The Salty Gold. Abstracts of the results and achievements of the RAAK International project on land based Integrated Multi Trophic Aquaculture

The Salty Gold Abstracts of the results and achievements of the RAAK International project on land based Integrated Multi Trophic Aquaculture February 2011 – February 2013

Introductie RAAK Het Zoute Goud is een project voor internationaal praktijkgericht onderzoek naar duurzaam zout water gebonden organische productie (zilte aquacultuur) op land. Met een looptijd van 2 jaar (Feb 2011feb 2013) zijn er binnen een samenwerkingsverband met meer dan 25 partners (onderzoeksinstanties, MKB bedrijven en consultants) vele onderzoeken uitgevoerd. Naast kennisverhoging is er veel gedaan aan kenniscirculatie door middel van excursies en workshops. Dit document geeft in het kort een overzicht van de excursies, workshops en de bereikte resultaten. In het kort nog even de feiten op een rij: RAAK Het Zoute Goud is een samenwerkingsverband tussen: • Hogeschool Zeeland, waarbij de Onderzoeksgroep Aquacultuur de penvoerder is • Imares (Wageningen Universiteit) • Zeeland Aquacultuur B.V. • La Solitude VOF • Instituto de Investigación y Formación Agraria y Pesquera (IFAPA ) • Zeeuws Agrarisch Jongeren Kontakt • 18 MKB bedrijven, intermediairs, adviesbureaus, kennisinstellingen actief in aquacultuur Het onderzoek is gedaan binnen de volgende 3 werkpaketten: 1) Stabiele en bedrijfszekere algenkweek in ondiepe vijverstystemen 2) Integrated MultiTrophic Aquaculture in vijversystemen 3) Nieuwe soorten voor productie in zout water vijversystemen In totaal zijn er 28 onderzoeken/publicaties gedaan, waarvan 21 door studenten, 3 door HZ medewerkers, 1 extern onderzoek en 3 publicaties in magazines. Tevens zijn twee onderzoeken gepresenteerd op posters tijdens het symposium van de World Aquaculture Society in Praag. Alle onderzoeken zijn d.m.v. een abstract opgenomen in dit document. Het originele rapport van ieder onderzoek is ofwel te downloaden op www.deltaacademy.nl ofwel op te vragen via de Onderzoeksgroep Aquacultuur (email: [email protected]). Al met al wordt in dit document teruggekeken op een geslaagd project, waarin veel praktijk gestuurde vragen onderzocht zijn, kennis ontwikkeld is, maar waar ook vervolgvragen uit voortgekomen zijn. Inmiddels is een nieuw RAAK project toegekend voor de komende 2 jaar waarin deze vragen verder onderzocht kunnen worden. In het nieuwe project RAAK Zilte Parels zal er met name praktijkgericht onderzoek uitgevoerd worden naar productdifferentiatie en -diversificatie van aquacultuur producten. Informatie is op te vragen bij projectleider Jasper van Houcke (email: [email protected])

Abstracts Werkpakket 1: Stabiele en bedrijfszekere algenkweek in ondiepe vijverstystemen Kweek van Chaetoceros muelleri op afvalwater viskweek Het kweken van schelpdieren in bassins op land (onder gecontroleerde omstandigheden) vereist dat er grote hoeveelheden microalgen voorhanden zijn om een goede groei en productie van schelpdieren te realiseren. Voor het kweken van deze algen (voor schelpdieren) zijn de nodige kosten verbonden. De grootste kostenposten zijn: grondprijs, het kweeksysteem en voedingstoffen voor de algen. Om schelpdierkweek op land rendabel te maken zullen, waar mogelijk, deze kosten gereduceerd moeten worden. Een stichting die zich bezig houdt met het kweken van vis op het land is stichting Zeeuwse Tong. Voor het project “De Zeeuwse Tong” is het van belang dat er een gesloten kringloop ontstaat in de zilte productie op het land. Dit houdt in dat tong gekweekt wordt zonder vervuiling, verlies van nutriënten of vervuild afvalwater. Hiervoor is een kringloop ontwikkeld. Eerst wordt de tong gevoerd met zagers. Op het afvalwater van de tong zullen hierna algen worden gekweekt. Deze algen worden aan schelpdieren toegevoegd, waarna de overgebleven algen met afvalwater weer naar de zagers worden verpompt. Hierna begint de kringloop weer opnieuw.

Algenconcentratie

Bij het promotie onderzoek van ir. M. Michels wordt er in een fotobioreactor gekweekt met de algensoort Chaetoceros muelleri, welke tot de diatomeeën behoort en zou kunnen dienen als voedselbron in de aquacultuur. Deze algen Algenconcentratie worden momenteel gekweekt op het standaard 8,00 Walne medium, wat hoge Walne (18-3 t/m 4-4) kosten met zich meebrengt. 7,00 In de toekomst zou deze Afvalwater '2' (16-5 t/m 24-5) 6,00 fotobioreactor mogelijk op 5,00 afvalwater van een viskwekerij kunnen draaien. 4,00 3,00 2,00 1,00 0,00 0

5

10 Tijd (dagen)

15

20

Eerdere experimenten met Chaetoceros muelleri laten zien dat het afvalwater in potentie geschikt is. Voor opschaling naar praktijkschaal is nadere studie nodig over de bruikbaarheid van het

afvalwater. Er is onderzoek en monitoring gedaan naar de groei van de algen en de opname van fosfaat, nitraat en silicaat door de algen op het Walne-medium en het afvalwater van de viskwekerij is. In het onderzoek is naar voren gekomen dat het afvalwater een prima vervanger is voor het huidig gebruikte Walne-medium. Er is een evenredige groei en opname van de nutriënten te zien. In een kleinschalige proef is een continu systeem met input en output getest, de manier waarop het op grote schaal toegepast zou moeten worden. De proef heeft laten zien dat opschaling mogelijk is en er een continue productie van algen met een dergelijk systeem mogelijk is.

