Tag - phytoplankton

How does rainfall affect shrimp pond water parameters?

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Problems in shrimp farming usually occur during severe drought or heavy rainfall. Observations confim major losses occur mainly during periods of rainfall. In the last two years, we have had droughts brought about by El Niño. The US Climate Prediction Center and the International Research Institute for Climate and Society have issued an announcement that there is a 60% chance of La Niña developing in the last quarter of 2016. In contrast to El Niño, with La Niña we will [...]


What Happens in Shrimp Ponds During Heavy Rains?

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• Water temperatures, oxygen, pH, alkalinity and salinity drop. • Phytoplankton crashes occur. • Organic material accumulates on pond bottoms. • Strong winds stir up the bottom sludge. • Toxic levels of hydrogen sulfide (H2S) are released. • Pathogenic bacteria replace beneficial bacteria. • The noise of rain pounding on the surface stresses the shrimp. • Shrimp molt because of the lower pH and phytoplankton changes. Outcomes: • Mortalities occur because of the changes in water quality, stress and pathogens. • Feed consumption drops. • Shrimp migrate to the bottom [...]


Phytoplankton a crucial component of aquaculture pond ecosystems

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Proper management critical for successful production Blue-green algae will often float to the pond surface and form scums that absorb heat and can elevate water temperatures. Ponds typically contain an abundance of phytoplankton. These organisms play an important role in pond ecology and influence water quality. Although phytoplankton usually are beneficial, under some conditions, they can be quite problematic in fish and shrimp production. Phytoplanktonic algae consist of thousands of species distributed primarily among the phyla Pyrrophyta, Euglenophyta, Chlorophyta, Heterokontophyta and Cyanophyta. [...]


Zooplankton and Phytoplankton

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Zooplankton Zooplanktons are planktonic animals that range in size from microscopic rotifers to macroscopic jellyfish. The distribution of zooplankton is governed by salinity, temperature and food availability in the environment. The smallest zooplankton can be characterized as recyclers of water-column nutrients and often are closely tied to measures of nutrient enrichment. Larger Zooplanktons are important food for forage fish species and larval stages of all fish. They also link the primary producers (phytoplankton) with larger or higher trophic-level organisms. The zooplankton community [...]


Aquaculture Feed Composition Helps Define Potential For Water Pollution

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Summary: A study found that feed for salmon and trout had higher organic carbon concentrations than did catfish, shrimp and tilapia feeds. Nitrogen and phosphorus concentrations were similar among salmon, trout and shrimp feeds, and higher than those in catfish and tilapia feeds. Whole body concentrations of organic carbon were greater in salmon and trout than in the other species. Salmon and shrimp had the highest whole body nitrogen concentrations. Phosphorus concentrations were greater in catfish and tilapia than [...]


Light Penetration In Water

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Summary: 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. Light penetration into water also is the energy source for photosynthesis by phytoplankton and other aquatic plants. Photons of light absorbed by water warm the water, decreasing with depth. The varying density of the water can create layers of thermal stratification within water bodies.   The depth [...]


Atmospheric Pollution Affects Water Quality

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Summary: Human activities have altered the concentrations of gases and other compounds in the atmosphere. 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. Due to higher carbon dioxide concentrations in the atmosphere, the amount of carbon dioxide that will dissolve in ocean water has increased. Decreased pH can thin the shells of some molluscan shellfish and reduce survival. Claude [...]


Silicon, Diatoms In Aquaculture

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Summary: The silicon plants take up in silicic acid from water strengthens cell walls. Among the phytoplankton, diatoms particularly need silicon. Diatoms have good nutritional value and do not degrade water quality, so shrimp farmers often attempt to increase their abundance relative to other planktonic algae. To support diatoms, farmers should use silica products that contain 20% silicon. However, silicates have lower neutralizing values than agricultural limestone or lime, which are cheaper and more readily available. Claude E. Boyd, Ph.D., [...]


Hepatopancreas Colors Related To Vibrios Predict Survival Of Shrimp To EMS

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Monitoring of Vibrio bacteria in shrimp larvae determined a relationship among hepatopancreas color, bacteria concentration and signs of early mortality syndrome. Shrimp with brown hepatopancreases had 3.50 x 103 CFU/g Vibrio with no EMS and high survival. Shrimp with white hepatopancreases had 6.02 x 107 CFU/g Vibrio and died within 10 days. Some animals with both brown and white hepatopancreas tissue had low bacterial concentrations, but survival depended on pond conditions. Management procedures used after the onset of mortality increased survival. Outbreaks of [...]


Better management practices for shrimp farming – Part II

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31. Water is a scarce and very precious natural resource. Try to maximize the efficiency of water utilization. 32. Exchange the water carefully. Do not frequently exchange or in-take the water. 33. During the first month, there should not be any water exchange. Starting the second month, if necessary, water exchange can be done but try to minimize it as much as possible. 34. Release the water when the plankton bloom is too thick i.e., dark green or dark brown water. 35. When [...]