WWW.WAS.ORG • WORLD AQUACULTURE • JUNE 2014 23 Land-based Integrated Multi Trophic Aquaculture (IMTA) production systems are part of an important development toward sustainable aquaculture (Smith and Barlow 1999, Chopin 2006). In the Delta Area of the southwest Netherlands, several companies have started pilot projects with extensive integrated marine aquaculture in landbased ponds. Most of these production systems cannot rely on open seawater with a stable composition because of fluctuations in temperature and nutrient concentrations. In IMTA, algal production is the basis of the food chain (Barbosa et al. 2009). To obtain continuous microalgae production, nutrients must be supplied and water must be filtered to remove unwanted organisms. Saline groundwater is rich in nutrients, contains no unwanted marine organisms and has a constant temperature. In some cases, the use of saline groundwater may be a solution to problems related to the use of open seawater. Saline groundwater is available in the entire Delta Area of the southwest Netherlands. In some cases, groundwater improves the performance of cultivated organisms, in other cases growth is inhibited, and occasionally, groundwater causes acute mortality. The composition of groundwater varies with local geology and history. In the Delta Area of the southwest Netherlands, with its history of flooding and reclamation of land, saline groundwater originates from intrusion from the sea and infiltrated floodwater. In some locations, saline groundwater can be found just below the surface; in other locations, suitable saline groundwater can only be found at nearly 200 m depth. Regional soil experts have limited information about the chemical composition of saline groundwater because it differs by location and depth. Prior to starting an aquaculture project using saline groundwater as a water source, exploratory drilling is needed to Composition, Treatment and Use of Saline Groundwater for Aquaculture in the Netherlands Tony van der Hiele, Jan W Rijstenbil, Jorik Creemers and Jouke Heringa locate a sufficiently saline aquifer. Usually chemical analysis is performed on a well-preserved sample as it reaches the surface. In most cases, aeration and filtration (iron removal) is needed to make the groundwater suitable for aquaculture. Short-term bioassay tests determine the suitability for aquaculture of chosen organisms. These bioassays are performed using a standard, 72-h protocol for algae growth (NENEN-ISO 10253:2006) and a 4-wk growth protocol for shellfish spat developed by the HZ University of Applied Sciences. If bioassays result in growth inhibition or mortality, it is important to establish the causes and to find economically feasible treatment solutions to make groundwater suitable. The research group Aquaculture in Delta Areas of the HZ University of Applied Sciences and AE3 Consultancy joined forces to map the experiences of 12 groundwater sources in the Delta Area of the southwest Netherlands to establish causes of growth inhibition/mortality and to find economically feasible solutions to treat these types of saline groundwater (Fig. 1). This article focuses on cases where problematic groundwater types are involved, concerning algal culture and shellfish cultivation. Bioassay results and the experience of companies indicate three problematic groundwater sources in the Delta Area of the southwest Netherlands: VAM (Van Antwerpen Milieutechniek), La Solitude Mussel Pilot and Grovisco Turbot farm (Fig. 1; Table 1). Saline Groundwater Composition and Chemistry Groundwater salinity per se does not necessarily meet the osmotic requirements of organisms grown in aquaculture. Sometimes, poor performance is obviously the result of low salinity. For yet unknown reasons, even in groundwater at 30 FIGURE 1. Locations of saline groundwater sources in the southwest Delta Region of the Nerthlands, indicating the sources mentioned in this article. Land-based Integrated Multi Trophic Aquaculture (IMTA) production systems are part of an important development toward sustainable aquaculture. In the Delta Area of the southwest Netherlands, several companies have started pilot projects with extensive integrated marine aquaculture in land-based ponds. (CONTINUED ON PAGE 24)
RkJQdWJsaXNoZXIy MjExNDY=