Control Ponds Research Articles

Evaluation of Porous, Geotextile Liners for Erosion Control in Small Aquaculture Ponds

AbstractTwo geotextile liners, one with 0.090‐mm openings and the other with 0.355‐mm openings, were each installed in three 0.04‐ha earthen ponds at the E. W. Shell Fisheries Center, Auburn, Alabama. Geotextile liners did not tear or decay during the 2‐year study, and they prevented erosion of pond bottoms compared with three unlined ponds. However, the liners with 0.090‐mm openings floated up into the water column in all three ponds, while the other liner floated up in one pond. Production, survival, and feed conversion ratio for hybrid catfish (♀ Channel Catfish Ictalurus punctatus×♂ Blue Catfish I. furcatus) did not differ (P > 0.05) among control and lined ponds. Phytoplankton abundance as estimated by chlorophyll a concentration was greater in lined ponds—especially in those lined with the less permeable geotextile—than in control ponds. This difference was attributed to differences in phosphorus uptake by bottom soil among lined and control ponds. Control ponds had higher turbidity than lined ponds in spite of greater chlorophyll a concentration in the lined ponds. This was the result of sediment resuspension by aeration in the unlined ponds. In laboratory tests, geotextiles with openings of 0.090–0.840 mm did not allow normal exchange of phosphorus between soil and water. Nevertheless, if the floating problem could be solved, porous geotextiles should be given further consideration for erosion control in small ponds and possibly in intensive, heterotrophic floc systems for commercial culture of marine shrimp and a few other species. They probably are too expensive for use in large ponds for green‐water culture of fish and shrimp.

VARIASI PERTUMBUHAN UDANG WINDU (Penaeus monodon) DAN IKAN BANDENG (Chanos chanos) PADA BUDIDAYA POLIKULTUR TAMBAK WANAMINA DENGAN JENIS VEGETASI MANGROVE YANG BERBEDA DI KOTA SEMARANG

The effort to support silvofishery application is needed to maintain the sustainability of coastal resources utilization. But, inappropriate knowledge of the aquaculturists and lack of evidence concerning the application of silvofishery in aquabusiness became the major problems of the effort. This research aimed to study the effect of silvofishery system with different mangrove specieses to the growth of Tiger shrimp and Milkfish. The research was conducted through experiment involving Avicennia marina and Rhizophora mucronata and control pond (without mangrove vegetation) as comparison. While the cultured biota including Tiger shrimp and Milkfish with polyculture system. The research was conducted with 2 replication for 3 months (90 days). The observation factors including the growth of culture biota including total length, standart lengt and weight. The result showed that the growth of Tiger shrimp was optimum in silvofishery pond involving Rhizophora mucronata. While the growth of Milkfish was optimum in silvofishery pond invlving Avicennia marina. Total length of Tiger shrimp from the experiment ranged from 10,3 – 19,6 cm at control pond; 10,3 – 20,6 cm at Avicennia pond; and 17,5 – 19,8 cm at Rhizophora pond. While standart length of Tiger shrimp ranged from 4,0 – 7,5 cm at control pond; 3,5 – 15,5 cm at Avicennia pond and 7,3 – 8,0 cm at Rhizophora pond. While the weight of Tiger shrimp ranged from 5 – 60 gr at control pond; 15 – 70 gr at Avicennia pond and 50 – 75 gr at Rhizophora pond. Measurement on the growth of Milkfish showed the range of total length from 11,0 – 28,5 cm at control pond; 22,3 – 32,0 cm at Avicennia pond and 17,5 – 28,5 at Rhizophora pond. While standart length of Milkfish ranged from 4,0 – 20,7 cm at control pond; Avicennia pond range from 17,8 – 25,5 cm; and Rhizophora pond ranged from 13,9 – 23,4 cm. Average weight of Milkfish ranged from 5 – 140 gr at control pond; 90 – 240 gr at Avicennia pond and 50 – 250 gr at Rhizophora pond.

