Effects of shrimp pond water on phytoplankton: importance of salinity and trophic status of the receiving environment

Aquaculture generates a large load of effluents rich in organic matter and nutrients that may be introduced into the environment. This study aimed to assess in a microcosm experiment, the effect of shrimp pond water mixed with Patos Lagoon estuary water on phytoplankton chlorophyll a and primary production, simulating two salinities. Chlorophyll a, dissolved inorganic nutrients and primary production were measured in two experiments. In Harvest I, salinity of shrimp pond and environment water was similar, and chlorophyll a showed different trends over time, according to the amount of nitrogen available. In Harvest II, with different salinities and high nutrient concentrations in environment water, chlorophyll a levels showed a similar increasing trend over time in all mixtures. Net primary production showed differences among treatments in the first sampling in Harvest I, but not in the second, whereas no differences were observed among treatments in Harvest II. We conclude that shrimp pond effluent can lead to short‐term variations in chlorophyll a and primary production levels, with similar salinities. Salinity differences result in lower chlorophyll a and primary production values than expected according to the nutrient input. Differences in salinity can be an important management strategy to choose the best harvest period.     

Determination of quinomethionate (6-methylquinoline-2,3-diyldithiocarbonate) residues in crops by in situ fluorometry.

A simple method is described for the quantitative determination of quinomethionate (6-methylquinoline- 2,3 - diyldithiocarbonate) in crops. The pesticide residue is extracted with acetonitrile and partitioned in petroleum ether. After separation from the co-extractives by thin layer chromatography (TLC), the fluorescence is measured directly on a silica gel TLC plate. An average of 89% recovery is obtained at the 0.05 ppm level in apples, peaches, pears, and tomatoes.     

Difference in factors explaining growth rate variability in European eel subpopulations: the possible role of habitat carrying capacity

As a key parameter in the management of fish populations, individual growth rate (GR) variations were examined in the European eel (Anguilla anguilla; > 150 mm) using extensive mark–recapture surveys in the lotic habitats of two small rivers of western France: the Frémur, supposed to be saturated, and at the same latitude, the Oir with densities fivefold lower than those of the Frémur. In both systems, generalised linear models were used to test whether spatiotemporal factors such as dominant habitat type or local density affect GR variability. In the presumed unsaturated system, the Oir, GR variability is mainly explained by a set of habitat suitability drivers (density, dominant habitat type). In the Frémur, GRs appear independent of differences in habitat density or productivity. Below saturation, an increase in density will decrease the GR through intraspecific competition. At saturation, intraspecific competition reaches such high levels that regardless of eel density and productivity, the resources available by individual are similar throughout the system. In these circumstances, the effect of density on growth was presumed undetectable. Despite these contrasted results, mean GRs observed in both catchments were closed (~20 mm·year^?1). This is an unexpected result as GR is expected to be higher in unsaturated systems. This similarity could be explained by the difference between the two systems in terms of: (i) sex ratio (the Frémur is dominated by male, whereas the female is dominant in the Oir), (ii) habitat type distribution or (iii) possible interspecific competition (important salmonid populations in the Oir).     

Determination of acidic herbicides and related compounds in water and soil by capillary gas chromatography using a nitrogen-phosphorus detector

Methods are described for the determination of acidic herbicides and related compounds in water and soil. Eight acidic herbicides and related compounds were extracted from water using either dichloromethane or an XAD-2 resin column. The acidic moieties were derivatized with 2-cyanoethyldimethyl(diethyl)aminosilane. The derivatized compounds were separated using capillary gas chromatography and quantitated using a nitrogen-phosphorus detector. Extraction from water using dichloromethane or an XAD-2 resin column resulted in recoveries greater than 90% at 0.1 ppb with an average coefficient of variation (CV) of 6%. In soils extracted with aqueous acetonitrile-acetic acid and partitioned into dichloromethane, recoveries at 500 ppb were greater than 75% with an average CV of 3.3%. The methods are rapid and there are few interferences.     

Synovial fluid changes in induced infectious arthritis in calves

The objective was to develop an experimental model of septic arthritis in calves and to evaluate the effect of treatment on cytologic and bacteriologic variables of synovial fluid. The right tarsus of 7 healthy Holstein bull calves were inoculated with 10(8) colony-forming units of viable Escherichia coli of a pap-positive strain (day 1). On day 2, joint lavage was performed and antibiotic treatment was instituted. Cytologic examinations, bacterial cultures, and pap factor determinations by polymerase chain reaction (PCR) were performed on synovial fluid samples that were collected daily until day 4, then every 4 days until day 24. Results of physical examination, the severity of lameness, and swelling were recorded. Clinical signs of septic arthritis appeared on day 2 and persisted until day 9 for all calves. Bacterial cultures from all calves were positive for E. coli on day 2, and remained positive until day 3 for 1 calf and until day 4 for 5 calves. In addition, PCR results were positive for all calves, with 6 positive through day 3 and 1 positive through day 4, after which a positive result was again obtained on day 24. Synovial fluid neutrophil counts and white blood cell counts were significantly increased on days 2-4; however, synovial total protein concentrations were increased (P < .05) throughout the experiment in comparison to day 1. Results of all bacterial cultures were negative on day 8, although clinicopathologic signs of inflammation persisted until day 20. This model successfully induced acute septic arthritis in calves. Rapid recovery occurred within 1 week when an appropriate treatment was instituted early in the course of the disease.     

