Integrated multitrophic aquaculture

There has been a growing concern in recent years about the impacts of aquaculture on the environment and natural resource supplies. It is estimated that 85% of the phosphorus, 80-88% of the carbon, 52-95% of the nitrogen and 60% of the mass feed input in aquaculture ends up as a particulate matter, dissolved chemicals or gasses. Uncontrolled nutrients released by aquaculture operations harm the industry in at least three ways: reduced water quality, loss of valuable nutrients and adverse effects on the health of cultured organisms. This situation has to be corrected. The most prominent characteristic of some aquaculture production systems is the presence of biofilters, which helps in internally treating the water containing waste from the cultured organisms. The future of aquaculture must be based on the development of sustainable environment-friendly systems such as the Integrated Multitrophic Aquaculture. This provides an effective way of treating aquaculture water and can be done by bacteria, microalgae, macroalgae and suspension feeders

Types and abundance of macro and micro-marine debris at Sebatik Island, Tawau, Sabah

The amount of marine debris is increasing worldwide and has become a matter of serious concern. It is important to identify the nature of debris to understand the sources and to devise practically feasible methods for managing this problem. This study was carried out at Sebatik Island on the east coast of Sabah with the aim of examining the types and abundance of macro – and micro-debris. The observations covered a period of December 2015 – May 2016. Debris collected from different stations was compared. Transect line method was used to assess the stranded macro-marine debris (SMD). Evaluation of floating macro- debris (FMD) was done by surveys of the selected areas. Density separation technique was applied in order to extract the micro marine debris (MMD). Results showed 14 types of SMD and 9 types of FMD in the study areas. Three major types of SMD and FMD were discarded plastic, organic debris and plastic bottles. Four types of MMD recorded at the beach and mudflat areas were fragments, fiber, films and polystyrene. Based on the comparison between stations (S), S2 showed the highest abundance of SMD with 80 items m-2. Meanwhile, FMD at one location was as high as 94 items m-2. Station S3 has the highest of MMD with 22 items ml-1. Plastic formed (40%) of the SMD category whereas FMD constituted 42 % at the Sebatik Island. Small fragments and film were the most abundant of MMD (32 %). This study highlights the scale of the marine debris problem in Sebatik Island and calls for a comprehensive plan of action to protect the Island’s marine ecosystem services

Aquaponic application in a marine hatchery system

Seaweeds of various species have been studied as nutrient biofilter for treating effluents from enclosed mariculture system since mid 1970’s. This study was conducted to determine the Euchuema spinosum (also known as E. den- ticulatum) effectiveness in reducing NH3+NH4+, NO2- and NO3- concentrations in the waste water of marine fish hatchery flow-through system. Four rectangular treatment tanks (0.5 x 0.55 x 0.5 m) were used in the experiment for 30 days. Each treatment tank planted with two E. spinosum cuttings with initial wet biomass of 50.28 ± 0.24 g and the waste water from the tank holding L. calcarifer juveniles flowed into each treatment tank using PVC pipe (ID = 25 mm) with an average flow-rate of 0.05 ± 0.01 L sec-1. The first treatment tank contained only seaweed (Swd) cut- tings, while the second and the third tanks were added with 8 kg substrate. The two substrates used were sand (S) and coral rubble (CR) with respectively sizes of 0.2 to 0.5 mm and 10 to 25 mm. A combination substrate of S+CR was added into the fourth treatment tank. Results showed that the water temperature ranged from 29.15 ± 0.86 to 29.31 ± 0.76 oC, pH ranged from 8.16 ± 0.13 to 8.22 ± 0.19 and salinity ranged from 30.135 ± 0.087 to 30.145 ± 0.091. The variance analyses of interaction factors (four treatment tanks X inflow-outflow) showed significantly different values (p<0.05) in terms of NH3+NH4-N concentrations. The NO2-N was also significantly different (p<0.05) in terms of inflow-outflow factor. This proved that the treat- ment tank efficiently removed the NH3+NH4-N and NO2- N. The highest removal of NH3+NH4-N and NO2-N was recorded in the CR+Swd treatment tank. No significant difference (p<0.05) of specific growth rate and yield of E. spinosum in the four treatment tanks was recorded. The average growth rate and yield of E. spinosum were 0.42 ± 0.12 % day-1 and 1.13 ± 0.30 g day-1 m-2, respectively in the Swd tank, 0.42 ± 0.13 % day-1 and 1.13 ± 0.32 g day-1 m-2, respectively in the Swd+S tank, 0.40 ± 0.13 % day-1 and 1.08 ± 0.31 g day-1 m-2 respectively in the Swd+CR tank, and 0.36 ± 0.11 % day-1 and 0.95 ± 0.27 g day-1 m-2 respectively in the Swd+S+CR tank. Besides, the new thal- lus of E. spinosum was slightly small and thin. Other algae such as Melosira sp. and Vaucheria sp, were noted to grow on the surface of four treatment tanks. This study sug- gested that a combination of coral rubbles and E. spinosum 26 are suitable for use in a hatchery seawater remediation of dissolved inorganic nitrogen