Werkpakket 2: Integrated MultiTrophic Aquaculture in vijversystemen Topic: GROUNDWATER CHARACTERISTICS Solutions for a filtration stop of mussels in a specific type of groundwater: Case mussel pilot La Solitude The farm ‘La Solitude v.o.f.’ started a pilot project for aquaculture. The goal of this project is the grow out of mussels (Mytilus edulis) in land based basins filled with groundwater. The problem is located with the groundwater that is being used for the mussels. It is not suitable for them, as soon as they are put in the groundwater they stop filtrating. The goal of this research was to find a theoretical and practical solution for filtration stop. By doing tests with mussels in combination with different types of water (Eastern Scheldt water, SEA Lab water and La solitude groundwater), which were treated in different ways, attempts were made to find a solution. The mussels were fed with algae to a concentration of 150.000 cells/ml every day so the filtration could be measured the next day. The dead mussels were also counted each day. The research is divided into two experiments. The first experiment searches for a practical solution for the farm by using an acclimatization period for the mussels. The mussels are put in a certain percentage of St. Philipsland groundwater which gradually increased to 100% over the course of 10 days. This acclimatization period did not have the desirable effect on the mussels, as the filtration remained low. An increased mortality rate was also seen when compared to mussels in Eastern Scheldt water. For the theoretical solution a few different groups were tested: organic compounds, metals and the macro ion balance. By adding sea salt, adding sodium(Na) and potassium(K) or by just adding potassium, it seemed that the mussels only filtrated good in St. Philipsland groundwater with addition of sodium and potassium. This indicates that the solution was to be found in the direction of the macro ion balance. By adding EDTA, to see if the effect of certain metals were the cause, certain ions bound by the EDTA would be less available to the mussels. This might improve the macro ion balance in favor of the mussels. At the highest concentration of EDTA added (1,88 *10-3 mol/L), the mussels filtrated best. Almost as good as the treatment with adding sodium(Na) and potassium(K). Adding EDTA and sodium(Na) and potassium(K) to St. Philipsland groundwater both seems to have a positive effect on the filtration of the mussels. By adding EDTA, certain ions which are available in surplus to the mussels, are made less available. By adding sodium and potassium certain ions are added instead. This both causes a shift in the ion balance. It can be concluded that the cause must be found in the direction of the macro ion balance. For further research it is advisable to look more into this direction to find the exact cause. As a practical solution the effect of algae growth on the macro ion balance can be useful.

Suitability of Kustlab groundwater for aquaculture purposes: bioassays with shellfish, ragworms, algae and sole Het Kustlaboratorium van Het Zeeuwse Landschap brengt drie belangrijke elementen samen in één plan: kustveiligheid, duurzame voedselvoorziening (aquacultuur) en landschaps- en natuurontwikkeling. De locatie van het Kustlaboratorium is gepland bij Burghsluis, op Schouwen-Duiveland. Voor aquacultuur is aanvoer van zoutwater nodig. Voor de geplande zilte aquacultuur kan hiertoe gebruik gemaakt worden het lokaal aanwezige Oosterscheldewater, maar een andere mogelijkheid is om gebruik te maken van het aanwezige zoute grondwater. In dit onderzoek zijn verschillende indicatorsoorten getest middels kortdurende bioassays om de geschiktheid van het zoute grondwater op de locatie van het kustlab te bepalen. Het grondwater is afkomstig van twee verschillende diepten: 22 meter –NAP en 45 meter –NAP. Het water van 22 meter –NAP is opgesplitst in voorbehandeld water met beluchting en (kaars)filtratie en niet voorbehandeld water. Het water van 45 –NAP is niet voorbehandeld. Tabel 1: Indicatorsoorten voor bioassays Indicator species

Life stage

Indicator

Duration (doorlooptijd)

Protocol

Conducted by

Sole (Solea Solea)

Larve

Movement and growth

9 days

OECD guideline 212: Fish, shortterm Toxicity Test on Embryo and Sac-fry Stages

Imares

Growth

3 days

ASTM

HZ University and Eco fide

Spat

Growth

28 days

HZ University

Half grown

Filtration activity

5 days

Protocol developed by HZ University and Zeeschelp Foundation Protocol developed by HZ University and Zeeschelp Foundation

Spat

Growth

28 days

HZ University

Half grown

Filtration activity

5 days

Juveniles

Growth

28 days

Protocol developed by HZ University and Zeeschelp Foundation Protocol developed by HZ University and Zeeschelp Foundation Protocol RIKZ-BCI

Diatom (Skeletonema costatum) Blue mussel (Mytilus edulis)

Manila clam (Tapes philippinarum)

Ragworm (Nereis virens)

HZ University

HZ University

HZ University

Restultaat en conclusie: Tabel 2: gewenste, neutrale of ongewenste reactie van kweekorganismen Testorganisme

Indicator

Alg Mossel

Groei Groei Filtratie Groei Filtratie Groei Mortaliteit

Tapijtschelp Zager Tonglarve

22m –NAP Niet Voorbehandeld water Gewenst Gewenst Gewenst Gewenst Gewenst Gewenst Ongewenst

22m –NAP Voorbehandeld water Neutraal Gewenst Gewenst Gewenst Gewenst Gewenst Ongewenst

45m – NAP Niet Voorbehandeld water Gewenst / Neutraal* Ongewenst Ongewenst Ongewenst Ongewenst Neutraal Ongewenst

*Twee vergelijkbare onderzoeken laten een verschil in uitkomsten zien voor de groei van algen op grondwater van 45m NAP. Toelichting ‘gewenste’, ‘neutrale’ en ‘ongewenste’ reactie. Gewenste reactie Gelijk aan blanco Neutrale reactie Achterblijven t.o.v. blanco, wel activiteit Ongewenste reactie Volledige uitval / geen activiteit

Bioassays met tapijtschelpen op 3 verschillende typen grondwater The research group Aquaculture of the HZ Delta Academy is investigating different water research projects. One of the research projects is the project Het Zoute Goud (The salty gold). The aim of this project is to enlarge the practical knowledge about sustainable aquaculture on land. Within this project, the effect of different types of groundwater (different locations) on land-based manila clam (Tapes phillippinarum) culture, has been studied. Experiments have been done with adult Manila clams and with Manila clam spat. The experiments with the adult clams contained the growth, taste and filtration with algae cultured on groundwater from Zeeland Aquacultuur b.v. (experiment 1). With the spat, the growth, color change of the shell and filtration, have been tested on different types of groundwater from three different locations: Zeeland Aquaculture b.v., Van Antwerpen Milieutechniek b.v. and from the Hatchery Roem van Yerseke (experiment 2). In both experiments, the culture on Eastern Scheldt water has been used as a reference. One group of the adult clams from experiment 1 have been fed 5,5 weeks with algae cultured on 50% of Eastern Scheldt water and on 50% of groundwater from Zeeland Aquacultuur b.v.. The other group have been fed 5,5 weeks with algae cultured on only Eastern Scheldt water. The clams stayed in buckets filled with Eastern Scheldt water. The results showed that there was no difference in increase of flesh weight between the two groups of this experiment. Also the results from the filtration tests from this experiment showed that there was almost no difference between the two groups. Also the flavor test didn’t indicate a difference between the groups of experiment 1, with the adult manila clams. There can be concluded that the feeding of algae cultured on 50% of groundwater from Zeeland Aquacultuur b.v. and 50% of Eastern Scheldt water doesn’t show a difference in increase of flesh weight, filtration and taste compared to the feeding of algae cultured on 100% Eastern Scheldt water. The Manila clam spat has been fed 5,5 weeks with algae cultured on 100 % Eastern Scheldt water. The results of this experiment showed that, the culture of spat in pure groundwater isn’t good for the growth of the spat. The groundwater from van Antwerpen Milieutechniek b.v. caused complete mortality for the spat after two weeks. The groundwater from de Hatchery Roem van Yerseke is also not good for the growth of the spat, but not all individuals died in this groundwater. The groundwater from Zeeland Aquacultuur b.v. does show some growth, but compared to the spat that has been placed in Eastern Scheldt water, this growth is minimal.