Enhancement of innate immune system, survival and yield inPenaeus monodonreared in ponds usingStreptococcus phocae PI80

The objective of this study was to evaluate the effect of dietary and water supplementation of probiotic Streptococcus phocae PI80 on growth, immune response and feed utilization of tiger shrimp Penaeus monodon in earthen ponds. The probiotic bacterium S. phocae PI80 was cultured in large fermenter (50 L) by adding additional carbon source in the form of molasses and glucose along with yeast extract as nitrogen source to enrich S. phocae PI80 biomass. This enriched S. phocae PI80 was administered to shrimp in feed (6.5 × 1013 bacterial cells mL−1) as well as in pond water (5 L/pond). Shrimp growth performance was significantly improved (P < 0.05) in 120 days culture when the average body weight of treated molasses + yeast extract (MY) (28.41 ± 0.874 g), glucose + yeast extract (GY) (27.013 ± 0.698 g) was significantly higher than control (23.63 ± 0.684 g). Food conversion ratio FCR was also found to be reduced significantly in ponds treated with probiotics when compared with control pond (1.89 ± 0.09). Vibrio and luminescent bacteria were found to be lower in the treatment receiving MY group, and we hypothesize that this may lead to greater shrimp survival. Furthermore, fermentation product of S. phocae PI80 added to pond water and feed additives enhanced the shrimp immune system. The results indicated that total haemocytes count (THC), phenoloxidase (PO) activity, NBT reductase assay and phagocytic activity significantly increased in shrimps treated with S. phocae PI80. Our study demonstrates that administration of S. phocae PI80 in the water and feed at 6.5 × 1013 colony-forming units (CFU) mL−1 bacterial cells induce immune modulation and enhances the immune ability of P. monodon in pond-reared shrimp and increased the shrimp production.

Assessment of a Phytogenic Feed Additive (Digestarom P.E.P. MGE) on Growth Performance, Processing Yield, Fillet Composition, and Survival of Channel Catfish

AbstractWe investigated the effects of a phytogenic feed additive (Digestarom® P.E.P. MGE) on growth performance, processing yield, fillet composition, and survival of pond‐raised channel catfish. Fifteen 0.4 ha ponds were stocked with 14,820 catfish (126 g/fish) per ha. Fish in control ponds were fed a 32% crude protein commercial floating diet whereas fish in test ponds were fed the same diet supplemented with Digestarom P.E.P. MGE at 200 g/ton. In a second study, ten 0.04 ha ponds were stocked at a similar density with fish that averaged 68 g/fish. At the end of the 6‐mo study, there was no significant difference in the amount of feed fed or the amount of weight gained between the control and Digestarom P.E.P. MGE fed fish. Food conversion ratio, net yield, and survival were also similar between the two groups. Carcass, fillet, and nugget yield were similar. Fillet proximate analysis revealed that fillet fat was lower (P &lt; 0.01) whereas fillet protein tended to be a little higher (P &lt; 0.10) in treated fish. In conclusion, there was a significant reduction in the amount of fillet fat in Digestarom P.E.P. MGE fed fish. Improved fillet composition (higher protein and lower lipid) is of commercial importance.

Management induced changes of antibiotic resistant strains of heterotrophic bacteria in shrimp farming ponds

Antibiotic resistant strains of heterotrophic bacteria and total aerobic heterotrophic bacteria were enumerated along with important water quality parameters in water and sediment samples collected from 3 shrimp farming ponds used for the monoculture of Penaeus monodon as well as from a control pond located outside the shrimp farm. The resistant strains of heterotrophic bacteria were screened against 3 antibiotics (ampicillin, chloramphenicol and oxytetracycline) at 25 and 50 μg/l. The counts of antibiotic resistant bacteria tended to rise in shrimp ponds with progressive rise in the days of culture, but were specially high during the period when both antibiotics and feed were applied in the system. It appears that antibiotics exerted a selective pressure in favour of antibiotic resistant bacterial strains and widespread use of antibiotics should be forbidden in shrimp ponds.

