A framework for profiling a lake's riparian area development potential

Some of the greatest challenges for managing residential development occur at the interface between the terrestrial and aquatic ecosystems--in a lake's riparian area. Land use planners need a framework they can use to identify development hotspots, areas were the next push for development will most likely occur. Lake riparian development profiles provide a framework for linking ecological and social factors important to development. In a test of this framework in northern Minnesota, researchers identified seven constructs influencing riparian area development: current general development, current housing development, and availability, accessibility, suitability, aesthetics, and proximity to services. Profiles display a lake's value for each construct relative to the range of values for all lakes in the county. Maps, developed using indicators for several constructs, allow us to identify how the factors interact and are dispersed across the landscape. These profiles help policy makers, planners, and managers identify lakes that are potential development hotspots so they can take timely steps to manage development or control the impacts of development.     

BIOLOGICAL AND ECONOMIC IMPLICATIONS OF SACRAMENTO WATERSHED MANAGEMENT OPTIONS1

ABSTRACT: This paper brings together spatially and temporally explicit mechanistic models of hydrodynamic, water quality, and ecological processes with an economic model to examine water management alternatives for California's Sacramento River and Delta ecosystem, a large‐scale watershed. Overallocated water supplies in most years, combined with increasing demand for water for environmental purposes, have created a politically charged atmosphere and a need for quantitative assessment of the implications of policy alternatives. By developing and analyzing a common set of policy scenarios, this integrated framework allows us to consider tradeoffs between agricultural economic factors, water quality, and population dynamics for two at‐risk fish species. We analyze two rather extreme types of policy options; one involves structural modifications to change the flow of water within the watershed but no change in water diversions, while the other reallocates water from agricultural users to fish and wildlife. Results suggest that substantial environmental improvements could be made at a relatively modest cost to farmers (1 to 4 percent reductions in revenues) but that those costs could be significant locally. In addition to tradeoffs between farmers and environmental interests, results suggest that policy makers may need to balance competing environmental objectives.     

The influence of soil macroinvertebrates on primary biodegradation of starch-containing polyethylene films

The primary biodegradability of polyethylene (PE) films containing different percentages of cornstarch (0–50%) and other additives (prooxidant, oxidized polyethylene) was tested using four species of earthworms (Eisenia fetida, Lumbricus terrestris, Aporectodea trapezoides, Aporectodea tuberculata), three species of cockroaches (Periplaneta americana, Blaberus sp.,Blattella germanica), termites (Reticulotermes flavipes), sowbugs (Porcellio laevis), and crickets (Acheta domesticus). These studies were conducted to elucidate the potential role of soil macroinvertebrates in degrading starch/PE biodegradable plastics. The results of the macroinvertebrate bioassays indicate that crickets, cockroaches, and sowbugs consumed starch-containing PE films most readily. In addition, the degree to which the films were attacked and consumed was directly related to the starch content of the film. Films with oxidized polyethylene and those containing prooxidant (vegetable oil and a transition metal catalyst) were also consumed. None of the four species of earthworms tested or the termites showed any activity toward the starch/polyethylene films. These results have important implications for determining the fate of novel plastic formulations which claim to be biodegradable in natural environments. Studies such as these, coupled with studies on microbial degradation, will help provide the type of information needed to assess the environmental fate of biodegradable starch/PE plastics and fill the voids in the scientific database regarding this rapidly developing field.     

STREAM IMPROVEMENTS AND FISH RESPONSE: A BIO-ENGINEERING ASSESSMENT1

ABSTRACT: Human modifications of natural streams in the name of habitat improvement take various forms, and the impacts of those improvements, both positive and negative, vary by orders of magnitude from stream to stream. The positive impacts are achieved through careful and timely planning, design, installation and monitoring of projects. Negative impacts are the results of rush jobs dictated by available money, a lack of consideration for limiting factors, untrained and inexperienced personnel, force-fitting structures instead of bending the flow, lack of a watershed plan, poor communication and cooperation among disciplines, not using the team approach, and single habitat solutions which neglect diversity and artificial constraints. These problems are discussed from various perspectives, but emphasis on an integrated, bioengineering approach is threaded throughout the discussion of the problems and benefits associated with stream improvements and fish response. A general systems approach is presented which uses common language as a focal point for interdisciplinary communication, which is one of the major problems in resource management. Various conceptual models are discussed to describe system complexities, and factors which constrain project evaluation in terms of biological, physical, economic and other components. Conclusions about why some projects are successful, while others are not, are followed by recommendations for concerted and diversified efforts to improve our success in stream stewardship.     

