Autumn-shed leaves are a vital component of stream ecosystems in forested watersheds and differences in rates of leaf input and retention yield in-stream standing stocks of organic matter that are highly variable at local scales. We tested if organic matter availability influenced the key ecosystem-level process of leaf decomposition. Specifically, we suspected that greater amounts of local organic matter 1) slow decomposition by detritivorous macroinvertebrates because animals disperse among a larger number of resource units and 2) increase microbial decomposition since larger amounts of litter increase inoculum potential. We tested these hypotheses with a randomized block design in three streams of the Black Forest (Germany). In each stream we identified three morphologically similar reaches and randomly assigned each a treatment that consisted of 1) an enhanced standing stock of organic matter via the installation of leaf litter traps, 2) a manually depleted standing stock of organic matter or 3) a control that was not manipulated. We quantified decomposition with a leaf-bag approach that utilized coarse- and fine-mesh bags intended to either allow or deter access by macroinvertebrates. As anticipated, standing stocks of organic matter responded significantly to the treatments. Decomposition was significantly faster in coarse-mesh bags than in fine mesh. Contrary to expectations, decomposition rates did not differ between treatments, nor did the number of detritivorous invertebrates that colonized experimental leaf packs. These results suggest that local variability in organic-matter standing stocks does not, in the short-term, alter either microbial or invertebrate decomposition as components of stream ecosystem functioning.
Susan M. Varlamoff
Program Coordinator, University of Georgia
College of Agricultural and Environmental Sciences, Office of Environmental Sciences
The land grant universities in the United States, of which the University of Georgia is one, transfer research results to the general public through the Cooperative Extension Service (CES). The CES was instituted in 1914 to provide farmers with the latest scientific information to increase crop yields and conserve the environment. This function is accomplished by educated (most with Masters degrees) and trained agents who have offices in each of the 159 counties of Georgia.
Even though agriculture is the number one industry in the state, most Georgia citizens (72%) live in the metropolitan areas where there are problems of water quality and quantity. The metropolitan area of Atlanta has 50% of the state’s 8.2 million people and grew 26% from 1990 –2000. This exploding population has contributed to the increased pollution of Atlanta’s urban watersheds where more than 1,000 miles of rivers and streams are impaired by pollution.
A 1995 U.S. Geological Survey study showed the median concentration of four major insecticides (chlorpyrifos, diazinon, carbaryl, and malathion) in urban watersheds exceeded the U.S. Environmental Protection Agency standard for protection of aquatic life in Georgia. Homeowner gardening practices, it appears, contribute to the nonpoint point source pollution of watersheds. Gardening is a popular leisure activity in the U.S. In Georgia, the growing season extends from March through October. Sixty-seven percent of Georgians are homeowners and 76% of them do their own landscape maintenance. It is important to note that professional landscapers who apply pesticides to commercial and residential landscape in Georgia must be trained in the proper use of gardening chemicals to prevent runoff into surface water through the University of Georgia Cooperative Extension Service. In addition, landscape managers are liable by law if they contaminate surface waters. In 1999, no program existed to train homeowners who use gardening chemicals.
The Georgia Pollution Prevention Assistance Division and U.S. Environmental Protection Agency awarded grants to conduct a survey of Georgia homeowners to learn about their gardening practices and to produce a training manual and homeowner brochures for a comprehensive educational program. An interdisciplinary team of scientists (horticulturists, agricultural economists, entomologists, and environmental specialists) developed the survey administered in the summer of 1999.
The survey results indicated 69 percent of homeowners choose gardening products they perceived to be environmentally friendly. Sixty-seven percent of Georgians knew there were alternatives to chemical pesticides and 69% said they were interested in learning more about pesticide alternatives. Homeowners indicated their preferred source for receiving gardening information is where they purchased plants, fertilizers and pesticides (79%), followed by a toll-free hotline (68%), information taught in schools (58%) and on television (50%).
The training manual was developed with careful attention to areas where homeowners lacked information and wanted more. It was written by an interdisciplinary team of scientists with expertise in horticulture, entomology, agronomy, and pollution prevention. Graphic artists designed the manual and accompanying brochures to make them attractive to the educator and reader.
The training manual and brochures were distributed to each of the Extension agents in 159 counties for use in workshops, on local TV and in newspapers, and by Master Gardeners who take homeowners’ calls with gardening questions. Materials are used extensively in the metropolitan Atlanta Clean Water Campaign aimed at reducing nonpoint source water pollution in urban streams and rivers. The campaign is a well-funded public relations effort that collaborates with the University of Georgia Extension agents to conduct homeowner workshops, to produce environmentally gardening tips that appear on television, radio, billboards, and inserts for water bills and advertising at the movie theaters. A retired Extension agent hosts a very popular television and radio show where environmentally friendly gardening tips are given. In addition, the Master Gardener certification program (5,000 trained in Georgia) emphasizes these principles and the Garden Club of Georgia will be offering training to their 67,000 members.
David R.Young1, Richard S. Caldwell2 and Janet O. Lamberson1
1U.S. Environmental Protection Agency, Newport, OR, U.S.A.,
2Northwestern Aquatic Science, Inc., Newport, OR, U.S.A.
Infaunal amphipods and total dissolved sulfides (TDS) were measured in surficial sediment from two sites in theYaquina Bay estuary on the central Oregon coast (U.S.A.) during summer 2000. Cores (0-5 cm) were collected from the intertidal zone during low tide and returned to the laboratory where they were centrifuged to separate out the interstitial water phase. Working in an oxygen-free atmosphere, these samples were processed for TDS using the methylene blue colorimetric procedure, and analyzed on a spectrophotometer. Total abundance of amphipods in cores from these stations also was determined. TDS concentrations ranged from < 1 µM to about 2000 µM. A negative correlation was observed between TDS and amphipod abundance in the surficial sediments. These results suggest that sulfidic sediments, usually associated with the occurrence of high macroalgal accumulation or other organic enrichment, can lead to reduced infaunal amphipod abundance. This research contributes to improved, protective nutrient criteria for nearshore waters.
^ David R. Young, U.S. Environmental Protection Agency, Newport, OR, U.S.A., T 541-861-4038 F 541-867-4049, firstname.lastname@example.org
РАЗРАБОТКА НЕКОТОРЫХ КОНЦЕПЦИЙ И ПРОБЛЕМ ЭКОЛОГИИ И ГИДРОБИОЛОГИИ p.34-38.