Toename nat gewicht tapijtschelp broed over tijd 3,0

Natgewicht (g)

2,5 2,0 Zeeland Aquacultuur

1,5

Van Antwerpen Milieutechniek Roem van Yerseke

1,0

Oosterschelde water 0,5 0,0

Tîjd

Also the filtration tests with the spat show the same results as mentioned above for this experiment. Only the spat in Eastern Scheldt water showed good filtration. Also the color of the shells of the spat shows clearly that groundwater has an effect on the color of the shell. The shells of the spat placed in groundwater become darker. On the other hand become the shells of the spat placed in Easternsheldt water lighter, a clear light growth edge can be seen. So, the groundwater from the three locations has a negative effect on the color, growth and filtration of the carpet clam spat, compared to the spat that has been placed in Eastern Scheldt water.

Bioassays with Manila Clams and Skeletonema costatum algae on water of GroVisCo, Seafarm and VAM INTRODUCTION Recently, more and more companies and pilots started with land based aquaculture. The source for marine aquaculture is good quality saline water, which can be available as seawater, but also as groundwater. This research focusses on the suitability of saline groundwater for aquaculture. Quality of the groundwater at different locations and depths in the Zeeland region, can vary and in some cases cause negative effects, for instance lower to no growth of shellfish. Therefore farmers and policy makers want to know in which cases (locations, depths) groundwater can be used for aquaculture. In this research the groundwater from the sources GroVisCo (Tholen), Seafarm (Kamperland) and Van Antwerpen Milieutechniek (Borsele) was investigated to test the suitability for algae cultivation and shellfish cultivation. Both SEAFARM and GroVisCo groundwater sources are being used in the companies as process water for fish farming (turbot). The water of VAM is known already to cause negative effects and is therefore treated with additional water treatments. METHOD Bioassays with Manila clam spat and the diatom species Skeletonema costatum have been carried out on groundwater from Grovisco and Seafarm. The groundwater from VAM had some additional pretreatment to improve ion balance or immobilize metals or organic substances which might have a negative effect on the test organisms. Also some combinations of treatments have been tested. RESULTS & CONCLUSION SEAFARM water is suitable for both algae cultivation as shellfish cultivation, though SGRs were not similar to the control (Eastern Scheldt water), growth was evident. Grovisco had no significant difference to the control for algae growth, even though Grovisco water had a lower salinity (20‰). Manila clams did grow on Grovisco water but not as good as the Manila clams on the control and SEAFARM water, probably due to the lower salinity. Notable is the significantly lower growth of Manila clams when fed on algae cultivated in the same groundwater in contrast to those fed on algae cultivated in Eastern Scheldt water. The water from VAM showed only mortality both in algae bioassays and Manila clam bioassays which means that the treatments for removing/immobilizing metals and organic components or combination treatments had no effect. Also improvement of the ion balance did not work. The cause of mortality must be sought elsewhere.

Topic: ROLE OF RAGWORMS IN IMTA Predation of Ragworms on Manila Clam spat in integrated aquaculture systems: a small scale experiment Introduction In Integrated Multi Trophic Aquacultuur (land based) projects in Zeeland, where pilots like Zeeuwse Tong and Zeeland Aquaculture gather a lot of practical information, it is assumed that ragworms consume part of the manila clam spat cultured in the same pond. Literature shows that the effect of worms living in the substrate on juvenile bivalves (meiobenthos) is researched at different locations. Some had little effect, others a larger effect according to Hiddink et.al. (2002). Negative effects are: - Direct effects caused by predation - Indirect effects caused by disturbance of the sediment; polychaetes consume, move and disturb large quantities of sediment. The number of meiofauna organisms killed by disturbance is larger than the number killed by predation (Tita et.al. 2000). Research question Do ragworms (Nereis virens) predate on manila clam spat (Ruditapes philipinarum) and is the assumed predation dependant on the size of the ragworms and the size of the manila clam spat? Experiment Two sizes manila clam spat (average 1,3 mm and average 3 mm, from the hatchery Roem van Yerseke), were tested for predation by two sizes of ragworms (0-10 cm en 10- 20 cm from ragworm farm Topsy Baits) both fed and not fed with commercial feed. Results The graph left shows the survival of manila clam spat % survival Ruditapes philipinarum spat length ± (average size 1.3 mm) after 12 days. Ragworms fed with 1,3 mm 100 commercial feed showed almost no predation on the spat, 93 93 100 whereas ragworms which were not fed, show a predation of 90 78 74 22 and 26% , respectivaly for ragworms of size 10-20 cm and 80 70 size 0-10 cm. The control showed 100% survival. 60 50 40

% survival Ruditapes philipinarum spat length ± 3 mm

30 100

20

95

Zagers groot + voer

Zagers klein + voer

95

95

100

90

10 0

95

80 Zagers groot + voer

Zagers klein + voer

Zagers groot zonder voer

Zagers klein zonder voer

Blanco tapijt

70 60 50

The graph on the right shows the survival of manila clam spat (average size 3 mm) after 12 days. Ragworms fed with commercial feed as wel as the ragworms which were not fed, show almost no predation (just 5%) on manila clam spat. The control showed again 100% survival.

40 30 20 10 0

Zagers groot zonder voer

Zagers klein zonder voer

Blanco tapijt

Conclusion This experiment shows that ragworms eat manila clam spat of average size 1.3 mm, when they are not fed with commercial feed. Spat of 3 mm size is probably too large for ragworms to consume. During observation it was not seen that ragworms actively hunt on manila clam spat, it could be that the ragworms swallow the spat allong with the sediment. The size of the ragworms makes no difference in predation on manila clam spat.

Crop rotation of Salicornia and Ragworms: research for the possibilities of a crop rotation system between Salicronia europaea and Nereis virens Introduction The Heerlijkheid van Wolphaartsdijk is a family-owned company cultivating Common glasswort (Salicornia 2 europaea) and ragworm (Nereis virens). Ragworms are farmed in a 2000m foil-lined basin. Both types of cultivation are season bound. The basin for ragworms is unused (dry) from April until September. During this dry period unwanted organisms in the system are eliminated. To optimize land-use and nutrient efficiency, the SME is interested in the possibilities of implementing seasonal crop rotation of King ragworm and Common glasswort. Research question: How do the cultivations of ragworm (Nereis virens) and Common Glasswort (Salicornia europaea) affect each other when these are combined in a crop rotational system in a ragworm cultivation basin?

Glasswort rests: Food for King Ragworm?

King Ragworm season: Adding nutrients by feeding

This exploratory research targeting crop rotation has a practical approach. Two systems have been designed; one replicating the glasswort season and the other replicating the beginning of the ragworm growth season.

Glasswort season: Using the nutrients from Ragworm cultivation?

