Philip E. Turk

Biological Characteristics and Biomedical Applications of the Squid Sepioteuthis lessoniana Cultured Through Multiple Generations

Providing squids--especially their giant axons--for biomedical research has now been achieved in 10 mariculture trials extending through multiple generations. The noteworthy biological characteristics of Sepioteuthis lessoniana are (1) this species is behaviorally and morphologically well suited to the laboratory environment; (2) the life cycle is completed in 4-6 months; (3) growth is rapid (12% and 5% wet body weight d-1 for 100 d and for the life span, respectively), with adult size ranging from 0.4-2.2 kg; (4) feeding rates are high (30% wet body weight d-1), and a variety of live crustaceans and fishes are eaten; (5) crowding is tolerated (about 4 squids m-3); (6) the incidence of disease and cannibalism is low; and (7) reproduction in captivity allows culture through three successive generations. Engineering factors contributed to culture success: (1) physical design (i.e., size, shape, and painted pattern) of the culture tanks; (2) patterns of water flow in the culture tanks; (3) water filtration systems; and (4) spawning substrates. Initial production (a few hundred squids per year) suggests that large-scale culture will be able to supply the needs of the biomedical research community. The size (> 400 microns in diameter) and characteristics of the giant axons of Sepioteuthis are appropriate for experimentation, and other studies indicate that the eye, oculomotor/equilibrium system, olfactory system, blood, and ink are equally suitable for research.

Denitrification in aquaculture systems: an example of a fuzzy logic control problem.

Nitrification in commercial aquaculture systems has been accomplished using many different technologies (e.g. trickling filters, fluidized beds and rotating biological contactors) but commercial aquaculture systems have been slow to adopt denitrification. Denitrification (conversion of nitrate, NO3 to nitrogen gas, N2) is essential to the development of commercial, closed, recirculating aquaculture systems (B 1 water turnover 100 day 1 ). The problems associated with manually operated denitrification systems have been incomplete denitrification (oxidation‐reduction potential, ORP\ 200 mV) with the production of nitrite (NO2 ), nitric oxide (NO) and nitrous oxide (N2O) or over-reduction (ORPB 400 mV), resulting in the production of hydrogen sulfide (H2S). The need for an anoxic or anaerobic environment for the denitrifying bacteria can also result in lowered dissolved oxygen (DO) concentrations in the rearing tanks. These problems have now been overcome by the development of a computer automated denitrifying bioreactor specifically designed for aquaculture. The prototype bioreactor (process control version) has been in operation for 4 years and commercial versions of the bioreactor are now in continuous use; these bioreactors can be operated in either batch or continuous on-line modes, maintaining NO3 concentrations below 5 ppm. The bioreactor monitors DO, ORP, pH and water flow rate and controls water pump rate and carbon feed rate. A fuzzy logic-based expert system replaced the classical process control system for operation of the bioreactor, continuing to optimize denitrification rates and eliminate discharge of toxic by-products (i.e. NO2 , NO, N2 Oo r

Design and function of closed seawater systems for culturing loliginid squids

The life cycle of loliginid squids has been completed in recirculating seawater systems. Two systems were required: a 2 m diameter circular culture tank (CT) with adjoining 2 m circular filter tank (3000 liters total volume of natural seawater) for culture of hatchlings, 1–60 days old; and a 6 × 2·6 × 1 m raceway culture tank (RW) with a smaller adjoining rectangular filter tank (14 850 liters total volume of artificial seawater) for the grow-out of adults. Both systems were equipped with temperature control apparatus, modular filter units (particle filters and activated carbon), foam fractionators, biological filters (crushed oyster shell) and UV sterilizers. The systems carried low bioloads, < 1·0 g/m3 and as high as 0·8 kg/m3, respectively. Water quality was excellent: NH4N was below 0·01 mg/liter in the CT and 0·10 mg/liter in the RW: NO2N was below 0·01 mg/liter in the CT and 0·03 mg/liter in the RW; NO3N was below 12 mg/liter in the CT and below 50 mg/liter in the RW; and pH was above 8·0 in both systems. The design of the systems proved to be behaviorally and physiologically suitable for squids and two species grew to adult size and produced viable young. These systems are compared to other squid maintenance and rearing systems and marine recirculating seawater systems.

