Can kelp extract (KELPAK) be useful in seaweed mariculture?

 

Bolton JJBolton JJ11, Robertson-Andersson D, , Robertson-Andersson D, Njobeni ANjobeni A11, Leitao D, Leitao D11, Anderson RJ, Anderson RJ22

and Ruck, Kand Ruck, K33

11Botany Department, UBotany Department, UCTCT22Seaweed Unit, M&CMSeaweed Unit, M&CM

33Jacobsbaai Sea ProductsJacobsbaai Sea Products

Honours project (2002, UCT). Daniela Leitao

- Growth of 15mm excised tips of Growth of 15mm excised tips of Gracilaria for 14 days (n = 15)Gracilaria for 14 days (n = 15)- 200ml glass culture dishes in laboratory 200ml glass culture dishes in laboratory @ @ 1515CC - Seawater or Provasoli ES medium Seawater or Provasoli ES medium (changed every 3 days)(changed every 3 days)- Range of 1:25 to 1:25 000 Range of 1:25 to 1:25 000

industrial-strength KELPAK added (6 industrial-strength KELPAK added (6 concentrations)concentrations)

Gracilaria tip experiment

1:25 and 1:125 seawater/ES:KELPAK 1:25 and 1:125 seawater/ES:KELPAK

Tips died after 2 days Tips died after 2 days

All others grew well (1:500, 1:2500, All others grew well (1:500, 1:2500, 1:5000, 1:25000)1:5000, 1:25000)

Gracilaria: weight of tips after 14 days

Seawater medium

0

5

10

15

20

25

30

Control 1:25000 1:5000 1:2500 1:500

KELPAK concentration

We

igh

t (m

g)

a a b b c

Gracilaria: weight of tips after 14 days

Provasoli ES medium

0

5

10

15

20

25

30

35

40

45

Control 1:25000 1:5000 1:2500 1:500

KELPAK concentration

Wei

ght o

f tip

(mg)

a

a ac b c d

Gracilaria: number of branches after 14 days

Seawater medium

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Control 1:25000 1:5000 1:2500 1:500

KELPAK concentration

BR

AN

CH

ES p

er ti

p

Gracilaria: number of branches after 14 days

Provasoli ES medium

0

0.5

1

1.5

2

2.5

3

Control 1:25000 1:5000 1:2500 1:500

KELPAK concentration

Bra

nch

es

pe

r ti

p

Larger scale aquaculture of Gracilaria and Ulva at a commercial abalone farm

Jacobsbaai Sea Products (JSP)

• Run as a experimental operation

• 20 volume exchanges per day

• Small Gracilaria and Ulva tanks (0.6 X 0.38 X 0.36 m) for experiments

• fresh seawater tanks

• turbot/abalone effluent tanks

• abalone effluent tanks

Methods

•Harvesting

• Two-weekly intervals

• Tanks are scrubbed to remove fouling epiphytic algae

• Samples were taken to record dry to wet weight ratios and for biochemical analysis

•Growth rate experiments

• Relative Growth rate (RGR = % d-1)

RGR = [ln(Wt / W0)] / (tt – t0)

JSP Kelpak experiments

3 replicates of each treatment3 replicates of each treatment

EXPT 1: Concentrations of Kelpak EXPT 1: Concentrations of Kelpak (1:5000, 1:2500, 1:500) added to (1:5000, 1:2500, 1:500) added to turbot/abalone effluent turbot/abalone effluent

EXPT 2: Chosen concentration of EXPT 2: Chosen concentration of Kelpak in two types of effluent, with Kelpak in two types of effluent, with and without fertiliser supplementand without fertiliser supplement

Gracilaria at JSP: RGR in different Kelpak concns. (Run 1)

00.5

11.5

22.5

33.5

Seawater Turbot 1:5000 1:2500 1:500

Medium

RG

R (%

/day

)

Temperature in JSP tanks: June/July 2002 (SD, maximum and minimum)

