Role of Aquaponics in the Sustenance of Coastal India – Aquaponics Is A
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International Journal of Fisheries and Aquatic Studies 2017; 5(2): 441-448 E-ISSN: 2347-5129 P-ISSN: 2394-0506 (ICV-Poland) Impact Value: 5.62 Role of aquaponics in the sustenance of coastal India – (GIF) Impact Factor: 0.549 IJFAS 2017; 5(2): 441-448 Aquaponics is a solution for modern agriculture in © 2017 IJFAS ecologically sensitive Indian mangrove Sundarbans: www.fisheriesjournal.com Received: 20-01-2017 A review Accepted: 21-02-2017 Deepta Chakravartty Department of Oceanography, Deepta Chakravartty, Asish Mondal, Propa Raychowdhury, Subhra Techno India University, EM Bikash Bhattacharya and Abhijit Mitra 4/1, Salt Lake Campus, Kolkata, West Bengal, India Abstract Asish Mondal Providing a concrete global food guarantee has been the vision of scientists, world leaders, and nations. Department of Oceanography, With a constantly growing per capita income in India, the demand for fish is on the rise. Over Techno India University, EM exploitation of aquaculture in mangrove areas, have resulted in loss of local habitat, and the restricted 4/1, Salt Lake Campus, Kolkata, shrimp exports. This is a critical environmental imbalance as the mangroves are the lungs of our planet. West Bengal, India India is the world’s second largest food fish producer and newer sustainable technologies must be adopted. Aquaponics is a combination of aquaculture together with growing vegetables and crops without Propa Raychowdhury the use of fertilizers. Integrated multi-trophic aquaculture (IMTA) involving aquasilviculture can be Department of Biotechnology, employed to integrate food with bio mitigation of the Sundarbans. Its application has potential in the Techno India University, EM Indian Sundarbans as a method for environment-friendly aquaculture. We investigate the possible use of 4/1, Salt Lake Campus, Kolkata, aquaponics as a means for food production without compromising the mangrove wetlands. West Bengal, India Keywords: Aquaponics, IMTA, mangroves, mitigation, sustainability Subhra Bikash Bhattacharya Department of Oceanography, Techno India University, EM 1. Introduction 4/1, Salt Lake Campus, Kolkata, Freshwater and irrigational land is gradually disappearing as result of industrialization and West Bengal, India excessive use of chemical fertilizers. This is resulting in the expansion of aquaculture from freshwater to marine and brackish water regions [1]. Nearly 73% of the Indian Sundarbans Abhijit Mitra population is directly or indirectly dependant on aquaculture as a means of livelihood [2]. Department of Marine Science, University of Calcutta, 35 B.C. World Bank mentions that fish comprises 16% of animal protein consumed globally. With per Road, Kolkata, West Bengal, capita income on the rise, this hunger for fish will only go up [3]. Global food fish production India has exceeding 66 million tonnes, with India ranking second at 4.2 million [4]. It is evident that aquaculture is constantly expanding hence new sustainable technologies need to be adopted to continue feeding the world. Intensive monoculture and over-exploitation of the mangrove wetlands for aquaculture production is one drawback of in this sector. Tiger shrimp culture in the Indian Sundarbans has resulted in the loss of wetlands and mangroves [5]. Apart from serving as an ecological niche for a variety of flora and fauna, the mangroves stand to detoxify the anthropogenic and natural wastes released daily. Tiger shrimp and pacific white shrimp have been flagged witha [6, restriction for export to the western buyer as they are produced by un-sustainable practices 7] . This adversely affects the export trade of food fish from the coastal regions of India, which include the Sundarbans. For improving the environmental stability or biological mitigation of the mangrove regions, mixed species polyculture with a combination of shrimps and fishes is a definite solution. Polyculture is a sustainable option which is a combination of various feeding habits resulting in fishes consuming natural available plankton and insects, followed by application of proper formulated feed for optimum harvest [8-12]. Another method called integrated multi-trophic Correspondence aquaculture (IMTA) refers to a system of culture where the wastes of a certain species are Deepta Chakravartty energy or carbon source for another species. This system includes fin-fishes and shrimp culture Department of Oceanography, Techno India University, EM along with shellfish and herbivorous fishes and marine algae varieties. Polyculture can be the 4/1, Salt Lake Campus, Kolkata, co-culture of different fishes in the same trophic level; however, IMTA includes maximum West Bengal, India utilization of all the various trophic grades [13, 14]. ~ 441 ~ International Journal of Fisheries and Aquatic Studies In addition to polyculture and IMTA, the technique of protecting our wetlands along with an insight on the aquaponics may be a probable solution to address the efficiency of the technology. concerns relating to threats to the mangrove ecosystem and water availability. With water conservation being a top 2. The Nitrogen Cycle priority in modern agricultural processes, aquaponics may The nitrogen cycle is well complimented by aquaponics (Fig. improve agricultural sustainability and performance with 1). Feed is administered to the fish grow-tanks, which is limited use of nutrients and maximizing land utility [15]. It’s a digested to produce waste. Fish excrete ammonia through tried and tested method to farm fish in grow-tanks using urine, faeces (approx. 