Cultural eutrophication activity. Polar regions have less human activity and subsequently less cultural eutrophication. One response to added amounts of nutrients in the aquatic ecosystem is the rapid growth of microscopic algae, also known as an algal bloom. In freshwater systems, the formation of floating algal blooms are commonly nitrogen-fixing cyanobacteria (blue-green algae). This outcome is favoured when nitrogen inputs are reduced and phosphorus inputs are increased. Large amounts of algae reduce the amount of dissolved oxygen available in the water for other organisms, which increases fish mortality rates. These areas affected by algal blooms are known as dead zones, and are
Natural population growth Natural population growth Natural population increase (in contrast to total population increase) happens as people are born (in contrast to immigration) into a country, and decrease as people die (in contrast to emigrate). Rates of population growth, usually expressed as a percentage, vary greatly. The immigrating population has increased by a huge margin in the past few years. Due to this rising trend of migration it is important that we look into how migration has affected the population, and the trends that follow with it. The countries that are to be looked into are Denmark, Finland, Iceland, Norway and Sweden.