Parasite surveys and environmental management for prevention of parasitic infection in cultivated Barbonymus gonionotus (Cyprinidae) in fishponds, in an opisthorchiasis endemic area of northeast Thailand

Snails and fishes from ponds in an area endemic for human liver fluke (Opisthorchis viverrini) in Khon Kaen Province, northeast Thailand, were surveyed for the presence of zoonotic helminth parasites during May-November 2007. The surveys were performed to obtain information on the potential for transmission of these parasites to fish cultivated for human consumption. Sixteen species/subspecies of snails from 7 families and 14 species of fish from 6 families were collected for parasitological examination. Four species of snails were found to be infected with a range of trematode species. Bithynia siamensis goniomphalos, the first intermediate host of O. viverrini, was the most commonly infected with trematodes, with a prevalence of infection of 1.69-25.00% in 10 ponds. O. viverrini was found in 1 of 1065 (0.09%) B. siamensis goniomphalos individuals examined in one pond. Metacercariae of Echinostoma revolutum, another agent of human infection, was found in the snail Idiopoma umbilicata in one pond. The fish Luciosoma bleekeri was infected with the trematode Centrocestus caninus in one pond. An environmental management trial was conducted in selected ponds in the endemic area to measure the effects of exclusion of snails and thus trematode parasites. After modifications to the ponds and boundaries, including the exclusion of snails, the ponds were stocked with Barbonymus gonionotus fingerlings. Batches of the fingerlings from the same nursery farm were determined to be free of parasites prior to their introduction to the ponds. The experimental ponds were examined monthly for the presence of snails. Fish were also sampled monthly for parasites. After 8 months, fish grown in environmentally managed ponds were larger than those of the control pond. However, fish in all ponds were found to be infected with the trematode Haplorchis taichui. The source of this zoonotic species is uncertain and will require further investigation and potential environmental management, both at farms and at hatcheries. (C) 2014 Elsevier B.V. All rights reserved.

Experimental canopy removal enhances diversity of vernal pond amphibians

Vernal ponds are often treated as protected environments receiving special regulation and management. Within the landscapes where they are found, forest vegetation frequently dominates surrounding uplands and can grow to overtop and shade pond basins. Two bodies of research offer differing views of the role of forest canopy for vernal pond systems. Studies of landscape conversion suggest that removing forest overstory within uplands can cause local extinctions of amphibians by altering terrestrial habitat or hindering movement. Studies of canopy above pond basins imply an opposite relationship; encroachment of overstory vegetation can be associated with local extinctions potentially via changes in light, thermal, and food resource environments. Unresolved uncertainties about the role of forest canopy reveal significant gaps in our understanding of wetland species distributions and dynamics. Any misunderstanding of canopy influences is simultaneously important to managers because current practices emphasize promoting or conserving vegetation growth particularly within buffers immediately adjacent to ponds. We evaluated this apparent contradiction by conducting a landscape-scale, long-term experiment using 14 natural vernal ponds. Tree felling at six manipulated ponds was limited in spatial scope but was nevertheless effective in increasing water temperature. Compared with eight control ponds, manipulated ponds maintained more amphibian species during five years post-manipulation. There was little evidence that any species was negatively influenced, and the reproductive effort of species for which we estimated egg inputs maintained pretreatment population densities in manipulated compared with control ponds. Overall, our experiment shows that a carefully circumscribed reduction of overhead forest canopy can enhance the capacity of vernal ponds to support wildlife diversity and suggests a scale dependence of canopy influences on amphibians. These findings have implications for the connection between current wetland management practices and the goals of wetland stewardship and conservation of wetland-dependent species.

Winter Pond Fertilization Can Increase Phytoplankton Density in Aquaculture Ponds