In the glasswort system, research topics were: • the germination of glasswort • salinity management • fertilization In the ragworm system, research topics were: • the consumption of glasswort by ragworms • the decay of glasswort in an inundated system. Results Right: Different growth forms probably caused by fertilization differences. Left: Salinity monitoring of water in sediment (initial irrigation with fresh water (germination period <2cm), followed by irrigation with saline (ground)water) Ragworms: Growth of King ragworms on a diet of (chopped) Common glasswort

Grow th over a period of 7 w eeks (%)

60 50 Small Ragworms <10cm + Glasswort

40 30

30,31 25,45

Mixed ragworms + Regular feed

20 10 0

large Ragworms >12cm + Glasswort

4,68

Conclusion - Results are promising, glasswort grows well in the system but extra fertilization give higher yields of glasswort. - Ragworms will only consume the green (softer) parts of glasswort. Wooden parts such as the root systems of glasswort could therefore cause a problem in the ragworm harvesting

with the current methods. - Salinization is an important factor to monitor and manage in closed (foil-lined) systems.

Predation of ragworms on Ulva: Can ragworms be used to control the growth of Ulva in shellfish ponds? The assignment included setting up an experimental structure in the SEA-lab were ragworms can be monitored. The main tasks of the assignment is to find the answer to the research question, which is done by carrying out small-scale experiments in the SEA-lab, monitoring the growth and decline of Ulva and the growth of ragworms feeding on Ulva; Compare the ragworms fed by Ulva with ragworms fed with fish food and measure the consumption of Ulva. The research question that will be answered will therefore be: What is the most suitable biomass of ragworms that will control the daily growth of Ulva in shellfish ponds ? The decision was made to keep the ragworms (Nereis Virens) in six aquaria were they would be fed on Ulva (Ulva Lactuca). These six aquaria would stay in the laboratory for approximately three months were the amount of Ulva was measured with an analytical balance, before being placed in the aquaria. After three months the weight increase of decrease of the ragworms will be measured. The results (see table 1) show us that the ragworms barely gain weight when only fed on Ulva even if enough seaweed is provided every day. Figure 1 Average weight of the ragworms

Weight Ragworms (g)

120 100 80

Tank A & B Ulva fed (big worms)

60

Tank C & D Ulva fed (small worms)

40

Tank E & F Fishfood fed (mixture size)

20 0 Week 1

Week 5 Week 8 Time (weeks)

Week 10

The decrease in biomass might be caused by the composition of the Ulva, which consists mainly of water and doesn’t contain many nutrients in relation to the volume. The seaweed might not have enough nutrients for the ragworms to grow as they normally do when provided with other nutrient rich food. There are only enough nutrients to keep them alive but not to grow.

Polychaete worms as a part of multitrophic water treatment: Possibiltities of Capitella sp. and Nereis diversicolor to remediate particular fish waste from a sea bass farm Research on the treatment of waste water of marine aquaculture began 15 years ago at a research institute based in the south of France (Ifremer). This treatment was based on the use of macro algae. Now Ifremer is interested in the possibilities of using Nereis diversicolor and Capitella sp.as a stepping stone for remediation of inorganic fish waste from the Sea bass farm at location. It is called a stepping stone because the waste will not only be treated by Nereis diversicolor and Capitella sp. for the particulate organic fish waste, but it probably will be treated afterwards by macro algae to decrease the concentration of nutrients. In the end, the water will be re-circulated into the fish farm. The possibilities of bioremediation of waste with the use of Nereis diversicolor and Capitella sp. were examined by using different scaled experiments. The initiator was interested in the possibilities of these polychaetes for remediation of particulate organic fish waste. These worms would not only be used for degradation of the particles but Capitella sp. and Nereis diversicolor also have an economic value (feed for fish or fish bait). During an experiment (on mesocosm scale) it was examined what the possibilities are for Nereis diversicolor and Capitella sp. to remediate particulate waste that comes from a sea bass farm. The focus will be on characterization of the particulate fish waste and water quality (nitrogen, phosphorous and organic matter) and biomass of worms (wet weight, dry weight and ash free dry weight). Two experiments were done. One experiment only with Capitella sp. and one experiment with both worms (Capitella sp. and Nereis diversicolor). Different densities of worms were used during the two different experiments. The objective of the first experiment was to evaluate the feeding capacity of Capitella sp. raised at different densities (0, -2 100, 1000 and 10.000 individuals per m ) and fed with fish waste. The objective of the second experiment was to compare the fish waste bioremediation by the two polychaetes Capitella sp. and N. diversicolor, raised individually and in combination (0 worms, 300 Nereis diversicolor, 150 Nereis diversicolor and 10.000 Capitella sp., -2 and 20.000 Capitella sp. individuals per m ). The underlying processes (converting waste load into biomass and converting of particulate organic fish waste into dissolved nutrients) are very dependent on the stocking density of worms and waste load of the fish farm (applicable to both experiments). Observed was that after 6 days of both experiments most of the particulate organic fish waste were used by the worms for biomass but also dissolving the nutrients in the water column. The treatments with the highest number of worms were breaking down the particulate organic fish waste very fast even a shortage of input was observed. This means that a bigger input of particulate organic fish waste is possible for more remediation. The treatment with both Capitella sp. and Nereis diversicolor was the most ideal because of the lowest mortal rate and good results on remediation. During the experiments several ideas came up to improve and change the follow-up experiments. One recommendation is to do a research on the ideal Capitella sp. Nereis diversicolor combination to enhance the reproduction of Capitella sp. but also the habitat of Nereis diversicolor. Also a flow through system could be a solution for a better experimental setup. During the experiment a shortage of particulate organic fish waste occurred. With a flow through system this could be prevented, necessary will be to do research on the ideal flow through ratio (l/h) and organic load.

Topic: CONTROL AND MONITORING OF A NATURAL (ALGAE) PONDS Control of Chaetomorpha linum in a micro algae pond: Research into unwanted growth of weed Introduction In the autumn of 2010 the seaweed Chaetomorpha linum (Kützing 1845) was first spotted in the natural algae pond of the Koninklijke Maatschap Wilhelminapolder. In spring 2011 the macroalgae had flourished and dominated the ponds ecosystem. The growth of Chaetomorpha is a problem as the pond is intended to grow microalgae which suffer under the direct competition with the seaweed. C. Linum is a filamentous macro algae that grows in dense mats. It is an opportunistic fast grower native to coasts and estuaries of nearly all continents. In its natural habitat it encounters and survives a wide range of ecological parameters. Research question: What are the most important environmental factors influencing the balance between Chaetomorpha linum and microalgae in the natural algae pond and what are possible management measures to control seaweed growth? Methods The competition between microalgae, macroalgae and the effect of each and every factor that influences the growth is a complex problem. To tackle this problem in a clear and meaningful way the problem was split up into a number of small and isolated subjects. Apart from a literature study the following factors were studied in a laboratory setting. Influence on growth of micro algae en seaweed of: • Nutrient amounts • The ratio between nitrogen and phosphorus • The physical condition of C. linum • Grazing by the polychaete worm Nereis virens • Salinity of the environment • Dehydration Conclusion Chaetomorpha linum is a tough, opportunistic weed. Literature shows that Chaetomorpha is capable of socalled luxury uptake (storage of nutrients) and therefore has an advantage over other organisms in environments with fluctuating nutrient concentrations. The studies have shown that no clear negative effect on the abundance is caused by either nutrient availability or salinity. Grazing and the drying of the seaweed did have an influence on the abundance or viability of Cheatomorpha. So far the best options for removing the seaweed seem to be drying or physically/mechanically harvesting the seaweed. Introducing Nereis virens or a similar herbivore to the pond could be a more long term solution and is probably suited as a biological control measure.

