Chemistry of Sediment Pore Water in Aquaculture Ponds Built on Clayey Ultisols at Auburn, Alabama

The composition of sediment pore water was determined for ponds constructed on clayey Ultisols at Auburn, Alabama. Pore water was anaerobic and contained much higher concentrations of ferrous iron (Fe²⁺), soluble reactive phosphorus (SRP), total phosphorus (TP), total ammonia-nitrogen (TAN), and sulfide (S²⁻) than surface or bottom waters. Concentrations of SRP and TP in pore water were higher in ponds with high soil phosphorus concentrations than in a new pond with less soil phosphorus. Increased concentrations of organic matter in soil or larger inputs of feed to ponds favored greater microbial activity in soils and higher concentrations of TAN in pore water. The pH of pore water was 6.5–7.0, and pH was apparently controlled by the equilibrium:

Movement of Fe²⁺, SRP, and S²⁻ from pore water into pond water apparently was prevented by the oxidized layer of soil just below the soil-water interface. Pond managers should concentrate on maintaining this oxidized layer to reduce the tendency for toxic substances to diffuse into the pond water.     

Phosphorus Fractions in Soil and Water of Aquaculture Ponds Built on Clayey Ultisols at Auburn, Alabama

Phosphorus fractions in soil and water were determined for a 22-year-old, 400m² fish pond constructed on clayey Ultisols at Auburn, Alabama. This pond had been used in pond fertilization and fish feeding experiments each year. Total phosphorus concenlrations in bottom soil were greater in deep water than in shallow water areas. Highest concentrations of phosphorus occurred in the 5–10 cm soil layer, but phosphorus had accumulated above its original concentration to depths of 20 to 45 cm ( x = 36.8 cm). The soil phosphorus accumulation rate was 2.68 g/m² per year. Less than 1% of the total phosphorus in soils from three ponds was extractable in distilled water or 0.5 M NaHCO₃. Sequential extraction with 1 M NH₄Cl, 0.5 N HCl, and 0.1 N NaOH removed less than 25% of the total phosphorus. The loosely-bound phosphorus fraction (1 M NH₄Cl extractable) was 0.4 to 5.2% of the extractable phosphorus. The ability to adsorb phosphorus decreased and the capacity to release phosphorus increased in pond soils as total phosphorus concentration increased. After 22 years of aquacultural production, phosphorus adsorption sites in a pond soil were only about half-saturated. Although soluble phosphorus accounted for 37% of the phosphorus in pond water, only 7% of the total phosphorus in pond water was soluble reactive phosphorus. The phosphorus pool in pond soil was over 500 times greater than that of pond water, but most of the soil phosphorus was strongly adsorbed and unavailable.     

小檗碱复合物和微生态制剂控制池塘有害蓝藻

选取天津市北辰区易爆发有害蓝藻的一口养殖虾池,面积为1hm2,水深1.3m,2015年5月7日投放凡纳滨对虾苗种1.0×106尾,6月24日向养殖虾池全池泼洒小檗碱—青蒿素复合物,自5月12日起至8月17日,养殖期间平均每14d采样1次,监测养殖虾池浮游植物组成及数量和主要水化指标,以探求有效调控凡纳滨对虾养殖池中有害蓝藻的方法。试验结果表明,加入小檗碱—青蒿素后,显著抑制了有害蓝藻,对微囊藻和颤藻的抑杀率接近100%和71%,蓝藻的总体抑杀率达到90%。微生态制剂显著降低了水中亚硝酸盐、氨氮及化学需氧量,pH控制在9以内;促进有益绿藻数量增长35.36%。试验结果说明在应急反应时,小檗碱—青蒿素显著地抑杀池塘有害蓝藻,而微生态制剂可在杀藻后期调控水质,维持藻相平衡,控制有害蓝藻数量,防止其再次爆发。     

精养蚌池蓝藻水华的综合防治研究

由铜绿微囊藻和水花微囊藻形成的水华浴称为“湖靛”，对珍珠蚌的养殖有毒害作用；分析了蓝藻水华产生的主要原因，从7个方面论述了综合防治“湖靛”的方法。     

Physical and Chemical Characteristics of Bottom Soil Profiles in Ponds at Auburn, Alabama, USA and a Proposed System for Describing Pond Soil Horizons