AbstractEffective winter fertilization would be beneficial under certain production systems in the southeastern USA. Maintaining a phytoplankton bloom during the winter has the potential to shade macrophytes, discourage filamentous algae, and provide natural foraging opportunities for fish during warmer days; this would be advantageous. An additional benefit of a winter bloom would be to produce turbidity, thereby possibly reducing bird predation. The objective of this study was to determine if winter fertilization could increase phytoplankton to greater biomass than in nonfertilized control ponds. Six ponds served as controls and six ponds received an initial dose of nitrogen at 20 kg/ha and phosphorus at 2 kg/ha in mid‐November. Over the following five weeks, treatment ponds received one‐half the initial dose once per week, and then continued to receive the half dose once per month in January, February, and March. Fertilization led to increases in total ammonia nitrogen, nitrite, and nitrate. The water temperature ranged from a low of 5°C to a high of 16.8°C (mean of 10.2°C) over the entire study. Even though water temperatures were low and light intensity is less in winter, fertilization caused a significant increase in chlorophyll a over the study. The increase in total algal biomass was not due to an increase in any specific algal group, but rather a general biomass increase in most algal groups. Cryptophyta tended to be the most common phytoplankton division throughout the study. Although this fertilization protocol increased algal biomass, there were no differences in zooplankton abundance between fertilized and nonfertilized ponds. In contrast to the currently held belief that winter fertilization is ineffective, this study shows that winter fertilization can increase algal blooms. Therefore, future studies should determine if blooms created from winter fertilization can increase growth of planktivorous fish, shade macrophytes, discourage filamentous algae, or produce turbidity which could reduce bird predation.

低平地都市河川におけるリアルタイム洪水シミュレーションモデルの開発

This study aims to develop a real time flood simulation model in an urbanized low-lying river basin (Tsurumi river of Japan). The model has been developed by enhancing the distributed hydrological model (WEB-DHM) to account for urban land surface characteristics and effects of flood control ponds and coupling 1D unsteady flow model to the enhanced WEB-DHM. The enhanced WEB-DHM model computes the flow rate in the upper stream and the 1D unsteady flow model computes the time-varying water surface level in the lower stream accounting for tides and effects of retention ponds. The system has been validated against past flood events along the study region with acceptable accuracy.

A flavonol, epicatechin, reverses the suppressive effects of a stressor on LTM formation

Learning and subsequent memory formation are influenced by both environmental and lifestyle factors, such as stress and diet. Epicatechin, a plant flavonol found in cocoa, red wine and green tea enhances long-term memory (LTM) formation in Lymnaea. By contrast, an ecologically relevant stressor, low-calcium pond water, suppresses LTM formation. We tested the hypothesis that epicatechin overcomes the suppressive effects of the stressor on LTM formation in the continued presence of the stressor. Snails trained in low-calcium pond water exhibit learning but not LTM. Epicatechin (15 mg l(-1)) in control pond water enhances LTM formation. When epicatechin was added to the low-calcium pond water an enhanced LTM similar to that seen in control pond water was observed. Thus, a naturally occurring bioactive plant compound was able to overcome the suppressive effects of an ecologically relevant stressor on LTM formation.

The Influence of Micropore Oxygen Aeration on the Pond Water Quality Environment

In order to know the effects of micropore oxygen aeration on the water quality and economic output, take each 3 of micropore oxygen aeration (experimental pond) and impeller oxygenation (control pond) to make the comparison, indexs of two different aeration methods water were detected from May, 2012 to October, 2012. Such as water temperature, dissolved oxygen, ammonia nitrogen and nitrite, phytoplankton, chemical oxygen demand (COD_Mn). Results showed that, (1) the indexes of the dissolved oxygen, ammonia nitrogen, chemical oxygen demand (COD_Mn) and nitrite of the experimental pond are all superior to that of the control pond, of which the concentration of the dissolved oxygen of the experimental pond is 8.37 mg/L which is higher than that of the control pond (5.7 mg/L). And, COD_Mn in the experimental pond is 7.54 mg/L, lower than that in the control pond (10.19 mg/L). The difference between the control pond and the experimental pond was statistically significant (p<0.01). The ammonia nitrogen of the experimental pond is 0.1 mg/L, obviously lower than the control pond (0.16 mg/L). Besides, the nitrite is 0.13 mg/L in the experimental pond, lower than that of the control pond (0.21 mg/L). (2) Compared with the control pond, the experimental pond has quite higher general abundance of algae, with about 5.69×10⁸ ind/L. Yet, there is no obvious difference between them. (3) Compared to the impeller oxygenation, the micropore oxygen aeration technology can be better to increase the dissolved oxygen in the aquaculture pond and improve the water quality. However, there is no significant influence to the phytoplankton abundance and diversity.

