacnids with zooxanthellae (Hill et al. 2004)

Abalone about 25 % higher

Values for fish, crustaceans and other molluscs usually below 1800 μg.g-1 (Hill et al. 2000)

Previous recorded highest DMSP accumulation in tridacnids with zooxanthellae (Hill et al. 2004)

Abalone about 25 % higher

DMS content in canned abaloneDMS content in canned abaloneDMS content in canned abaloneDMS content in canned abalone

DMS in cans up to 44 μg.ml-1

Taste threshold of DMS in water about 1000 times lower

DMS in cans up to 44 μg.ml-1

Taste threshold of DMS in water about 1000 times lower

DepurationDepuration experiment experimentDepurationDepuration experiment experiment

Variation is consistent with that found in bivalve mollusks (Hill et

al. 1995)

Variation is consistent with that found in bivalve mollusks (Hill et

al. 1995)

0 100 200 300 400 500 600 700 800Time (days)

0

50

100

150

200

250

DM

SP

re

ma

inin

g (

g.g

-1)

smal

lest

smal

l

med

ium

larg

e

0

250

500

750

1000

1250

1500

DM

SP

(µg

.g-1

)Wild abaloneWild abaloneWild abaloneWild abalone

Smallest 10 -20 g

Small 100 -200 g

Medium250 – 750

g

Large > 1 000 g

Effect of DMS content on taste/odour of the product (quality control)?

Important taste consequences in seafoods (Peavy & Riley, 1993; 1994) which limit cultivation e.g. tridacnids

Excessive DMS in cod is commercially problematic, but very low concentrations of DMS are part of the “valued flavor” of some clams and oysters (Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al. 1968; Hill et al. 2000)

Effect of DMS content on taste/odour of the product (quality control)?

Important taste consequences in seafoods (Peavy & Riley, 1993; 1994) which limit cultivation e.g. tridacnids

Excessive DMS in cod is commercially problematic, but very low concentrations of DMS are part of the “valued flavor” of some clams and oysters (Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al. 1968; Hill et al. 2000)

Continuing studies…Continuing studies…

The effect of DMSP on abalone physiology

Partitioning of DMSP – are there tissue properties that

specifically act to exclude DMSP?

May affect enzyme function (Karsten et al. 1996) therefore

have specialised enzymes developed to function in a high

DMSP environment (Hill et al. 2004)?

The effect of DMSP on abalone physiology

Partitioning of DMSP – are there tissue properties that

specifically act to exclude DMSP?

May affect enzyme function (Karsten et al. 1996) therefore

have specialised enzymes developed to function in a high

DMSP environment (Hill et al. 2004)?

The FutureThe Future

Physiology of DMSP production by macroalgae

Can the DMSP production in Ulva be reduced by altering the

cultivation conditions?

Evaluate the role of DMSP as antioxidant in algae by studying

its photophysiology (stress to photosystems)

Physiology of DMSP production by macroalgae

Can the DMSP production in Ulva be reduced by altering the

cultivation conditions?

Evaluate the role of DMSP as antioxidant in algae by studying

its photophysiology (stress to photosystems)

  THANK YOU

ACKNOWLEDGEMENTS

I would like to extend special thanks to the following people and organizations without whose help this project

would be impossible:

Swedish and South African Collaborative Program

I & J Mariculture farm

JSP Mariculture farm

Wild Coast Abalone

Abagold

N R F JSP

A small experiment was instigated to see if DMS was detectable in

abalone.

1 – 2 g of tissue was removed from 5 abalone fed a mixed (kelp, Ulva and

Gracilaria) diet.

Samples were placed in 20 ml of Methanol

Measurement of DMS:

Quantitative conversion of DMSP to DMS through alkali hydrolysis

DMS analysis via gas chromatography

A small experiment was instigated to see if DMS was detectable in

abalone.

1 – 2 g of tissue was removed from 5 abalone fed a mixed (kelp, Ulva and

Gracilaria) diet.