Water quality remediation using aquaponics sub-systems as biological and mechanical filters in aquaculture

This paper presents data obtained through trials on small-scale aquaponics sub-system which performs the roles of biological and mechanical filters for aquaculture water quality remediation. Aquaponics is a bio-integrated food production system, consisting of closed recirculating aquaculture combined with hydroponics. The trials were conducted on Nile tilapia (Oreochromis niloticus), and green beans (Phaseolus vulgaris) and the Chinese cabbage (Brassica rapa chinensis) over a period of 70 days. The results revealed that the system is more efficient in terms of plant growth and does not adversely affect the growth of captive stock of fish. Mean (± S.D.) values of water temperature, DO, pH, NH3-N, NO2-N, NO3-N and PO4-P during the trial were 25.2 ± 0.25 °C, 6.6 ± 0.13 mg/L, 7.14 ± 0.06, 0.23 ± 0.02 mg/L, 0.39 ± 0.22 mg/L, 0.89 ± 0.37 mg/L and 0.45 ± 0.04 mg/L, respectively. The average total weight gain by O. niloticus was 637.2 ± 8.49 g, and feed conversion ratio (FCR) was 1.47 ± 0.01 which indicated the efficiency of Nile tilapia in converting feed mass – a universally standard measure of efficiency of feed assimilation into weight gain, especially when there is no additional source of nourishment. High survival rate (95 ± 2.8%) was noticed during the trials. The average (±SD) values of biomass gain by P. vulgaris and B. rapa were 951.6 ± 1.6 g and 85.3 ± 13.4 g, respectively. The system was cost-effective and efficient in purging the toxic waste from water, resulting in remediation of water quality for the recirculating aquaculture system. This reflected the effectiveness of biofiltration which is currently assessed by its ability to completely remove the ammonia and minimize the generation of nitrite

Use of coral rubble, aquamat and aquaponic biofiltration in the recirculating system of a marine fish hatchery

A preliminary study on the effect of combination biofilters, including coral rubble, geotextile AquamatTM (Meridian Aquatic Technology, Silver Spring, MD, USA), and algal aquaponics in a marine fish recirculating system was investigated. AquamatTM is an innovative product fabricated from highly specialized synthetic polymer substrates. AquamatTM forms a complex three-dimensional structure that resembles seagrass in appearance, and has been used to support high stocking densities in fish culture ponds and enhance biological processes. In addition, coral rubble was used, and two seaweed species, Eucheuma spinosum and E. cottonii, were evaluated for their usefulness as aquaponic biofilters in a recirculating system. Results showed that the four different biofilters operating within the recirculating system were significantly different (P<0.05) in NH3-N and NO3-N concentrations. The lowest mean NH3-N concentration was recorded in the recirculating tank using AquamatTM + seaweed + coral rubble, while the highest mean NO3-N concentration was recorded in the recirculating tank using AquamatTM + coral rubble. Fish weight gain and survival rates were not significantly different (p<0.05) in the four recirculating systems. In the second experiment, three varieties of Eucheuma spp. grew poorly, and produced no noticeable effects on NH3-N, NO2-N and NO3-N concentrations. Eucheuma cottonii decayed in the early days, while the two varieties of E. spinosum decayed after 35 days. Once decayed, water quality impairment followed This study concluded that Eucheuma species were not suitable as a method of biofiltration in a recirculating culture system. While these seaweeds do remediate water quality, they themselves require a good environment to perform this role. When conditions are not optimal for the stocked organisms, the co-culture system can produce negative results. Follow-up investigation is needed to determine the suitability of such integrated aquatic systems for a large-scale fish production in recirculation system

Perubahan nutrien mengikut kedalaman di muara-muara sungai dan luar pantai, perairan Pantai Barat, Sabah

Kajian dilakukan di 17 muara sungai dan 16 kawasan luar pantai (1-3 kilometer daripada muara) di perairan Pantai Barat, Sabah. Tujuan kajian adalah untuk mengetahui kepekatan NH4-N, NO3-N, PO4-P, JF-F, SiO2-Si dan JNI-N serta untuk mengetahui perubahan kepekatan nutrient mengikut kedalman (permukaan, pertengahan dan dasar). Keputusan mendapati kepekatan nutrient di kawasan kajian adalah rendah dan tiada perbezaan mengikut kedalaman kecuali untuk JF-F (ANOVA Sehala). Ini menunjukkan bahawa kawasan kajian (muara dan luar pantai) adalah kawasan dinamik di mana nutrient adalah terbaur di dalam turus air. Kepekatan JF-F yang berbeza mengikut kedalaman adalah berkemungkinan disebabkan oleh aktiviti mikrob di dalam sedimen kerana min kepekatan di permukaan dan pertengahan adalah lebih rendah berbanding di dasar

Adopt and adapt nature’s design principles to create sustainable aquaculture systems

