Matt Slater – IMARE – Bremerhaven - Germany
Slater, M.J.1, Beltran-Gutierrez, M.,2 MacDonald, C.L.,4 Ferse, S.C.A.,2 Kunzmann,
A.,2 Mgaya, Y.D.,3 Seemann U. 1, Msuya, F.E. 3, and Stead, S.M. 4
1
imare GmbH, Germany; 2 Leibniz Center for Tropical Marine Ecology (ZMT), Germany; 3
University of Dar es Salaam, TZ; 4 Newcastle University, UK
Overview
 Benefits of integrating detritivores into existing
aquaculture units
 Integration research : varying conditions and co-culture
species
 Shellfish – medium organic content - temperate
 RAS Finfish – high organic content - temperate
 Macroalgae – low organic content - tropical
 Future challenges
 Holding conditions (particularly in RAS)
 Freshwater
 Hatchery technology
Biodeposits from aquaculture
Uneaten diet
Faeces / pseudofaeces
Biofouling / shelldrop
Waste stream
10-150 g/m2/d
Impact footprint (accumulation of organic and nutrient rich matter)
Detritivore integration – measures of
benefits
• Biodeposit processing - Biodeposit diet palatability
• Additional product - Animal growth
• Nutrient processing - Bioremediation
• Conditions acceptable - Survival / site fidelity
Diverse detritivore integration
 Australostichopus mollis in co-culture with greenlip
mussel, Perna canaliculus in longline culture
 Holothuria forskali in co-culture with European
Seabass, Dicentrarchus labrax, Japanese Flounder,
Paralichthys olivaceus, and Turbot, Psetta maxima
 Holothuria scabra in co-culture with red macroalgae,
Kappaphycus striatum in lagoon culture
Detritivores in longline mussel culture
• Tank trials feeding Australostichopus mollis mussel
biodeposits
• Consumption (rates)
• Growth
• Survivorship
• Co-culture of A. mollis in association with mussel
farms
• Growth - weight change
• Survivorship
•
Nutrient processing
Bioremediation
• Sediment nutrient +/-
Biodeposit diet palatability A. mollis
• A. mollis consuming biodeposits (Perna canaliculus waste ca 18% TOM)
6.7g (ww) /d-1 ± 1.59 (ca. 65-120 g animal)
Growth under mussel farms
Change in average weight at varying densities - 4 months
% weight change
25
N=6
N=12
2,5
5
N=36
15
5
-5
-15
-25
15
Density (.m2)
Mussel farm
Control
Two-way ANOVA: Between sites p < 0.02 / between densities p < 0.01 / site x density p = 0.8
Growth in tank trials
Bioremediation of biodeposits
TOC (% sed dry wt)
1.6
1.5
1.4
1.3
1.2
1.1
1
0
2
4
6
Experimental period (wks)
ANCOVA Sea cucumber vs. Control wks 1-4, F1,25 = 4.72, P<0.05
8
Detritivores in RAS finfish culture
• Trials of direct and indirect co-culture of Holothuria
forskali with olive flounder, Paralichthys olivaceus
• Growth - weight change
• Survivorship
• Tank trials feeding Holothuria forskali with Dicentrarchus
labrax and Psetta maxima biodeposits
• Consumption (rates)
• Survivorship
• Growth
•
Nutrient processing
Bioremediation
• Sediment nutrient (TOM) +/-
Biodeposit diet palatability H. forskali
• H. forskali (D. labrax waste ca 57% TOM) 2.9 g (ww)/d-1 ± 1.97
• H. forskali (P. maxima waste ca 45% TOM) similar = ca. 3.5 g ww (ww)/d-1
• A. mollis (P. canaliculus waste ca 18% TOM) 6.7g (ww)/d-1 ± 1.59
Bioremediation of biodeposits (short)
4,2
Total Nitrogen (%)
4
3,8
3,6
3,4
3,2
3
Waste diet
Control 5d
Control 10d SC grazed 5d SC grazed 10d
Waste sample Type
Control vs. Treatment 10 d (T=-3.3, df=4 p<0.05). N = 3 for all treatments
MacDonald, C. L.E, Stead, S.M., Slater, M.J., 2013. European Seabass (Dicentrarchus labrax) waste as a food source for the sea
cucumber Holothuria forskali - palatability, growth and remediation impacts. Aquaculture International. 21, (6) 1279-1290.
