aquaculture

According to Dan Hutchinson, a New Zealand company backed by an international team of scientists is claiming a biofuel breakthrough by turning algae nutured on sewage waste into a viable diesel substitute. Aquaflow Bionomic Corporation was now increasing its capacity to produce one million litres over the next year from the Blenheim sewage ponds – a world first with the commercial production of biodiesel outside the laboratory. The process had been designed so that plants could be set up at sewage ponds anywhere, providing a large quantity of fuel close to markets. The new fuel could also be made from dairy farm effluent and waste from food-producing factories. Spokespeople from Aquaflow claimed the United States Department of Energy had identified algae as the most promising large-scale source of alternative fuel after the last oil shock.

In fact, some 300 algae and related species were identified from work done at the original National Renewable Energy Laboratory study ponds in California, Hawaii, and at Roswell, New Mexico. The study found the process was costly compared with fossil fuel at the time (1998) but the cost difference has significantly reduced or disappeared these days. The closeout report (authored by J. Sheehan, T.G. Dunahay, J.R. Benemann, P.G. Roessler, and J.C. Weissman) is a weighty 328 pages long and is available as a .pdf for free download.

The abstract: The Aquatic Species Program was a relatively small research effort intended to look at the use of aquatic plants as sources of energy. Its history dates back to 1978, but much of the research from 1978 to 1982 focused on using algae to produce hydrogen. The program switched emphasis to other transportation fuels, particularly biodiesel, beginning in the early 1980’s. This report summarizes the research activities carried out from 1980 to 1996, with an emphasis on algae for biodiesel production.

From the report:

High oil-producing algae can be used to produce biodiesel, a chemically modified natural oil that is emerging as an exciting new option for diesel engines. At the same time, algae technology provides a means for recycling waste carbon from fossil fuel combustion. Algal biodiesel is one of the only avenues available for high-volume re-use of CO2 generated in power plants. It is a technology that marries the potential need for carbon disposal in the electric utility industry with the need for clean-burning alternatives to petroleum in the transportation sector.

Freeengergy news reports there is significant international interest in the production of biofuels using aquatic plant species. Michael Briggs, from the University of New Hampshire, Physics Department, has published a report entitled Widescale Biodiesel Production from Algae. From the report:

For any biofuel to succeed at replacing a large quantity of petroleum, the yield of fuel per acre needs to be as high as possible. At heart, biofuels are a form of solar energy, as plants use photosynthesis to convert solar energy into chemical energy stored in the form of oils, carbohydrates, proteins, etc.. The more efficient a particular plant is at converting that solar energy into chemical energy, the better it is from a biofuels perspective. Among the most photosynthetically efficient plants are various types of algaes.

Slightly off topic, but interesting never-the-less, this article describes how to construct a very simple low-cost compound microscope. The designers claim the microscope is one that just about anyone can build and will produce a magnification of about 75 times.

From the introduction: A One Dollar Compund Microscope:

Microscopes may be thought of as very intricate and mysterious instruments but in reality, they are not as complicated as one may think. Building this simple instrument is not only a fun project, it will help you understand how microscopes work. This microscope, which will cost you no more than about a dollar or so to build, is essentially identical to the expensive microscopes that professionals use. Through this project you will gain an appreciation for the need of using corrective optics to reduce the aberrations. Obviously, the performance of this simple microscope cannot be compared with those more expensive professional instruments, which will produce much clearer and brighter images. Nonetheless, it should compare well to the low-cost microscopes that are sold in the toy or hobby shops. It is our experience that so called “toy microscopes” are a real disaster because they commonly give little more than diffuse images or shadows, and can give a young person a bad impression about microscopes consequently causing them to loose interest in these instruments. However, an instrument of suitable quality has the potential of sparking a young person’s interest and opening up a world of discovery to them.

K. F. Shim and S. I. Ong, from the Department of Zoology, National University of Singapore, published a research document entitled ‘Iron requirement of the guppy (Poecilia reticulata Peters)’ in the Journal of Aquariculture & Aquatic Sciences, Volume 6, Number 2. The publication is available from petsforum.com.

