can kelp extract (kelpak) be useful in seaweed mariculture?
DESCRIPTION
This presentation was given at the 2003 Phycological Society of Southern Africa meeting in 2003. The presentation asks whether a seaweed extract (normally used on land plants) can also be used to increase seaweed produciton.TRANSCRIPT
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