Tag Claude E. Boyd

A few anions and cations, and un-dissociated silicic acid represent the largest fraction of dissolved inorganic solids in water. The total concentration of ions is called the salinity. The total dissolved-solids concentration usually is roughly equal to salinity in freshwater. Unlike seawater, freshwater varies greatly in salinity and proportions of individual ions. Calcium and bicarbonate are dominant ions in river water, but sodium and chloride are dominant in seawater. Water contains many other inorganic substances, as well as many trace elements. 

In life cycle analysis of aquaculture, there is a danger of the entire array of embodied resources and impacts being assigned to the production facility. Producers have no control over the inefficiencies or impacts associated with feed production, but can help lessen resource use through good management practices. 

The creation and application of reference tables for acceptable concentration ranges of physical and chemical water quality variables for culture organisms would be challenging due to the differing tolerances found among the many farmed species. 

The authors believe that dry-out periods likely destroy most organisms in pond bottoms, and liming of the entire bottom area should be done only to neutralize soil acidity and increase pH for organic matter decomposition by soil microorganisms. 

The main pond bottom soil management practices used in semi-intensive culture are pond dry-out and liming between crops. These practices accelerate organic matter decomposition, neutralize soil acidity and destroy unwanted organisms. 

Copper is used for control of the blue-green algae responsible for off-flavors in aquaculture animals, treating diseases and parasites, and avoiding cage net fouling. Although copper is an essential nutrient for plants and animals, an excess can negatively affect the environment and human health. 

Light penetrating water is scattered and absorbed exponentially as it passes downward. The presence of dissolved organic matter and suspended solids further impedes light penetration, and different types of solids absorb different wavelengths. 

Acid rain typically does not heavily affect aquaculture operations, and application of agricultural limestone can buffer water against the impacts of acid rain at facilities that use stream water. 

The amount of aeration can be increased as feeding rate increases to conserve energy. Aeration in shrimp ponds usually can be reduced from mid-morning until early evening. Research has demonstrated that considerable energy can be saved by using aerator automation systems. 

The silicon plants take up in silicic acid from water strengthens cell walls. Among the phytoplankton, diatoms particularly need silicon. 

Hydrogen sulfide, which can form in pond bottom sediment, is toxic to aquatic animals because it interferes with reoxidation of cytochrome a3 in respiration. 

Nitrite, an intermediate compound in the oxidation of ammonia nitrogen to nitrate by nitrifying bacteria in soil and water, is considerably more toxic than nitrate. Exposure to nitrite causes gill lesions and edema in the skeletal muscles of fish, and also affects respiration. 

Ammonia nitrogen occurs in aquaculture systems as a waste product of protein metabolism by aquatic animals and degradation of organic matter, or in nitrogen fertilizers. Exposure can reduce growth and increase susceptibility to diseases in aquatic species. 

A carbon footprint is an estimate of the total carbon emissions resulting from the production, use and disposal of a product or service. Carbon footprints for aquaculture products result mainly from the use of manufactured feed and mechanical aeration. 

The ideal pH for most aquaculture species is between 6.0 and 8.5. Lower pH values may result in decreased growth and survival, and greater susceptibility to disease. pH typically is lowest in the early morning, increases during the afternoon and declines at night.