Soil cores were taken from each of three, 2-, 23-, and 52-yr-old research ponds (650–1,010 m² area) at Auburn, Alabama. Many physical and chemical variables changed in intensity with increasing depth in cores. Compared to original compacted pond soil, sediment contained more moisture; had lower bulk density (<1.4 g/cm³); possessed higher percentages of silt and clay; had greater porosity, specific surface area, and cation exchange capacity; and contained greater concentrations of organic matter and nutrients. Sediment organic matter was highly decomposed as evidenced by low proportions (5–15%) of carbon and nitrogen associated with the light fraction (soil retained on a 53-μm sieve). Sediment depth at 100-cm water depth increased with pond age (11.7 cm, 28.3 cm, and 48.3 cm in 2-, 23-, and 52-yr-old ponds, respectively), but sediment composition did not change greatly over time. Successive layers in cores were as follows: 1) water near the soil-water interface with a high concentration of solids; 2) high moisture content sediment with dry bulk density <0.3 g/cm³; 3) lower moisture content sediment with bulk density between 0.3 and 0.5–0.7 g/cm³; 4) rapid transition of bulk density from 0.5–0.7 g/cm³ to 1.4 g/cm³; 5) original compacted soil with bulk density of 1.4–1.7 g/cm³. We propose that these five layers be referred to as F (flocculent layer), S (stirred or mixed sediment), M (mature, bulk, un-mixed sediment), T (transitional layer), and P (original, undisturbed pond bottom) horizons, respectively. Superficial, oxidized sediment is termed an S_o horizon, and the reduced part of the S horizon is termed an S_r horizon. The upper part of the T horizon is an MT horizon when it is similar to the M horizon, or a FT horizon when it resembles the P horizon. A system for delineating horizons in pond soil profiles will be valuable in future attempts to classify pond soils.     

Effects of Aeration, Alum Treatment, Liming, and Organic Matter Application on Phosphorus Exchange between Soil and Water in Aquaculture Ponds at Auburn, Alabama

Application of readily-oxidizable organic substrate to laboratory soil-water systems and fish ponds caused anaerobic conditions in bottom soil and water, and concentrations of soluble reactive phosphorus (SRP) increased. Aeration of ponds increased total phosphorus (TP) concentrations by suspending soil particles in the water, but SRP concentrations declined because of increased oxy- genation of bottom water and soil, Alum [Al₂(SO₄)₃·14H₂O] treatment of ponds reduced SRP and TP concentrations in ponds, but the low concentration of alum used, 20 mg/L, had little residual effect on phosphorus concentration. Application of agricultural limestone at 0.2 kg/m² to ponds with soil pH of 5.5 and Ca²⁺ concentration of 5 mg/L did not affect SRP and TP concentration. Unless pond soils were anaerobic at their surfaces, a condition not acceptable in thermally-unstratified fish ponds, soils released little phosphorus to the water. Strong adsorption of phosphorus by soils in intensive ponds with feeding is beneficial, because removal of phosphorus by aerobic soils is a control on excessive phytoplankton growth. In fertilized ponds, phosphorus must be applied at frequent intervals to replace phosphorus removed from the water by soils.     

Water Temperature in Inland,Low-Salinity Shrimp Ponds in Alabama

Water temperature in eight ponds and air temperatures were monitored at 2-h intervals during the 2010 growing season at an inland, low-salinity shrimp farm in Alabama. There was a high correlation (P < 0.01) between mean daily air and water temperatures; pond water usually averaged 3° to 4°C warmer than air. Monthly mean water temperatures among eight ponds differed by 3.40°C in May and by 2.83°C in September, but there was less than 1°C difference among ponds in June, July, and August. Differences in temperature among ponds were not related to pond water surface:volume ratio, but in July and September there was a negative correlation (P < 0.05) with increasing aeration rate. Negative correlations (P < 0.05) between average water temperature over the entire culture period and survival and production of Pacific white shrimp, Litopeneaus vannamei, possibly resulted from variation in crop duration and were not causal. Nevertheless, differences in water temperature among ponds in May and September were great enough to have possibly caused differential shrimp survival and production among ponds.     