Samples were placed in 20 ml of Methanol

Measurement of DMS:

Quantitative conversion of DMSP to DMS through alkali hydrolysis

DMS analysis via gas chromatography

Preliminary investigations Preliminary investigations Preliminary investigations Preliminary investigations

DMSP and DMS DMSP and DMS DMSP and DMS DMSP and DMS

Ever notice the salty sea smell when you're out on or near the ocean?

Trace concentrations of a volatile sulphur compound, Dimethylsulfide (DMS), were

discovered in the Earth's atmosphere about three decades ago.

The gas was also found to occur in ocean surface waters.

Some phytoplankton synthesize the molecule dimethylsulfoniopropionate (DMSP)

DMS is released by algal cells following death and ‘sloppy feeding’ by

zooplankton.

DMS a naturally produced biogenic gas essential for the Earth's biogeochemical

cycles.

Assumptions: (To be confirmed by taste tests and future studies)

DMSP is not produced by animals and may accumulate following feeding

DMSP is proportionately converted to DMS (Hill et al. 1995)

DMS causes the taste change (Hill et al. 1995, 2000, 2004)

DMSP loss is through excretion (e.g. planktonic copepods (Hill et al. 1993) or mucus loss (corals,

giant clams - Hill et al. 1995, 2004).

No DMS in live abalone (Hill et al. 1995)

Post mortem DMS content is due to:

DMS production from DMSP resulting from heat treatment during canning

Bacterial activity: DMSP lyase

Abalone do not have DMSP-lyase (true for other invertebrates - Hill et al. 2004)

Assumptions: (To be confirmed by taste tests and future studies)

DMSP is not produced by animals and may accumulate following feeding

DMSP is proportionately converted to DMS (Hill et al. 1995)

DMS causes the taste change (Hill et al. 1995, 2000, 2004)

DMSP loss is through excretion (e.g. planktonic copepods (Hill et al. 1993) or mucus loss (corals,

giant clams - Hill et al. 1995, 2004).

No DMS in live abalone (Hill et al. 1995)

Post mortem DMS content is due to:

DMS production from DMSP resulting from heat treatment during canning

Bacterial activity: DMSP lyase

Abalone do not have DMSP-lyase (true for other invertebrates - Hill et al. 2004)

DMSP and DMS in herbivoresDMSP and DMS in herbivoresDMSP and DMS in herbivoresDMSP and DMS in herbivores

The FutureThe Future

DMSP physiology

Important taste consequences in seafoods (Peavy and Riley 1993, 1994)

which limit cultivation e.g. Giant clams.

Values in cod and other finfish in the range 0.2 – 1 umol.g-1 are

considered commercially problematic, BUT very low concentrations of

DMS are part of the “valued flavor” of some clams and oysters

(Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al. 1968;

Hill et al. 2000)

Abalone physiology

Partitioning of DMSP – have tissue evolved properties that specifically

act to exclude DMSP

Can affect enzyme function (Karsten et al. 1996) therefore have

specialized enzymes formed to function in a high DMSP environment (Hill

et al. 2004).

Does it play role in ameliorating tissue oxygen stress (Sundra et al.

2002).

DMSP physiology

Important taste consequences in seafoods (Peavy and Riley 1993, 1994)

which limit cultivation e.g. Giant clams.

Values in cod and other finfish in the range 0.2 – 1 umol.g-1 are

considered commercially problematic, BUT very low concentrations of

DMS are part of the “valued flavor” of some clams and oysters

(Ackman & Hingley, 1968; Iida & Toukuaga, 1986; Brooke et al. 1968;

Hill et al. 2000)

Abalone physiology

Partitioning of DMSP – have tissue evolved properties that specifically

act to exclude DMSP

Can affect enzyme function (Karsten et al. 1996) therefore have

specialized enzymes formed to function in a high DMSP environment (Hill

et al. 2004).

Does it play role in ameliorating tissue oxygen stress (Sundra et al.

2002).