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Dam removal is often proposed as way to restore ecological integrity to rivers and streams, but ecological responses to dam removals are poorly understood, especially for downstream benthic communities. We examined the responses of benthic macroinvertebrate and algal assemblages in downstream reaches to the removal of a small, run-of-river dam on Manatawny Creek, Pennsylvania. Benthic macroinvertebrates, algae, and habitat characteristics were monitored upstream and downstream of the dam for 4 mo before removal, 3 mo after partial removal (i.e., when the impoundment was largely eliminated but sediment remained trapped behind the remaining structure), and 12 mo after complete dam removal. Macroinvertebrate density,...
The microbiotic crust study is among new focuses in investigating on the desertification control. Based on determination of algal crusts with different successive ages (4-, 8-, 17-, 34-, 42-year-old) and unconsolidated sand in the desert area, species composition and clustering analyses were carried out in this study. Results on successional orientation revealed that (1) the abundance of Cyanophyta, specially of Scytonema javanicum gradually decreased; (2) the abundance of Chlorophyta, Bacillariophyta and a species of Cyanophyta, Phormidium tenue increased; (3) the biodiversity increased gradually with the community succession; and (4) biomass of microalgae increased at the early stage, but decreased at the later...
In the United States, environmentally impaired rivers are subject to regulation under total maximum daily load (TMDL) regulations that specify watershed wide water quality standards. In California, the setting of TMDL standards is accompanied by the development of scientific and management plans directed at achieving specific water quality objectives. The San Joaquin River (SJR) in the Central Valley of California now has a TMDL for dissolved oxygen (DO). Low DO conditions in the SJR are caused in part by excessive phytoplankton growth (eutrophication) in the shallow, upstream portion of the river that create oxygen demand in the deeper estuary. This paper reports on scientific studies that were conducted to develop...
Algae are the fastest-growing plants in the world. Industrial reactors for algal culture are open ponds, photobioreactors and closed systems. Algae are very important as a biomass source. Algae will some day be competitive as a source for biofuel. Different species of algae may be better suited for different types of fuel. Algae can be grown almost anywhere, even on sewage or salt water, and does not require fertile land or food crops, and processing requires less energy than the algae provides. Algae can be a replacement for oil based fuels, one that is more effective and has no disadvantages. Algae are among the fastest-growing plants in the world, and about 50% of their weight is oil. This lipid oil can be used...
Categories: Publication; Types: Citation; Tags: Algae, Algal oil, Biodiesel, Economy
Didymosphenia geminata (didymo) is a freshwater alga native to North America, including Glacier National Park, Montana. It has long been considered a cold-water species, but has recently spread to lower latitudes and warmer waters, and increasingly forms large blooms that cover streambeds. We used a comprehensive monitoring data set from the National Park Service (NPS) and USGS models of stream temperatures to explore the drivers of didymo abundance in Glacier National Park. We estimate that approximately 64% of the stream length in the park contains didymo, with around 5% in a bloom state. Results suggest that didymo abundance likely increased over the study period (2007–2009), with blooms becoming more common....
The articles in this issue of the Canadian Journal of Botany arose from presentations given at The Fifth International Symposium on Inorganic Carbon Utilization by Aquatic Photosynthetic Organisms held from 24 to 28 August 2004 at Saint-Sauveur, Quebec, Canada. They represent the current state of our understanding of CO2-concentrating mechanisms in these organisms and highlight recent molecular, physiological, and ecological advances made in this field of study. The influence of CO2-concentrating mechanisms on global carbon sequestration, species diversity, and population dynamics are also explored.Key words: algae, CO2-concentrating mechanisms, cyanobacteria, photosynthesis.Les articles dans ce numéro de la Revue...
To investigate the mechanism for diel (24 h) changes commonly observed at fixed sampling locations and how these diel changes relate to downstream transport in hypereutrophic surface waters, we studied a parcel of agricultural drainage water as it traveled for 84 h in a concrete-lined channel having no additional water inputs or outputs. Algal fluorescence, dissolved oxygen, temperature, pH, conductivity, and turbidity were measured every 30 min. Grab samples were collected every 2 h for water quality analyses, including nutrients, suspended sediment, and chlorophyll/pheophytin. Strong diel patterns were observed for dissolved oxygen, pH, and temperature within the parcel of water. In contrast, algal pigments and...
The cycles of the key nutrient elements nitrogen (N) and phosphorus (P) have been massively altered by anthropogenic activities. Thus, it is essential to understand how photosynthetic production across diverse ecosystems is, or is not, limited by N and P. Via a large-scale meta-analysis of experimental enrichments, we show that P limitation is equally strong across these major habitats and that N and P limitation are equivalent within both terrestrial and freshwater systems. Furthermore, simultaneous N and P enrichment produces strongly positive synergistic responses in all three environments. Thus, contrary to some prevailing paradigms, freshwater, marine and terrestrial ecosystems are surprisingly similar in terms...
Climate change is likely to impact terrestrial and aquatic ecosystems via numerous physical and biological mechanisms. This study outlines a framework for projecting potential impacts of climate change on lakes using linked environmental models. Impacts of climate drivers on catchment hydrology and thermal balance in Onondaga Lake (New York State) are simulated using mechanistic models HSPF and UFILS4. Outputs from these models are fed into a lake ecosystem model, developed in AQUATOX. Watershed simulations project increases in the magnitude of peak flows and consequent increases in catchment nutrient export as the magnitude of extreme precipitation events increases. This occurs concurrently with a decrease in annual...