Winter survival of third stage Trichostrongylus colubriformis larvae: effects on infectivity and fecundity of adult worms

Two groups of six lambs were fed with grass cut from two plots which had been contaminated by spreading Trichostrongylus colubriformis larvae. One plot received larvae in December, the other in April. The post mortem examination results showed that the infectivity of overwintering larvae was significantly higher than that of fresh larvae. An inverse relationship was demonstrated between infectivity of larvae and egg production of adult worms developed from these larvae. The results are compared with those obtained under laboratory conditions.     

Effects of Topical Application of Sunflower-Seed Oil on Experimentally Induced Wounds in Horses

The objectives were to evaluate clinical and histopathological aspects of topical application of sunflower-seed oil (Helianthus annuus) on the healing process of experimentally induced wounds in lumbar and metacarpal areas of healthy horses. Six adult horses were used. Eight wounds were surgically produced on each horse: two 6.25-cm² wounds cranial to the sacrum on each side of the lumbar region and two 2.89-cm² wounds close to the proximal epiphysis of the metacarpus on the lateral aspect of each forelimb. Left side was used for macroscopic observations and right side for histopathological analysis. The experimental lesions were treated daily with sunflower-seed oil, whereas saline solution was used in control lesions. Macroscopic and histopathological analyses were performed on tissue harvested at 3, 7, 14, and 21 days. Complete healing time for all wounds was recorded. For lumbar region’s wounds, a contraction of 90.78% was recorded for those treated with oil and of 79.27% for control wounds after 21 days of treatment. For metacarpal region’s wounds, a contraction of 47.63% was recorded for wounds treated with oil and of 30.21% for control wounds. Wounds in the sunflower-seed oil treatment group had an elevation of polymorphonuclear cells, a newly formed vascular bed during the inflammatory phase, and a better alignment of collagen fibers during the remodeling phase. In conclusion, topical application of sunflower-seed oil was beneficial in the healing process of experimentally induced skin wounds in horses, with best results for treatment of lumbar wounds, making it a therapeutic option in equine wound healing.     

3D Reconstruction of the Mouse's Mesonephros

The present work reports on the three-dimensional reconstruction of the segmented mesonephros during the embryonic development of the mouse. With a light microscope and an automatic reconstruction of surfaces, aspects of the mesonephros are described. These surfaces are obtained by using digitized contour lines. A new interpolation method called DSI (Discrete Smooth Interpolation) enables correction of the distortion induced by microtomy in paraffin sections. After a tri-angulation step, this method uses a smoothing algorithm, which implies a spatial redistribution of the vertices of the triangles to correct the rotational and translational misalignment. The use of this 3D program improves the understanding of the development patterns and helps us to appreciate changes in the rebuilt mesonephros. By 10.5 embryonic days, tubules emerge from the Wolffian body and begin their formation, then between 11.5 and 13.5 embryonic days, tortuous mesonephric tubules bound to the Wolffian duct form small curls, which grow and finally unwind. At the same time, mesonephric tubules unbound to the Wolffian duct appear, and on 13.5 embryonic days, the Müllerian duct is visible. After 14.5 embryonic days, the segmented mesonephros keeps its general aspect but decreases in size. At this time, each gonad is provided with both Wolffian and Müllerian ducts. Later, the Wolffian duct differentiates into the definitive male duct system, whilst the Müllerian duct regresses. Conversely, the paramesonephric duct differentiates into the definitive female duct system, whilst the mesonephric duct in turn degenerates. By this time degeneration has begun in the cranial portion of the mesonephros and this process progresses caudally. The spatial organization of the mesonephric tubules and the precise organization of all connections between these elements and the ducts may be well defined. Such approach can allow for a high definition of the normal pattern of mesonephros differentiation.     

Recurrent Amyloodiniosis on Broodstock of the Brazilian Flounder Paralichthys orbignyanus: Dinospore Monitoring and Prophylactic Measures.

Broodstock of the Brazilian flounder Paralichthys orbignyanus (Valenciennes, 1839) kept in the laboratory suffered recurrent heavy infestations by the ectoparasitic dinoflagellate Antyloodinium cf. ocellatum . Between 10 January and 26 February 2003 we monitored A. cf. ocellatum dinospore (infectious motile stage) abundance in a maturation system in order to predict amyloodiniosis outbreaks. Though daily water exchange rate of the tank containing the specimens was 150% of total tank volume (2,500 L), by 15 January the dinospore abundance in the tank reached 1,800 cells/L and on 25 January 7,200 cells/L. There was a subsequent small decrease in dinospore abundance, but by the end of the study period counts were still around 3,000 cells/L. Infested fish were successfully treated with copper sulfate (1.5-mg Cu/L for 24 h during 7d). Observation of the biofilm from the bottom of the tank showed a high number of resting cysts (tomonts) of A. cf. ocellatum after treatment. Apparently, the copper sulfate forced the detachment of the trophonts (feeding parasitic growth stage), and generated the high number of tomonts at the bottom of the tank. The copper sulfate concentration used in the treatment was not effective to kill the tomonts. After a disease outbreak in March 2002 and fish recovery, the biofilm with tomonts at the bottom of the tank was removed by brushing and the use of hydrochloric acid (HC1 30%^v/_v). After this, no infestation occurred for at least a month. Meanwhile, fish in a nearby tank, where biofilm was not removed, had three amyloodiniosis outbreaks. Our results show that the water exchange rate applied was not sufficient to eliminate the dinospores from the water column, or to remove and eliminate the tomonts from the biofilm. We suggest that cleaning the biofilm of tanks after treatment of infested fish should be considered as a prophylactic measure in order to avoid recurrent amyloodiniosis.