Effects of copper sulfat and cu-based fungicide to vannamei low salinity culture The white shrimp Litopenaeus vannamei (Boone, 1931) is the most important shrimp species in world aquaculture, although in recent few years it has been introduced to several Asiatic countries, The pollution of coastal waters, the outbreaks of shrimp diseases and the feasibility of shrimp culture in low salinity waters have led to rapid growth of inland shrimp farming; this has become a growing business in many areas of the world, because it allows expansion in disease-free areas, thereby reducing health risks (Fast & Menasveta 2000, Li et al. 2008). L. vannamei is a hyper-hypo-osmoregulator; its isosmotic point is close to 24.7 psu (Castille & Lawrence 1981) and due to its ability to tolerate a wide range of salinities (0.5-40 psu), it has become a popular species for low salinity culture (Roy et al. 2007), which is a growing activity in some inland area. Shrimp culture practices include the use of bioactive compounds such as disinfectants, therapeutics, feed additives, fertilizers and algaecides (Dias-Bainy 2000). Among these, copper sulfate is used to control macroalgae and bivalve growth in about some percentage of the commercial shrimp farmers Copper is an essential element for living organisms: it is a key component of enzymes that act as catalysts in several metabolic processes, and it is required for the synthesis of the main crustacean respiratory pigment (hemocyanin), of oxidation-reduction enzyme systems, as well as of other compounds, which are essential for normal growth and development (Davis & Mertz 1987, Li et al. 2007a). However, when present in relatively high concentrations, Cu2+ becomes toxic and has harmful effects at the cellular, systemic or whole organism level (Yang et al. 2008). This might be the case in semi-intensive shrimp farms, since the low water exchanges used in most of these farms may cause copper accumulation in the pond water and sediments (Lacerda et al. 2006). This accumulation might affect the survival and growth of cultured shrimp especially in inland waters, because an important factor for metal toxicity is their chemical species (Erk et al. 2008), and it is generally accepted that toxicity is inversely related to ambient salinity At low salinities shrimp actively maintain an hyper-osmotic internal environment, and the associated water fluxes necessary to maintain the homeostasis of the organisms (Roast et al. 2001) may facilitate metal uptake and a corresponding increase of the internal metal concentrations, due to the increased activity of the ionic pumps (Erk et al. 2008). This may cause metal homeostasis breakdown, which in turn affects important physiological and biological functions at the molecular and cellular level, causing damage to the cell micro-and ultrastructure and to different organelles, such as mitochondria, endoplasmic reticulum and nucleus membrane (Yang et al. 2008). This interaction metal-salinity should be considered to establish criteria of acceptable water quality for inland shrimp culture, because it may induce adverse shrimp responses.
Posted on: Sun, 21 Dec 2014 17:50:41 +0000
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