17%) and their gills (approx.. 80%). necessary aqua-feed and additives. The nutrient rich water is The nitrification cycle is the process by which the ammonia pumped out into grow-bedswhere vegetables and crops are produced by the fish is converted by Nitrosomonas bacteria to grown and harvested. The water which gets filtered by the nitrite and then by Nitrobacter to nitrate which acts as nutrient growing crops then goes back to the fish tanks. For the for the plants [17, 16]. Sundarbans, brackishwater aquaponics may be adopted for Ammonia (NH3) in water exists as total ammonia nitrogen shrimp and fish polyculture along with mangrove sampling (TAN), described by the following equation [15]: production which has been discussed later in the paper. Such + + programmes can improve aquaculture production along with NH4 ↔ NH3 + H (1) providing stability to the region. Aquaponics can be effectively used to treat waste water Feeding rate is a crucial factor in generation of ammonia in an effluents of the aquaculture ponds. Fish farming discharge aquaculture pond, and this can be described by [18, 15]: water is high in nitrogen, phosphorus and solids which can be utilized by constructed mangrove grow beds. Re-utilizing PTAN = (Daily Feed in Grams) X (%age of Protein Content in these nitrogenous compounds is beneficial since this can Feed) X 0.092 (2) cause ammonia and nitrite toxicity [16]. In the following sections we will discuss about the types of aquaponics PTAN is the total ammonia production in grams per day. systems and their derivates which can be recommended for Fig 1: The nitrogen cycle in aquaponics - + -1 In aquaponics, the growth of plants from the aquaculture NH3 + 1½O2 ↔ NO2 + H2O + H + 84 kcal mol (3) + water fed system results in consumption of NH4 which in + turn converts NH3 to NH4 for balance according to equation Followed by the second step conversion by Nitrobacter (1). Nitrifying bacteria present in the plant grow beds/bio bacteria: - filters convert ammonia to NO3 from which plants take up [15, 19 20] - - -1 their nitrogen requirements in aquaponics (Fig. 2) . NO2 + ½O2↔ NO3 + 17.8 kcal mol (4) This process is catalyzed first by Nitrosomonas bacteria by the following equation: Hence the stocking density of plants is a crucial factor to balance the nutrient requirements for crop production. ~ 442 ~ International Journal of Fisheries and Aquatic Studies negative aspects. The weight of gravel requires strong support structures. It is subject to clogging with suspended solids microbial growth and the roots that remain after harvest [26]. Fig 2: A. Beneficial colonies of bacteria as green bio-film on gravel plant grow beds in an aquaponic system. The action of Nitrosomonas and Nitrobacter species of bacteria in conversion of ammonia from Fig 4: Gravel system methods - the aquaculture effluent water into NO3 for plants to take up nitrogen. B. Planting tomato saplings in the gravel beds. (c) Nutrient Film Technique (NFT). This is a method in which the plants are grown in long narrow channels (Fig. 3. Types of Aquaponics and related Systems 5). A thin film of water continuously flows down each (a) Floating raft method. In a raft system (also known as channel, providing the plant roots with water, nutrients float, deep channel and deep flow) the plants are grown and oxygen [27, 28]. Troughs are used in this method which on polystyrene boards (rafts) that float on top of water is lightweight, inexpensive and versatile. Troughs can be (Fig. 3) [21, 22]. A significant amount of nitrification occurs mounted over rearing tanks to efficiently use vertical on the undersides of the polystyrene sheets. The system greenhouse space [29]. Few drawbacks of NFT method are provides maximum exposure of roots to the culture water a separate bio filter is required, because there is not a and avoids clogging. The sheets shield the water from large amount of water or surface for the beneficial direct sunlight and maintain lower than ambient water bacteria to live. In addition, the plumbing used in a temperature, which is a beneficial feature in tropical hydroponic NFT system is usually not large enough to be systems [23]. Most often, this is in a tank separate from the used in aquaponics because the organic nature of the fish tank. Water flows continuously from the fish tank, system [23]. The thin film of water that flows through NFT through filtration components, through the raft tank (nutrient film technique) channels absorbs oxygen by where the plants are grown and then back to the fish tank. diffusion, but dense plant roots and associated organic The beneficial bacteria live in the raft tank and matter can block water flow [30].