Biologische beheersing van Chaetomorpha linum in een vijver in Wilhelminadorp Introduction The algae pond in Wilhelminadorp is suffering from heavy competition by seaweed (Chaetomorpha linum). Because this has an impact in the production of the algae (and shellfish), methods should be developed for removal and control of the seaweed population. Research question: What are the most suitable methods for removing and controlling the Chaetomorpha linum population in the algae pond of the Koninklijke Maatschap Wilhelminapolder? Research For the removal of the Chaetomorpha several (mechanical, biological and chemical) methods will be analyzed. After weighing the pros and cons of each methods some will be selected for further study. Cost efficiency will be determined by means of tenders without engagement. Control of repopulation by Chaetomorpha is probably dependent on light as the seaweed biomass is located in the middle section of the algae pond. No seaweed is found in the deeper area’s (light limitation) and at the shores (previous research: sun induced drying). In the SEA Lab an experimental set-up has been made; samples of Chaetomorpha are kept under light and dark conditions. The results of the experiments will be referenced with results from within the algae pond (same experiment is being conducted in the algae pond at Wilhelminadorp). Since light is not the only factor which is affected by dense algae cultures, experiments with increased pHvalues (pH can get up to 10 in same algae ponds) are also set-up. Every week samples will be weighed and appearance (photo’s) will be determined by means of quantitative analysis.

Conclusion Results show that the removal of Chaetomorpha is probably most suitable by means of mechanical methods instead of biological methods . Mogelijke opties voor het verwijderen van Chaetomorpha linum zijn: een maaiboot, een kraan of een zeil dat in de onderste water kolom wordt geplaatst. Om te bepalen wat de beste methode is voor het verwijderen van Chaetomorpha linum zijn deze onderworpen aan een multi criteria analyse. Hierbij worden de methodes beoordeeld op een aantal criteria die in overleg met de opdrachtgever zijn opgesteld.

Monitoring seepage pipes feeding natural reservoirs with saline groundwater: a water system analysis Introduction Fam. Bolier farms lobsters in two (combined) natural water basins at Tholen. Since problems occurred with oxygen depletion, fam. Bolier installed several seepage pipes (with saline groundwater). The first step to further optimize the water quality, is to indicate the effect of these seepage pipes on the water quality. Research question How does the water system of fam. Bolier function in terms of water quantity and water quality? Water Balance The discharge of water flowing in- and out of the basins is measured (different tides induce different groundwater pressures and thereby different discharges). The precipitation and evaporation measurements of a nearby weather station are taken into account. Downward or upward seepage groundwater will be calculated as a rest term. Based on this, the retention rate of water in the basin is calculated. Substance Balance The chemical water quality is analyzed at different locations; at the inflow, in the basins, and at the outflow. Based on the chemical water quality and on the water balance, the load and uptake of substances is calculated. Results The results of this research were that there has been a significant difference involving residence time between the two basins. The big basin has got a quite high residence time (532 days) and a low concentration of nutrients; the smaller basin has got a lower residence time (68 days). In none of these basins the N-P ration is met. Conclusion In conclusion, this project met the requirements of our costumer request, but our recommendations are that a further study of this water system and a look into the events happening in the summer will give a higher accuracy in the results.

Topic: OPTIMIZATION OF LANDBASED SHELLFISH CULTURE Recirculation on a land based shellfish farm Zeeland Aquaculture is a pilot farm for cultivating shellfish on land and founded by Roem van Yerseke and Koninklijke Prins & Dingemanse. At Zeeland Aquaculture, cultivated shellfish are oysters, and clams. In former times, fishing for shellfish took place in the Eastern Scheldt but due to stricter legislation this is currently more difficult. At Zeeland aquaculture the shellfish are fed by micro-algae, in winter times Skeletonema costatum, because it`s a winter proof algae. The name skelet is owing to the silicate skeleton in the algae. Zeeland Aquaculture cultivates the algae themselves. In the figure below the total cultivation process is showed and explained by numbers. The required cultivation water gets pumped from the Eastern Scheldt to the Algae ponds. Meanwhile the water gets filtered up on to 50 µm, with goal that as less as possible (biological) material and organisms can enter the algae ponds, because they can have a negative influence on the algae growth. On the Eastern Scheldt water, three different nutrients are added with different concentrations, NH4CL, MAP, and NA2SiO3. Not only the nutrients are important for the algae growth, vitamins and trace elements are also, but can`t be really measured because they occur in low concentrations. Thereafter a low concentration of algae is added and the water is aerated. By aeration, the algae are brought to the surface level of the water so they can take up a maximal amount of sunlight, what is important for the photosynthesis. Photosynthesis is a process where the algae produces glucose and oxygen from light energy and CO2. When the algae have been growth to the desirable concentration, the algae get pumped to the shellfish ponds. In the shellfish ponds, the algae are consumed by the shellfish. When the water is clear, that is when all the algae have been consumed, the wastewater called effluent, will be pumped to the Eastern Scheldt and this process will be done again. However, the pumping of this effluent is very expensive. For Zeeland Aquaculture is tested if this effluent can be used again, circulated. Method The method used is the trial and error method. At the Eastern Scheldt water, the three different nutrients were added. With the Hach-Kit, the concentration of five nutrients was determined. After that, the algae cultivation took place. When this cultivation was done, the oysters and clams were added to the algae. When the algae were consumed the effluent of the beakers got filtered and the nutrient concentrations were determined. New nutrients were added to original cultivation water to have the same nutrient concentration at the beginning of the experiment. This process was repeated until a grow inhibition of the algae occurred. Conclusion For the growth of algae there are a couple of nutrients which are needed. Phosphor, nitrate and silicate are some of them and that where the nutrients that have been measured. There are dozens of trace elements and vitamins in the Eastern Scheldt water that occur in a low concentration and cannot be really measured. As can be seen in the results, at the third cultivation, an grow inhibition of the algae takes place. Not the nutrients were totally consumed, they were always added when needed. Daresay there is a difference in nutrient consumption in the experiment. At the first cultivation higher nutrient concentrations were consumed. At the third, less were. Now assumed causes for the grow inhibition is that the vitamins and trace elements are totally consumed after two cultivations. Another reason could be that an accumulation of toxic substances arises because constantly the same water is used and there is no real exchange of substances in the beakers. So as conclusion there are two causes mentioned, it is even possible that both of the causes occur.

