Early prenatal diagnosis of an infratentorial arachnoid cyst: Association with an unbalanced translocation

Arachnoid cysts are an uncommon central nervous system malformation, representing only 1 per cent of all intracranial masses. We report the second-trimester prenatal diagnosis of a posterior fossa arachnoid cyst, associated with an unbalanced X;9 translocation.     

Prenatal diagnosis using deletion studies in Duchenne muscular dystrophy

Accurate carrier testing and prenatal diagnosis in Duchenne muscular dystrophy (DMD) families is facilitated when an Xp21 deletion is found to be segregating within a family. We discuss the results of the DNA testing in two families, one in which DNA from affected males was available for study and the other in which no DNA from an affected male was available. Factors complicating the counselling of DMD deletion families are outlined.     

Wetland loss and substitution by the Section 404 permit program in southern California,USA

To test the effectiveness of the 404 permit program in preventing a net loss of wetland resources, 75 Section 404 projects permitted in the years 1987–1989 and located in a portion of southern California were evaluated. From this group of projects, 80.47 ha of wetlands were affected by Section 404 permits and the Army Corps of Engineers required 111.62 ha of wetland mitigation. To verify the successful completion of each mitigation project, all 75 project sites were visited and evaluated based on the amount of dead vegetation, growth and coverage, and the number of invasive species. Based on the field verification results, the actual amount of completed mitigation area was 77.33 ha, resulting in a net loss of 3.14 ha of wetland resources in the years 1987–1989. By comparing the types of wetlands lost to the types of wetlands mitigated, it is apparent that, in particular, freshwater wetlands are experiencing a disproportionately greater loss of area and that riparian woodland wetlands are most often used in mitigation efforts. The net result of these accumulated actions is an overall substitution of wetland types throughout the region. Results also indicate that, typically, large-scale mitigation projects are more successful compared to smaller projects and that successful compliance efforts are not evenly distributed throughout the region. We recommend that better monitoring, mitigation in-kind, mitigation banking, and planning on a regional or watershed scale could greatly improve the effectiveness of the Section 404 permitting program.     

Utility terrestrial biodiversity issues

Results from a survey of power utility biologists indicate that terrestrial biodiversity is considered a major issue by only a few utilities; however, a majority believe it may be a future issue. Over half of the respondents indicated that their company is involved in some management for biodiversity, and nearly all feel that it should be a goal for resource management. Only a few utilities are funding biodiversity research, but a majority felt more research was needed. Generally, larger utilities with extensive land holdings had greater opportunities and resources for biodiversity management. Biodiversity will most likely be a concern with transmission rights-of-way construction and maintenance, endangered species issues and general land resource management, including mining reclamation and hydro relicensing commitments. Over half of the companies surveyed have established voluntary partnerships with management groups, and biodiversity is a goal in nearly all the joint projects. Endangered species management and protection, prevention of forest fragmentation, wetland protection, and habitat creation and protection are the most common partnerships involving utility companies. Common management practices and unique approaches are presented, along with details of the survey.     

Mapping shifts in spatial synchrony in grassland birds to inform conservation planning

Spatial synchrony, defined as the correlated fluctuations in abundance of spatially separated populations, can be caused by regional fluctuations in natural and anthropogenic environmental population drivers. Investigations into the geography of synchrony can provide useful insight to inform conservation planning efforts by revealing regions of common population drivers and metapopulation extinction vulnerability. We examined the geography of spatial synchrony and decadal changes in these patterns for grassland birds in the United States and Canada, which are experiencing widespread and persistent population declines. We used Bayesian hierarchical models and over 50 years of abundance data from the North American Breeding Bird Survey to generate population indices within a 2° latitude by 2° longitude grid. We computed and mapped mean local spatial synchrony for each cell (mean detrended correlation of the index among neighboring cells), along with associated uncertainty, for 19 species in 2, 26-year periods, 1968–1993 and 1994–2019. Grassland birds were predicted to increase in spatial synchrony where agricultural intensification, climate change, or interactions between the 2 increased. We found no evidence of an overall increase in synchrony among grassland bird species. However, based on the geography of these changes, there was considerable spatial heterogeneity within species. Averaging across species, we identified clusters of increasing spatial synchrony in the Prairie Pothole and Shortgrass Prairie regions and a region of decreasing spatial synchrony in the eastern United States. Our approach has the potential to inform continental-scale conservation planning by adding an additional layer of relevant information to species status assessments and spatial prioritization of policy and management actions. Our work adds to a growing literature suggesting that global change may result in shifting patterns of spatial synchrony in population dynamics across taxa with broad implications for biodiversity conservation.     

The Importance of Natural Processes in Understanding Ecosystem Change: A Case Study of Limed Lakes

In order to determine what effects human activities have on natural processes, it is important to thoroughly understand those processes. Unfortunately, we know little about what natural processes are operating, and even less about how they have functioned historically. This paper discusses the importance of natural processes in affecting surface water acidification and the necessity for developing quantitative estimates of natural, as well as anthropogenic, contributions to the acidification of surface waters. A review of the literature and the analysis of chemistry data from six limed lakes in New York and Massachusetts have identified a number of possible processes that may play important roles in acidifying surface waters. At present, these processes are poorly understood and require further research. Once we have such knowledge, we will be able to clearly see the effects of human activities on natural processes and modify those activities in ways that will mitigate negative impact in a predictable manner.     

Fish Cognition and Consciousness

Questions about fish consciousness and cognition are receiving increasing attention. In this paper, I explain why one must be careful to avoid drawing conclusions too hastily about this hugely diverse set of species.     

Nitrogen critical loads and management alternatives for N-impacted ecosystems in California

Empirical critical loads for N deposition effects and maps showing areas projected to be in exceedance of the critical load (CL) are given for seven major vegetation types in California. Thirty-five percent of the land area for these vegetation types (99,639 km²) is estimated to be in excess of the N CL. Low CL values (3–8 kg N ha^?1 yr^?1) were determined for mixed conifer forests, chaparral and oak woodlands due to highly N-sensitive biota (lichens) and N-poor or low biomass vegetation in the case of coastal sage scrub (CSS), annual grassland, and desert scrub vegetation. At these N deposition critical loads the latter three ecosystem types are at risk of major vegetation type change because N enrichment favors invasion by exotic annual grasses. Fifty-four and forty-four percent of the area for CSS and grasslands are in exceedance of the CL for invasive grasses, while 53 and 41% of the chaparral and oak woodland areas are in exceedance of the CL for impacts on epiphytic lichen communities. Approximately 30% of the desert (based on invasive grasses and increased fire risk) and mixed conifer forest (based on lichen community changes) areas are in exceedance of the CL. These ecosystems are generally located further from emissions sources than many grasslands or CSS areas. By comparison, only 3–15% of the forested and chaparral land areas are estimated to be in exceedance of the NO₃^? leaching CL. The CL for incipient N saturation in mixed conifer forest catchments was 17 kg N ha^?1 yr^?1. In 10% of the CL exceedance areas for all seven vegetation types combined, the CL is exceeded by at least 10 kg N ha^?1 yr^?1, and in 27% of the exceedance areas the CL is exceeded by at least 5 kg N ha^?1 yr^?1. Management strategies for mitigating the effects of excess N are based on reducing N emissions and reducing site N capital through approaches such as biomass removal and prescribed fire or control of invasive grasses by mowing, selective herbicides, weeding or domestic animal grazing. Ultimately, decreases in N deposition are needed for long-term ecosystem protection and sustainability, and this is the only strategy that will protect epiphytic lichen communities.