Aquaculture Plant Research Articles

Mitochondrial DNA sequences of six sturgeon species and phylogenetic relationships within Acipenseridae

Summary Studies on mitochondrial DNA variability amongst six sturgeon species reared in Italian aquaculture plants are reported. Restriction analysis by Rsal of mitochondrial cytochrome b and D-loop fragments amplified by PCR permitted identification of interspecific variations that would be suitable as markers for species diagnosis. Data obtained by partial sequencing of the cytochrome b gene, analyzed through maximum parsimony, neighbour joining, and UPGMA distance methods, revealed species clusters that support previous morpho-meristic and geographical data for sturgeon classification into sub-genera. According to our cluster analysis, the genera Acipenser and Huso are monophyletic. Moreover, these and previous cytogenetic data suggest that three 120-chromosome species (H. huso, H. dauricus and A. ruthenus) are at the base of sturgeon differentiation, which occurred through two different events of polyploidization.

Toxicity identification evaluation of ammonia, nitrite and heavy metals at the stensund wastewater aquaculture plant, Sweden

The Stensund Wastewater Aquaculture plant was built in 1989. The plant is contained in a greenhouse because of its northern location with a temperate climate. The plant receives wastewater from 40 persons and has a residence time of 30 days. The purification concept is to use a constructed aquatic food chain (algae, zooplankton and fish) combined with hydroponic culture of higher plants to further deplete the nutrients in the wastewater. However, the production of algae and zooplankton has not been working as expected from pilot studies. The purpose of this investigation was to study if toxic chemicals were limiting the production of zooplankton (Daphnia magna) in the aquaculture treatment system. Grab samples were taken at six sites and tested for acute toxicity to Daphnia magna and analyzed for BOD, COD, ammonium-, nitrite-, nitrate- and total nitrogen, total phosphorus and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn). Toxicity to D. magna was also determined after addition of EDTA, sodium thiosulphate and pH adjustment of the water to 6, 7 and 8, in order to assess if heavy metals and/or pH-dependent toxicants were present. Potential toxicants, with concentrations high enough to intoxicate Daphnia magna, were Cu, ammonia and nitrite. Subsequent improvement of nitrification reduced the ammonia and nitrite concentrations as well as the toxicity. Furthermore, the improved production of algae and Daphnia at the Stensund Wastewater Aquaculture plant verified that the primary cause of toxicity was ammonia.

Toxicity identification evaluation of ammonia, nitrite and heavy metals at the Stensund Wastewater Aquaculture Plant, Sweden

The Stensund Wastewater Aquaculture plant was built in 1989. The plant is contained in a greenhouse because of its northern location with a temperate climate. The plant receives wastewater from 40 persons and has a residence time of 30 days. The purification concept is to use a constructed aquatic food chain (algae, Zooplankton and fish) combined with hydroponic culture of higher plants to further deplete the nutrients in the wastewater. However, the production of algae and Zooplankton has not been working as expected from pilot studies. The purpose of this investigation was to study if toxic chemicals were limiting the production of zooplankton (Daphnia magna) in the aquaculture treatment system. Grab samples were taken at six sites and tested for acute toxicity to Daphnia magna and analyzed for BOD, COD, ammonium-, nitrite-, nitrate-and total nitrogen, total phosphorus and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn). Toxicity to D. magna was also determined after addition of EDTA, sodium thiosulphate and pH adjustment of the water to 6, 7 and 8, in order to assess if heavy metals and/or pH-dependent toxicants were present. Potential toxicants, with concentrations high enough to intoxicate Daphnia magna, were Cu, ammonia and nitrite. Subsequent improvement of nitrification reduced the ammonia and nitrite concentrations as well as the toxicity. Furthermore, the improved production of algae and Daphnia at the Stensund Wastewater Aquaculture plant verified that the primary cause of toxicity was ammonia.

Histological study of the development and sex differentiation of the gonad in the European eel

The histological structure of the gonads was studied in yellow eels sampled from a coastal lagoon and from stocks reared in an aquaculture plant showing different sex ratios. Gonad development related to body size rather than to age and underwent an intermediate stage characterized by a structure of an early testis but containing oogonia and oocytes. This gonad was called the Syrski organ and the stage juvenile ambisexual. Ovaries were found in eels from 22–30 cm in length, possibly derived from undifferentiated gonads or from Syrski organs. Fully differentiated testes were found in eels >35 cm, derived from Syrski organs. These observations support the results of previous research. From elvers and in eels up to 15–16 cm in length, growth of the gonadal primordium is due to primordial germ cell migration. In eels > 15 cm multiplication of primordial cells begins. Oogonial clones were found in eels > 18 cm in length, whilespermatogonium B clones were observed in eels >30 cm in length. The dynamics of sex differentiation was different among stocks with different ultimate sex ratios: ovaries were found in shorter eels in stocks with a prevalence of females, in longer eels in stocks with a prevalence of males. This result supports the hypothesis of a metagametic (environmental) sex determination. The somatic cells in contact with germ cells and those in the interstitium appeared early during gonad development and preceded germ cell differentiation. This suggests that somatic cells are the targets of the environmental factors influencing sex differentiation.