Evaluation of Growth,Survival, and Production of an Endangered Fish,Labeo gonius (Hamilton) Fingerlings in Earthen Nursery Ponds

ABSTRACT

Nursery rearing of an endangered fish, Labeo gonius (Ham.) was studied in relation to varying stocking densities in earthen ponds. The experiment was conducted for 8 weeks in nine nursery ponds having an area of 0.012 ha with an average depth of 1 m. Four-day-old hatchling stocked at 0.6 million/ha was designated as treatment-1 (T₁), 0.8 million/ha as treatment-2 (T₂) and 1.0 million/ha as treatment-3 (T₃), respectively. At stocking, all hatchlings were of same age group with a mean length and weight of 0.66 ± 0.08 cm and 0.001 ± 0.0001 g, respectively. Hatchlings in all the experimental ponds were given wheat flour for the first 7 days, finely ground mustard oilcake for the next 7 days and a mixture of rice bran, and mustard oilcake (1:1) for days 15 to 56. The rate of feeding was 20 kg/million hatchling/day for the first two weeks, 25 kg for the second two weeks, 30 kg for the third two weeks and 35 kg for the fourth two weeks. The physicochemical parameters of water and plankton were monitored simultaneously and were within the acceptable range for fish culture. Growth parameters (final weight, final length, weight gain, length gain and specific growth rate) and survival of fingerlings were significantly higher in T₁ (0.6 million hatchling/ha) than those in T₂ (0.8 million/ha) and T₃ (1.0 million/ha), respectively. Feed conversion ratio (FCR) was significantly lower in T₁ followed by T₂ and T₃ in that order. The estimated gross and net productions of fingerlings were significantly higher in T₁ than in T₂ and T₃, respectively. Significantly higher number of fingerlings was produced in T₃ than those in T₂ and T₁. Despite this, consistently higher net benefits were obtained from T₁ than from T₃ and T₂. Overall, highest growth, survival, production and benefits were obtained from T₁ where stocking density of hatchlings was 0.6 million/ha. Hence, of the treatments evaluated, stocking density of 0.6 million hatchling/ha appears to be the most efficient stocking density for rearing of L. gonius fingerlings in earthen nursery ponds.     

Effects of Major Water Quality Variables on Shrimp Production in Inland,Low‐Salinity Ponds in Alabama

Common water quality variables in nine, inland low‐salinity shrimp ponds in Alabama exhibited wide variation in concentrations among ponds and over time. Shrimp performance also varied considerably among ponds in 2008 as follows: survival, 16–128%; production, 928–5950 kg/ha; feed conversion ratio (FCR), 1.18–2.89. Measured water quality variables were not at concentrations high enough to be lethal to shrimp; but water temperature, dissolved oxygen, carbon dioxide, total ammonia nitrogen, calcium, and magnesium were occasionally outside optimum ranges for shrimp production and may have stressed shrimp. Survival and production both were positively correlated (P < 0.05) with increasing concentrations of methyl orange alkalinity, total alkalinity, and calcium hardness. Negative correlations (P < 0.05) between production and higher pH and water temperature may have resulted from lower water temperature and pH during final days of the crop in ponds harvested in October rather than from an actual effect of temperature and pH on growth. Nevertheless, those variables that were outside optimal ranges or correlated with shrimp survival or growth should be further investigated to ascertain whether or not excursions outside optimum ranges are harmful and to determine if observed correlations are causal.     

Fish assemblage shifts and species declines in Alabama, USA streams

Abstract –  Recognition of faunal changes requires long-term monitoring, which is lacking for all but a very few streams. Fish surveys are often focused on single, often imperiled, species. While such studies meet the goals of monitoring single species, assemblage-based data are required for detection of assemblage change and declines in common species, and yet these studies are relatively rare. Assemblage-based data may be important in identifying potential ecosystem problems before the loss of ecosystem function that results from catastrophic biodiversity decline. In 2005–2006, we sampled fishes in three streams in the Chattahoochee River drainage, Alabama in order to assess fish assemblage persistence and individual species declines. To achieve these comparisons we used historic data from two time periods, 1970s and 1995. Although comparisons to historical collections were used conservatively, we found dramatic assemblage shifts over time, even using conservative metrics. Examination of individual species persistence over time in these watersheds uncovered species losses at both the site and stream scale. Metrics of similarity, persistence, and Spearman's rank correlation indicated low similarity of fish assemblages and high species turnover over time. Specifically, cyprinid species have been lost and have been replaced with more cosmopolitan species. Comparison of three time periods allowed the estimation of when assemblages changed through time. Changes in land use, increases in the human population and less overall water availability may be agents of habitat degradation partially responsible for fish faunal changes.     