Ultrasound demonstration of masses in a 15 week fetus: Hydrops in a fetus with umbilical cord occlusion

A fetal abnormality detected at 15 weeks by ultrasound consisted of cystic appearing masses in the neck and back region. The differential diagnosis included gonadal dysgenesis (Turner's syndrome) with cystic hygroma, neural tube defect, e.g. encephalocele or meningomyelocele, and fetal hydrops. Intrauterine fetal demise occurred at 17 weeks. The fetus had marked edema possibly related to umbilical cord occlusion.     

Organochlorine contaminants in Morelet's crocodile (Crocodylus moreletii) eggs from Belize

Non-viable eggs of Morelet's crocodile (Crocodylus moreletii) were collected from Gold Button (GBL) and New River lagoons (NRL) in northern Belize and screened for organochlorine (OC) compounds using gas chromatography (GC) with electron capture detection (ECD). All egg samples from both lagoons (n = 24) tested positive for one or more OCs. Primary contaminants were p,p-DDE and methoxychlor, detected in 100% and 29% of the eggs examined, respectively. Concentrations of individual OC contaminants ranged from 1 ppb (ng chemical/g egg) to > 0.5 ppm (microgram chemical/g egg). Total concentrations of OCs (sum of all OCs) for one egg collected from a nest at GBL reached as high as 0.7 ppm. Sediment samples from both lagoons also tested positive for OCs (lindane, aldrin, methoxychlor, heptachlor epoxide, p,p-DDT, among others). Nest media (soil and plant material) collected from crocodile nests at GBL were positive for p,p-DDT, methoxychlor, aldrin, endosulfan II, and endrin aldehyde. Based on the 24 egg samples analyzed to date, crocodiles from both lagoons are being exposed to OCs. Such exposure may present a health threat to populations of crocodiles in Central America.     

Herbicide movement and dissipation at four Midwestern sites

This study was conducted to evaluate atrazine (2-chloro-4-ethylamino-6-isopropyl-1,3,5-triazine) and alachlor (2-chloro-N-(methoxymethyl)acetamide) dissipation and movement to shallow aquifers across the Northern Sand Plains region of the United States. Sites were located at Minnesota on a Zimmerman fine sand, North Dakota on Hecla sandy loam, South Dakota on a Brandt silty clay loam, and Wisconsin on a Sparta sand. Herbicide concentrations were determined in soil samples taken to 90 cm four times during the growing season and water samples taken from the top one m of aquifer at least once every three months. Herbicides were detected to a depth of 30 cm in Sparta sand and 90 cm in all other soils. Some aquifer samples from each site contained atrazine with the highest concentration in the aquifer beneath the Sparta sand (1.28 microg L(-1)). Alachlor was detected only once in the aquifer at the SD site. The time to 50% atrazine dissipation (DT50) in the top 15 cm of soil averaged about 21 d in Sparta and Zimmerman sands and more than 45 d for Brandt and Hecla soils. Atrazine DT50 was correlated positively with % clay and organic carbon (OC), and negatively with % fine sand. Alachlor DT50 ranged from 12 to 32 d for Zimmerman and Brandt soils, respectively, and was correlated negatively with % clay and OC and positively with % sand.     

Variation of foraging rate and wing loading, but not resting metabolic rate scaling, of insect pollinators

Morphological, physiological and behavioural variation with body size (i.e. scaling) may affect costs of living in a particular environment for insects and, ultimately, pollination or foraging success. However, few studies have directly assessed the scaling of these traits at the species level. Using two similar-sized pollinator species (the hawkmoth Macroglossum trochilus and the fly Moegistorhynchus longirostrus), we compare intraspecific scaling relationships of resting metabolic rate (RMR), foraging rate (FR) and wing loading (WL) to address this paucity of data. Scaling of RMR was similar for both taxa although the intercepts for the relationships differed. However, these two species showed variation in WL scaling relationships and fundamentally different FR scaling. For M. longirostrus, FR scaling was positive but non-significantly related to body mass while for M. trochilus FR scaling was negative. This suggests that variation in FR and WL, but not RMR scaling, among these flies and hawkmoths may impose significant energetic costs which could affect animal–plant interactions in the wild.