Investigations of phagocytosis concerning the immunological defence mechanism of Mytilus edulis using a sublethal luminescent bacterial assay ( Photobacterium phosphoreum)

1. 1. A simple method for the determination of phagocytosis activity using mussel hemocytes by measuring the bioluminescence is presented. 2. 2. The immunological defence activity based on phagocytosis is measured and quantified by a luminescent bacterial assay with Photobacterium phosphoreum. 3. 3. The measuring system allows us to establish the stress of the immunological defence mechanism of organisms exposed to chemicals and polluted rivers or sewage. Results with reference substances and the phagocytosis indices of exposed mussels from Norwegian aquaculture plants compared to those of mussels from the German Wadden Sea are given as examples.

Role of Activity Rhythm on the Fish Behavior Control in an Aquaculture Plant

Ecological activity rhythm is discussed to apply to the aqua-culture system. Diurnal swimming rhythm of fish larvae of Pagrus major and Paralichthys olivaceus are determined by the time series data of swimming locomotion of yolk-sac and 30 days after hatched out larvae. As this rhythm commonly indicates in many marine fish behavior, Fourier analysis of fish locomotion data is useful. Relation between rhythmic motion and physical environmental factor such as light intensity in the aquaculture plant and internal tide in the sea are discussed

Computer-Aided Modeling of Aquaculture Plants

Mathematical modelling of dyanamic processes is often considered an intricate and timeconsuming task. Program packages for simulation, time series analysis and identification in combination with modern data logging equipment allow the task to be handled in a simpler and more efficient wayThis paper gives a short description of the different tools, and one example illustrates how a stochastic growth model and a simulation program can be utilized to simulate the weight distribution of fish in an aquaculture plant as a function of time, temperature and feeding level. The model allows for stochastic variation in all parameters and input variables and may be utilized among plant managers for examination of production strategies and among researchers to study the key variables affecting growth

Computer Aided Control and Monitoring of Aquaculture Plants

A computer system for control and monitoring of aquaculture plants has been developed by the Norwegian company NODEC. The system is based on a local area network which interfaces a computer system to the primary instruments located at various sites in the plant. Special software modules have been developed to handle different tasks such as data gathering, automatic control, alarming, logging, trend analysis and reporting. Special effort has been made to develop a user-friendly high level man-machine interface. A sofware libary is available for monitoring and control of; Water quality, Water distribution. Heating systems, Biomass and Feeding systems.

Oxygen Control on Aquaculture Plant

The breeding of edible fish under controlled conditions is a rapidly growing business. By automation, possibly incorporating computer equipment, the operation of aquaculture plant can be optimised; the automation equipment making it possible to monitor and con trol vital parameters. One parameter essential to optimum operation involves the monitoring and control of th oxygen content of the water. Here there is need for a measuring system which is absolutely reliable for very long periods. This especially applies to the sensor. This article describes several ways of automating oxygen control, and an oxygen sensor that does not require regeneration.

Computer Aided Control and Monitoring of Aquaculture Plants

Abstract A computer system for control and monitoring of aquaculture plants has been developed by the Norwegian company NODEC. The system is based on a local area network which interfaces a computer system to the primary instruments located at various sites in the plant. Special software modules have been developed to handle different tasks such as data gathering, automatic control, alarming, logging, trend analysis and reporting. Special effort has been made to develop a user-friendly high level man-machine interface. A sofware libary is available for monitoring and control of; Water quality, Water distribution. Heating systems, Biomass and Feeding systems.

Computer Aided Modeling of Aquaculture Plants

Abstract Mathematical modelling of dyanamic processes is often considered an intricate and timeconsuming task. Program packages for simulation, time series analysis and identification in combination with modern data logging equipment allow the task to be handled in a simpler and more efficient way This paper gives a short description of the different tools, and one example illustrates how a stochastic growth model and a simulation program can be utilized to simulate the weight distribution of fish in an aquaculture plant as a function of time, temperature and feeding level. The model allows for stochastic variation in all parameters and input variables and may be utilized among plant managers for examination of production strategies and among researchers to study the key variables affecting growth