Flow regime in a restored wetland determines trophic links and species composition in the aquatic macroinvertebrate community.

In a restored wetland (South of Spain), where different flow regimes control water exchange with the adjacent Guadalquivir estuary, the native Palaemon varians coexists with an exotic counterpart species Palaemon macrodactylus. This controlled m\acrocosm offers an excellent opportunity to investigate how the effects of water management, through different flow regimes, and the presence of a non-native species affect the aquatic community and the trophic niche (by gut contents and C-N isotopic composition) of the native shrimp Palaemon varians. We found that increased water exchange rate (5% day(-1) in mixed ponds vs. 0.1% day(-1) in extensive ponds) modified the aquatic community of this wetland; while extensive ponds are dominated by isopods and amphipods with low presence of P. macrodactylus, mixed ponds presented high biomass of mysids, corixids, copepods and both shrimp species. An estuarine origin of nutrients and primary production might explain seasonal and spatial differences found among ponds of this wetland. A combined analysis of gut contents and isotopic composition of the native and the exotic species showed that: (1) native P. varians is mainly omnivorous (2) while the non-native P. macrodactylus is more zooplanktivorous and (3) a dietary overlap occurred when both species coexist at mixed ponds where a higher water exchange and high abundance of mysids and copepods diversifies the native species' diet. Thus differences in the trophic ecology of both species are clearly explained by water management. This experimental study is a valuable tool for integrated management between river basin and wetlands since it allows quantification of wetland community changes in response to the flow regime.

Chronic renal failure and bladder augmentation: stomach versus sigmoid colon in the canine model.

A canine model for chronic renal failure and bladder augmentation with a segment of stomach or sigmoid colon (or control) was developed to evaluate the possible benefit of net chloride ion excretion noted in an earlier canine model for gastrocystoplasty. Gastrocystoplasty animals behaved similar to control animals relative to the sigmoid cystoplasty animals, tolerated significantly greater acid loading, did not have hyperchloremia with acidosis and had less weight loss with acidosis. Gastrocystoplasty seems to be superior to sigmoid cystoplasty in the azotemic canine.

Symphyseal diastasis in the absence of the exstrophy-epispadias complex.

Symphyseal diastasis in the absence of exstrophy or epispadias is rare. We reviewed 11 reported cases and present 2 of our own. Based upon our findings, we recommend a thorough physical examination in all patients. A voiding cystourethrogram in those with the radiographic finding of symphyseal diastasis in the absence of exstrophy or epispadias may be helpful. A significant number of patients have associated congenital anomalies.

Collateral urethral duplication in the frontal plane: a spectrum of cases.

Collateral urethral duplication in the frontal plane is a rare anomaly. We report 3 cases of this variant of urethral duplication and review the literature. Double stream was the most frequent complaint and associated midline defects were common. Management, including a unique method of surgical intervention, is discussed.

Gastrocystoplasty and colocystoplasty in canines: the metabolic consequences of acute saline and acid loading.

An experimental canine model was developed to quantitate the net transmural ion flux of colon and gastric segments used for augmentation cystoplasty. Gastrocystoplasty (4) or colocystoplasty (4) was constructed in 8 female mongrels. Acute intravenous saline and acid loading experiments were performed 2 to 4 weeks after cystoplasty. The mean solute excretion rates for sodium, chloride, phosphorus and ammonia exhibited opposite trends during acute saline and acid loading in this experimental model. The net flux of chloride, ammonia, phosphorus and sodium ions in the colocystoplasty animals was from the mucosa/urine surface to the serum (reabsorption). The opposite trend was true for the gastrocystoplasty. By not reabsorbing ammonium chloride, the gastrocystoplasty preserved an important renal mechanism for systemic acid elimination. This may help to prevent the hyperchloremic metabolic acidosis that can develop when urine comes in contact with small or large bowel segments.