Test of Intercropping &lt;em&gt;Myxocyprinus asiaticus&lt;/em&gt; in the &lt;em&gt;Eriocheir sinensis&lt;/em&gt; Pond

In order to reveal whether the Myxocyprinus asiaticus and the mitten crab Eriocheir sinensis be intercropping well in pond-culture and whether have any influence on specification, production and benefit of the river crab, During March to November, 2011. We chose three mitten crab Eriocheir sinensis ponds of similar hydrology condition and environment in Liu farm, Taizhou city, Jiangshu province to start the test of intercropping Myxocyprinus asiaticus in the mitten crab pond. The control pond mainly cultivates Eriocheir sinensis auxiliary with Macrobrachium nipponense, siver carp and Siniperca chautsi, while the testing ponds intercropping Myxocyprinus asiaticus juveniles additional. Stocking density of the 2 nd pond and the 3 rd pond is, respectively 750 and 900 fish/hm 2 with averaging 10 cm in body length. After 250 days' cultivation, the average weight of each one is 997.8 g with survival rate of 91.2%. The average output of the 2 nd pond is 342 kg/hm 2 and the 3 rd pond is 405.75 kg/hm 2 . Compared with the contrast pond's 35,505 yuan/hm 2 net profit, the 2 nd pond and the 3 rd pond separately has 22,995 and 27,032 yuan/hm 2 more net profit with growth rate at 64.77 and 76.14%. The average specification of the Eriocheir sinensis in these three ponds is 169 g/one. Specification of the Eriocheir sinensis in the intercropping pond has no obvious difference with the one in the control pond.

Carbon sequestration in the soils of aquaculture ponds, crop land, and forest land in southern Ohio, USA

Soil samples were collected from four aquaculture ponds (yellow perch culture), a control pond (without aquaculture activities, fallow pond), crop land (under corn), and forest land to estimate the carbon (C) sequestration potential in the Piketon county, Ohio, USA. The averaged total of C was 6.5 ± 2, 8.8 ± 2, 8.53 ± 0.2 and 10.49 ± 1.1 Mg/ha (Mg=10(6)g) in < 0.25 mm fraction; 15.2 ± 2, 16.0 ± 3, 11.49 ± 0.8 and 17.23 ± 3.4 Mg/ha in micro aggregates (0.25-2.5 mm); and 22.1 ± 3, 26.4 ± 3, 12.16 ± 1.6 and 18.51 ± 4.3 Mg/ha in macro aggregates ( > 2.5mm), for aquaculture ponds, control ponds, cropland and forest land, respectively. The soil/sediment C pool followed the order of forest > crop land soils > aquaculture pond soils.

Reproductive Physiology in Eastern Snapping Turtles (Chelydra serpentina) Exposed to Runoff from a Concentrated Animal Feeding Operation

The eastern snapping turtle (Chelydra serpentina) is widely distributed throughout the eastern and central US and is a useful model organism to study land-use impacts on water quality. We compared the reproductive condition of turtles from a pond impacted by runoff from land applied with animal manure from a concentrated animal feeding operation (CAFO) relative to animals from a control pond. Turtles from the CAFO site were heavier and had higher plasma concentrations of vitellogenin (VTG, mean ± SE; females; 859 ± 115 vs. 401 ± 127 ng/mL from controls) and testosterone (T, males; 39 ± 7.0 vs. 3.8 ± 6.9 ng/mL from controls). No VTG was detected in males. Body mass was positively correlated with VTG and T. Our results suggest that nutrient pollution of the CAFO pond indirectly resulted in higher plasma VTG in females and T in males because of an increase in body mass. The population-level consequences of these effects are not clear, but could result in females producing larger clutches.