生物改良池塘养鳜试验

为建立低消耗、低排放、高效益的新型养殖模式,在鳜养殖池塘引入微生物、水生植物以及投放其他鱼种进行生产试验。在0.2 hm2鱼池中,投放4 cm鳜鱼种2790尾,经过185 d的饲养,单产达到415 kg/667m2。鳜池连同饵料鱼池共0.65 hm2面积,平均利润3977元/667m2,商品率90%。在局部生态系统条件下,池塘水质实现了自净,水质指标符合鳜生长要求,养殖用水比常规养殖相对减少。     

Potassium Adsorption by Bottom Soils in Ponds for Inland Culture of Marine Shrimp in Alabama

Potassium is applied to correct ionic imbalance in pond water for inland culture of marine shrimp in Alabama. This study evaluated the loss of potassium through adsorption by bottom soil. Adsorption by bottom soils of potassium added in fertilizers continued over 4 yr. Exchangeable potassium concentration in bottom soils did not increase after the first year, but potassium loss to bottom soil continued over 4 yr. Laboratory work on soil–water systems contacted bottom soil with potassium‐enriched pond water for 8 mo: nonexchangeable potassium fixation accounted for 75% of potassium adsorption. Soil total potassium adsorption averaged 518 mg/kg. Bottom soil samples exposed to consecutive 50 mg/L potassium solutions (potassium chloride in distilled water) and agitated by shaker led potassium adsorption by soil to decline from 406 mg/kg in first exposure to 70 mg/kg in sixth exposure. During the next six exposures, potassium adsorption was similar, between 61 and 95 mg/kg in each exposure, averaging 1804 mg/kg of potassium. Pond soils contain smectite clay, have a large capacity to adsorb potassium by nonexchange processes, and remove added potassium from water for years. The only reliable way to determine when potassium fertilizer may be added to Alabama inland shrimp ponds is to monitor potassium concentration in water.     

Filtration of Green Algae and Cyanobacteria by Freshwater Mussels in the Partitioned Aquaculture System

Abstract.— The freshwater mussel Elliptio complanata was provided water containing green algae and cyanobacteria delivered from the Partitioned Aquaculture System (PAS) at eight flow rates to determine algal filtration rates as mg of particulate organic carbon (POC)/kg wet tissue weight per h. The dominant taxon in cyanobacterial waters was Microcystis while the dominant taxa in green algal waters were Scenedesmus and Ankistrodesmus . The cell counts of Scenedesmus and Ankistrodesmus were the only algal taxa that were significantly different between the incoming water and water filtered by mussels. Filtration rates of POC obtained from green algal water were significantly greater than from cyanobacteria-dominated waters at all flow rates. A significant increase in mean filtration rate was observed as flow rates increased. The filtration rate of green algae increased as POC concentration increased, peaking at 28 mg C/L. A maximum filtration rate was not observed with cyanobacterial waters.     

沉水植物在池塘养殖生态系中的水质改良作用

池塘养殖生态系是一种人工生态系统,其特点是水体面积小,深度浅,水交换量较低,而养殖密度又较高,且一般通过大量投饵来提高鱼产量。如此,鱼体排泄物和多余残饵的沉积与分解,往往会使池塘底泥和水体中的营养盐和有机物浓度升高,透明度下降,从而引起了一系列问题[1]:化学耗氧量(C     

Impact of Predation by Backswimmers in Golden Shiner,Notemigonus crysoleucas,Production Ponds

Laboratory and field studies were conducted to determine the population dynamics and potential for predation on golden shiner, Notemigonus crysoleucas, fry by the backswimmers, Notonecta indica and Buenoa scimitra. Both species were found to be highly effective predators under laboratory conditions. N. indica invaded newly flooded ponds within 2 weeks of putting spawning mats with eggs into the ponds and were thus present when fry were vulnerable to predation. B. scimitra invaded ponds at a slower pace and would not be as likely to cause extensive predation. N. indica had significantly lower (P = 0.05) population levels in ponds that had been established for one year. The potential loss from backswimmer predation could easily exceed 2.3 kg per 100 m of shoreline, assuming 40% of the fry lost to predation would survive to harvest. Diesel fuel treatment of backswimmer populations in 0.05-ha ponds resulted in about a 50% control of N. indica, mostly during the first 24 hours. B. scimitra were not as susceptible to the diesel fuel treatment. Several classes of insecticides were evaluated in the laboratory as potential control agents; Curacron, an organophosphate, and Cymbush a, synthetic pyrethoid, produced 100% mortality of N. indica at a concentration of 0.01 ppm. B. scimitra was even more sensitive to these compounds.     

