The role of warm, dry summers and variation in snowpack on phytoplankton dynamics in mountain lakes.

Climate change is altering biogeochemical, metabolic, and ecological functions in lakes across the globe. Historically, mountain lakes in temperate regions have been unproductive because of brief ice-free seasons, a snowmelt-driven hydrograph, cold temperatures, and steep topography with low vegetation and soil cover. We tested the relative importance of winter and summer weather, watershed characteristics, and water chemistry as drivers of phytoplankton dynamics. Using boosted regression tree models for 28 mountain lakes in Colorado, we examined regional, intraseasonal, and interannual drivers of variability in chlorophyll a as a proxy for lake phytoplankton. Phytoplankton biomass was inversely related to the maximum snow water equivalent (SWE) of the previous winter, as others have found. However, even in years with average SWE, summer precipitation extremes and warming enhanced phytoplankton biomass. Peak seasonal phytoplankton biomass coincided with the warmest water temperatures and lowest nitrogen-to-phosphorus ratios. Although links between snowpack, lake temperature, nutrients, and organic-matter dynamics are increasingly recognized as critical drivers of change in high-elevation lakes, our results highlight the additional influence of summer conditions on lake productivity in response to ongoing changes in climate. Continued changes in the timing, type, and magnitude of precipitation in combination with other global-change drivers (e.g., nutrient deposition) will affect production in mountain lakes, potentially shifting these historically oligotrophic lakes toward new ecosystem states. Ultimately, a deeper understanding of these drivers and pattern at multiple scales will allow us to anticipate ecological consequences of global change better.

Interdisciplinary evaluation of consecutive patients with unilateral cleft lip and palate at age 6, 15, and 25 years: a concurrent standardized procedure and documentation by plastic surgeon; speech and language pathologist; ear, nose, and throat specialist; and orthodontist.

PURPOSE: To evaluate surgical results, speech, hearing, and craniofacial morphology after primary cleft repair performed from 1973 to 1979. METHODS: During the years 1972 to 1985, all primary cleft surgeries were performed by 1 plastic surgeon, using Tennison lip closure combined with a periosteoplasty on the clefted alveolus at age 3 months. By mobilizing mucoperiosteal flaps, bony bridges were induced in the alveolar process in approximately 60% of the cases. All patients had the soft palate closed at age 24 months by a pushback technique. All children with complete unilateral clefts without soft tissue bands (unilateral cleft lip and palate) primary operated on 1973 to 1979 were included in the material, except 3 patients with a syndrome and 2 patients of foreign ethnicity. The material involved 30 consecutive patients with unilateral cleft lip and palate (20 boys and 10 girls; 16 left-sided and 14 right-sided clefts) who were operated on. Standardized records including photos, radiographs, lateral cephalograms, plaster model, and recording of speech and hearing were collected according to the treatment protocol at age 6, 15, and approximately 25 years. RESULTS: Evaluation included craniofacial descriptive cephalometric analysis, dentoalveolar morphology, dentofacial aesthetics, speech concerning articulation and nasality, and hearing status. Number of surgical interventions after primary surgery was recorded. Secondary revisions and candidates for orthognathic surgery are reported. Ten consecutive patients (case nos. 11-20) are demonstrated as clinical reports. CONCLUSIONS: : This longitudinal study shows how a multidisciplinary evaluation adequate for intercenter comparison can be performed when standardized procedures, registrations, and documentations are available.

Prevalence of major anatomic variations in oral clefts.

BACKGROUND: The authors describe morphologic variations of oral clefts in a large population-based sample, especially variations in severity and laterality. The authors present 3616 cleft cases treated in Norway for oral clefts between 1967 and 1998. METHODS: Classification of cleft morphology was based on clefting in 9 anatomical focal areas. A three-digit coding system provides a total of 63 possible cleft combinations. Their distribution in the population is presented as a whole and stratified by the baby's sex and the presence of accompanying malformations. The relative proportion of cleft types is illustrated in modified striped Y Kernahan diagrams. RESULTS: Clefts of the lip or palate are more severe when both cleft types are present. Among babies with cleft lip, 18 percent of lips were severe (i.e., complete cleft of the primary palate) in the absence of cleft palate, compared with 81 percent severe when cleft palate was also present. Similarly, among babies with cleft palate, 40 percent were severe (complete cleft of the secondary palate) in the absence of cleft lip, compared with 93 percent when cleft lip was also present. The more severe the cleft lip, the more likely that the baby had an accompanying cleft palate. Girls were more likely to have severe clefts, as were patients who had other types of congenital disabilities. Although cleft lip was more frequent on the left side, clefts were not more severe on the left side. In bilateral cleft lip, the severity was similar on both sides. CONCLUSION: The authors' data provide a population-based reference for common and rare variants of oral clefts.