Stormwater nitrogen removal performance of a floating treatment wetland

The nitrogen (N) removal efficiency and effluent quality of two parallel stormwater retention ponds, one retrofitted with a floating treatment wetland (FTW) and one without any vegetation, was compared in a field trial. This study shows that inclusion of FTWs in stormwater retention ponds has potential to moderately improve N removal. Median FTW outlet event mean concentrations (EMCs) were lower than median inlet and control pond outlet EMCs for all species of N, except for NH(4)-N. Performance was statistically better from late spring to end autumn due to higher organic nitrogen (ON) removal and denitrification in presence of the FTW. Low dissolved oxygen (DO), higher temperature and increased organic matter (OM) and microbial activity below the FTW, likely facilitated the higher denitrification rates observed over this period. Greater sediment N accumulation in the FTW pond also contributed to its higher overall N removal. Higher OM availability in the FTW pond due to release of root exudates and supply of detritus from plant die-back may have contributed to floc formation in the water column, increasing particulate ON settlement. Enhanced ON mineralisation may also be responsible but was probably limited in summer due to the low DO induced by the FTW. Direct uptake by the plants appears to be of less importance.

APPLICATION OF ORGANIC FERTILIZERS WITH PRESERVING OF HIGH QUALITY OF WATER IN FISH-BREEDING PONDS

We estimated the water quality in fish-breeding ponds under influence of traditional (dung) and non-traditional fertilizers (distilled grain). We suggested that the processes of zooplankton development stimulation and water reservoirs self-purification are occurring mostly during vegetative period. Application of distilled grain stimulates the development of primary filtrators of Cladocera suborder much more intensively than applying of dung. According to the saprobiological assessment the water of both experimental and control ponds refers to the mesotrophic type of water reservoirs, namely β-mesosaprobic zone. Keywords: zooplankton, water quality, saprobity index , fertilizer, distilled grain, fish-breeding ponds .

An Ecological Engineering Pond Aquaculture Recirculating System for Effluent Purification and Water Quality Control

Water pollution arising from traditional pond aquaculture is a major problem facing China. A series of combined ecological engineering facilities composed of an ecological ditch, an ecological pond, and a subsurface flow constructed wetland together with three series‐connected culture ponds were designed as an ecological engineering pond aquaculture recirculating system (EPAS) to control water quality and pollution from the effluent. Results from running experiment of the system revealed that, the mean removal rates of the ammonia nitrogen (NH4+‐N), total nitrogen (TN), total phosphorus (TP), potassium permanganate index (CODMn), and chlorophyll a (Chl‐a) during the experiment period were 44.2, 47.6, 63.4, 61.5, and 83.0 by the ecological engineering facilities, respectively. With the fish density of 0.82 kg/m3 and daily water exchanges of 9.6%, the NH4+‐N, TN, TP, CODMn, and Chl‐a in the culture ponds were kept below 0.799 ± 0.129, 3.015 ± 0.427, 0.443 ± 0.131, 7.172 ± 2.071 mg/L, and 3.098 ± 1.046 µg/L, respectively, which were significantly lower than those in the control pond (p &lt; 0.05). Compared with traditional static pond aquaculture, the EPAS constructed in this study could increase unit output from 0.75 to 0.82 (mean value) kg/m3, and reduce the feed coefficient by 8.2%. These data implied that the EPAS might improve the water quality and provide a good culture environment, thus contributing to improve the culture efficacy.

Using paleolimnology to track the impacts of early Arctic peoples on freshwater ecosystems from southern Baffin Island, Nunavut

Paleolimnological approaches can be used to determine the ways in which past Arctic peoples have affected the ecosystems in which they live, and simultaneously to reconstruct the climate and other aspects of the environment that may have influenced local populations. Here we analyze sediment cores from seven ponds on the south-western coast of Baffin Island, Nunavut, in order to assess the impacts of early Arctic peoples on freshwater ecosystems. Prior to the historic Inuit occupation, the study area was extensively inhabited by Thule culture Inuit (ca 1200–1600 AD) and by an earlier Arctic group, the Dorset culture Palaeo-Eskimos (ca 500 BC–1500 AD) and their predecessors from as early as 2500 BC. The study ponds were selected to cover a gradient of the intensity of human activity in their catchments. The ecological impacts of early hunting societies can be detected using paleolimnology because the butchering of marine mammals released nutrients that eutrophied nearby ponds and left distinct geochemical signals in the sediments. The degree of eutrophication in the small freshwater ponds depended on the length of the occupation, as well as the amount and type of marine mammals taken as primary prey items (eg, whales, walrus, or seals). All sediment cores were AMS 14C dated to establish their chronologies, and analyzed for diatoms and stable isotopes of nitrogen (δ15N). Both diatoms and sedimentary δ15N have been previously demonstrated to respond sensitively to nutrient enrichment from Inuit whalers. Our δ15N and diatom data record nutrient enrichment in lakes surrounded by either long-term Thule or Dorset settlements. The Dorset sites that were the locations of periodic seasonal gatherings did not register any evidence of eutrophication in the nearby ponds, reflecting the shorter, less intensive nature of these occupations. Similarly, nearby control ponds with no evidence of significant human activity in their catchments showed little-to-no changes in δ15N profiles and diatom assemblages. Due to slow rates of decomposition, nutrients from butchered marine animal bones continue to influence the freshwater sites into which they drain, as evidenced by higher than typical nutrient and production-related water chemistry variables.