Sustainable development of aquaculture faces many constraints. An approach that offers solutions to these challenges is emulating nature’s patterns and strategies. There are many elements of sustainability employed by nature that can be adopted for aquaculture systems through necessary adjustments (or adaptations). Analysis of empirical data generated by a series of experiments on different aquaculture systems generated new knowledge of practical importance. An outcome of the analysis pertaining to two important aspects of aquaculture, the sex control in captive stocks of commercially important protogynous hermaphrodite grouper and the operation of integrated multi-trophic aquaculture systems is presented here. Both cases serve as outstanding examples of the relevance of examining and applying nature’s principles for finding sustainable solutions to aquaculture problems

Adopt and adapt nature’s design principles to create sustainable aquaculture systems

Sustainable development of aquaculture faces many constraints. An approach that offers solutions to these challenges is emulating nature’s patterns and strategies. There are many elements of sustainability employed by nature that can be adopted for aquaculture systems through necessary adjustments (or adaptations). Analysis of empirical data generated by a series of experiments on different aquaculture systems generated new knowledge of practical importance. An outcome of the analysis pertaining to two important aspects of aquaculture, the sex control in captive stocks of commercially important protogynous hermaphrodite grouper and the operation of integrated multi-trophic aquaculture systems is presented here. Both cases serve as outstanding examples of the relevance of examining and applying nature’s principles for finding sustainable solutions to aquaculture problems

Biodynamics in tropical integrated aquaculture systems and challenges in producing organic food using low-carbon methods

Biodynamics of water quality and related issues in integrated aquatic farming systems, especially the Integrated Multi-Trophic Aquaculture (IMTA), are reviewed in this paper. Combining several species in one system in addition to the microbiological organisms that become part of a production unit achieve biodynamics that is truly remarkable and mimics the processes that nature utilizes through biodiversity and interlinkages. Nutrient cascading is the most visible process in such a system. Some of the features that characterize IMTA include: harmonious functioning of multiple species, self-manuring, in tune with nature, wellbeing of captive stocks and low-carbon processes. Basically, IMTA has three loops: fed species and biofiltration, and the water quality impacted by processes in the first two loops. Maintaining homoeostasis in the system can be challenging for a number of reasons, including species-specific water quality requirements, turnover of dissolved gases (mainly oxygen and nitrogen) and particulate matter. Ammonia fluctuates with pH and temperature. Dissolved oxygen is influenced by temperature. While at neutral pH (7.0), more than 95% of ammonia is in ionized, non-toxic form (NH4+), the percentage of toxic un-ionized ammonia (NH3) increases with pH at a given temperature. NH3 is highly toxic. It produces stress at 0.1 mg/L by damaging the gills and disrupting metabolism, and death at higher concentrations. Nitrite is toxic when its concentration exceeds 0.4 mg/L. Concentration lower than this value can be fatal for more sensitive species. Process of nitrification that converts ammonia to nitrite and nitrite to nitrate requires at least 6 mg/L of dissolved oxygen. The culture system should remain well aerated, at slightly alkaline pH and moderately warm temperature, and must have substrate for nitrifying bacteria. Roles of the various types of filtering devices for organic and inorganic wastes are discussed in this paper

Effects of cage culture on dissolved inorganic nutrient and surface sediment composition in Sulaman Bay Lagoon, Sabah, Malaysia

The major nutrient inputs into Sulaman Bay lagoon are wastes from a nearby village together with particulate organic matter and surface sediment as runoff from mangrove area, as well as from aquaculture activities. The main objective of this study was to determine the dissolved inorganic nutrients (DIN) of water and nutrients of surface sediment in Sulaman Bay lagoon. The data could be was used in developing management strategies for the sustainable aquaculture activity in lagoon ecosystem. Water sample and surface sediment were collected from six stations: five located inside the lagoon and one station at a point that connected the lagoon with South China Sea. The parameters determined included ammonium-nitrogen (mg/L), nitrate (mg/L) and phosphate (mg/L) in water, and particle size, total nitrogen (mg/g), total phosphorus (mg/g), total organic carbon (%) and total inorganic carbon (%) as carbonate equivalent in sediment samples. The highest concentrations of 0.072 mg/L nitrate, 0.121 mg/L of ammonium-nitrogen and 0.058 mg/L of phosphate were obtained from the sea opening point, station nearby village with mollusk culture and village waste drainage areas respectively. Sediment in the Sulaman Bay lagoon was mainly in the form of silt, sand and gravel. The values of total nitrogen and total phosphorus (mg/100g of sediment) were observed to be higher than the values obtained in all stations located inside lagoon. No significant (p>0.05) differences was observed in the total nitrogen of sediment among the stations located inside the lagoon. The highest total organic carbon (TOC) of 22.5% was observed in stations near to the village and cage culture area. The highest value of TOC from the aforesaid stations were significantly different (P 0.05) from the TIC values at other stations. However, the concentration of organic carbon, total nitrogen and total phosphorus in the sediment was higher not only due to commercial cage culture, but also from other human induced activities such as discharge waste from the village, and leafy material with surface sediment as runoff from nearby mangrove vegetation