Larger mosquitoes tend to result from a longer lifespan, which is dangerous because it gives mosquitoes a better chance of harboring pathogens that cause human diseases. Chaves makes the case that cities should separate their sewage overflow from their rain runoff to avoid creating ideal habitat for mosquitoes.
Lakeshore development reduces food supplies for fish
Freshwater fish, especially stream fish, rely on terrestrial insects as a portion of their food supply. But little is known about their importance to fish in lakes, where the size and shape of a lake can determine how much its fish rely on shoreline food sources. Tessa Francis, a post-doctoral researcher at the National Oceanographic and Atmospheric Administration (NOAA), wanted to know if the urbanization of lakeshores affects the amount of terrestrial insects available as food to the lake's fish inhabitants. To answer her question, she analyzed fish stomach contents over the course of a year in four Pacific Northwest lakes, surveyed fish in 28 Pacific Northwest lakes and compiled published data on fish populations in lakes across North America.
At undeveloped lakes, insect outbreaks often happen in pulses, in which insects emerge over a short time period, but Francis and her team found no signs of these pulses in highly developed areas. This disparity was apparent in fish food availability: In the four lakes, terrestrial insects comprised up to 100 percent of the diet of fish in undeveloped lakes, in contrast to a maximum of 2 percent in developed lakes, a pattern that was also apparent at the regional and national scale.
Francis' research also showed that trout in developed lakes had a 50 percent lower daily intake of energy. Lower energy intake can slow growth and compromise fish reproduction, she says, which will ultimately lead to
|Contact: Christine Buckley|
Ecological Society of America