Phosphorus concentrations can be very low so that the metabolic needs of an organism, population, or species cannot be met, and thus it is considered as the limiting factor. [Phosphorus is a component of the DNA and ATP molecules] Diatoms are the best competitors for phosphorus and their kinetics can be an order of magnitude faster than those of cyanobacteria; r and K strategists, respectively. [The former group has higher growth rates and a superior ability to disperse, while the latter has the ability to more efficiently use resources (e.g., reserve storage) and regulate its metabolic activity] Daphnia can exert significant control through grazing. Diatoms and Greens are considered a good food quality based on their biochemical/morphological characteristics. For example, their highly unsaturated fatty acid, amino acid, protein content and/or digestibility. However, Daphnia –in contrast with Diaptomus- is a filter feeder and does not have any selectivity in the choice of its preys. Filamentous cyanobacteria are not edible by Daphnia because they cause mechanical interference (clogging) of the feeding apparatus. Lake Washington sockeye salmon (Oncorhynchus nerka) have some of the highest recorded juvenile growth rates for this species. Hence, they impose the highest consumption demands on Daphnia. They have found a threshold of 0.4 ind l−1 (which usually occurs the end of May) as the level above which sockeye become strongly selective for Daphnia and avoid other prey taxa. Otherwise, salmon can be fed by other smaller zooplankton groups. Seston is the particulate matter such as plankton, organic detritus and inorganic particles such as silt suspended in seawater.
Grinnell Glacier in Glacier National Park (US) showing recession since 1850 of 1.1 km
Between 1976 and 2000, the area of Furtwängler Glacier (Mount Kilimanjaro ) was cut almost in half, from 113,000 m² to 60,000 m².
The Boulder Glacier retreated 450 m from 1987 to 2005.
Sea levels are rising The sea level has risen more than 120 m since the peak of the last ice age about 18,000 years ago. The bulk of that occurred before 6,000 years ago. From 3,000 years ago to the start of the 19th century sea level was almost constant, rising at 0.1 to 0.2 mm/yr…
… since 1900 the level has risen at 1 to 3 mm/yr; since 1992 satellite altimetry indicates a rate of about 3 mm/yr.
Greenhouse gases and their sources The basic mechanism http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/
Average concentrations of atmospheric carbon dioxide in the year 2005 were about 380 parts per million. Prior to 1700, levels of carbon dioxide were about 280 parts per million. This increase in carbon dioxide in the atmosphere is primarily due to the activities of humans.
The Wall Street Journal (December 4, 1997) Τ he shorter the solar cycle (the more active the sun), the higher the temperature .
The amount of solar radiation received at the outer surface of Earth's atmosphere was once assumed to not change much from an average value of 1366 W/m². The variations in total solar output are so slight (as a percentage of total output) that they remained at or below the threshold of detectability until the satellite era, although the small fraction in ultra-violet wavelengths varies by a few percent. Total solar output is now measured to vary (over the last two 11-year sunspot cycles) by approximately 0.1% or about 1.3 W/m² peak-to-trough of the 11 year sunspot cycle.
Solar variation has probably been the cause of some climate change, for example during the Maunder minimum. A 2006 study and review of existing literature, published in Nature, determined that there has been no net increase in brightness since the mid 1970s, and that changes in solar output within the past 400 years are unlikely to have played a major part in global warming http://en.wikipedia.org/wiki/Solar_variation http://en.wikipedia.org/wiki/Maunder_minimum
The world’s response to desertification “ must be equal to that demanded by global warming, the destruction of the stratospheric-ozone layer, and the loss of biodiversity .” Klaus T ö pfer (UNEP)
Desertification Desertification already affects nearly 1 billion people, and over 41% of the Earth’s land area. Desertification is most pronounced in Africa where 65% of the agricultural land may be degraded.
Chernobyl disaster The Chernobyl disaster was an accident at the Chernobyl Nuclear Power Plant on April 26, 1986 at 01:23 a.m., consisting of an explosion at the plant and subsequent radioactive contamination of the surrounding geographic area. The power plant is located in Ukraine, at the time part of the Soviet Union. It is regarded as the worst accident ever in the history of nuclear power.
- The bottom layer of water (the hypolimnion), because it is cold, tends to not mix with warmer surface water (the epilimnion), and therefore has no opportunity for oxygen replenishment from the atmosphere. - The central basin of Lake Erie is the primary problem area because the western basin is sufficiently shallow that the deepest waters warm enough to mix into the epilimnion in early summer. In contrast, the deeper eastern basin is not threatened by oxygen depletion because decomposition of algae and sediments cannot deplete the much greater water volume in its hypolimnion over the span of the spring and summer.
Pathogenic microorganisms Escherichia coli Pathogenic viruses and bacteria in coastal waters can infect swimmers. E. coli can be the causative agent of several intestinal and extra-intestinal infections such as urinary tract infections, meningitis, peritonitis, mastitis, septicemia and gram-negative pneumonia.
The Exxon Valdez oil spill was one of the most devastating environmental disasters ever to occur at sea, seriously affecting plants and wildlife.
An "invasive species" is a plant or animal that is non-native (or alien) to an ecosystem, and whose introduction is likely to cause economic, human health, or environmental damage in that ecosystem. At least 25 non-native species of fish have entered the Great Lakes since the 1800s; they have had significant impacts on the Great Lakes food web by competing with native fish for food and habitat. Invasive Species