Geosmin and Off-Flavor in Nile Tilapia (Oreochromis niloticus)

Abstract

The concentration of geosmin (1,10-trans-dimethyl-trans-9-decaol) in fresh tilapia were analyzed by applying high-vacuum distillation, extraction and gas chromatography techniques. The distribution of geosmin in the fish was determined by examining tissues from various parts of tilapia, along with the rates of geosmin absorption and purging. Analysis showed that when geosmin was added to fish flesh at concentrations ranging from 2.8 to 390 μg per kg of flesh, the rate of recovery was 51 to 89%. Sensory evaluation detected muddy flavor in freshwater tilapia with geosmin content ranging from 7.55 to 9.85 μg/kg of fish flesh. However, panelists failed to detect muddy flavor in brackish water tilapia that contained geosmin only in the range of 1.5 to 2.6 μg/kg. Among various tissues of the fish, the intestines contained the highest geosmin concentration, and appeared in descending order in the abdominal, skin and muscle tissues. After holding for 2 h in water with 5 and 50 μg/l geosmin, tilapia absorbed 17.6 and 42.2 μg/kg geosmin in the flesh, respectively. Holding the fish over longer periods in water with higher geosmin content resulted in a greater amount of absorption. In contrast, transferring muddy-flavored fish to static clean water purged geosmin from the fish but it required at least 16 days to eliminate the muddy flavor.     

Growout of Pacific White Shrimp, Litopenaeus vannamei, Stocked into Production Ponds at Three Different Ages

This study was designed to determine the production characteristics of the Pacific white shrimp, Litopenaeus vannamei, stocked into grow‐out ponds at three different sizes and ages. To meet this goal, three groups of postlarvae (PL) were obtained. The first group was placed in a nursery system for 21 d (N21), the second for 14 d (N14), and the third was stocked directly into ponds (DS). Shrimp from each nursery treatment (three tanks per treatment) were pooled and then subdivided for stocking into four replicate 0.1 ha ponds per treatment, another four ponds were stocked directly (DS) with PL₈. All 12 ponds were stocked on the same day at a density of approximately 35 PL/m², and cultured over a 16‐wk period and then drain harvested. After harvest, mean average weights (15.4, 16.9, and 14.9 g), survivals (63, 62, and 64%), FCRs (2.7, 2.5, and 2.7), and average yields (3592, 4005, and 3374 kg/ha) were determined for N21, N14, and DS, respectively. No significant (P > 0.05) differences were observed among treatments. Regardless of nursing time, nursed juveniles did not differ significantly in production characteristics from shrimp stocked directly from the hatchery.     

Impacts of Bolbophorus damnificus (Digenea: Bolbophoridae) on Production Characteristics of Channel Catfish,Ictalurus punctatus,Raised in Experimental Ponds

Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (≥34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) was unknown. Laboratory and field studies were conducted to evaluate sublethal acute (early stage) and chronic (late stage) trematode infection impacts on catfish production. Fish raised in ponds seeded with ram's horn snails from ponds harboring active B. damnificus outbreaks resulted in infection prevalence ranging from 1.6 to 20.4%. Compared to fish raised in ponds not seeded with infected snails (0% prevalence), fish biomass, number harvested, and total feed fed were significantly lower. These data agree with previous studies where mild infections reduced feed consumption, fish production, and economic returns. Infected fish were collected from ponds and used in a laboratory growth study. Once removed from the infection source, weight gain, growth rate, feed consumption, and feed efficiency were equal to or greater than trematode‐free fish. This suggests that although early B. damnificus infection (premetacercarial development) can severely impact production, infection has little impact on performance once metacercarial cysts are fully developed, and the infection source is removed.     

Production of Walleye,Stizostedion vitreum,in Earthen Ponds Fertilized with Organic and Inorganic Fertilizers and Stocked at Three Rates

Walleye, Stizostedion vitreum, fry were raised at densities of 20,30 and 40/m³ in ponds initially fertilized with alfalfa and yeast and supplementally fertilized with liquid inorganic fertilizers. Liquid fertilizers were added weekly to maintain N and P concentrations of 600 and 30 ug/L, respectively. Fish growth was not affected by stocking rate, but survival was significantly (P < 0.05) reduced in ponds stocked at the two higher rates. The fertilization procedure we used did not provide a sufficient forage base to support more that 20 walleye/m³.     

文蛤池塘养殖技术

文蛤(Meretrixmeretrix)营养丰富,肉味鲜美,有天下第一鲜的美誉,是我国滩涂养殖的传统品种之一。丹东地区20世纪90年代开始进行文蛤池塘养殖试验,并取得成功,得以迅速推广。现介绍如下。1　文蛤养殖池塘的选择1 1　位置　选择位于中低潮区,风浪较小,底质为细沙质或泥沙质的