Bioremediation of biodeposits (long)
Total Carbon (% sed dry wt)
70
60
50
40
30
Sea cucumber
Control
20
10
0
0
4
Time from experimental outset (weeks)
Unpaired t-test (at 8 weeks), t=-3.11, df=4, P<0.05). N = 3 for all treatments
8
Detritivores in Lagoon Macroalgae culture
• Trials of indirect co-culture of Holothuria scabra with
macroalgae, Kappaphycus striatum / Kappaphycus spp.
(Sediment TOM 2.8% )



Growth - weight change
Survivorship
Economic value
Integrating H. scabra with K. striatum
Sea Cucumber Growth under macroalgae
T1 Seaweed 550 g/m2 + sea cucumber 100g/m2
T2 Seaweed 550 g/m2 + sea cucumber 200g/m2
T3 Sea cucumber 200g/m2 (no seaweed)
Growth in (g/d-1)
4
3
300 g SC /m2
2
380 g SC /m2
355 g SC /m2
-1
12
10
8
6
4
2
1
Time from experimental outset (weeks)
Mixed model growth g/day-1 100g vs 200g SC - (χ2 = 10.89, df = 1, p<0.001), N = 4 for all treatments
Seaweed Growth in IMTA
400
Seaweed ind. weight (g)
350
300
T0 Seaweed 550 g/m2 no sea cucumber
T0: Seaweed and no sea cucumber
T1 Seaweed
550 g/m2
+ sea cucumber 100g/m2
T1: Seaweed
+ sea cucumber
100g/m2
T2: Seaweed
+ sea cucumber
T2 Seaweed
550 g/m2 + sea cucumber 200g/m2
200g/m2
250
200
150
100
50
0
0
N = 4 for all treatments
2
4
Time from experimental outset (weeks)
6
Detritivore integration and unit area profitability
• Calculated at trial conditions
• Economy of scale in caging
• Optimisation of production cycles
Summary
 Sea cucumber/detritivore integration viable with
widely varied:
 Co-culture species – shellfish/finfish/macroalgae
 Production systems – longline / RAS / lagoon
 Levels of impact / eutrophication
 Temperature / seasonal regimes
Future directions – EU, overseas and FW
 Hatcheries and production systems in EU
 Holothuria forskali - other warm and cold water species
 Taking novel integration of detritivores to nations with large-scale
existing culture
 Viable integration with shrimp, tilapia, bream…
 FW detritivores in existing systems
 Pond / raceway culture of finfish with e.g. Astacus astacus
 RAS culture of high-value finfish with e.g L. vannamei
 Novel holding systems required!
Thanks - Cooperation / Acknowledgements
• Muungoni Seaweed Collective, Zanzibar
• IMS, Zanzibar
• Selonda UK
• MHSA / Indian Ocean Trepang, Madagascar
• Galway Mayo Institute of Technology
• Marifeed Pty
Direct or indirect co-culture?
40
35
Ind. Fish Wt. [g]
30
25
20
15
10
5
0
1
1
1
3
3
3
6
6
6
12
12
12
Tank Number
Weight of P. olivaceus at exp. onset and after 6 weeks exp. duration in direct co-culture with H. forskali
(courtesy of S. Spreitzenbarth)
Boom to bust fisheries
Sustainable Sea Cucumber Production?
 Shandong Homey (16,000 ha) and Dalian Zhangzidao fishery
(67,000 ha).
 Source : Q-Series Sustainable Seafood UBS Investment Research