Pseudofaeces threshold and growth inhibition of Pacific Oysters (Crassostrea gigas) De Japanse oester (Crassostrea gigas) is in 1964 in de Oosterschelde geïntroduceerd om de oestersector te redden na de massale sterfte van de platte oester (Ostrea edulis.). Als gevolg van deze introductie maakt de Japanse oester nu deel uit van de schelpdierenkweek in Nederland. Over de productie van pseudofaeces en het effect daarvan op de groeiontwikkeling van de Japanse oester in het Nederlandse klimaat is weinig bekend. In het kader van het RAAK project wordt onderzoek gedaan om kweekmethode van schelpdieren zoveel mogelijk te optimaliseren. Deze kennis kan in de toekomst worden gebruikt door de schelpdiersector. Een te hoge algenconcentratie zorgt voor overbelasting van het spijsverteringskanaal en het teveel wordt dan als pseudofaeces naar buiten gebracht. De algen worden hierbij uit het water gefilterd door de kieuwen maar niet naar het spijsverteringssysteem getransporteerd. Het voeren van te hoge algen dichtheden veroorzaakt remming van de groei volgens literatuur. Tijdens het onderzoek werden de oesters gevoerd met de Zeeland Aquacultuur alg, een alg die tot de Skeletonema soort behoort. Het onderzoek bestond uit twee fasen. In fase 1 werd onderzoek gedaan naar de pseudofaecesgrens in cellen per milliliter, bij drie verschillende temperaturen en oesters van verschillende groottes. Gedurende drie weken werd er dagelijks een bekende algenconcentratie toegevoegd aan de emmers, waarna visueel gemonitord werd of de oesters pseudofaeces produceerden. De definitie van de pseudofaecesgrens in dit onderzoek houdt in dat meer dan 50% van de oesters pseudofaeces produceerden. De pseudofaecesgrens in cellen per milliliter van grote en middelgrote oesters bij verschillende temperaturen staat weergegeven in tabel 1. 5 °C ps-grens grote oesters (± 10 cm)

100.000

12 °C 150.000

20 °C 150.000

ps-grens middelgrote oesters (± 6 cm) 25.000 25.000 50.000 Tabel 1 pseudofaeces grens (in cellen per milliliter) van grote (10cm) en middelgrote (6 cm) Japanse oesters bij de temperaturen 5, 12 en 20 graden Celsius. In fase 2 van het onderzoek werd onderzocht wat voor effect de productie van pseudofaeces heeft op de specifieke groeisnelheid van de Japanse oester. Het onderzoek werd uitgevoerd in drie 45 liter aquariums met verschillende behandelingen in algenconcentraties ten opzichte van de pseudofaecesgrens van kleine oesters (3 cm). Gedurende 42 dagen werd de algenconcentratie en temperatuur bij elke behandeling zo constant mogelijk gehouden. Bij elke behandeling zijn visueel pseudofaeces waargenomen. De hoogste specifieke groeisnelheid van 0.31 ± 0.12 % werd waargenomen bij een algenconcentratie van 40.000 cellen per ml. Bij algenconcentraties van 20.000 en 100.000 cellen per ml was de specifieke groeisnelheid lager, namelijk 0.10 ± 0.026 % bij 20.000 cellen per ml en 0.14 ± 0.09 % bij 100.000 cellen per ml. Er is een optimum in specifieke groeisnelheid van kleine Japanse oesters (3 cm) rond een algenconcentratie van 40.000 cellen / ml. Dit rapport laat zien dat de optimale algenconcentratie om kleine oesters (3 cm) te voeren ligt rond de 40.000 cellen / ml. Voeren boven deze concentratie is verspilling van kostbare gekweekte algen en draagt niet bij tot een hogere specifieke groeisnelheid.

Topic: MACRO ALGAE Macro algenfilter voor afvalwater tarbotkweek In 2006 the company GrovisCo started the raise of Turbot with a remote system called RAS. RAS (Recirculating Aquaculture System) is an indoor system with the advantage that the climatic conditions throughout the year can be controlled. The water consumption is kept low, because most of the water in this system is being recirculated. A disadvantage of the RAS system is the waste stream leaving the company. This also happened at GrovisCo, and the company must pay tax on the waste stream that they discharge. This waste water is rinsing water coming from the drum filter. The waste water contains fish faces, food and a high concentration of nutrients. The organic parts form a floating layer on the water. The tax is determined on the amount of COD (Chemical Oxygen Demand) present in the water. To remove nutrients from salt water, a filter based on macro algae could be used. In addition to purification of waste water, this has the advantage that the produced macro algae can be sold. Previous research at GrovisCo conducted by HAS Den Bosch and Van Hall Larenstein, showed that Ulva Lactuca is not capable for the purification of GrovisCo wastewater. The death of the macro algae occurred under the influence of high flow rates and competition from microalgae. Because the macro algae Laminaria digitate and Sacharina latisisma are more resistant against the larger flow rates, these macro algae were investigated if they were suitable for the purification of the wastewater at GrovisCo. The macro algae were from Hortimare. To create the right conditions for the macro algae, a test setup was built for the waste water flow. The experimental set-up consists of a compartment where the water is pre-treated, and a subsequent compartment in which the macro algae are placed. The pre-treatment of waste water consist of the removal of the floating layer by means of skimmers, and the sedimentation of organic material by means of a settling tank. In the compartment with the macro algae a paddle wheel is placed to regulate the flow. From this compartment the water flows toward the ditch. To determine the purification capacity of the macro algae (absorption of nutrients) there was a measurement twice a week at the inflow, after pre-treatment and at the outflow. To monitor growth, the biomass of the macro algae is measured twice a week. The pH and temperature were both monitored. To follow the development of the macro algae there was a weekly visual inspection of the macro algae with the use of a microscope. There is no decrease measured in concentration of nutrients or in the growth of algae. Purification of the wastewater has not occurred. Despite of the pre-treatment of wastewater the high content of organic material in the first compartment landed on the algae and choked the macro algae (a sticky layer is observed on the macro algae). There was also Gammarus (shrimp-like species) and Nematodes (worm-like) observed, who had eaten the macro algae. The macro algae Sacharina latissima and Laminaria digitata are both not suitable for the purification of the wastewater with high organic fraction. Recommendation for future research is to remove (or to mineralize) the organic fraction sufficiently from the wastewater stream before the water comes in contact with macro algae.