5

7

9

11

13

15

17

19

2100

:30

02:3

0

04:3

0

06:3

0

08:3

0

10:3

0

12:3

0

14:3

0

16:3

0

18:3

0

20:3

0

22:3

0

Time

Tem

pera

ture

( C)

CONTROL (no KELPAK)

KELPAK @ 1:5000

KELPAK @ 1: 2500

KELPAK @ 1: 500

Gracilaria: Number of branches per 10cm apex (Runs 1 & 2)

020406080

100120140

Control 1:5000 1:2500 1:500

Medium

Num

ber

of b

ranc

hes

Effects of various Kelpak dilutions in turbot

effluent on RGR (% d-1) of Ulva at JSP

0

1

2

3

4

5

6

7

RUN 1 RUN 2

RGR

% /

d

TURBOT CONTROL CON 1:5000 CON 1:2500 CON 1:500 SEA WATER

Effects of Kelpak in turbot effluent on

tissue N of Ulva at JSP

40

45

50

55

60

Run 1 Run 2

Tiss

ue N

mg.

N pe

r g

Control 1:5 000 1:2 500 1:5 00 small sea

Fertiliser treatmentAs used on I&J farm at GansbaaiAs used on I&J farm at Gansbaai

6 parts Maxiphos to 1 part ammonium 6 parts Maxiphos to 1 part ammonium sulsulphphateate

Added weekly, for 8 hours in non-flowing Added weekly, for 8 hours in non-flowing water in the day (08:30 to 16:30)water in the day (08:30 to 16:30)

Concentration in water after fertilization: Concentration in water after fertilization: 575575M ammonium/ 280M ammonium/ 280M phosphateM phosphate

Effect of 1:2500 Kelpak and fertilizer (separately or combined) in turbot effluent on RGR (% d-1) of Ulva lactuca at JSP.

0

1

2

3

4

5

6

7

8

RUN 1 RUN 2

RGR

% d

TURBOT CONTROL TURBOT + FERTTURBOT + FERT +KELPAK TURBOT + KELPAKSEA WATER

Effects of Kelpak (1:2500) and fertilizer in turbot effluent on tissue N (mg N per g) Ulva at JSP.

3035404550556065707580

Run 1 Run 2

Tiss

ue N

mg

per

g.D

W

Control fert kelpak & fert kelpak 1:2 500 small sea

Abalone effluent: RGR’s

0

1

2

3

4

5

6

7

8

RUN 1 RUN 2

RG

R %

d

ABALONE CONTROL ABALONE + FERT ABALONE + FERT +KELPAK

ABALONE + KELPAK SEA WATER

Abalone effluent: tissue N

30

35

40

45

50

55

60

65

70

75

Run 1 Run 2

Tiis

ue

N.

mg

/gD

W

Control fert kelpak & fert kelpak 1:2 500 small sea

Conclusions: First demonstration of effects of seaweed extract First demonstration of effects of seaweed extract

on seaweed growth?on seaweed growth? Tips of Gracilaria (lab.) – most growth with Tips of Gracilaria (lab.) – most growth with

Kelpak at 1:5000 - suggestion of increased Kelpak at 1:5000 - suggestion of increased branching at Kelpak 1:25 000branching at Kelpak 1:25 000

Suggestion of increased Suggestion of increased GracilariaGracilaria branching with branching with Kelpak treatments at JSP (turbot/abalone effluent)Kelpak treatments at JSP (turbot/abalone effluent)

Kelpak causes increase in Kelpak causes increase in Ulva Ulva growth at JSPgrowth at JSP Best growth of Best growth of UlvaUlva with fertiliser plus Kelpak at with fertiliser plus Kelpak at

1:2500 (high N content)1:2500 (high N content) Beneficial concentrations of Kelpak similar to Beneficial concentrations of Kelpak similar to

those in agriculturethose in agriculture