Mariculture of the loliginid squid Sepioteuthis lessoniana through seven successive generations

Abstract Sepioteuthis lessoniana is a commercially important squid throughout the Indo-West Pacific and is a useful species in biomedical research. It has now been cultured through seven successive generations in closed, recirculating seawater systems. Egg viability was highest in the parental generation (34.9%) and significantly decreased in the next six generations with a viability rate of 1.56–13%. The highest hatchling survival was in G 4 (80.3%) and the lowest was in G 3 (26.3%). Water quality was maintained at acceptable levels during each successive generation (NH 4 2 3 8.0). Life spans ranged from 169 to 262 days (5.6–8.7 months) with a mean of 208 days (6.9 months). The seven generations reached mean adult sizes at 500–900 g. The age of sexual maturity for females was recorded for all populations except G 6 and ranged from 146 to 224 days (4.9–7.5 months) with an average of 171 days (5.7 months). Sex ratios did not consistently vary from 1:1 in any generation. Live food (i.e., crustaceans and fish) was the only food supplied throughout their life cycle.

Pilot-scale production of mysid shrimp in a static water system

Studies were conducted to determine the potential for large scale culture of the mysid shrimp Mysidopsis almyra. Reproduction was consistent, as newly hatched mysids were always present in the culture trays. At the end of 45 day preliminary trials, the populations in the culture trays had increased 323.3% and 256.6%. A larger pilot-scale system connected to a biological filtration tank was constructed and operated for 17 weeks. Two rectangular trays (125 cm × 50 cm × 8 cm deep) were placed one above the other; water volume in each tray was 20 l. The room was kept dark. Temperatures were maintained at 26(2) °C and salinities at 20(2)‰. A total of 1,000 adult mysids were placed in the culture tray and the hatchlings were collected and moved into a hatchling tray. Water circulation was static except for twice-daily water exchanges; newly hatched Artemia nauplii (24 h incubation) were fed to the mysids immediately after each water exchange. Feeding presented no technical problem to the pilot-scale culture of mysids in static water systems but the cost of Artemia did represent the largest expense. Mean (SD) mysid production throughout the 17 weeks of the trial was 133(69) hatchlings d–1 with highest production [244(30) hatchlings d–1] occurring between weeks 11 and 13. Mean survival in the hatchling tray after the 14 day growth periods was 41.4%. Reproduction occurred at ammonia-nitrogen and nitrite-nitrogen concentrations as high as 1.5 mg l–1 and 0.250 mg l–1 respectively, and at pH values as low as 7.6. When pH decreased to 7.38, reproduction halted abruptly and mortality increased sharply.

Effects of different food items on the culture of the mysid shrimp Mysidopsis almyra (Crustacea: Pericaridea) in a static water system.

The effects of several food items on larvae production and survival ofthe mysid Mysidopsis almyra were compared. A total of sixdiets were used. The diets were: 1) phytoplankton (Isochrysisgalbana), 2) an artificial diet (Liqualife®, Cargill,Minneapolis, MN), 3) a mixed diet composed of both zooplankton (mostlycopepods)and phytoplankton, 4) 750 mg g−1 of HUFA enrichedArtemia nauplii and 250 mgg−1 of the artificial diet, 5) newly hatchedArtemia nauplii (24-hour incubation at 28°C) and 6) newly hatched Artemia naupliienriched with HUFA (SELCO®, INVE Inc., Ghent, Belgium) for 12 hours. Mysidsfed HUFA enriched Artemia nauplii (diet 6) had the highestproduction and survival rates, although not significant (P > 0.05), comparedto diets 3, 4 and 5, while the phytoplankton and the artificial diet hadsignificantly lower production and survival rates (p > 0.05).

A fuzzy logic application to aquaculture environment control

One of the major problems facing modern filtration technology is the cost-effective filtration of nitrate, NO/sub 3/. The design of a cost-effective, integrated nitrogen removal system including both nitrification and denitrification processes is paramount to the continued development of commercial recirculating aquaculture systems. Current nitrification systems are adequate and many are commercially available; however, current techniques for denitrification are almost exclusively based on water exchange. The purpose of this research is to produce the first commercial, autonomous denitrification filter, using extant biotechnology (i.e., biological reactors and artificial intelligence). The goal of the study has been to design a fuzzy logic system to control the operation of a denitrification bioreactor developed by the University of Texas Medical Branch, Marine Biomedical institute, for use in a closed recirculating aquaculture system. The development of a prototype system was accomplished through a multi-disciplinary program involving computer scientists, bioengineers, biochemists and aquaculturists.