Production of nutrient enriched Ulva for the purpose of fish feeding and its effects on fish growth A strategy to promote sustainable aquaculture is the development of integrated aquaculture. FAO describes integrated farming systems as: "an output from one subsystem in an integrated farming system, which otherwise may have been wasted, becomes an input to another subsystem resulting in a greater efficiency of output of desired products from the land/water area under a farmer’s control". A number of studies are currently testing the integrated approach and early results show considerable potential for the bioremediation of nutrient-rich waters (Pagand, 1999, Angel, 2004). Another issue regarding the sustainability of aquaculture is feeding of the fish. With the Figure 1. Several elements of the experiment. A: high rate algae pond (HRAP) where the ulva is farmed; B: Aeration propeller of the high rate algae pond, which keeps the ulva in current situation of fish stock decreasing constant movement. C: ulva used in the experiment; D: Fish used during the experiment, worldwide, aquaculture could become an Salpa Sarpa, during the biometry. important step to allow the replenishment of the oceans in regards to this particular life form. The food for fish is expensive which makes the price of rearing the fish higher and often contains fish meal and fish oil. Ulva spp., commonly known as the “sea lettuce” is a member of the Ulvaceae family. This species of algae is known for being opportunistic, due to its morphology that allows a quick intake of nutrients in the water (Pettett, 2009). This characteristic is also what makes it a species of interest for studies regarding biological water treatment. In the study of integrated aquaculture, this species is also investigated for its potential of serving as fish feeding. The main focus of this project is to study how to increase the quality of the ulva as a fish feed and test its viability as a food for the herbivorous fish, Sarpa Salpa.

Results are not yet available.

Topic: RAS: RECIRCULATING AQUACULTURE SYSTEMS Influence of ammonium on Senegal sole physiology: ammonium and growth, osmoregulation and stress in the flatfish Solea senegalensis In this research the necessity of knowledge about the influence of ammonium on the Senegal sole will be fulfilled. The Senegal sole (Solea senegalensis) is a species related to the common sole (Solea Solea) but only occurs at the shoreline of Spain and Morocco, as shown in figure 1. Furthermore previous research has shown that there is an influence on the Senegal sole by ammonium, but only on the stress system of the fish. This research will focus on the relation between the amount of ammonium and the influence on the liver, the blood, the growth and the gills, therefore measuring several substances. What is the effect of different ammonium levels, low and high, in seawater on the biological conditions of the Solea senegalensis? A raising of ammonia concentration in seawater is likely to affect the metabolism of the juvenile Solea senegalensis. Therefore the soles were placed in tanks with water and an extra addition of ammonium to raise the concentration of ammonia. This was done to find out the influence of ammonia on the metabolism of the Senegalese sole. The fish were placed for 24 days in tanks with a average ammonia concentration of 0.29 ± 0.04 mg/L (high) or 0.13 ± 0.01 mg/L (medium) or 0.00 ± 0.00 mg/L (control).

The influence on the growth was that the weight gain and the relative growth rate where negative without a significant difference between groups. And with a significant difference between the control (0.90 ± 0.00 g/cm3) and the high (0.84 ± 0.01 g/cm3) group for the condition factor. The stress parameter glucose shows as significant difference between the control (2.1 ± 0.2 mM) and high (5.0 ± 0.5 mM) group. In the gills no significant differences were found. In the enzymes several differences were found. Most of these differences suggest an energy shift in relation to stress response. Therefore the Senegalese sole seems to adapt to the toxic situation by a different use of energy, but this influences the health indicated by the condition factor.

Werkpakket 3: New species Topic: Landbased European lobster cultivation Lobster cultivation on land: desk study and experimental research on the land based culture of the European lobster (Homarus gammarus) INTRODUCTION Seepage fed water bodies (eight hectare) near Scherpenisse (the Netherlands) are leased by the family Bolier. Since a few years they experimented with restocking of benthic lobster juveniles (Homarus gammarus) in these water bodies. Recently the permit for fishing lobsters in the Eastern Scheldt has been withdrawn thus endangering the restocking program. One of the possible solutions is land based culturing of benthic larvae. PELAGIC LARVAE The first batch of 600 larvae (300 larvae per batch) were placed in rectangular aquaria (45 l) at a stocking density of 3 larvae/liter. These aquaria were filled with saline groundwater (salinity 29 g/l) and were aerated. 25% of the water was refreshed daily and 100% was refreshed after a whole week. Due to high mortality larvae were transferred to either big (70 l) or small (25 l) aerated cylinders filled with saline groundwater. Stocking density was kept at 3 larvae/liter. 25% of the water was refreshed daily and 100% was refreshed after a whole week. The mortality in these rectangular aquaria were high probably due to cannibalism. After one week there was a mortality of 50% in the first batch and 70% in the second batch. In the big cylinder the mortality was 97%. Only 1-6 larvae reached the forth larval stage (benthic stage) in these big cylinders. In total 21 larvae reached the fourth larval stage. This gave a survival rate of 25%. BENTHIC LARVAE The benthic larvae were divided into two housing systems; individual and collectively. The individual housing was done in unheated aerated small aquaria (2,5 liter) filled with saline groundwater (salinity 29 g/l). In this system water was refreshed daily (25%) and weekly (100%). The collectively housed larvae were placed in a basin (1 m2) with a sandy bottom at 20°C. Empty oyster shells were provided as shelter-possibilities. 25% of the water in this system was refreshed weekly. All 9 benthic larvae survived in the individual housing system. These larvae had an average carapace length of 6 millimeter. 5 out of the 20 collectively housed larvae survived thus giving a mortality of 75%. The larvae in the collectively housing system had an average carapace length of 10,4 millimeter. CONCLUSION This research concluded that the type of housing systems is essential to survival of pelagic lobster larvae. Rectangular aquaria and big cylinders as housing systems resulted in unacceptable mortalities The small cylinder generated a lower mortality, however compared to conical tanks as used in literature some room for improved remains. Growth of benthic larvae is higher at 20°C compared to the unheated aquaria. However individual housed larvae resulted in lower mortality.

Kreeftenkweek in zoute inlagen: berekeningen van draagkracht en inschatting van de productie van zeekreeft (Homarus gammarus) in natuurlijke zoute inlagen. INTRODUCTION This research is carried out for the Bolier family. The family lives near the Easterscheld, in the neighborhood of the village of Scherpenisse. For many years, wild lobster were caught in the Easternscheld and sold by the family. Lobsters which were smaller than the legal market size were placed in two saltwater ponds. A while ago, the legislation to catch wild lobsters, which the family used to had, was withdrawn. This project is started to investigate the possibilities for breeding lobster(larvae) and grow them out in the saltwater ponds. The possibilities for breeding lobster larvae will be investigated by the means of experiments with a female lobster. The carrying capacity of the ponds will be researched and an production estimation for lobster culturing in the ponds will be made.