Use of Aluminum Sulfate to Reduce pH and Increase Survival in Fingerling Striped Bass Production Ponds Fertilized with Nitrogen and Phosphorus

AbstractPrevious studies revealed inorganic nitrogen (300 μg/L) and phosphorus (30 μg/L) additions thrice weekly is effective in controlling the density of Prymnesium parvum, a flagellated haptophytic golden alga with ichthyotoxicity in fish culture ponds. However, increased pH resulting from this treatment is also toxic to fry and fingerlings of Striped Bass Morone saxatilis. We evaluated the efficacy of aluminum sulfate (alum) in lowering pH in ponds fertilized for P. parvum control. The effects of alum on dissolved N and P concentrations, as well as the efficacy of this fertilization treatment for P. parvum control, were also examined. Striped Bass fingerlings (27.93 mm total length) were raised for 42 d in 10 plastic‐lined ponds (0.1 ha) fertilized for P. parvum control. Five ponds received alum applications at a rate of 1 mg/L for each 1 mg/L phenolphthalein alkalinity when afternoon pH was ≥9.0. The remaining five ponds served as controls and received no alum. Among alum ponds, morning pH was reduced by an average of 1.2 units and afternoon pH by an average of 0.8 units compared with controls. However, the alum treatment did not maintain afternoon pH below 9.0. Alum reduced concentrations of total P, soluble reactive P, total Kjeldahl N, nitrite + nitrate N, and total N but not ammonium N. The fertilization regimen was not as aggressive in controlling P. parvum in alum ponds as it was in control ponds, which may be attributed to N and P removal by alum. Striped Bass production was poor in all ponds, probably because of high pH. Future studies should investigate higher alum treatment rates (e.g., phenolphthalein alkalinity : alum = 1:1.5 or 1:2) along with modification of the timing or frequency of fertilization.

Culture of Chinese carps using anaerobic fermented cow manure (Slurry) and comparison of survival and growth factors versus traditional culture

The objective of this project is to compare growth and survival rate in Chinese carps reared under traditional culture conditions versus those reared in ponds treated with slurry (anaerobic fermented of cow manure). This experiment was conducted using two treatments one treatment using slurry and the other using cow manure plus chemical fertilizer as the control with three replicates for each. Chinese carp were stocked at the density of 2375 individuals/ha ( Silver carp 60%, Bighead 15%, common carp 17% and grass carp 8%). In this investigation common carp and grass carp were fed with formulated diets and fresh grass, respectively. The survival rate in the slurry treatment was higher than that in traditional treatment. Survival rates were 98, 100, 84 and 52 percent for silver carp, bighead, common carp and grass carp, respectively in the slurry treated ponds and 96.0, 98.3, 82.8 and 20.0% percent in the control ponds. The results showed that survival rate and yields were higher in the slurry treated ponds than that in the control. The increasing percent of yield were 13.5, 2.6, 18.4 and 85.3 in silver carp, bighead, common carp and grass carp, respectively. The survival rate for grass carp was two times higher in the slurry treatment than control. Zooplankton abundance in slurry ponds was higher than that in control, but blue-green algae density in slurry treated ponds was less than (over 50%). In general the results indicate that slurry with higher nutritional content is more effective on the survival and growth rate of fishes and also is more efficient in the proliferation of plankton in particular zooplankton. Slurry also reduces the use of chemical fertilizers.