From the abstract:

The iron requirement of the guppy, Poecilia reticulata Peters, was determined by feeding them eight different levels of iron (0.0, 0.010, 0.020, 0.040, 0.080, 0.320, and 0.640 g/kg dry diet) for fifteen weeks. Growth and feed conversion was not significantly affected by the dietary iron. The red blood cell count, hemoglobin content, and hematocrit value was significantly reduced in fish fed an iron-deficient diet. Iron, copper and zinc content of the liver, spleen, kidney, blood, skin and muscle, heart, gills, and ovary was determined. The iron content was significantly lower in fish fed the iron-deficient diet while the copper content was significantly elevated. However, the zinc content in the organs was not affected by the levels of iron in the diets. the level of iron required by the guppy to prevent microcytic, hypochromic anemia was found to be 0.080 g/kg of diet.

R A Leng, J H Stambolie, and R Bell from the Centre for Duckweed Research and Development at the University of New England Armidale, New South Wales, Australia; have published a research report on the potential of duckweed as a high-protein feed resource for domestic animals and fish.

From the summary:

Duckweeds have received research attention because of their great potential to remove mineral contaminants from waste waters emanating from sewage works, intensive animal industries or from intensive irrigated crop production. Duckweeds need to be managed, protected from wind, maintained at an optimum density by judicious and regular harvesting and fertilised to balance nutrient concentrations in water to obtain optimal growth rates. When effectively managed in this way duckweeds yield 10-30 ton DM/ha/year containing up to 43% crude protein, 5% lipids and a highly digestible dry matter.

Duckweeds have been fed to animals and fish to complement diets, largely to provide a protein of high biological value. Fish production can be stimulated by feeding duckweed to the extent that yields can be increased from a few hundred kilograms per hectare/year to 10 tonnes/ha/year.

Mature poultry can utilise duckweed as a substitute for vegetable protein in cereal grain based diets whereas very young chickens suffered a small weight gain reduction by such substitution. Pigs can use duckweed as a protein/energy source with slightly less efficiency than soyabean meal.

Little work has been done on duckweed meals as supplements to forages given to ruminants, but there appears to be considerable scope for its use as a mineral (particularly P) and N source. The protein of duckweeds requires treatment to protect it from microbial degradation in the rumen in order to provide protein directly to the animal.

The combination of crop residues and fresh duckweeds in a diet for ruminants appears to provide a balance of nutrients capable of optimising rumen microbial fermentative capacity. These diets can, therefore, be potentially exploited in cattle, sheep and goat production systems particularly by small farmers in tropical developing countries.

Patrick Lavens and Patrick Sorgeloos, from the Laboratory of Aquaculture and Artemia Reference Center at the University of Ghent, in Belgium have edited a technical paper entitled Manual on the Production and Use of Live Food for Aquaculture. It is available as a free download.

The topics comprehensively covered include micro algae, rotifers, artemia, zooplankton, cladocerans (daphnia and moina), nematodes and trochophora larvae.

From the introduction:

Whereas in the 1970s the production of farmed marine finfish and shrimp relied almost exclusively on the capture of wild fry for subsequent stocking and on-growing in ponds, tanks or cages, the complete domestication of many marine and brackishwater aquaculture species was only achieved during the last two decades. However, since then the controlled production of larvae from captive broodstock, or in other words the hatchery production of fry, has now become a routine operation for most cultivated fish and shellfish species; billions of fish and shellfish larvae (i.e. bivalve molluscs, penaeid shrimp, salmonids, European seabass, Gilthead seabream etc.) currently being produced within hatcheries all over the world.

The cultivation of larvae is generally carried out under controlled hatchery conditions and usually requires specific culture techniques which are normally different from conventional nursery and grow-out procedures, and especially with respect to husbandry techniques, feeding strategies, and microbial control. The main reason for this is that the developing larvae are usually very small, extremely fragile, and generally not physiologically fully developed. For example, their small size (ie. small mouth size), the uncompleted development of their perception organs (ie. eyes, chemoreceptors) and digestive system, are limiting factors in proper feed selection and use during the early first-feeding or start-feeding period. Moreover, in species such as shrimp, these are not the only problems as the developing larvae also have to pass through different larval stages, eventually changing from a herbivorous filter feeding behaviour to a carnivorous hunting behaviour. It is perhaps not surprising therefore that larval nutrition, and in particular that of the sensitive first-feeding larvae, has become one of the major bottlenecks preventing the full commercialization of many farmed fish and shellfish species.