Loc

METHOD According to literature, lobster larvae can be hatched as followed: A female lobster, which carries eggs underneath her tail, is placed in a tank. These tank is connected to an flow through system. By raising the water temperature, the eggs will develop faster than in nature. After the hatching, the larvae will be placed in two conical bins. These bins have a water inlet in the bottom. When water enters the tank this way, a turbulent flow develops. Due to this flow, the larvae will be spread equally in the water column. While the larvae live in this tank, they will be fed with living Artemia. The larvae are pelagic in the first three till four weeks of their life. After this period they become benthic, and starts living on the botom. In the pictures on the right, the conical tanks , the female lobster and a newborn juvenile are shown. Before calculating the carrying capacity, the kinds and the area which substrates have in the ponds had to be determined. The substrates which are present in the ponds are: cobblestone, stone rubbish, peat, clay and silt. Numbers for the carrying capacity in grams per square meter are found in literature for some of these substrates. For values which were not found, assumptions were made. In the table aside, the carrying capacity per substrate is shown. Production of lobster in the ponds depends on yearly mortality and growth of the lobster. Left: fase 1 juvenile (pelagic), right: fase 4 juvenile (bethic) RESULTS & CONCLUSION In this research, 300 lobster larvae are hatched from two female lobsters. Three larvae survived till the benthic fase. The maximum carrying capacity of the biggest pond is estimated on 1500 kg. The small pond can contain almost 300 kg of lobster. This are lobster in the age of 0 – 5 years. The production model for lobster is based on these carrying capacities. Mortality and growth are taken into account. Based on an production model, between 1100 and 2500 lobsters can be harvested in the big pond. In the small pond, these numbers are 220 and 450 respectively. In order to hold an stable population, over 7000 juveniles have to be stocked in the big pond per year. In the small pond, this number is almost 1500. These are fase IV juveniles.

Work package/Topic

Publication title:

Type of publication:

Authors:

WP1 Algae

Culture of the algae Chaetoceros muelleri on waste water of a turbot farm

Research report

Roel Maas en Niels Gelderland

Publication date: July 2011

WP2 Integrated Aquaculture Groundwatercharacteristics Zout grondwater, de bron voor binnendijkse aquacultuur Solutions for a filtration stop of mussels in a specific type of groundwater: Case mussel pilot La Solitude

Role of ragworms in IMTA

Control of a natural algaepond

Optimization of landbased shellfish culture

Suitability of Kustlab groundwater for aquaculture purposes: Bioassays with shellfish, ragworms, algae and sole Literature research groundwater characteristics Bioassays met tapijtschelpen op 3 verschillende typen zout grondwater Gebruik van grondwater voor zilte aquacultuur op land in Zeeland: ervaringen en resultaten van drie jaar onderzoek (periode 2009 – 2012) Bioassays met tapijtschelpen en Skeletonema op grondwater van VAM, Grovisco en SEAFARM Predation of Ragworms on Manila clam spat in integrated aquaculture systems: A small scale experiment Crop rotation of Salicornia and Ragworms: Research for the possibilities of a crop rotation system between Salicornia europaea and Nereis virens Predation of ragworms on Ulva: Can ragworms be used to control the growth of Ulva in shellfish ponds? Polychaete worms as a part of multitrophic water treatment: Possibilities of Capitella sp. and Nereis diversicolor to remediate particular fish waste from a sea bass farm. De potentie van zagers in zoute Integrated Multi-Trophic Aquaculture systemen Wisselteelt zeekraal en zagers: effect van stikstofgiften op productie van zeekraal Control of Chaetomorpha linum in a micro algae pond: Research into unwanted growth of a weed Biologische beheersing van Chaetomorpha Linum in een vijver in Wilhelminadorp Monitoring seepage pipes feeding natural reservoirs with saline groundwater: A water system analysis

Artikel in HZ Discovery Research report Research report Review Research report Artikel in Aquacultuur magazine Research report

WP3 New species

Samara Hutting, Kristiaan van Rooijen

Dr. J. Rijstenbil Tessa Steenbakker, Wendy Wosten

Research report

February 2012 February 2012 June 2012 July 2012 December 2012

Gerard van der Pluijm, Artis Vansovics, Jerre Wiersma

Research report

January 2013 June 2011

Minor research, Vlissingen Research group Aquaculture, Vlissingen Extern: AE3 consultancy Minor research, Vlissingen Research group Aquaculture, Vlissingen Minor research, Vlissingen Research group Aquaculture, Vlissingen

2nd year study project, Vlissingen

Research report Artikel in Aquacultuur magazine

Vera van Bruggen

February 2012

Internship study, Montpellier Research group Aquaculture, Vlissingen

Research report

Gijs Doornbusch

Research report

Marijn Biekart Maarten Fritz, Lieke Beezemer, Jorn Schoordijk, Erik Mastenbroek. Frauke Hünnekes, Tim van Roon, Rita Lemos & Laura Schneegans Emiel Almekinders, Lyudmil Doshev, Arnoud Rijk, Lauran Verstaeten Joris Gommers, Benno Janse, Marijn Koole, Pim van Zevenbergen, Tianyi Hu Jorn Schoordijk en Maarten Fritz

Research report Research report

July 2012 January 2013??

Minor research, Vlissingen Final thesis, Vlissingen

January 2012

2nd year study project, Vlissingen

February 2012

2nd year study project, Vlissingen

January 2013

2nd year study project, Vlissingen

January 2013 January 2013

2nd year study project, Vlissingen Minor research, Vlissingen

January 2013

Minor research, Vlissingen Minor research, Vlissingen Internship study, Montpellier Internship study, Cadiz

Research report

Recirculation of water in a land based shellfish farm Effect pseudofecesproductie op groeiontwikkeling van oesters

Research report Research report

Effect pseudofecesproductie op groeiontwikkeling van tapijtschelpen

Research report

Macroalgenfilter voor afvalwater tarbotkweek Production of nutrient enriched Ulva for the purpose of fishfeeding and its effects on fish growth Influence of ammonium on Senegal sole physiology; Ammonium and growth, osmoregulation and stress in the flatfish Solea senegalensis Lobster larvae culture on land: Desk study and experimental research on the land based culture of the European lobster (Homarus gammarus) Kreeftenkweek in zoute inlagen, berekeningen van draagkracht en inschatting van de productie van Zeekreeft (Homarus gammarus) in natuurlijke zoute inlagen.

Research report

Erik Bisslik en Govert Kersten Pieter Bas Dijkman, Bart de Clerck, Koen Schippers

Research report

Rita Lemos

June 2012 February 2013 (expected)

Research report

Jan Janse

February 2012

Research report

Pim van Meerkerk

Research report

Johan de Bat

Desk study report

Internship study, Vlissingen

January 2012

Monitoring of a natural algae pond

Verkennende literatuurstudie abalonekweek

Research group Aquaculture, Vlissingen

February 2012

Research report

January 2012

Minor research, Vlissingen

Jasper Schlahmilch Wouter Bareman, Joshi Lenferink, Anna Roman and Tianwen Xia

Macro algae

RAS

December 2011

Research done by/research type:

August 2011

June 2012 April 2012

Internship study, Vlissingen

Internship study, Vlissingen Research group Aquaculture, Vlissingen